'94 TS 3800: HUGE coolant leak - and other fluids

[jarl]

Ok... here I am, with my '94 in pieces. Or at least trying to...
How, for Pete's sake... HOW do you disconnect the heater pipe from the left side of the lower intake manifold???

Until now everything has been almost smooth, and I think I already identified the source of the leak (pictures later). But the @#$ heater pipe doesn't want to come out. It doesn't even bulge...

What I am missing here?

BTW: Big thank you for your previous post!

[Jrs3800]

As long as you have made sure you removed the 15mm nut that holds the Pipe to the Tensioner bracket( under the power steering pump, there is a 15mm that holds that tube... Also I am pretty sure you already removed the 10mm bolt from the Tube on the intake manifold... The tube can be a PITA... If you have a skinny flat blade screwdriver you may be able to tap it between the tube face and the manifold and be able to pop it out that way.. Thats usually how I have to remove mine as they want to hang onto the corrosion..

Any other questions, please ask..

If you can't get the pipe off I may be able to snap a few pics for you tomorrow afternoon..

[jarl]

Thank you for all your help...
I was finally able to remove it by prying between the manifold and the bracket on the pipe (the one used to fix it against the manifold).

What I found is that someone had already changed the gaskets, and apparently had overtightened the screws crushing the plastic part around the coolant passages. At least that's what it looks like. The interesting thing is that I found that the right rubber seal had disintegrated, shredded in pieces, and there was a large amount of oily sludge right underneath it, above the transmission. I hope that was the main oil leak. THANK YOU all for talking me into changing the lower intake manifold!

Now I need to clean the mating surfaces, but it looks like it going to take some time... any trick/magical product for doing this?

Also: there's some sort of cover on the right of the lower intake manifold, held in place with three bolts, and it looks like there's a coolant passage behind it. Has anyone had a leak around this cover?

[Jrs3800]

as for cleaning, I like to have some small rags to stuff the ports in the head( intake ports ) to avoid getting anything into the combustion chamber... and I like to have the Lifter valley covered with a towel, again to help avoid any debris... From there I used a scraper first, followed by a cookie( 3M Abrasive pad ) on my air angle grinder.. Followed with Acetone or Brake cleaner to clean the metal of any oils..

The cover that you are referring to does cover a coolant passage... Its not common for that cover to spring a leak... And about the only time you'll ever get a gasket for it is in a head gasket kit.. You might be able to get that from a dealer, but I have yet to see that cover leak on an L27, Thats not to say it could never happen, just simply in all of the years I have messed with 3800's I have never seen one leak..

as for the lower gaskets, yes they can be overtightened and become crushed.. This is the reason you will not want to overtighten the bolts.. Take the time to clean the intake bolts and use some Medium Grade Thread Lock( Blue ) when installing the bolts so that they will not back out..

Being that you have made it this far you must be Mechanically inclined.. And your saving a good chunk of $$$ too..

[jarl]

Hmmm... Let's assume for a minute I don't have an air angle grinder... Would a fine sandpaper (400-600) or a dremel tool with a small wire wheel work? I applied a Permatex chemical gasket remover to one of the surfaces and, while it works wonderfully on the intake passages, there are some areas around the coolant passages that look darker, and are raised a bit. They look different than the residue from the gasket elsewhere...

I was wondering how on earth did GM dealt with the slight corrosion on the mating areas, since they say not to use abrasives or scrapers...

[Jrs3800]

Yeah a wire wheel will work as well.. You might have some pitting on the heads where the coolant ports are... You could hit them with a little sand paper to get a better smoother surface.. I am lazy and use air tools all of the time, thats where the air angle grinder comes in.. I takes a minute to get the head/s good and clean.....LOL... Even a green scotchbrite pad should work..

The corrosion I try to get as smooth as possible.. But if you feel there is a little more pitting than you feel good about, you can smear on a thin layer of RTV near the coolant ports so that the gasket will seal a little better and help reduce the chance of a leak.. This is what I do when I have some pitting..

[jarl]

After a loooong time of not being able to work on the car, yesterday -finally- I managed to tighten the last screws and reinstalling the serpentine belt. I have not refilled/replaced fluids yet, but she's almost ready.

Putting together the things didn't take that long, but the heater pipe gave me problems to insert it again -of course-. I think the o'ring got damaged in the process... but we'll see.

In any case: when I was cleaning the mounting surface for the throttle body, I found an area around the water passages that was very brittle (guess how I found out?). The thin "lip" that holds the gasket from the wet side broke for maybe 1/2". Since it's on the wet side (under pressure) I'm not sure this would be critical, but there's some chance the gasket will not seal correctly. I applied some black silicone in the area as a precaution, but there's some chance I'll need to replace the plenum in the not-so-distant future

I'm starting a separate thread about that for clarity. I'll keep you posted

[jarl]

Well... I put some coolant and fired her up.
What I got:
- no dripping on the floor -absolutely amazing-
- a belt making ugly noises... or something running from the belt chirping
- white smoke coming out the tailpipe
- white smoke coming out from underneath the throttle body

I let the engine to warm up to working temperature, and made a brief tour including a short segment at 45 mph. Now the white smoke is gone, and the belt noise -whatever it was- is gone.

My guess is that coolant was being sucked through the throttle body from somewhere -probably the small part that broke-, and also dripping on top of the exhaust pipe underneath the throttle body. In any case, it looks like temperature stopped the leaks somehow (maybe it allowed the gaskets to conform better to the surfaces... who knows?).

I'm going to wait until the engine cools down and try to fire her up again. Hopefully the smoke and noise are gone for good.

[LMP]

Future viewers might like to know than this other thread
http://www.automotiveforums.com/vbul...d.php?t=969122
is a follow up to the present one.