Okay so quick run down..

It's been cold here for a while, and I had minimal heat for the duration .. I figured it was from a leaking heater hose letting some air into the lines.. I kept an eye on engine temps and they stayed low (under 180, but depending on temp outside as low as 165)

Fast forward a bit, it gets warm out, (40's) and I'm driving home, look at the temp gauge and see its overheating, pulled over and checked temp via odb it showed 230-240ish... ouch Normally I have the app on my phone running, for whatever reason I didn't this day ..

let it sit for a bit, ran the fans/blower got it down to ~200 and limped home, ran like crap to begin with but I managed to get home temps staying in 200-210 range (any higher I pulled over and let it sit for a bit before resuming my trek) this was a few miles I had to go


Replaced the heater hose, and thermostat for good measure. Did full purge of air from the system. The truck started up and kept temps in the 190-200 range (190deg stat, quick replacement was going to find the 180deg part # later)

Anyways, took it for a test drive, ran fine for 30-45mins keeping temps in the range above, then started creeping up over 200.. then 210 215 and i'd shut it down. I started it back up again a few minutes later to cycle water through to cool more via heater core and temps dropped back down to 19x range... What the heck?

Got back home, and had to stop and repeat the procedure above a few times... same results


Got home and looked things over, the upper rad hose is full of air again. What the heck?


Now my fear is it's head gaskets, truck has 170k on it I've had it for 10-15k of those I have no idea what has/has not been done to the truck prior.

I cannot think of another reason that much air would be in the system under pressure while the vehicle is in use..


I'm open to other suggestions/thoughts but need to confirm my suspicions before determining next steps....

 

My questions I have are:

Does it have the black expansion tank?

Have you checked freeze plugs?

Pull 1, 7, 2, and 8 spark plugs - look for one with a white insulator.

Exhaust smoke white?

Have you examined engine bay while temp is rising?

Check footwells with carpet lifted, soaked in coolant?

Milky colored oil?

That's a start at least.

 

Wow a reply.. haha thanks ihscouts...

1. Black tank, I replaced it last year though with one from rovah
2. Where are the freeze plugs located?
3. Can do that easily..
4. No, exhaust looks normal to me
5. Yes, nothing stood out as abnormal (no leaks etc)
6. This was an issue before replacing the heater hose, so hard to tell if its old/new.. Only on the pass side
7. Nope, oil color and level appeared normal

 

Been where your at a time or two......

2. Freeze plugs (Rave calls em "core plugs") are located on both sides of engine block (three per side) around the line of the knock sensor location (just a bit higher).

6. This is what I'm thinking, heater core leak or at least a hose leak. Dry it up, fill er up and repeat overheat. Other alternative is to remove dash -- not my first choice either but somehow your going to have to remove the heater core from the possibility list.

3. I'll wait to see the results for, very important.

 

Ok ...

Not sure what you are looking for with white ceramic (they are all white.. varying degrees of course)

#6 seems cleaner than the others...




Some of the guys on the local FB page got me a bit worreid about a hole behind the sleeve... and suggested an exhaust gas tester for the coolant, may pick one of those up and give it a shot..

 

Beautiful pics of the plugs, couldn't have asked for better. What I was looking for is the four corners of your motor - that's where the water jacket enters the heads AND through the head gaskets which is a common area for a head gasket to let go when your loosing coolant. Good news is that I don't see any steam cleaned, all 8 have carbon on the thread barrel and the insulators look like they should although you might be a little lean on 6 or it was just properly indexed to the intake valve. The only way you could steam clean an inner plug; 3, 4, 5, 6 is if the liner was an issue and usually it leaves a telltale sign on the plug. These cylinders are what's called Siamesed, they're sharing the jacket internally (a little closer to one another than the outers) and no ports through the block to the heads.

Anyways, I would test the coolant to keep ruling out. I have a couple more suggestions while we're still guessing;

Intake does have coolant running through it and it too can develop leaks in the back and front. The front is easy to spot because you can see the water trails on the valley pan. Sometimes just tightening up the intake bolts is enough to stop leakage. Sometimes it requires replacing the valley pan (intake gasket).

The throttle has coolant running through it - not for cooling but to remove ice. Air cools the faster it moves and condenses the moisture within it.

The water pump has a weep hole. It's located between the internal seal and bearing. To check if there isn't evidence of a leak is to pull up on your pump pulley (motor off) and if the pulley moves it's time to replace it. Your not loosing gobs of coolant but enough to gain air and no heat in the core.

Lastly the radiator. Check that you don't have wet spots or a thin stream. Remove the shroud and run up the motor to get it hot again. Have you looked inside the radiator? Is it clean up at the top where the bars start crossing to the other tank?

 

Oh, had another thought. The most common spot for the head gaskets to let go is not to let go into a cylinder but off the back end of the motor. You have to feel back behind the motor where the head and block meet. Usually it's 8 - passenger side but I've seen 7 do it too. Usually it gets so bad there's a puddle on the floor before anybody notices.

 

I'll take a look behind the motor and see if anything is apparent.

The rad seemed ok from looking in the top, I wanted to get it tested by a local rad shop though.


One thing now that i'm thinking harder bout this I recall on a few occasions pulling into work and seeing what seemed to be steam coming from the front of the rad (possibly...) was a very tiny amount almost unnoticable (slight breeze made it dissapear). This was also when it was really cold out (0deg? maybe colder)

Good news on the plugs, i debated trying to get an inspection camera to stick down in the plug holes and see if I can see signs of steam cleaning in there
(one of these perhaps.. Digital Inspection Camera) but money is very tight at the moment.. I need to work towards a keep or not on this truck unfortunately..

I don't recall seeing coolant by the throttle body, I had to replace some pushrods on the drivers side after I got the truck so I had all that apart and the hoses were solid. (leaking a bit back then, but not since I did the work).

Also, the water pump is about 1.5yr old, allmakes if I remember right, got it from Rovah as well


will double-check the water pump too..


Something else that may or may not help, when I was bleeding the air from the system the truck started to overheat slightly with the cap off the expansion tank. I'm not sure what the relevance of that is here but if it helps then cool .. .

Also, initially I was able to bleed the air out of the system, and the bubbles did stop (But the truck started overheating.. ) so this could cause a problem for me with the coolant co2 tester as well i suppose.

 

Damn, still not out of the woods on the head gaskets, not yet. If you can do a compression test on each cylinder to look for weak compression or leaking compression..... this would over-pressurize the cooling system by leaking past the head gaskets in a running motor and force coolant out which with the cap off the expansion tank sounds about right. The coolant test is just adding coolant to a bottle, motor cold. As far as the cooling system pressure test it's doing the exact same thing, looking for leaks by pressurizing the system. It's kinda like a compression test in reverse....

 

Probably head gaskets.

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Especially if it is using water - like a large beer glass every week or so.

See my post

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