98 GP GT Bad coolant leak

[bedlamparkcustoms]

So I had to rescue my daughter stranded on the highway this morning. There was a massive coolant leak and she says the car was smoking before she stopped. I was able to get it off the highway to a nearby gas station where i could see, after the smoke cleared, that the drive belt was now off, not snapped but off and coolant pouring out of the bottom of the car. Got it towed home and from what I can see, it doesnt seem like the pump is where the leak is coming from. It appears somewhere below the pump. Could this be the UIM / LIM gaskets??? There is an oil leak but doesnt seem to be coolant in the oil or vise versa. And what would make the belt come loose? And to top it all off, now the key wont come out of the ignition. HEEELPP!!!
thanks!

[rickisrad]

well the first thing is to look for what caused the belt to come off. Usually a frozen pulley would cause that, spin every pulley on the car to see if they move freely. The car may have overheated because the belt came off and there was no water pump to cool things off. once you find the issue that caused the belt to come off and fix that then you need to pressure test the cooling system to find the leak. If it were the UIM,LIM gaskets you would be able to see the coolant leaking from the gasket areas mainly at the corners where the RTV seals at.

[Tech II]

Large leak like that I would suspect the plastic elbow coming out of the lower intake....assume this is a 3.8.....do pressure test like Rick suggested....

[bedlamparkcustoms]

Thanks guys! Yes, it is the 3.8 not supercharged. All pullys spin freely and there is oil leaking from the head gasket but no coolant from what I can see. Tech II, when you say the plastic elbows on the lower intake, is that the same as the two coming from the belt tensioner? I think that may be the problem since all the coolant is leaking on the lower passenger side. I'm thinking I should replace the tensioner & elbows, and the LIM & UIM gaskets too. Does this sound like a good idea? The last thing I want to do (or can do today) is throw money at it with no results.
Pressure testing. Any write ups on that?
Thanks again. Big help!!

[rickisrad]

you need a special tool to pressure test the system. I am not sure if autozone or someone else rents them. They can be expensive, the one in the pic was around $200 dollars and then 30-50 bucks for any additional attachments you may need. you do not need to replace the tensioner if it is not bad. the plactic elbows run about $10 each at the dealer or dorman sells a set with both of them for around the same price. I would definately replace the intake gaskets (with aluminum framed), elbows, and plenum. check the balancer for any damage, belts usually do not fly off without a cause unless the belt was that worn or stretched.

[Brandybuck]

(It sure sounds to me like the leak might be from one of the plastic coolant bypass elbows, but I'm no pro. It's certainly not the intake manifold gaskets)

Replacing the UIM and LIM gaskets, however, might make it easier for you to replace at least one of your plastic coolant bypass elbows.

#31 in the above diagram is your larger coolant bypass elbow.

Here's a YouTube video I found very helpful when changing my upper and lower intake manifold gaskets: http://www.youtube.com/watch?v=YZjEKSqR5Qg.

This method will only get you to one of the two coolant bypass elbows. They're plastic, so they deteriorate over time, especially with the Dex-Cool. If you want to replace the other elbow as well, you may not want to follow this procedure exactly. If you do follow it, notice you'll need to do some fancy wiggling to get the LIM back into place - you'll have to simultaneously guide the elbow into its proper slot while maneuvering the rest of the LIM into its place, all just over your new LIM gaskets with silicone on them.

I believe that to access the other elbow you need to remove the alternator - it's somewhere in that vicinity.

[rickisrad]

^^ replace both while you are in there. if you do have any doubts about the tensioner or waterpump now would be the time to replace them. Be carefull with the wiggling, it can dislodge the gaskets or RTV bead. the ac delco dealer adhesive is what I use, it seems to hold up better. make sure you clean the surface where the rtv goes with alchohol first that way it sticks well.

[Brandybuck]

^^ (RTV silicone is what I meant - it's the small tube of black stuff that comes (or should come) with a good set of LIM gaskets. http://en.wikipedia.org/wiki/RTV_silicone.) I got my UIM and LIM gaskets at Autozone for a combined total of about $90. The kit included several o-rings, the RTV, and a gasket for the connection between the throttle body and the plenum (I didn't replace this gasket since I never separated the throttle body from the plenum; I took them out in one piece.)

[Tech II]

You don't have to put any sealer on the plastic elbows......just make sure the openings are clean of any rust/crud/debris....I just use petroleum jelly on the o-rings, to make installation easier....

[bedlamparkcustoms]

Guess I’ll hold off on the pressure test until I get everything back together. I was thinking maybe the tensioner failed and caused the belt to come loose. Could that be? The belt is in good shape but I’ll change that too, it is a few years old. And how can I tell if I need a new plenum?

Brandybuck, the diagram and link are perfect! Thanks! I got the tensioner unbolted and the elbow to the lower intake was in bad shape.
This is the underside...

I’m not seeing the elbow to the water pump though. Looks like the tensioner went right into the water pump. I had to wrestle with it to get it free. When I get the tensioner out completly I’ll have a better view, which leads me to another question. How do I get the two hoses out of the tensior?

Should they just pull out once the clamps are released and is the sleeve between the hoses and tensioner screwed in?

Thanks again

[Brandybuck]

You know you need a new plenum if the sealing surface of the old one is corroded/melted, especially around the EGR tube. There should be a metal tube protruding from the underside of the plastic plenum. When this heats up, it can melt the plastic surrounding it over time, forcing people to replace the plenum. But I believe (don't quote me on this, though) that if the underside of your plenum looks smooth and isn't corroded or melted anywhere, then you can replace it. That's how I dealt with mine, anyway. After cleaning the old gasket residue off of it with a scraper, it looked as good as new, so I put it back on.

(The same goes for your metal LIM; if the sealing surfaces are pockmarked with corrosion, then you'll either need to fill up the corrosion pits with RTV silicone before you replace it, or else get a new LIM for the extreme cases.)

[Tech II]

It's possible, there is nothing wrong with the tensioner.....coolant leaked onto the belt, and under the right conditions, could have caused it to slip off.....

Since you have removed the clamps from the heater core hoses, just twist them off the adapters.....I see the bolts backed out of the adapters in the picture.....tighten them before twisting the hoses off.....the adapters have o-rings....moving them while loose could cause them to leak later......

Once you have the tensioner off, you will find an orange o-ring on the bottom of the tensioner......that has to be replaced along with the plastic elbow going to the lower intake.....thoroughly clean the openings in the block, tensioner, and the lower intake.....apply petroleum jelly to the lower o-ring and to the o-rings on the elbow.....pull the tensioner into the block evenly with the bolts.....

The upper plenum leaks coolant, as has been stated, at the EGR opening.....at this time in the vehicle's life, it may have already been replaced.....after replacing the elbow and lower o-ring on the tensioner, and reattaching the heater core hoses, the next step is to properly burp the coolant system of air.....Lisle funnels with radiator cap adapters, works well on this engine......I don't think you need to pressure test the system, after seeing that elbow, but you can if you want.....

If you are still losing coolant, AND there are no EXTERNAL leaks, then you could possibly have a problem with the upper plenum......but make sure the system is properly bled first......no sense pulling the upper plenum for nothing......

[rickisrad]

^^ yeah no need to pressure test the system unless you run into another problem. That elbow was definately the cause like Tech II stated. with that kind of leak hitting the belt it definately could have slipped off. I would replace the belt if it got saturated with coolant though. you might want to replace the valve cover gaskets while you are in there, just to stop or prevent the common leak there also.

[bedlamparkcustoms]

Well it's been a few days, got a lot going on at 1 time. Anyway, In an effort to save time & $ I planned to hold off on replacing the UIM & LIM gaskets for now. I removed the tensioner assembly, cleaned it up, went to remove the bits of the old elbow from the intake and just my luck, it fell in rather than coming out. That can‘t be good. So now I’m forced to remove the intake manifold to get the old elbow piece out.
I followed the steps on the YouTube link, thanks again Brandybuck. Got the plenum, throttle body and all the manifold bolts out but the manifold wont budge . I see a torx type bolt below the manifold & above the water pump. Does this need to come out also, and if so what size torx do I need? Or, if that’s not it, what am I missing? Here’s the bolt in question…

[rickisrad]

No that does not have to come out!!