Coolant leak when engine cold

[Cidacious]

I had no coolant leaks at all until Tires Plus did a coolant flush for me. The next morning big puddle of coolant under car. Start car and gushy dripps coming off of the man trans. this lasted about 10 seconds then completely dry, no leaks. Took it to TP, they said could not find leak, I showed them residue on trans, they said thats weird. Next morning same thing puddle, gushy 10 seconds. left it overnight with them and they checked it next morning and said LIM or a head gasket is bad. I remember the tech telling me that he briefly pressurized the system to 25psi to check for leaks. The system is only rated for 15, I think. The shop of course says they are not responsible, and they wouldn't know if the head gaskets were bad until they get the manifolds off. I was going to do the manifolds anyway because I had a slight lope, but when I get them off is there a way to tell if I should go ahead and do the heads? Thanks everyone for your thoughts!

[55trucker]

I'd be absolutely certain that the leak is not something of a more simple problem before tearing off the intake assembly or the heads for this leak. Have a look at the heater core supply hose fittings under the throttle body. They are an O-ring seal that push/locks into a rotating quick disconnect fitting on both supply & return. Also take a look at the throttle body heater bypass under the upper plenum. It's a short vertical hose located between the plenum and the intake manifold hidden out-of-sight by the throttle body.

[Cidacious]

Thanks trucker, I looked around for that. I pulled the air cleaner and tube out of the car, and started the car with my shop light handy and found coolant coming out of the LIM onto the head and then pooling on top of the oil pump distributor cap, then pouring off of that. When I took the UIM and LIM off I found that the two verticle bolts were totally missing, this may have played a hand in it. I would be done with the project by now, but finding parts have become a problem. According to the service manual I have to replace all the rubber grommets on the LIM bolts. Nobody has them accept for GM. GM had only 15 total. Now they only have 3. I spent $100 just on those dumb bolts and isolators.(can't buy them separate). I had to wait for Linder technical services to get a batch of injectors ready too. I was thinking about doing the Oil distribution valley gasket too, but it technically wasn't leaking yet, and it would take a week to get it from GM, and they are the only suppliers. I think when Tires plus removed the upper radiator hose they put way too much force on it and compressed some of the soft dry rotted isolators, and that broke the seal.

[Cidacious]

On a side note I know I am going to kick myself in 3 or 4 years when I have to do my 92 GTP because I put the final new GM isolators in my 91 co-daily driver.

[pocket-rocket]

I've never in my years of working on an LQ1 replaced those isolators. I've also never had a problem with them.

[jmgtp]

When I took the UIM and LIM off I found that the two verticle bolts were totally missing, this may have played a hand in it.

They're not missing. The vertical bolts are meant to draw the lower intake manifold down and compress the gaskets so you can install the bolts that secure it to the heads. I've gotten away installing the 91-95 lower intake without using the bolts to draw it down but the 96-97 manifolds it pretty much becomes necessary or the bolts to the heads do not line up. After the lower intake manifold is installed you remove the vertical ones.

Sounds like your LIM gasket is leaking at the coolant ports, or the o-ring isolator to the UIM is bad. Should be an easy and cheap fix for a 91-95 motor. Also check to be sure it is not the quick release style heater core fitting in the lower intake... those go bad all the time. They too are pretty cheap and you can even find them in the 'help!' section of the auto parts store.

[pocket-rocket]

I've gotten away installing the 91-95 lower intake without using the bolts to draw it down

[Cidacious]

GM says 12 bolts are what is required for the car and considering that there are 14 holes it makes sense that the two mid ones are used only during install then removed and used on the sides towards the end. I think since I have 12 extra, I will pick two of the best old ones and leave them in the bottom. Does anyone see a problem with this?

[Cidacious]

I bought the Felpro UIM, LIM and o-ring package and to my suprise when I opened it up I found two EGR gaskets and the Oil manifold gasket!!!! I bought it from Autozone, $21.99, and on their website and everyone elses (rockauto, oreilly, advance, pepboys) just shows LIM UIM and o-ring. Thats great because GM only has a few Oil manifold gaskets left, and they take a week to ship, and I didn't find any of the listed places that had them to buy separately. I wonder if the Felpro head gasket set comes with the cam carrier gaskets.... Once again not advertised, and GM is limited on those as well and they are 33 bucks each w/discount.

[jmgtp]

I wonder if the Felpro head gasket set comes with the cam carrier gaskets....

If you're talking about the entire top end gasket set then yes it does come with it. If you mean just the head gaskets, no it does not come with them. I know, I've bought both.

[Cidacious]

Lim set fixed leak, and idle is better. I couldn't get isolators off old bolts so no vertical bolts in use, or were used during install. although some of you didn't use them with no problems, so not too worried.