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

[jarl]

Ok... I guess my question is which are the most likely culprits of fluid leaks on a '94 Transport with the 3800 Series I engine.

The one that has me very concerned is a very fast coolant leak. There is obviously a leak on the intake manifold near throttle body, but there's obviously another -much bigger- leak toward the back of the engine. The coolant is dripping from the driver's-side rear cradle mounting area, if that helps. I know the intake manifold gasket (the one between the upper and lower parts of it) fails very often on Series II engines. Are Series I prone to the same thing?

Beside this, the engine leaks oil and transmission fluid. Not too much, but enough to ruin the driveway if you leave the car there. Other than the valve covers, is there any other usual place to check for oil leaks? And for ATF?

Finally, this car has another annoying "detail": under some circumstances, that I have not been able to determine completely, the engine stalls. This happens when the car is still at red lights or intersections, even if I put the transmission in neutral. Any idea what should I look for first?

Thanks!

[jarl]

BTW: I checked the tube nipple on the intake manifold, and it looks like it has been replaced already with the metal one, and I don't think it's leaking. Ideas?

[96tsport]

Engine light coming on? Could be an old fuel filter & not sure about your engine but a bad IAC can cause problems and or a coolant temp sensor. Should check out some spark plugs too. Your engine is not known to have intake coolant leaks like the 3.1 or 3.4

[jarl]

LMP: Do you mean the heater hoses for the rear of the car? I thought those were used on Canadian models only. I'll try to check anyway... It's just so difficult to check that area...

'96: The check engine light is on, indeed. My car has the ODB "1.5", though, and the person who tried to pull the codes seemed a little less than competent at that, so I guess I'll have to check that again. I found (and replaced) some cracked vacuum hoses, but I have the alternator out of the car (broke the terminal on the cable that goes to the battery ) so I can't check if this made any difference right away.

I know the '94 Series I are not supposed to have intake leaks (these have an aluminum lower intake and plastic upper), but there's coolant collecting on the spaces on the lower intake in front of the throttle body... so I guess the gasket between top and bottom of the intake manifold just failed. I can't believe so much coolant is escaping from there, though.

[jarl]

The arrow point at the source of the visible leak... it's the hidden one that is giving me problems, though

[Jeffrv]

Jarl:
I had a coolant leak in that location by the EGR valve on my 95 TS with 3.8..intake manifiold gasket leak. When I changed mine, it was loosing about a liter a month of antifreeze. A simple pressure test shows that clearly.
As far as the rear heater hoses ( and the associated valves) they are installed on all vehicles with optional rear heaters, not just Canadian cars ( altho all Canadian cars had them)
Jeff

[jarl]

Thank you for confirming this, Jeffry. So the leak was on the gasket between the two components of the intake manifold, right?

If I were to run the car as it is right now, I bet it would leak a liter in one hour, or maybe even less time. My impression is that it is too much for that gasket, but I'll replace it anyway. How hard is it to replace it? Do you have a link to a good thread or site with the information, or you followed the service manual instructions?

I know there was a TSB regarding the intake manifold of several models, but I don't know if this particular model was affected or if the information on the service manual is still valid.

Also: I checked the options list inside the glovebox, and according to it my TS doesn't have the rear heater option.

J

[Edit: I found this: http://www.youtube.com/watch?v=iVdN627dtx0 ... Interesting, but doesn't explain the full thing...]

Originally Posted by Jeffrv

Jarl:
I had a coolant leak in that location by the EGR valve on my 95 TS with 3.8..intake manifiold gasket leak. When I changed mine, it was loosing about a liter a month of antifreeze. A simple pressure test shows that clearly.
As far as the rear heater hoses ( and the associated valves) they are installed on all vehicles with optional rear heaters, not just Canadian cars ( altho all Canadian cars had them)
Jeff

[Jeffrv]

Yes it was leaking between head and manifold. At 1 liter her hour, that does sound a bit more than just a gasket, but could be possible. Other area would be frost plug/block heaters to look for. I still think having the sysytem pressure tested will pinpoint your problem and possibly save needless work. Pressure testers can be had for the $100 range or perhaps you could borrow one.
Changing the gasket was pretty straightforward, except the manual says not to take the upper plenum off unless you are changing parts. I spent a day and a half trying to get the manifolds off as an assembly before giving up and removing the upper plenum then the lower manifiold..in about a hour and a half. many members have strongly cautioned against using aftermarket gaskets to put the engine back together, they just don't seem to last as well as actual GM parts. Also, while you are there, it would be a great time to change heater hoses, you can actually get at them!
Jeff

[jarl]

I'm sorry I think I missed something

On the attached image (from Autozone repair guides), the green color is where the coolant is pooling (above the lower intake manifold), and it's apparent the coolant is leaking between parts 163 and 164 (between the lower and upper parts of the manifold). Are you saying the leak actually comes from the gasket between the lower manifold and the head (#113 on the image)?

I thought the gasket that needs replacement is the one between the two parts of the intake manifold (not shown on the image). It looks like the P/N of that gasket is MS95830 (Felpro).



The gasket:

[Jeffrv]

Yes, on my 95 it was the failure of the gasket #113 that caused my leak. At first I thought it was the thermostat gasket, and you could see coolant in the nooks and crannies of the lower manifold, but once a pressure test was applied, it was easy to see where the problem was. Wind at road speed blows oil and coolant leaks all over the place, and there really wasn't, in my case, much of a leak at idle, engine needed to be working for it to become apparent.
Jeff

[Jrs3800]

If the gaskets have never been replaced on this motor, you need to go ahead and replace them.. The lower gaskets should run about $20-25, and the upper to lower gasket should be about $15..

[jarl]

Thank you for keeping the thread alive
I don't know about the past of this car. It looks like it has been neglected somewhat before the previous owner decided to have some stuff fixed, but I don't know if gasket #113 has been replaced. I agree I should change it, but with my luck I wanted to keep my intervention in the car to an absolute minimum, and taking it to a mechanic is not an option at this time.

Jeffry: I'm afraid I didn't mention something very important: the leak happens even at idle. I'm fixing other things on the car (interior stuff) and I don't drive it much... just a few miles every other week to keep the battery charged. The last time I looked under the car -after being parked a day or two- I saw a large pool of coolant on the floor, and when I started the engine to see where it could be coming from I saw the large amounts of coolant dripping quickly under the car, around the driver side rear cradle mount. The pool of coolant on the lower intake manifold has always been there and the area under the throttle body looks wet, so my assumption was that it came from there. I might be wrong, though...

[Jrs3800]

I think your assumption may be right... If its leaking near or around the throttle body the dribbling coolant would fall on the drivers side of the cradle.. so you may be onto something..

The areas I circled in the pic below is where the upper to lower gasket is prone to leaks.. as well the Throttle body gasket can leak too..

[jarl]

Great... I guess...

I already bought the lower intake gaskets this afternoon, but of course there's always the option of returning them. The question is: is it common for '94 3800 Series 1 to require these lower intake gaskets replaced? If we were talking about a newer 3.1 or 3.4 I wouldn't doubt it for a minute, but I have learned the hard way the "if it's not broken, don't fix it" (BTW: What are the chances of screwing up something big time while replacing the lower gaskets? I have been working on cars for years, but I have tried to stay away from the engine's guts from day one )

Assuming I decide to change the gaskets: the instructions for the lower gaskets (Felpro) say not to use any kind of adhesive, but all the information I find on the web says otherwise. Should I use RTV when installing the gasket? If so, does it need to be the "high temperature"-"sensor-safe" type? What about the upper gasket (Felpro as well but didn'tcome with instructions)? Should I apply RTV to it as well?

Thanks!

[Jrs3800]

We'll start with the upper to lower gasket first... This gasket will be install dry, use no adhesive at all.. You may consider using Medium grade threadlocker( Blue ) to help keep the bolts from backing out.. When you go to tighten the upper intake I believe it should be 7 Ft lbs, what ever you do try not to exceed 10 ft lbs.. Good and tight with a 1/4 " Ratchet will do the trick..



Onto the lower intake gaskets..

Some will look worse than these, some will look better..
What you will notice is a crack in the gasket as it has degraded to the point of a coolant leak.. Some of the leak made it to the outside of the motor, the other part of the leak was wicking over to cylinder # 5 port front bank.. Look at the pic and you'll see the nasty looking port of the intake gasket..


The gasket on the rear side doesn't look bad, but it was seeping coolant to the outside..


No matter what, being that the engine is a 94 I would replace those gaskets.. The front gasket off the motor I was working on crumbled when I took it off... I had a good idea that that would happen so i had the lifter valley covered with towels to catch anything that might fall in..

For the lower gaskets, if they didn't come with a tube of Silicone black( sensor safe ) then I would use Permatex Ultra Black ( High Temp sensor safe )... Once everything is clean and ready for the gasket install, add a good dab of the Ultra Black at each corner of the block and head and set the end seals in place, then add those same dabs on top of the seals, set the gaskets in place( they have set pins ) and add those small dabs again... From there you will be able to install the intake..

Some of the cross brackets for the alternator and power steering pump will have to go.. Under the alternator will be the bypass hose / heater tube.. The metal tube is held in place with a 15mm nut, its location is under the power steering pump( wish I had a pic for you ).. The tube is in the intake with a 10 mm bolt... You may have to fight that one out of the intake, but be careful as you don't want to break it... Your intake kit may include the O ring for the tube...

If I could be there to help you, you'd see how easy it really is compared to other cars/ vans...lol... I'd rather do gaskets on an old 3800 Dustbuster anyday over a 3400 U body van( I still have scars from the 3400's )

If you have any other questions just ask..