Okay, new problem, the engine is overheating

[Rummel6]

I have a 2011 Tahoe LS with 195k miles on it and it has a new water pump, thermostat, expansion tank, and replaced hoses at firewall. The issue I’m having is that when I pass someone at high rpms, the engine starts to overheat. I have to pull over, shut the engine off, and wait a few minutes. Also, when this happens, I have no heat. Please help because I can’t figure out this problem.

 

[Tonyv__]

If you have no heat. Also assuming your heater core isn’t clogged. You may be low on antifreeze. After replacing all those parts. You have to continuously check your tank to make sure all the air pockets have been filled and that it’s topped off

 

[drakon543]

you may have a pocket of trapped air. at low rpms the flow is low enough to get around the trapped air. at higher flow it will compress the air and cause a blockage. you can either keep driving it at lower rpms and hope it works it way out and top the system off as needed as suggested above. your other choice is to drain the system back down atleast halfway approximately water pump level. then start the truck and as the truck is running slowly refill the coolant system until its topped off.

 

[Rummel6]

I have done both I’m thinking honestly I may be over spinning the water pump and causing the belt to slip since I have replaced everything on the front of the motor

 

[Rummel6]

My brother seems to think it may be running lean also but not sure on that because figured it would kick a lean code

 

[bill1013]

Check the tension on the serpentine belt as it may be slipping. Also, old belts get hardened and slick, so they work okay a lower RPM but lose it when you get on it. You may just need to change out the belt.

 

[OR VietVet]

How clogged up is the air flow thru your radiator? I agree though that sounds like low on coolant from air pocket(s). Does the thermostat have the little weep hole in it?

 

[Rummel6]

Tensioner is tight and I’ve topped it off a couple times and the radiator I would think is clogged I kee this thing clean

 

[wsteele]

Did the symptoms start after you replaced all the water pump, hoses, etc., or was that why you replaced all that stuff?

 

[Rummel6]

No it just started happening I replaced all those parts because the engine was squeaking but ended up being the cam needed replaced from that stupid afm so I did the full delete everything g has been fine for the last 8 months

 

[wsteele]

No it just started happening I replaced all those parts because the engine was squeaking but ended up being the cam needed replaced from that stupid afm so I did the full delete everything g has been fine for the last 8 months

OK, so although not 100%, the odds definitely favor a problem being introduced in the change over to new parts. Could be defective components, mis-install, etc.

How does the oil look, any water in it? Any oil in the water? etc.

 

[Rummel6]

No water in oil

 

[avalonandl]

Look up Burping the LS engine cooling system on line

Also is the water pump new?

They fail alot on the LS....

 

[Rummel6]

Yes water pump was new it’s duralast from autozone

 

[wsteele]

No water in oil

Things I would look at are perhaps a defective pump, hoses (a flap can be created by defect, or how it was installed where the inner layer flaps down and blocks flow, more prevalent on aeroquip style hose than normal water hoses, but you never know). etc.

 

[OR VietVet]

You said you topped off a couple of times. Adding coolant means you did not add enough the first time or had an air pocket or you are leaking still or maybe have internal problems like head gaskets.

 

[97audia4]

I have done a radiator on the side of the road and a water pump at the race track so I have bled the system enough to do it well.

I also fill it, run it low Rpm with no cap on the surge tank, slight revs from a friend and be ready to fill it again when the thermostat opens up, you do not want to to get below the bottom hose or you will have air.

Repeat so there are no bubbles coming out when you rev to 3k RPM. Fill to the hot line put the cap on and let it cool down. Come back and top it off if its dropped at all.

 

[Rummel6]

So took the cap off and rev it today got some bubbles out but when I mash the gas the rad fluid in the expansion tank drops down then come back up even if I put the cap back on not sure why

 

[Rummel6]

So took the cap off and rev it today got some bubbles out but when I mash the gas the rad fluid in the expansion tank drops down then come back up even if I put the cap back on not sure why

 

[Geotrash]

So took the cap off and rev it today got some bubbles out but when I mash the gas the rad fluid in the expansion tank drops down then come back up even if I put the cap back on not sure why

Based on this, I think it's worth doing a leak down test on this engine. Before this post I was thinking thermostat, but after reading this I'm thinking a leaking cylinder head gasket - this is classic behavior when there's a breach between a combustion chamber and the cooling jacket. The only other thing I can think of is perhaps the cap on the expansion tank not holding as much pressure as it should, and preventing the cooling system from being able to handle as much heat without boiling the coolant somewhere in the system.