98 GP GT 3.8l overheating with new parts

[craigw71]

I have replaced the Radiator, Waterpump and upper/lower hoses. I am on my 3rd thermostat (2 Superstat and 1 OEM regular stat). Upper hose is really hard and cold even after I bleed the air from the system.
This was done due to the original radiator splitting and leaving me on the side of the Interstate.
It did overheat. There are no leaks that I can find, no noticeable smoke coming out of the exhaust. And it is really hard to start now whether hot or cold.
Am I burning the coolant and fouling the plugs in the process? Why am I still overheating????

[richtazz]

you need to check and see if your UIM (Upper Intake Manifold) has failed, a very common issue on 95-99 3800 Vin-K 3800's. The factory UIM is too thin around the EGR stovepipe, and will erode causing an internal coolant leak that normally ends up in cylinders 5 and 6. AS this leak gets worse, it can pump so much coolant into the cylinder that it hydrolocks and can bend a connecting rod or blow a head gasket/crack the head.

[craigw71]

So does anyone have the procedures to do the UIM?
I guess that would explain the hard starting pretty quick. UIM and new plugs and wires on the list to do now.

[richtazz]

The UIM is not a difficult job, but I would suggest having a repair manual handy for fastener torque values and torque sequences. The proceedure is kinda long to post here, but you could try autozones website. They have repair proceedures for many cars on there.

[craigw71]

4pm:
OK, so yesterday and today I replaced al of the following: UIM Gasket, Wires, and plugs.
Car is back running smooth at idle again, white smoke is gone for now, but it still overheated when I was checking it out. Upper hose got hot so I am assuming that the thermostat opened properly.
Someone tell me whatelse I could have missed. I dont have any leaks that I can see.

6pm:
I'm going back into the inards and replace the Lower Intake Gasket like my gut was telling me to do all along. I just checked it after letting it cool for a couple of hours and it was trying really hard to start so I just gave up. Evidently the guy that overheated my car, did it for so long that it blew the lower gasket also as I still have coolant getting into the plugs on 5 and 6.

Wish me luck, I'll let you know in a couple days how it goes.

[tblake]

NO, the lower intake gasket wont allow coolant into cylinders 5 and 6. If your plugs are white from coolant and you getting high pressures into the coolant system very fast right after startup, chances are you have a blown headgasket.

[craigw71]

Hey guys,
I got down into the Lower Intake tonight and the gasket is in pretty bad shape. I found the areas where it has failed and let coolant into the back of the valve chamber.



There was also 2 of the 4 coolant ports that were 60% and 100% blocked. The other 2 were clean and ok. Dex-cool is out of my engine for good. Will do the yearly flush and clean from now on.
I dont think the original owner did a very good job of overall maintenance so now I am going to have to catch it up.

I'll go and get the parts from the dealer tomorrow so I know I get the latest parts.
Other than the LIM Gaskets and the Elbow at the idler pulley, what else would I need to be getting?

[tblake]

I dont know man. You say that you have high pressures in your cooling system right after startup???? I myself might pull the heads off too and replace the head gaskets. While the UIM is off check to see if its melted near where the EGR stovepipe is. What richtazz said earlier in the post.

[craigw71]

I would love to pull the heads off while I have it open but I have never done that. What is involved? Just unbolting like the Plenum and UIM then that would be easy.

If it is more along the lines of removing the valves then I would think twice.

What do you think? DIY or not?

I have the ability and dont mind my hands getting dirty but not any specialized tools .

Thanks for the help so far.

[richtazz]

If you pull the heads off, they should be checked at a machine shop for trueness. You wouldn't want to put a warped head back on and do it all over again. To remove the heads, you don't have to mess with the valves, but you will have to loosen the rocker arms and remove the push rods obviously. the biggest obstacle is getting the exhaust manifolds loose, as the bolts corrode and can be a bear to remove without breaking any bolts off.

[craigw71]

Hey guys, me again. Can you tell the excitment in my voice.

I just completed the UIM/LIM gasket replacement and everything looks great but I am still billowing white smoke from my exhaust, I guess from burning coolant.

Am I looking at replacing the head gaskets now? any advice before I start the tear down again?

I need drink, this is getting on my nerves.

[tblake]

Is it still running rough? Did you replace the plugs? If you did how did the new ones look? Do you have access to a compression tester? If you can get one (maybe borrow it from autozone for free), disable the fuel system by pulling the fuel pump relay, also unplug the ignition module to keep from sparks arching all over the place. Then block the throttle open and check compression. After 6 puffs of air, allow the compression guage to sit there and watch and make sure that the pressure isnt dropping. If it is, remove the radiator cap and listen for air bubbles escaping. Do this for all six cylinders and compare the results.

[tblake]

Oh, by the way, you could grab a can of panther piss (PB Blaster) and start soaking the exhaust manifold bolts just in case you have to go further inside.

Please post your findings, Good Luck!!!!!!!!!!!!!!!!!!!

[richtazz]

REmember, coolant could have gotten on the converter grid, and may burn off for a couple of days. If the steaming decreases, and you don't see the coolant level dropping, then you may be fine. If the coolant is dropping it's head gasket time.

[craigw71]

AHHH, didnt think of that, there may be a good bit of liquid in the CAT. I will check the level when I get home but I am afraid it will be low and lead me into the heads.

We'll see, I'll let you guys know.

OBTW, Thanks for all the help so far on this problem, I really do appreciate it.