Thanx for posting video, i am contemplating doing a coolant change/ flush on a 07 venture. Grand Prix is much easier, not sure if i want to do the van myself(getting old). I saw a 07 Terraza with a similar low heat from heater core until revs were up a little and am curious as to why this was happening.
I believe it gets air locked. There have been lots of suggestions for repairs, honestly my favorite is a little bleed valve to vent off any accumulated air in the heater core system. I haven’t done that repair yet.
Had same problem on 09 Montana first time it happened I changed the water pump, impeller was corroded pretty badly. Topped up with fluids worked great for a couple years. This spring it started to blow cold again at idle. Thought water pump again but nope, all good. Checked and tested thermostat all checked out. Did heater core flush front and aux heater, no blockage. Then spent hours trying to bleed the air out of the system once air was all out I could barely hold my cold hands in front of the vent felt like they were going to burn. Anyways now I am just thinking why didn’t I just change the thermostat out because of course it is failing 6 months later. But I am hoping to borrow or find a vacuum coolant fill kit suppose to be so easy to fill coolant with and get all the air out.
Did you ever find out why the 2007 Uplander was not giving you heat at idle, or under 2000 RPM? Hint... Manufacturer defect. No official fix, but a guy in the Chevy forums came up with the idea of rerouting the heater lines to get rid of all the twists and turns. Worked perfectly. Evidently the pump is not strong enough to keep the water flowing unless and until the engine stays revved up over 2000 RPM. Dealing with it myself right now. Something involving bypassing one of the two lines with a 4 foot length of heater hose. A professional mechanic came along and affirmed his fix and decided to bypass both lines. He was very thankful for the person whop came up with the idea for pointing him in the right direction and saving him a ton of headaches as he had a customers van he was worried about taking back in the shop after having done two flushes and getting nowhere. Another fix that GM was totally against was getting an assist pump from say a marine outfit to mount and wire in someway. It worked, but GM got real hot under the collar about it. This would have very likely been an official recall, but for the Bankruptcy all them years ago. The bypass with a new heater hose routing to shorten and remove unnecessary twists, turns, dips and climbs is the gold standard fix even if GM refuses to weigh in on the issue. Anything else you do will at best be a temporary fix. The only official word from GM was an admission that the heater Core was mounted in a far less than preferable position. Possibly I think they were meaning it was mounted too high causing the routing to not be able to push the water with the water pump.
@@Turbo231This is the simplest understandable instruction I was able to find and came from the guy who happenstanced upon the original fix that was later affirmed by the mechanic. Seems to be straightforward enough, but it does require you to irrevocably destroy the stock connection in order to implement. That can be an intimidating drastic course of action for most people. "1) Basically, remove the 5/8" Hose from the thermostat housing and replace with the new hose end. 2)Remove the lower hose from the heater core, and connect the other end of the 4' hose with a nice gentle sweep of the hose around the engine. 3)Start and purge air if required, and enjoy heat from a very poor performance water pump. My technical opinion is that the original OEM pump does not meet the minimum flow requirements of the bends and joints in the original flow pattern. By reducing the bends significantly, the poor quality pump can achieve flow rates to fill and push fluid through the heater core. This is a very quick and simple way to test your system, and if it works, leave it alone. This modification in no way will limit the performance of the cooling system, as it is simply removing restrictive passages thus providing a warm -- hot vehicle! Good luck, and fix that Chevy or Pontiac! K. Carlen" The reason I find it to be intimidating is due to the fact that it seems that by removing the lower hose from the heater core you are removing the route of the lower hose that initially connects to a junction that splits into two directions. If you disconnect that and replace it with a direct routing to the thermostat housing what happens to the other lost route that is negated by virtue of completely bypassing the junction fitting that otherwise would have split the lower hose from the heater core into two directions. What exactly is the function of that lost water route lost in bypassing the junction fitting? I would presume it would be the hose that goes to the auxiliary heater core in the back of the van. There are actually two of the three way junction fittings. One for the upper and one for the lower heater core connections (inlet and outlet).
@@thedolphin1247 excelente information and I really appreciate what you did to help us,i did exactly what the instructions said and so far the heat is working like brand new,put new thermostat and coolant and this thing is super hot,millions thanks for you help again,God bless you my friend!!!!!
@@mizantlaveracruz ... Glad I could help. I just did the fix on my 2008 Uplander less than a month ago. It would appear the crux of solving the issue is getting rid of the metal tubing that runs along the engine for both the inlet and the outlet coolant paths. Taking those out of the equation seems to be enough. Easy enough to do by disconnecting the hoses that extend from the metal tubing to the three way junctions at both ends. Then just install the new hoses in between the span between the four three way inlet/outlet junctions. No need to actually even remove the metal tubing. I can confirm with a definite certainty that the Uplander Heater fix outlined in my posts did in fact make a world of difference. Having said that I did an amateurish job of it having neither the experience, or detailed instruction to perform the heater hose bypass. I was forced to rely on observation study and a huge dose of common sense in working out where to apply the scalpel and how to suture in the bypass, but in the end it improved the heating in the van more than significantly. Certainly enough to have made a profound difference. I only did one of the hoses. I was disappointed my four foot replacement hose was arguably not as long as I would have liked. I fully intend to undertake another operation to bypass the second metal pipe so that both the inlet and outlet pathways both bypass the metal tubes and perhaps lengthen the other hose I already replaced using a coupler in order for me to route it more effectively. Even still I have to say doing it the way I did it has made a world of difference. More than enough to prove to myself that I was on the right track and the source I got the information from was valid. It should also be noted that I fully flushed the system first and installed new Dex-Cool after which there was some improvement. I also replaced the thermostat and the cap while I was at it. I also replaced the cabin air filters which also resulted in some improvement, but after the bypass things vastly improved. Don't neglect the cabin air filters They can and do get clogged and the compartment area where they are located inside the glove box behind the little door you have to remove to get to the filters collects large pieces of debris. Twigs and leaves primarily in my case. The filters somehow create a static electrical charge that attracts small dirt and dust particles and is also made with charcoal to clean the air of any poisonous and stinky vapors that would otherwise make it into the vehicle, so replacing them periodically is very important. Clean them at least. An air compressor makes it fairly quick and easy.
Y he is is the best I have found so far. Could you do one on how to find/get to the EGR valve? We have spent a month trying to find it on mine. Don't want to pay a mechanic for something my husband can do.
Just wondering if you ever figured it out. I have a 06 uplander with the same problem. Just Luke warm heat at idle, and nice hot heat when at 2000rpm. Did a coolant flush dint help.
Apparently the heater core lines are the issue thanks to their high location, they tend to trap air up there. Thinking of installing a bleed valve on each line and see if bleeding those lines when it gets bad helps. Guess even small little cracks in the block/head let air get in the system every time the car cools down.
to whom it concerns YOU HAVE TO USE A COOLANT BURP KIT to get it to stop overheating also! have someone reb up the motor to get the flow pushing water through the system and get the hose area that sets above its own bleed screw its stupid what chevy did harbor freight $30
@@Earnhardtx Yeah, if your car is hitting the boiling point with coolant, you have other issues. Between system capacity, circulation, and the coolant itself having a higher boiling point than straight water, your cap, while important, can be missing and your cooling system will still run fine.
@@Turbo231 Not uncommon to go over 212'f, most t-stats don't open until 195.Most cooling fans turn on at 227'.A 15psi Rad cap will raise the boiling point by 45'.
www.buymeacoffee.com/turbo231 If you like this video and want to support the channel, feel free to buy me a coffee...and thank you!
Thanx for posting video, i am contemplating doing a coolant change/ flush on a 07 venture. Grand Prix is much easier, not sure if i want to do the van myself(getting old). I saw a 07 Terraza with a similar low heat from heater core until revs were up a little and am curious as to why this was happening.
I believe it gets air locked. There have been lots of suggestions for repairs, honestly my favorite is a little bleed valve to vent off any accumulated air in the heater core system. I haven’t done that repair yet.
Had same problem on 09 Montana first time it happened I changed the water pump, impeller was corroded pretty badly. Topped up with fluids worked great for a couple years. This spring it started to blow cold again at idle. Thought water pump again but nope, all good. Checked and tested thermostat all checked out. Did heater core flush front and aux heater, no blockage. Then spent hours trying to bleed the air out of the system once air was all out I could barely hold my cold hands in front of the vent felt like they were going to burn.
Anyways now I am just thinking why didn’t I just change the thermostat out because of course it is failing 6 months later.
But I am hoping to borrow or find a vacuum coolant fill kit suppose to be so easy to fill coolant with and get all the air out.
This was still a million times easier than doing my Montana without the special “GM Thermostat Wrench” for the 3400 SFI.
I haven’t come across that yet, but good to know.
Did you ever find out why the 2007 Uplander was not giving you heat at idle, or under 2000 RPM? Hint... Manufacturer defect. No official fix, but a guy in the Chevy forums came up with the idea of rerouting the heater lines to get rid of all the twists and turns. Worked perfectly. Evidently the pump is not strong enough to keep the water flowing unless and until the engine stays revved up over 2000 RPM. Dealing with it myself right now. Something involving bypassing one of the two lines with a 4 foot length of heater hose. A professional mechanic came along and affirmed his fix and decided to bypass both lines. He was very thankful for the person whop came up with the idea for pointing him in the right direction and saving him a ton of headaches as he had a customers van he was worried about taking back in the shop after having done two flushes and getting nowhere. Another fix that GM was totally against was getting an assist pump from say a marine outfit to mount and wire in someway. It worked, but GM got real hot under the collar about it. This would have very likely been an official recall, but for the Bankruptcy all them years ago. The bypass with a new heater hose routing to shorten and remove unnecessary twists, turns, dips and climbs is the gold standard fix even if GM refuses to weigh in on the issue. Anything else you do will at best be a temporary fix. The only official word from GM was an admission that the heater Core was mounted in a far less than preferable position. Possibly I think they were meaning it was mounted too high causing the routing to not be able to push the water with the water pump.
Yeah, I like the simplicity of just running hose.
@@Turbo231 There is also this. About ready to do this procedure myself as I am getting my Dex-Cool first thing in the morning as I just finished flushing my entire system, I figured why not give everyone a copy of something directly from GM for the Uplander from back in 2010. P.S. Lets just say the rerouting of the hose is a an answer for your prayers, but the damned routing of the stock inlet and outlet HVAC hoses is so damn convoluted its pretty damn scarry to take a knife to the existing stock hose system, so for most people including myself I would not call it simplicity, but calling it the gold standard in fixes is in all fairness pretty much right on point no doubt. In addition to the below posted bleed/burp procedure from GM I am attempting to give you the link direct to the GM forum so you can read the actual posts about the rerouting of the hoses yourself. If you start at the first post and keep reading you will eventually get to it. Leastwise I am pointing you in the right direction and you can judge for yourself the voracity of the information I have offered everyone. I bought my 2008 Uplander V6 LS 3.9 L extended cab back in July 2022 with 115,000 miles on it. I live in Colorado and with no heat I was forced to dig deep on how to fix the heat. chevroletforum.com/forum/uplander-31/2008-uplander-heat-problem-20931/page10/
There is an official release from GM on how to bleed/burp the system from back in 2010. Here is a copy and paste of it.
GM 3.9L 3900 Coolant Radiator purge bleed burp procedure
1. Close the radiator drain cock.
2. If a complete engine block drain was required, install the coolant drain plugs
to the engine block. Refer to Draining Fluids and Oil Filter Removal for the
3.5L engine or to Draining Fluids and Oil Filter Removal for the 3.9L engine.
Important: Use a 50/50 mixture of DEX-COOL antifreeze and clean,
drinkable water.
3. Slowly fill the cooling system with a 50/50 coolant mixture until the coolant
level is visible and stable. Refer to Approximate Fluid Capacities .
4. Install the pressure cap loosely (threaded on about one turn).
5. Start the engine and raise the engine speed to 2500 RPM and hold it there for
40 seconds, then shut engine off.
6. Remove the pressure cap and fill the coolant system until the level is visible
and stable.
7. Install the pressure cap loosely (threaded on about one turn).
8. Start the engine and raise the engine speed to 2500 RPM and hold it there for
30 seconds, then shut engine off.
9. Remove the pressure cap and fill the coolant system until the level is visible
and stable.
10. Install the pressure cap loosely (threaded on about one turn).
11.Start the engine and raise the engine speed to 2500 RPM and hold it there for
20 seconds, then shut engine off.
12.Remove the pressure cap and fill the coolant system until the level is visible
and stable.
13. Install the pressure cap, fully threaded on.
14. Fill the coolant recovery bottle to the indicator line, then add 400 milliliters
(13.5 ounces) more.
15.Start the engine and run it above 2500 RPM until it is hot enough to open the
thermostat, this will allow the trapped air to be purged from the engine.
16.Complete a series of three, 4-second-duration idles with 4-second-duration
3000 RPM cycles.
17. Turn the engine off and allow it to cool down to room temperature.
18. Fill the coolant recovery bottle to the indicator line.
19. Inspect the concentration of the engine coolant using the J 26568 .
20.Rinse away any excess coolant from the engine and the engine compartment.
© 2010 General Motors. All rights reserved.
Good Luck Everyone and your most welcome.
It is my hope that the many hours I spent scouring the net for this information benefits as many people as possible. P.S. Keep up the great work on your channel Turbo231. Your subscribers certainly owe you thanks too since I would not have posted the information here had your channel not impressed me enough to subscribe myself.
@@Turbo231This is the simplest understandable instruction I was able to find and came from the guy who happenstanced upon the original fix that was later affirmed by the mechanic. Seems to be straightforward enough, but it does require you to irrevocably destroy the stock connection in order to implement. That can be an intimidating drastic course of action for most people.
"1) Basically, remove the 5/8" Hose from the thermostat housing and replace with the new hose end.
2)Remove the lower hose from the heater core, and connect the other end of the 4' hose with a nice gentle sweep of the hose around the engine.
3)Start and purge air if required, and enjoy heat from a very poor performance water pump.
My technical opinion is that the original OEM pump does not meet the minimum flow requirements of the bends and joints in the original flow pattern. By reducing the bends significantly, the poor quality pump can achieve flow rates to fill and push fluid through the heater core. This is a very quick and simple way to test your system, and if it works, leave it alone.
This modification in no way will limit the performance of the cooling system, as it is simply removing restrictive passages thus providing a warm -- hot vehicle!
Good luck, and fix that Chevy or Pontiac!
K. Carlen"
The reason I find it to be intimidating is due to the fact that it seems that by removing the lower hose from the heater core you are removing the route of the lower hose that initially connects to a junction that splits into two directions. If you disconnect that and replace it with a direct routing to the thermostat housing what happens to the other lost route that is negated by virtue of completely bypassing the junction fitting that otherwise would have split the lower hose from the heater core into two directions. What exactly is the function of that lost water route lost in bypassing the junction fitting? I would presume it would be the hose that goes to the auxiliary heater core in the back of the van. There are actually two of the three way junction fittings. One for the upper and one for the lower heater core connections (inlet and outlet).
@@thedolphin1247 excelente information and I really appreciate what you did to help us,i did exactly what the instructions said and so far the heat is working like brand new,put new thermostat and coolant and this thing is super hot,millions thanks for you help again,God bless you my friend!!!!!
@@mizantlaveracruz ... Glad I could help. I just did the fix on my 2008 Uplander less than a month ago. It would appear the crux of solving the issue is getting rid of the metal tubing that runs along the engine for both the inlet and the outlet coolant paths. Taking those out of the equation seems to be enough. Easy enough to do by disconnecting the hoses that extend from the metal tubing to the three way junctions at both ends. Then just install the new hoses in between the span between the four three way inlet/outlet junctions. No need to actually even remove the metal tubing. I can confirm with a definite certainty that the Uplander Heater fix outlined in my posts did in fact make a world of difference. Having said that I did an amateurish job of it having neither the experience, or detailed instruction to perform the heater hose bypass. I was forced to rely on observation study and a huge dose of common sense in working out where to apply the scalpel and how to suture in the bypass, but in the end it improved the heating in the van more than significantly. Certainly enough to have made a profound difference. I only did one of the hoses. I was disappointed my four foot replacement hose was arguably not as long as I would have liked. I fully intend to undertake another operation to bypass the second metal pipe so that both the inlet and outlet pathways both bypass the metal tubes and perhaps lengthen the other hose I already replaced using a coupler in order for me to route it more effectively. Even still I have to say doing it the way I did it has made a world of difference. More than enough to prove to myself that I was on the right track and the source I got the information from was valid. It should also be noted that I fully flushed the system first and installed new Dex-Cool after which there was some improvement. I also replaced the thermostat and the cap while I was at it. I also replaced the cabin air filters which also resulted in some improvement, but after the bypass things vastly improved. Don't neglect the cabin air filters They can and do get clogged and the compartment area where they are located inside the glove box behind the little door you have to remove to get to the filters collects large pieces of debris. Twigs and leaves primarily in my case. The filters somehow create a static electrical charge that attracts small dirt and dust particles and is also made with charcoal to clean the air of any poisonous and stinky vapors that would otherwise make it into the vehicle, so replacing them periodically is very important. Clean them at least. An air compressor makes it fairly quick and easy.
Seems like you get very little bubbles in the water there as you start the engine. Gasses escape into coolant ?
More like the water pump churning up air bubbles on initial fill.
Comments helped just air vent adaptor needed by core on top hose .
Yeah, that seems like it would be the best solution.
Y he is is the best I have found so far. Could you do one on how to find/get to the EGR valve? We have spent a month trying to find it on mine. Don't want to pay a mechanic for something my husband can do.
Next time it is over here for service I can find it for you. It’s the only thing connected to the exhaust manifold AND the intake.
Air in the system still causing poor heat?
It’s a known issue might be related to cracks in the block that let air into the system as it cools.
Just wondering if you ever figured it out. I have a 06 uplander with the same problem. Just Luke warm heat at idle, and nice hot heat when at 2000rpm. Did a coolant flush dint help.
Apparently the heater core lines are the issue thanks to their high location, they tend to trap air up there. Thinking of installing a bleed valve on each line and see if bleeding those lines when it gets bad helps. Guess even small little cracks in the block/head let air get in the system every time the car cools down.
to whom it concerns YOU HAVE TO USE A COOLANT BURP KIT to get it to stop overheating
also! have someone reb up the motor to get the flow pushing water through the system and get the hose area that sets above its own bleed screw its stupid what chevy did harbor freight $30
Where is the exact location of the thermostat?
Just inside the housing attached to the block. Can’t miss it.
Update? My 07 is doing the same thing. 16 degrees and no heat!
I need to do the video of burping the heater core system. That’s the best best as it is a high point in the system.
Will the rad cap cause it to overheat
No. It shouldn’t overheat even if the rad cap was missing.
@@Turbo231 Oh yes it will.The Cap raises the boiling point of the coolant.
@@Earnhardtx Yeah, if your car is hitting the boiling point with coolant, you have other issues. Between system capacity, circulation, and the coolant itself having a higher boiling point than straight water, your cap, while important, can be missing and your cooling system will still run fine.
@@Turbo231 Not uncommon to go over 212'f, most t-stats don't open until 195.Most cooling fans turn on at 227'.A 15psi Rad cap will raise the boiling point by 45'.
I do like a Lot of the vehicles you show,good work.
Thanks for the video.
You are welcome, need to do it to my 2002 Grand Prix.
Same as my 05
I believe it should work for any 3900 engine.
Is this the same on a 3500???
Not sure but likely similar.
Never use an aftermarket thermostat
There are some things that need to be OEM, but a thermostat is not one of them.
on that car you should check the heater core. if you want better heat
Yeah, there are issues with these and heater cores and air getting pulled/trapped in the system. Will explore it more this winter.
Water pump
Might need one soon