Briggs and Stratton Cylinder head gasket replacement
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- Опубликовано: 22 июл 2024
- Briggs and Stratton Cylinder head gasket replacement. 18-21hp OHV engine - 33Cu in. This is a typical engine in Craftsman, MTD, John Deere and many other lawn tractors with a single cylinder Briggs and Stratton OHV engine. This repair is very common and manifests itself as smoke coming from the exhaust after running for a few minutes, an oily spark plug with lots of buildup on it, etc. You can do a leak-down test on the engine to diagnose the failure if you have a tester. If not, you can sometimes just manually rotate the engine to TDC (top dead center) and remove the oil dipstick and you will actually hear air hissing back into the crankcase as you slowly turn the engine by hand from the top of the engine. This is air leaking from the combustion chamber into the pushrod opening via a defect in the gasket. ALL the damaged gaskets I have replaced on these engines leak in the same spot.... between the piston area and the pushrod area. It doesn't take much of a leak to cause the engine to run poorly. Most gaskets show a tiny degradation in that piston/pushrod area. That's all it takes. There are 3 or 4 different part numbers for the new head gasket. These gaskets are all identical EXCEPT for the bore /piston diameter. Make sure you install the proper gasket for your engine. The first two numbers of the engine model number tell you the size. Example: 331777-1372-G2 is a 33 cubic inch engine and would use gasket part number 794144. A 313777-XXX-XX would use gasket part numbe 699168 (which supersedes to 796584 updated gasket).
Thanks for your head gasket replacement guide. It helped me doing the task. BTW. I went to our local lawnmoverstore for get a new head gasket. The old man said. If your head gasket is blown, you also have to get your cylinderhead planned. Else the head gasket change only will give you a few hours of happiness. I went home and checked my cylinderhead for warping with a steel ruler. It was warped as f***. So i went to the next big town and get my cal head planned. Got the engine assembled and valves adjusted. Everything runs smooth. Thanks to you and the old man at the lawnmovershop.
When I have the head off the engine, I run a straight edge down it to see if it's flat. Sometimes, they are not too bad and I clean them up with a file on the high spots. If the engine has been neglected for most of it's life, I replace the entire head assembly (head, valves, seats, rockers, etc) with a new one. The complete head kit including all gaskets is about $110.00. Many times, one (or both) of the valves will seize in the valve guides and you end up bending a push rod after a short amount of use. I take each engine case by case and determine what the practical life of the engine is and how much a customer wants to spend on the repair. I would rather replace the head and give them a break on labor and have a pretty good idea that the engine has been put back into service with the proper repairs and the customer will get decent life from it.
Be'n a gearhead, I've gotta say this is a EXCELLENT video... Verry well produced and narrated... A true professional!!!
+Robert Jones Thank you. Just trying to get the information out there to help the do-it-yourselfer's. Not perfect, but enough to get the job done. Thanks Robert!
Excellent video showed exactly how and what to do in a concise manner. My engine runs great now. Thanks for the help.
Great video Dan. Explained perfectly for all to understand. Please do more on this type of B/S Intek engine . Ty
Dan...Thanks so much for this video. It is well done and very helpful. I've worked on small engines for many years but it really helps to see a video that points you in the right direction. You've got a new subscriber here. Thanks again!
Beautiful. Showed me exactly what I needed. Thought first to get rings but it's gotta be my gasket also. Haven't even opened it yet but looking at your video it's gotta be that gasket.
That's exactly what I did.
Pulled the head, found a cracked piece of the compression ring welded to the top of the piston ( didn't expect that ).
Rebuilt the engine with a .020 over piston, it's a little hard to start due to the increased compression but runs like brand new.
I would advise just having the cylinder re-sleeved and going back with a std. size piston to avoid compression lock, the starter is not designed to turn an engine with compression over what it was designed for .
+Rusty Nuckles As far as the compression goes, I bet you have too much clearance on your valves and the compression release is not working. Check the valve/rocker clearance for proper clearance and take a look at the rockers as the compression stoke comes towards TDC, you should see one of the rockers tip a valve open just a tiny bit to release some of the pressure. It might be the exhaust valve OR the intake valve (depends on the particular engine model) but one of the valves should be doing this. If the rocker-to-valve clearance is excessive, the valve won't open enough to dump the pressure and the starter motor won't have the torque to spin the engine. Question: When you had the engine opened up, did you notice if the camshaft had a working compression release on it? Many times these little parts break off and the compression release stops working. I would be surprised if this wasn't your problem with the hard starting. What is the engine model/type/code?
Thank you. Your video was very informative and described my problem. The instructions were great. Thanks for giving me the confidence to do this on my own.
lots of people seem to want to jump on replacing starters or batteries when all they need is a simple valve adjustment. I have to say I have never peformed a valve adjustment but, I know just because it may start slow or sound like its dragging isn't always a starter or battery problem.
Thank you Dan!! I Greatly appreciate the help.. I got her all together and she didn't start.. I figured my TDC was on wrong cycle so took 10min to readjust and she fired right up! Thanks again!!!
I will probably do a more detailed video soon ( no snow here=not much work to do) on setting valve clearances and how the compression release works on those Briggs OHV engines. I see lots of folks trying to solve "electric starter" problems on there Craftsman tractors where the engine won't spin using the electric starter only to find the root cause is the valve clearance is too loose and the compression release is not working. I usually see these machines after the owner has replaced the battery 3x and tried everything else they can think of. Glad yours is running!
Dan Small Engine k
Thank you, your video gave me the confidence to fix this myself, I am sure now it is not too complicated.....much appreciated!
@@georgiaboyoutdoors4536 ?
Great video! Thank you. Well done!
on another Head Gasket video dealing with the Briggs and Stratton engine they had little caps on the valve ends
I have not heard of the compression release you explained - thank you
I have seen some with caps and some without. Not sure if they do that on certain engines only or what.
Great video, very informative. Thank you!
Great video! Thank you for the information, it will help a lot.
Dan in we were in auditorium showing your video to a group of DIY-er's such as myself. You would be getting a standing ovation for your video for a terrific video. I am hoping you also made video for setting valves.
I just went into your site a video uploads and sadly I see you've not uploading anymore. I think you had a real gift in being able to explain things. example about starters batteries mistake That was me....
Hi, Thanks for the kudos. I was just thinking the other day, I haven't uploaded anything new in a long time. I have been running a few different businesses and I'm just short on time. I actually had a 28" Simplicity snowblower in my shop last week that had a bunch of odd issues. I spent a ton of time on it and in the end, I basically gutted the entire lower drive system and replace most of the bronze bushings. It would have been a great video! Next time I get something big in, I'll do a video. Thanks for your feedback. I'm glad they liked the video!
Great job man
Great video with great information 👍 thanks!
I also had one of these, but it had overheated and blew to the outside instead of between the valves and combustion chamber. The plastic flywheel fan at the top had broken and cause the whole thing to overheat
Great guide, I'll be facing this job in my lt1000 soon, it's smoking alot and spewing oil out of the dipstick, I was wondering if I can do the job without taking off the rockers and pushrods to avoid shimming later on.
Superb video. Thanks.
great video
Really well done
That’s nice got it out easy! I’m out of Luck ! Have two bolts that the head round out & can’t get it loose one in the top area & one in bottom! Bought it used Troy-bilt pony with 17.5 bridge & Stratton Motor! Now my problem is have a bad head gasket & I wanna replace it! Someone messed that bolts! Probably didn’t use the right tools! Got any idea? Please help 🙏!
Great video!!
Hi, I have a vtwin intek that started surging pretty bad lately. I checked my fuel flow which is good, put on new fuel filter, cleaned the carb and replaced some of the gaskets, check the sparked plugs and regapped the coil to .0010 (.008 to .012 recommended) and fresh gas but it's still surging. I've had valve noise (tapping) as well for quite some time as i really did not have the sense to adjust the valve's until last year ( still taps) plus my mom over filled with oil one time and smoke was blowing out the exhaust manifold lol. Lawn mower's getting up there in age (15 years old). I think i got some head gasket issue's as the spark plug threads were a little wet, although it does not smoke all that much. So i am gonna pull the heads and check the valves. Wonder if my piston rings are still good yet. You happen to know the compression psi for the intek v twin ? Maybe she needs a total rebuild lol....... Good vid
Thanks for you video. really helped me diagnosis mine. same engine and same model tractor. Do you have a video on setting the valve lash? without a leak down tester, is there any other way to make or do a leak down test?
Very good. Right to the point.
hey Gary my 115 john deere had a similar situation took it apart and found the release switch on the camshaft came apart due to the plastic holding a little pin had melted
Yup, it happens all the time.
The compression release is on the intake valve (not the exhaust valve like I said in the video). You will notice the slight blowback into the carb when slowly turning/starting the engine for the compression release. I suspect the compression release is on the intake valve to make the EPA happy... wouldn't want any raw fuel to be released out the exhaust port into the atmosphere... makes sense.
Thank you! big help :)
My 20 horse intek engine after sitting the winter ran rough after start up then belched out big cloud of smoke then would not run. Would a blown head gasket stop engine from starting? Engine cranks with key but just makes a metal like rattle sound! Any ideas?
enjoyed your explaination of the procedure of investigating issues. Question, how much air pressure should be applied while using leak down test??? thanks
Great work...I have a Kawasaki FS_541v and it's burning oil and when it's hot will backfire...I'm thinking it's a head gasket? Engine only has 400 hours on it
Hi Dan I need your help ! I have a brand new ( Troy-Bilt TB30 R Neighborhood Rider 30" Riding Mower - 420cc ) My son lifted it up from the front to clean the deck out and gas spilled out over the air cleaner ( I fixed that ) the engine won't start and there is oil in the cylinder ! I tried cranking the engine over with the spark plug out and the oil just keeps coming out ! Briggs and Stratton looks like the one in this video but mine is 10.5 HP
I have a 17.0 one, but this one was a gift, it comes without the carburetor, don't you know witch carburetor is the one for that one? or i can put any other from other engine? i hope you can understand this is not my main language xD
THANK YOU
Thank You for the great video. will this same gasket work work on an 18.5 single cylinder intek? Again Thank You.
Yes
Hi Dan.I'm working on the same.but the lower push rod was bent when I pulled the head.
Hey John, If you have a bent push rod, you probably have a damaged valve guide and that valve is sticking/jamming and this is WHY the push rod bent.... When the engine overheats or the oil is low(usually both), the valves don't get properly lubricated or cooled. Once this happens, the valve stems get scratched up, you start to get metal transfer from the valve guide to the valve stems and the valve eventually jams in the head and the push rod will bend since it's the weakest link in the valve train. This is very common. If the engine is decent and the tractor is not too old (5-8 years old), I would replace the entire head assembly (head, valves, rockers, etc - comes in one package from Briggs) and replace the push rod ( or rods if they are both bent) and reassemble the engine. The new head (updated from the head you probably have) has slightly larger cooling fins and a new metal shroud that goes around the head/cylinder to channel the air from the flywheel down past the head (for cooling). Make sure to swap out the metal shield since the head is slightly larger and you need a bit more length on the shield to cover everything... (It's not critical but if you plan on keeping it , I would swap the shield since it comes in the head kit).
Check leakdown to check rings, valves, and head gasket. If the rockers are loose, the valve seat is loose. Replace the head.
I was wondering if you could put heads back without messing with valve lash I will give that a try THANKS 😅
What you are describing on the compression stroke with the momentary release is what is messed up on my machine. The compression is so high that the engine gets really tight and is hard to turn on the compression stroke. Thus making it hard to start. I will go back and adjust my valves again, but I swear I think they are dead on. Should it be a loose adjustment or tight? My range is .005-.007 on the exhaust and .003-.005 on the intake.
When the compression stroke is just coming up, you should see one of the valves( I think the intake ) just open up slightly and release some of the compression. If you don't see it, you probably have a broken compression release assembly on your camshaft. I have seen them break many times and you would have to open up the engine sump to get access to it. A cam is about $80.00 bucks and you will need the sump cover gasket as well. I would VERIFY you have no compression release buy setting the lash to .000 and slowly turning the engine by hand to see if you get ANY valve action on the upward compression stroke. You should see one of the rockers/valve open a tiny bit as the piston comes up and about 1" from the top, the rocker should "snap" closed. If you don't see any such action, you probably have a broken release on the camshaft. I see it all the time on the 15 cu in Snow blower engines. I think Briggs had a bad run of them about 10 years ago.
Don't most ohv Briggs take all the same head gasket or are they diffrent
on changing out the head gasket when all is clean and ready to put back together. can you use permatex copper spray a gasket on the part were you get the blow by. would that hold any better. or just replace the gasket?
That won't help and might actually hurt it. The real problem is they need add an additional bolt between the cylinder and the pushrod area to clamp the head to the block better. That engine has been around for a very long time so that change will never happen.
awesome video Dan. Where can I get (or can I make my own) the compression gauge setup you're using? Thanks!
Ebay, it's the cheapest and it will be fine for what you are doing.
Hey first off, thanks for the video tutorial!
I picked up a Briggs 13.5 OHV that has Zero compression ( I don't own a leak down tester ) before I pull the head, do you think this is my problem?
Valve lash: .005, push rods not bent,
Have you ever had to lap the valves in these things?
Thanks again.
+Rusty Nuckles Hey Rusty, I lost my login to this account so I have been offline for a while. It could be a stuck or bent valve. It the engine was run low on oil or overheated, the valves will sometimes seize in the head and stay open. It could also be a loose valve seat. The valve seats are pressed into the head and they sometimes come loose and get stuck under the valve 9holding it open). The best way is to pull the head and see what you have.
What would a shop charge for this exact repair? I know there is a range but just curious.
dan what is the proper valve lash for intake and exhaust ive heard and read some guys just set both at .004 what would you recommend. Thanks
4&6
I just replaced the gasket and put everything together like before. Engine turns and I can hear/see white smoke comes from air filter area, but it won't start. It is keep turning, but it won't start. It used to start before changed the gasket. Did I mess up something with rockers? I had hard time to put them back. Do I need to open it back up and do something with rockers? Any suggestion would be appreciated. Thanks
Adjust the valves
Shoot it 😂
The compression release is on the exhaust valve
Thanks!
I'm working on the same motor and tractor and the same gasket issue, in the same place. Easy fix, but that is really a poor design. Not enough metal and gasket to seal long term. Even the manual says that the gasket will need replacing every so often. So, this is now maintenance????
Yeah, It's probably about cost and service revenue. I agree they should improve the gasket so it has a metal ring around the cylinder to prevent leaks. Ideally, the head needs another bolt between the push rod area and the cylinder to clamp the gasket firmly. Of course Briggs won't redesign the engine for something like that... too costly.
Hey Dan! What was your torque spec on this engine for the cylinder head?
The cylinder head bolts are supposed to torqued to 220in lbs. That's about 18.3 Ft Lbs. (or 25Nm for the Canadians). Be careful not to go crazy tightening them up. If you snap one, you will probably never get it out of the block. Also, check the valve cover to make sure it's got a nice flat surface for the new gasket and tighten it to 60in lbs (like 5ft lbs) just to snug it up and prevent leaks. Set your valve clearance to .003-.005 on the intake and .005-.007 on the exhaust per the Briggs spec. I notice that once the engine gets warm, the rockers tend to make a little noise but the spec is the spec - so use it. I like to use a tiny bit of Blue RTV to seal the rocker cover because I hate oil leaks. Sometimes I assemble the valve cover using just a gasket (no sealer) and run it for a while then re-check the head bolts once it's cooled down. I check the valve clearance again and then reassemble using a small amount of Blue RTV to prevent oil leaks. Since these head gasket blow quite often, I clean the head and block with Carb cleaner or Starting fluid to get ALL the oil off the surface so I get the best seal possible. The gasket should be reliable for another 5-10 years depending on how cool and lubricated you keep your engine. In Boston, I find nests under the engine covers all the time and this prevents proper cooling. If you start your tractor in the spring and little pieces of debris seem to blow out from the engine area, you probably have a nest. This can damage the coil by it getting pulled into the flywheel with all the nesting debris. Also, the mice like to chew through the wires on the coil (both low and high voltage wires) so check it before you start it in the spring to save yourself that trouble. Also, clean oil filled properly to the full mark will help prevent overheating!! Good luck.
man i just did a head gasket.firgured that would fix my carb from misfiring.but it turns on a lil better on full throttle then on half throttle it backfires then a huge loud spark and the engine stalls.any ideas?i rebuilt the carb 4 times.but not recently.
You probably have a partially sheared flywheel key and the timing is off. Remove the top cover and flywheel nut and see if the slot in the crankshaft and the slot in the flywheel are offset. They should be lined up. If not, pull the flywheel and replace the key. That engine typically runs well so the backfiring could be a timing issue. Also, make sure the valves are adjusted properly. They should have about .007 -.009" clearance or so. You might have one of them too tight and it's keeping a valve partially open. Check the flywheel key first.
Ill check it again.it looked like it was slot wasnt off setted.but ill check it again and ill space out the valves @ .007 and @.009 thanks
Torque 190cc ohv Briggs troy built presure washer
great video, what is the head gasket part number?
thanks
It depends on the size of the engine. Check the engine code and find the correct gasket. It's probably 796584 or 794114 . The gaskets are similar but the size of the bore is different so make sure you check your particular engine number and get the correct gasket. If you are replacing the entire cylinder head (instead of just the gasket), the kit will come with 2 new head gaskets and you choose the correct size for your bore. The new head gaskets actually have a stamp on them that says "31" or "33". The complete head kit is 796026 and it replaces older heads 794123, 796005, 794223 or 793990. It comes with the valves and springs installed and new rockers and lock nuts. It also has the valve cover gasket, intake gasket (o-ring), exhaust gasket and a new heat shield. The new style heat shield is slightly larger than the original and goes around the cylinder to direct the flow of air past the cylinder fins and head fins for proper cooling. There is a tiny screw on the bottom of the cylinder that needs to come out to remove the old heat shield but it's tough to reach. I think a 1/4" wrench will remove it. Make a decent effort to replace the old shield with the new one provided in the head kit but If you just can't get it out, you can use the old shield by bending it around the new cylinders head's larger fins. I'm sure it will cool just fine using the old modified shield if you just can't get the old shield out.
Thanks for the info Dan
Can this also cause the oil, to come out the exhaust?
In a round about way it could. But, that would most likely be another issue such as worn piston rings, over-filled oil, or a bad crankcase breather. Or, it could be a combination of these.
Could you have left the cover on the valves on and taken it off as one piece with the head? Seems like you could.
m00n69 on this particular head, you could have. But, you would have to take it off to put the head back on. You have to be able to verify that the push rods are in the dimple of the rocker arms. And, you have to verify the valve lash. Also, some models will have to bolts that you have to access through that area.
I put .010" on both rocker arms
O. I like.005
@Phillip Hall too bad Cometic doesn't make a head gasket for these things. I sanded mine down last time and seems to be lasting longer (blown 2 x). Wish they wouldn't have uses aluminum and made these cast iron or steel
Great video, but then your warnings scared me off. First, how do you move the piston to Top Dead Center? And secondly, you said if it was my first time, I might have to remove the rocker arms and then you gave a lot of warnings that I didn't understand. I'm a farmer and I can't afford not to fix things myself, but can I replace the head gasket the same way you did?
Sorry for the missing details. Just turn the flywheel on top of the engine until both valves are closed and the piston is at the top of the cylinder. You can loosen the rocker adjustments with a 9/16" wrench in most cases. set the clearance for around .005" or so on each valve. Check the Briggs book for exact spec. I will probably publish a valve clearance video soon since many folks have hard starting issues with these engines and start replacing starts and batteries only to find out the root cause is a simple valve clearance problem. Remember - the compression release is on intake valve and if your clearance is too large, you won't bleed off enough pressure and your starter motor won't have the balls to turn the engine past the compression stroke..
Dan, after you follow your step to turn the flywheel until both valves are closed and the piston is at the top of the cylinder, is there a reason or need to have to make any adjustments to the rockers before putting everything back? That is where I am a little lost. Thanks for your help. PS- I'm in New England as well !
What was the valve lash
HI John, It's around .008 or so. It doesn't have to be exact. I keep mine a bit tighter because I hate the noisy rocker/lifter sound they make when they warm up. The biggest problem with those valves is leaving them too loose so the compression release doesn't do it's job. If the compression release doesn't crack the valve open a tiny bit on the compression stroke, the starter motor won't have enough power to spin the engine. This is a common problem where folks keep replacing the battery, starter motor, cables, relay, etc. when really the problem is that the compression release is not working because the valve lash is too loose. When I set them, honestly, I do it by feel most of the time and just make sure they have some clearance when closed.
Hey Dan. I changed my head gasket on my 2000 14.5 OHV Briggs and Stratton engine because it was smoking like crazy. As it turns out the gasket was broken. After the repair It started right away but only at high idle. When I lowered the idle speed it stalled right away so I drove it with the idle high. It ran for about a half hour then it started to backfireand and eventually stopped. I tried to start it the next day and it started right away. ( with the air filter off ) It would allow me to run the motor at low idle as well but was backfiring through the carb big time. Could you tell the problem and how to fix it? Thanks. Deny
+Deny Konecny
So, according to Briggs, the head gasket failure occurs because of excessive engine heat. This isusually a result of - 1. low engine oil, or 2. Overheating due to clogged fins or a nest under the engine cover thatprevents the flywheel fan from blowing air past the cylinder and head. Once the engine gets too hot, the head gasket starts to break down and leak (usually into the push rod chamber (i.e.
crankcase)). The engine starts to use more oil and it usually gets pretty low before you realize something's wrong. I suspect you also have a problem with the
valves sticking open on your engine due to damaged valve guides. On about 50% of the head gasket jobs I do, I replace the cylinder head assembly with a new one because the valve guides are damaged or scored and the valves will eventually seize in the guides. Since I only want to fix it once and I want happy customers, I replace the entire head if it looks like it's in bad shape. I have also had instances where the valves move fine in the head but the valve seats leak where they are pressed into the head because they were overheated at one point. When I reassemble the engine, I usually do another leakdown test to verify the head gasket has sealed properly and both valves are sealing properly. You can hear air leak from the ports if you have a bad seal, bent valve or a loose valve seat. A complete
cylinder head is about $125.00 and comes assembled with rockers, springs, etc and new gaskets all ready to be bolted on. In your case, you should do a leakdown test to see if the valves are leaking at TDC with both valves closed. If the leakdown test doesn't show any major leak, you may have sheared the flywheel key and this is causing the backfiring. Check the flywheel key and make sure it's not partially sheared...
+Dan Small Engine .Thanks for the quick reply Dan. Being that I am not a mechanic the first thing I did is recheck my valve lash and low and behold the exhaust setting was way off. As a matter of fact the guide seemed very loose. I reset the valve, put everything back together and it started right away. No backfiring or stalling. Thanks for your help. Cheers
i have same issue model number is unreadable same engine/tractor can you give me the part number for the head gasket/gasket kitset thxs
Could be 796584 or 794114. You need to get the first 2 numbers from the engine model code that tell the displacement of your engine. The gaskets are similar but the diameter is slightly different depending on the size of the cylinder. These gaskets fit 16hp-21.5hp I think so there are 2 or 3 different sizes. If you are replacing the entire head with a new one, that cylinder head kit comes with all the various gasket sizes you will need for anything in that family. I think the kit number is 796183.
Hello are you using a 3/8 or 1/2 torque wrench
+Joe Briggs It doesn't matter what size torque wrench you are using. Set it for 220 inch pounds (or 18.5 foot pounds...i.e. 220 inch pounds divided by 12 = 18.333 ft lbs, or for the Canadians - 24.856662385 N-meters) It's all the same torque.
how much would a repair like this cost?
$150-$250 in the Northeast. Probably less in the south?
Lol. My plug is dripping with oil when pulled!
That number you showed don't mean nothing. The numbers for the engine are on the valve cover. Of course you know.. good vid man just ribbin ya
You forgot to mention to resurface the cylinder head on a wide, flat belt sander or large diameter sanding disc to remove warpage and restore flatness, and to prevent another blown or leaking head gasket.
I wouldn't use a belt sander or disk. It's really a machine shop function unless you have a fly cutter in your garage. Most of the time, they are not bad and you can clean them up with a good quality flat metal file. Hit the high spots and not to remove much meat. Clean good with carb cleaner or acetone before you assemble it. Unfortunately, the design of that head with no bolt on the pushrod valley side is a bad design. A new gasket may only last 7-8 years. Make sure all your cooling fins are clear and keep the oil full. It's all about cooling.
No adjustment
That’s a leak down tester
You’ll confuse the wontbe mechanics
Looks like Briggs designed this engine to blow head gaskets there is way to much distance between the head blots where the blew out Briggs could have designed that engine to have a threaded boss for at least one more head bolt DESIGNED TO FAIL 100%
How do you get the piston up to the top dead center when reassembling the engine?
charles mayer you rotate the flywheel/crankshaft by hand. If the head is on, you can use a blunt object stuck through the spark plug hole to feel the movement of the piston. To add the piston has to be at TDC on the compression stroke and not the exhaust stroke.