Coolant Overheating

[$ Khalid ! 9130]

Well I dont know if i’m in for a expensive bill for the TB. So this happened yesterday actually, I was out running some errands and noticed the AC wasn’t cooling properly, but put it off to the extreme temps we got going on here. I stopped at a store just around the block form my house and noticed the Coolant Temp was full in the red. Immediately I shut the car and poped the hood. Couldnt see any smoke or anything of concern, so I fired it up and parked it. Later I checked the coolant reservior and it was bone dry!



So early morning today filled up the coolant to the top and let it run with the AC on for abot 15 mins and temp stayed in the middle so didnt think of it much and shut the car and went home.

Just now I had some stuff to move and checekd all the coolant etc before starting. Let it run for about 20 min as I loaded it with the AC running. As soon as I pulled out of my parking the coolant temp kept creeping up. Didnt get past the block and it was near the red. Shut it down and poppped the hood. Coolant seemed OK, but noticed a leak near the back of the engine. Let it cool for a sec, turned it around and brought it back home.





Let it sit for a while and went through the AC fuses etc, all seemed fine. Started it up again and the needle was past the half way mark and stayed there until I switched the AC on and it raced to the red!

Other observations, the engine oil doesnt seem burnt or even low. Checked the radiator cap and it looked OK. Checkd to see if it was the Fan by seeing if it would stop as soon as the vehicle is switched off or on its on and it continued to spin until coming to a stop by itself. The fan clutch spins as soon as the AC is turned on. When the coolant isn’t t over heating AC blows perfectly

I dunno why but I am feeling completely at a loss on how to proceed

 

[Mooseman]

So that's actual coolant and not the water condensate that dripped out? If it is leaking coolant, it should be addressed. That would explain the low coolant.

However, even with the coolant topped up, it still gets hot so the two things I would check are the thermostat and the fan clutch operation. If the tstat has never been changed, I would just replace it. It's a high failure rate part. ACDelco is recommended for proper operation as others have been shown to not operate within proper temps. I have discovered that Mahle makes them for ACDelco so if you can find those at a better price, then it's an option. As for the fan, with the A/C running and the engine hot, it should be pulling fairly hard. You could try the rag test like we do for the EV clutch (yours is a thermal). Or check to see if it's better when you don't use the A/C (yeah, I know ). If it seems to keep the temps lower, I would suspect the fan clutch.

Now since yours is an '08, it has the thermal fan clutch. Given the temps you encounter over there, I would stick with ACDelco as it performs to spec and is better built. I tried to find it on RA and Amazon and I can't find it so I suspect that they are no longer produced by them. You might have to go to a Hayden. Make sure it's the thermal version as RA and Amazon also lists the EV version for your year for some reason.

 

[$ Khalid ! 9130]

the water condensate that dripped out? If it is leaking coolant, it should be addressed. That would explain the low coolant.

After going through it again it seems to be water condensate as its coming from the hoses going into the front wall of the cabin. If so I'm wondering where all the coolant went as there's nothing I see on the ground 🧐

I'll take it around the block after a while in slightly cooler temperatures without the AC and check if it runs cooler. I believe I did the thermostat when I got the TB so about 7 years ago I believe. So maybe it's time for another one 🥲

 

[Mooseman]

It might have puked out of the tank when you overheated and when it cooled down, it sucked it back in minus that you lost. Hopefully you didn't blow the head gasket. Keep an eye on the oil for milkshake, coolant smell coming from the exhaust, engine misfires, loosing coolant for no apparent reason, blowing coolant out when it's not even overheating, etc.

These things should alert us way earlier when it gets hot like this. I get worried when it's over the 100c mark and watch it like a hawk. I would shut it down if it were to go to halfway to overheat.

 

[$ Khalid ! 9130]

The head gasket is my main concern but I'm hopeful it's not that as of this moment. Symptoms of a head gasket would be mainly smoke from exhaust if I'm not correct!? Another thing going through my head is water pump maybe? Will try the Rev in Neutral to see if Temps come down a bit and single out the water pump

Update: Just went down and checked it out, the coolant seems to be level, started the car and let it idle for a while, the needle went up to the 100 mark and stayed there. So I thought I’d take it around the block. AC was off. Was able to go around twice before it went back to the red. I am also smelling something but it seems to be the water dripping on the exhaust manifold and burning up, I am not sure of the burning smell. Checked the oil it seems fine.

 

[Mooseman]

Water pumps usually fail either by the bearing or leaking. They don't really stop pumping unless the impeller has either rusted away or came off the shaft, which rarely happens.

Any of the symptoms I listed can be indicative of a leaking head gasket.

 

[TollKeeper]

Water pumps usually fail either by the bearing or leaking. They don't really stop pumping unless the impeller has either rusted away or came off the shaft, which rarely happens.

Any of the symptoms I listed can be indicative of a leaking head gasket.

Unless its a replaced waterpump with a plastic impeller pressed onto the metal shaft. I have seen a couple instances (not on this engine specifically) that the plastic impeller looses its pressed connection on the water pump, and no longer, or hardly, spins.

 

[Joe_67]

If it were me, I'd pressure test the cooling system to check it for leaks (it seems likely that you have one), replace the thermostat and the radiator cap. If you are worried about the head, you could also get a block tester and do that.

 

[$ Khalid ! 9130]

I don’t believe the water pump has ever been replaced AFAIK

@Joe_67 That is what I am leaning towards. I am terrified of driving it though and will most likely need to tow it to a shop

 

[Mooseman]

If the head gasket is already blown, it won't make any difference. You'll have to drive it to determine that. Just do the checks as described and go from there.

 

[$ Khalid ! 9130]

Blown head gasket would lead to rough idle, low on power and sluggish acceleration if I am not mistaken? Didn't experience any of these when I took it around the block a while ago

 

[Mooseman]

Not necessarily. I've seen blown head gaskets that ran perfectly fine except for a symptom or two like coolant in the oil or bubbles coming out of the radiator. Not all blown head gaskets go into the combustion chamber. Some lean into an oil passage or only allow exhaust gasses into the coolant. I had the latter on my snowmobile. It ran perfectly fine but pushed exhaust gasses into the cooling system, blowing out coolant out my reservoir. It only went one way and not burning coolant.

 

[$ Khalid ! 9130]

Hmmm. Will have to diagnose it further tmrw and check if my guy at the shop wants me to bring the vehicle for inspection

 

[Joe_67]

Like mooseman I've seen head failures where the car runs just fine. One was the exhaust ending up in the coolant (complete w/ coolant temps going high). Another was a minor misfire on one cylinder that I first took to just be a bad plug or wire. It wasn't a major, chugging, flashing engine light event. Just a little hiccup with a normal P030x.

If you're even slightly handy and have a place to work, pressure testing and block testing aren't hard. Big box auto parts stores often have the (simple) tools needed among their loaner tools and I'm sure there are any number of people on YouTube happy to show you how. It also wouldn't hurt to ask around for a mobile mechanic. There are a couple that run around my area. I have a roadside service, but still avoid the tow at all costs.

 

[$ Khalid ! 9130]

Another was a minor misfire on one cylinder that I first took to just be a bad plug or wire. It wasn't a major, chugging, flashing engine light event. Just a little hiccup with a normal P030x.

Damn!! I have been having an intermittent CEL with a misfire being reported for a while now. I thought it was a plug as well or wiring. Its been gone a while now so my mind never went there.

I would very much be working on the TB myself if the weather wouldn't fry me. I live in Saudi so tools and parts aren't readily available either.

 

[Joe_67]

Damn!! I have been having an intermittent CEL with a misfire being reported for a while now. I thought it was a plug as well or wiring. Its been gone a while now so my mind never went there.

I would very much be working on the TB myself if the weather wouldn't fry me. I live in Saudi so tools and parts aren't readily available either.

I wouldn't go straight to worst assumptions based only on that. Misfires are common. Head gasket problems not so much. On mine I never did check the compression. I just pulled the plug and found it contaminated with coolant. But those would be the two things (and could be one or both) - compression loss and/or coolant fouling plug. You said your misfire has been "gone a while now." Unless it's Christine and you drove it a lot in reverse, it would be most likely to just keep getting worse rather than better.

In any case, if you don't have a way to work on it you probably can't fix it. So just get it to the shop however you need to. The pressure testing and block testing are basic, routine and relatively inexpensive things as are things like thermostat and radiator cap replacements. If you have bigger things to worry about than coolant leaks or faulty thermostat it should show up in a basic cooling system check and service.

 

[Mektek]

The photos of the heater hoses at the firewall and the puddles below suggest that you may have a pinhole leak in the heater hoses. I cracked the plastic quick connects and ended up directly clamping generic new heater hoses directly to the metal fittings.

 

[$ Khalid ! 9130]

I wouldn't go straight to worst assumptions based only on that. Misfires are common. Head gasket problems not so much. On mine I never did check the compression. I just pulled the plug and found it contaminated with coolant. But those would be the two things (and could be one or both) - compression loss and/or coolant fouling plug. You said your misfire has been "gone a while now." Unless it's Christine and you drove it a lot in reverse, it would be most likely to just keep getting worse rather than better.

In any case, if you don't have a way to work on it you probably can't fix it. So just get it to the shop however you need to. The pressure testing and block testing are basic, routine and relatively inexpensive things as are things like thermostat and radiator cap replacements. If you have bigger things to worry about than coolant leaks or faulty thermostat it should show up in a basic cooling system check and service.

Will do. Thanks

The photos of the heater hoses at the firewall and the puddles below suggest that you may have a pinhole leak in the heater hoses. I cracked the plastic quick connects and ended up directly clamping generic new heater hoses directly to the metal fittings.

Come to think of it, I noticed there would be a drip onto the cat from the exhaust manifold, I dismissed it as condensation from the condenser but I guess you are right. Could be a leak in those hoses. Thanks for pointing that out. I have a video but I need to figure out how to post it

Updates: Videos are attached

 

[Mooseman]

That looks like clear water to me. Try to look at a better angle to see if it's coming out of the rubber nipple in the firewall. To check for a coolant leak at hose connections, once the engine is COLD, feel them at the connections with your hand for a slimy feeling orange liquid. If you have a leak, even a pinhole, you'll feel it even if it's too slow to see it drip.

 

[D Man]

Is the carpet wet in the cabin? Have you thought of a heater core or hose.

 

[$ Khalid ! 9130]

Is the carpet wet in the cabin? Have you thought of a heater core or hose.

Haven't checked that. Will have a look and see. Thanks

 

[Mike534x]

Now since yours is an '08, it has the thermal fan clutch. Given the temps you encounter over there, I would stick with ACDelco as it performs to spec and is better built. I tried to find it on RA and Amazon and I can't find it so I suspect that they are no longer produced by them. You might have to go to a Hayden. Make sure it's the thermal version as RA and Amazon also lists the EV version for your year for some reason.

I rechecked RA as well, it looks like the AC Delco version might be discontinued? It was listed a little over a month ago. The other part sites that had it in stock show out of stock as well, so it looks like the Hayden unit "might" have to be the go-to for thermal clutches it seems.

 

[Mooseman]

Quite possible since this platform has been out of production for 13 years. Could also be that Behr got out of its production too. Both the thermal and EV seems to be gone.

 

[$ Khalid ! 9130]

Update it seems to be the connector for the heater core that is leaking. Could be the gasket. Sadly the connector isn't available till Saturday. I thought about changing the hose as well just to be safe judging by the temperature here. That isn't available till next week. So guess its the waiting game till then

 

[$ Khalid ! 9130]

Update:

Well seems like I got to the bottom of this. Turned out the hose had broken off at the plastic connector at the hgeater core and had leaked out all my coolant. I had ordered the connector only as the hose is still a week away.



Thought I would look at it anyway as I couldnt bother waiting day to take it to the shop. Turns out the hose took the nozzle end of the plastic coneector with it.





Cut off the clamp and broke of the old plastic conector or what was left of it and used a generic hose clamp to tighten the hose directly to the inlet as i learned that the plastic connectors are one time use only, didnt want to waste this part.









A stupid mistake on my part was I was filling coolant in the reservior and not the radaitor as I am soo used to my Dads Yukon which has the reservior as the radiator fill.



So I drove it and it was still overheating. Then it clicked that the cap is a different on the reservior so I opened the radiator cap and as you can guess it was bone dry. Filled it up with 50-50 water and Dexcool and the TB is back in business.

Took it for a nice long drive temps staying under the half way mark.

I do intend on replacing the hose with the connector to stock fitting once the parts arrive, but for now I can happily cruise in my TB again.

Have to say its been a long time since I wrenched on cars and yesterday reminded me why I enjoy it so much!!