2009 overheating

[Will_K]

Alright... here's the vehicle history in brief.

I acquired this car in February 2024 with blown head gasket and oil with obvious coolant in it. I replaced head gaskets with new steel head gaskets, water pump, coolant, radiator hoses, thermostat. Everything was fine until this winter when my daughter (for whom I bought the car) indicated it wasn't heating (she mostly drives to high school which is a 2 mile drive, and work which is about 4 miles, and soccer practice/games which can be more)... wasn't entirely obvious it was a serious problem. But it was starting to give overheating warning messages, coolant wasn't obviously low, but I decided I'd drive and concluded it might be time for a heater core. I decided I'd also replace the radiator while I had the system drained.

Last weekend I finished reassembly after replacing the heater core and radiator and ran the vehicle for a test drive hoping I'd confirm everything was okay and send her on her way... I got some heat, but still got an overheat warning and heat wasn't more than slightly warm and went back to cold.

At this point, I'm suspecting my thermostat was bad - guessing stuck closed. I didn't expect that as a possibility with under 2 years on the thermostat. The thermostat was an Advance auto Carquest part, 1 year warranty. I ordered a GM part to install this weekend.

I usually fill with a vacuum fill system, I watched a video using a large funnel and the bleeder valve so I tried that last night while I'm waiting on parts. The system took on another half gallon of coolant. But still (running parked at 3500 rpm to get temperature up) the overheat warning came on and coolant went back up the funnel. Some metal flakes were apparent in the funnel.


To my mind, it's possible the metal flakes may have been in the system as I hadn't flushed it previously, just drained. Is it possible that may have led to premature water pump failure and that's part of the problem? Is the thermostat consistent with what's happening? Is there anything else? (At this point I'm pretty much replacing all the mechanical components of the cooling system... radiator hoses were replaced 2 years ago)

I suppose it's probably prudent for me to do a cooling system flush with the thermostat out to make sure all debris is cleaned out.

 

[cavell]

I’ve always used composite gaskets on 3.4. Been told there are mls gaskets out there but never used them. Did you mill heads?
After motor has cooled do you get any air pressure from surge tank when you loosen cap? Sure sign of bad headgasket.

 

[Will_K]

At this point it just plowed forward and pulled the cylinder heads. I can't say the head gaskets had any deterioration or leaks, as happens the head and block had some coolant and that was apparent on gaskets. They didn't tear apart or anything.

The gasket passages had some debris buildup. It's not really the smoking gun i was hoping for... bearing in mind that I did do a coolant flush before disassembling, best guess at this point is that it caused trapped air.

I also double checked the torque before doing the 95 degree last step in bolt torque sequence. I'll do another water only flush before final fill.

I'm also ordering a new coolant reservoir. I have a 2007 ford focus that had a vacuum leak during vacuum filling and it was a seam leak on the reservoir. Does that happen on equinox reservoirs that are 17 years old?

 

[cavell]

I’ve done 10+ headgaskets jobs so I’m confident on my process. Do you have scan tool that shows coolant temp? Pretty cheap. $50. If motor is cool, loosen fill cap and open bleeder screw. You will get coolant to drizzle out. I fill system. Drive around till it’s hot. Stop. Let motor cool. Check surge tank level.
I fill surge tank to cold line. Never to top. Once motor cools the level always drops.
The surge tank level should never vary hot/cold by more then 1”.

 

[Will_K]

I'm not fully reassembled yet to run the engine.

Here's where I'm at. I have some kind of leak. It remains after replacing radiator, heater core and head gaskets. I can tell because the system won't hold vacuum with the vacuum fill system. It doesn't get coolant into the oil. It doesn't get combustion gasses into the coolant.

I have clamped off both hoses to the reservoir with 20 psi vacuum. The reservoir side holds a vacuum. The engine side of the clamps leaks.

I am thinking it has to be a hose or pipe between the engine and the heater core.

I added up dye and I'll fill with water then try a pressure test to see if I can locate a leak.

I haven't reassembled the alternator and serp belt for the engine to drive the water pump yet.

 

[Will_K]

I have everything reassembled.... except the oil filter and fluids. Amazon sent the wrong filter.

The coolant system leak? After a pressure test it turned out to be 2 bad hose clamps. One was a screw clamps on an upper radiator hose at the thermostat housing. It had a bend. The other was on the short hose at the front of the engine by the bleeder.

I still think everything else was needed because of tbe debris in the system, but that leak was pissing me off to find

 

[cavell]

did you mill heads? It’s required with mls gaskets. I use torque wrench even though I do the final 95deg twist and have estimated torque to be 75lbs, approx. I read online mls were available but I’ve never actually found them for sale. I always use composite gaskets. Mostly cuz that’s what GM uses.
Why did you decide to use mls gaskets?

 

[Will_K]

Didn't mill heads, I wasn't a fan of how the fiber gasket fell apart before the original head gasket replacement.

I think they call them MLS but the aren't all steel like I've seen on, for example, F150 MLS head gaskets. Here's new ready to install vs what I took off.

 

[cavell]

I did heads on a vue 3.0 and they were definitely mls. I shattered my wimpy torx socket removing old head bolts. I recall 3 torque/angle steps on the vue.

Ur pic seems to show composite gaskets on head. I also do not mill heads on equinox stuff.

Ha, and I never remove exh manifolds. If I can help it.
I see 2 left exh valves are whitish from burning coolant. Vs the right one which is darker. They say bad intake gaskets can lead to leaking coolant issues.

 

[Will_K]

Follow up: the car has had to be refilled on coolant here and there but never been able to pinpoint a coolant leak.

The exhaust manifold wasn't terrible to get off, when I did the rebuild I had put in all new studs and nuts... hate how if you look at Rockauto they list 10 mm studs when they're 8 mm, but I digress.

I had jumped to the conclusion that maybe the issue is some microcrack in the head or something that opens when the engine is hot... no other explanation, and the child is going to college at the end of the month - I'd rather send her off with a car that I don't know when she's gonna need me to play mobile mechanic. So, off to salvage for cylinder heads.

First car I try, I open the valve cover and find that creamy caramel cover of coolant mixed with oil, so I move to the next car. The way the wheel stands are set up, the front end is nose up... not great for all the disassembly involved.

I find a car that all the original hardware is there and no sign of water in the oil under both valve covers, so I do the work to disassemble the heads and lower intake and buy them all together. 2 sessions of 2 hours each. About $150, including $27 in core deposits I'd get back when I returned the next time.

Of course, that's the smallest part of the project budget... there's a gasket sets, new cylinder head bolts, fluids, a few trips to Harbor Freight to buy tools I should already have but can't find (again)

So I'm now past the lower intake manifold on the re-assembly process, looking for screws (side note- I dropped the lifter keeper with the 2 screws somehow as I was installing the RH head. It was dark. This was not in the engine bay. I don't know where they went. And when I returned to salvage, the donor car had been crushed out so my plan to easily get to the same bolts on that same car didn't work out)

Here's what I found... On the RH cylinder head the first cylinder bolt (middle cylinder, towards exhaust side, rear bolt) in the tightening sequence had failed. On the LH cylinder head, the second (middle cylinder, towards intake side, rear bolt) failed. Both bolts fractured above the flange of the bolt head.

 

[cavell]

I did remove firewall exh manifold from head last month. Seems the bolts are not hard to reach. If you have 20” extension. I think I did not torque them enough on install. I get an exh noise when cold. Sometimes. I might tweak them. Car just sits. Plates expired in 2023. Ha. So previous owner was not driving it. It’s done. Seems to run ok. Just a spare car for me.

 

[Will_K]

Further update, after replacing cylinder heads, 2 major problems.

First I got a couple pushrods switched. I put a short intake valve on an exhaust valve on cylinder 6 and a long exhaust pushrod on an intake in cylinder 5... the pushrod bent and after swapping correct ones in (i had an extra set from the donor car) a cylinder 5 misfire remained. Suspected the lifter crushed or something.

Also a leak remained, turns out I have a timing cover leak.

Working on both

 

[cavell]

I disassembled and cleaned 1 set once and 2 lifters would not pump up. Got loud rattle. I replaced them and all was well.
A clean, dry lifter will allow you to depress plunger as body has no oil and you only feel the internal spring resistance.
I crank motor with fuel pump fuse removed to get oil pressure. Then start car. You don’t set valve rocker clearance on 3.4 so having oil in lifters during assembly is not critical.