Coolant Leak

[RonnieH]

I have a very small coolant leak - experience tells me small leaks only become major headaches in time. My Vette is an '89 (27,000 miles). Anyway, there is some type housing on the intake just below the thermostat housing. It is just to the driver's side. One of the alternator support brackets is just above this housing. There are 2 torx head screws in this housing. I can see very small amounts of coolant bubbling from under this housing. I am at a loss as to what this housing is. It looks to be an integrated part of the intake, but I can see a seam/gap from which the coolant is leaking while under pressure and there are the two torx head screws holding it down. Can anyone explain what this housing is and what can be done to eliminate the leak? I would guess it is more than merely tightening down the torx screws. If the screws need to be removed/tightened during this process, what needs to be removed for easy access to the screws.

I would like to flush the radiator, but doing that before correcting the leak would only cause the leak to worse after cleaning out the system.

Thanks for any help you can provide.

 

[Ken]

I'm coming up with nada, nothing, zero, zilch... I can't develop a mental picture of my '87 stock configuration, and I can't find anything in two of my C4 maintenance books (neither Helm nor Haynes).

Take a picture - it would help.

 

[RonnieH]

Thanks for checking and the quick response. I thought about the picture as well, but as luck would have it, the digital camera is not working as it should. I have a feeling it will be easier and cheaper to get the camera working. This housing or whatever it is, is right under one of the support brackets for the alternator. The picture may be the only true way to describe it. I say a housing, but it looks as if it is built into the intake. If the two torx screws are removed, I don't believe the piece comes off. Where the coolant is leaking looks just like a small slit in the intake. Heck if I know!!!!

 

[RonnieH]

Looked at the leak again last night and suddenly got smarter (having glasses on helps). Leak is actually a small leak from the intake gasket. Last time I changed an intake gasket, it had a 2 Barrel Carb. sitting on it, so you can guess how long ago that was. Guess what I need now is if anyone knows of a good link/thread describing the procedure for removing the intake manifold. I'm thinking this is probably something I may not attempt myself. Not that it scares me to do it, but that I replace the intake gasket and after putting it all back together, have another leak due to pinching the new gasket or incorrectly torqueing down the bolts. The leak is so small, I could probably seal it with a high temp. RTV or high temp. Permatex. Has anyone ever tried that solution with success? The leak is very, very small. If it wasn't for noticing the faint odor after cutting off the car in the garage, you would never know there is a leak.

 

[Ken]

If you try and patch it, it's just going to start leaking again before long; this is a common occurence as the car ages. It has something to do with the fact that dissimilar metals (iron block/aluminum heads & intake) are used when building the engine. Corrosion occurs more rapidly in that case.

Your best bet is to replace the gaskets.

 

[RonnieH]

I tend to agree. Do you know of any threads/articles relating to changing gaskets. I would like to get some background before taking on the task. Trial and error is sometimes painful, time consuming and expensive. I would sure love to take advantage of someone elses experience. Thanks for the reply.

 

[Edmond]

There was an article in one of the Chevy magazines. I think it was JonM who posted a thread to it.

You're going to have a lot of bolts to take off to change that intake manifold gasket. First thing is the plenum, which are held on by T40 torx bits. Then you'll have to take off the valve covers to get access to the lower bolts of the runners. You'll have to take off the throttle body, which is only 4 bolts. Then there are all the vacuum lines, the EGR and all that fun stuff.

Put a day aside to get it done. It is very straight forward, really nothing complicated about it but there are a tedious number of bolts. The EGR bolts are 3/8's. There is also the brake booster line in the back of the plenum which I believe is 5/8's.

And be prepared to replace some of those brittle plastic vacuum lines because of the their age and the fact that you will end up breaking some of them.

There is also an electrical type connection on the bottom of the plenum along with two vacuum lines on the passenger side.

And also take off the clip that holds the throttle body cables in place, that bolt is a 10mm bolt. That bolt also serves purpose as holding the plenum in place with the runners.

 

[OLDCHEV]

Why not start out simple.

My 1990 Chevrolet Service Manual says to drop two pellets of GM stop leak into the system after changing the coolant. I do not have the part number handy but, the stuff looks just like the pellets in Barrs Stop Leak. I would use a small amount and drive it for a couple of hours.

Nothing to loose except a little gas, which will be repaid by the pleasure of driving a Vette!

 

[Ken]

Why not start out simple.

Damnit! Why didn't I think of that? Sometimes I forget the simplest things... :duh

 

[G Winter]

I have used the GM stopleak pellets many times. usually for small heater core leaks. Have had very good luck with it and has never plugged anyting it shouldn't . It still won't be a long term fix, in a yr or two you may have to fix it right but at least you can bide your time.
I have been told that GM puts the pellets in new cars in productions for a saftey measure.


Glenn

 

[Mart]

2 Torx head screws sounds like it is just the front to intake bolts, take the two bolts out put some thread sealer on them and reinstall with correct torque.

Just my .02 worth, I've seen a couple of bolts come loose before , they were on mine, but I did'nt notice it until I had everything but the intake off.:duh
Mart

 

[tonylong]

Just finished the same go round with my '89, after three years of a small leak.
The GM part no for the pellets is 3634621, they are a set of 6, use two at a time. The first pair went in 2-3 months ago. The leak dropped from a pint every two days to a half-pint a week. This car is a daily driver (25 miles a day). I just put in another pellet today.
Haven't noticed any other problems such as over heating, etc. All seems normal. I never saw any actual coolant leaking enywhere, it just seemed to disappear and the "Low Coolant" lamp would come on. If it gets worse again, I'll try re-torqing the head and manifold bolts.
LOL HTH