1991 TPI ran fine before I started but had a coolant leak/seep from the intake manifold gasket. After replacing my intake manifold gaskets and reassemable (without replacing putting coolant) I started her up. Coolant coming from front. Shut her down. Check all the hoses and try again. same thing but can't see were its coming from. check everything again and decide to fill the cooling system. As I am filling the water tank with the second bottle of water I can hear the water draining but no water coming out the bottom. check my oil and its half way up the stick. I take the plenum off and turns out the intake plenum was full of coolant.

My questions:
1) Were could I have gone so wrong as to have a coolant leak what seems directly into the oil valley?
2) How can coolant get up into the plenum?

 

The throttle body has a coolant passage in it.. Would have to be a pretty massive leak from what you describe though..

Any chance you hooked the throttle body coolant line to a vacuum port instead?

 

I have the u shaped hose coming out of the front middle of the intake manifold to the bottom right passage in the TB and the hose that disappears under the a/c box on the firewall into the the bottom passage on the leftside of the TB.

 

Not sure from your description.. The coolant goes onto a nipple that is part of a thing that bolts up under the body. There is a vent line from the passenger side valve cover to the side of the throttle body (may or may not have a brass tube as part of it)..

Inverting either would allow coolant to drain into crank through valve cover and the throttle body to suck coolant into the vacuum port.

You could have a badly botched intake to head gasket issue which would allow large amounts of coolant into the crank, but wouldn't allow coolant into the plenum so....

 

Thanks for your reply. I removed the TB to check the coolant routing and they appeared to have been connected to the correct passages. The TB nipples both appeared to have had coolant in them before and the two other ports don't have water stains and are smaller ports.

I just can't see how I could have botched it so bad. It's a flipping gasket. When I filled the water tank it sounded like it was draining directly into the block, not a small leak. it took less than 2 min to empty 2 gallons of water from the tank into the oil pan

 

Blown head gasket, probably number 7, and filled up cylinder with coolant and backed up into top of head and on up to plenum. Take your spark plugs out and watch for the coolant to gush out. That's your bad cylinder gasket.

 

l98tpi, the car ran fine before I started this. Even if was a blown HG, that's a lot of volume to fill to get up all the way into the Plenum. And it started and ran before I filled the Rad.

 

Where was the gasket leak before you took the manifold off? In the front? Did you check the bottom of the intake and in the ports for cracks when you had it off? It sounds like a gasket slipped during install or a cracked intake.

 

Go ahead and bypass the TB. Its easy enough and at least you can eliminate that as a problem and it will be one less thing to deal with if you hafta take the TB/plenum off again. Since you dont live in Minnesota it should never be a problem.

Good luck!

 

I can't believe what I have been reading here, first of all the engine only had a minor seepage problem so why would a head gasket be blown? Second, the throttle body coolant passage does not enter into the throttle body intake area at all, it simply circulates coolant through the bottom and IF it did leak it would leak down onto the manifold. Cracks, a small possibility since there was a seepage problem before so as long as it obviously has to come apart again go ahead and spend some extra time cleaning all the gasket surfaces and inspect for any cracks but I really doubt if you will find any. Once you get it apart you will see right away what happened so grab the wrenches and get it torn back down. Last, leave the tube of silicone on the work bench with the exception of a dab in each corner where the head meets the block and a VERY thin skin on the gaskets to hold them in place during assembly. Check the service manual for the torque sequence of the intake bolts and follow it. One thing I always do is use a thread chaser to clean the bolt holes, you may have a false torque reading if a bolt is bottoming out before it is holding the intake tight. Take your time & do it right.

 

sounds like there was a problem installing the intake manifold's gaskets/intake.

Try again:
Remove intake, clean the intake/head surfaces throughly, clean the surfaces again, install new gaskets & deck seals(or RTV), set intake on, torque hadware by sequence, reassemble the remaining components, add fluids as needed.

 

Thanks for all your replies. I think Midnight85 is right that I won't know till I tear the manifold out, AGAIN. I thought I was careful and I did take my time and the surfaces were very very clean. The gaskets are visable and appear to be in the same location as the stock ones so if they had slipped they both side slipped the same and not much and certainly not enough to produce a gap around the ports (I would think). The coolant in the plenum is even more puzzling because I have removed the TB and can't fugure out were the coolant came from. I'll tear it apart this weekend.

 

EGR passage is a direct path from the intake manifold to the plenum....and there are cooling passages around the EGR valve/ports due to the extreme heat thats carried there.

I'd also take a very close look at the intake for cracks or warped surfaces.

I don;t think a head gasket (JMO) would send water into the plenum without "hydro-ing" a piston, after all, the piston is going down when the intake valve is open and IF that were filling with water the next stroke would be disasterous...ask me how I know.

 

OK, but, the only coolant in the system was what was left after I drain the raditor so the manifold was dry and the EGR valve, as I understand it, is closed at idle. When I started it up I never gave it any gas to rev or put a load on it. I really think I have two seperate problems. Water pump pushing coolant into plenum somehow and huge gap at the manifold mating to head somehow.

 

Use the right intake gaskets which are unique to the '91 and have retainers that fit into counterbores at the front and rear of the head bolt holes which maintains alignment (most importantly around the coolant passageways).

Make sure the coolant restrictors are positioned at the rear of the Intake - assuming you can find intake gaskets that have the retainers and the restrictors. These gaskets (with the retainers) are used on the ZZ4, current production 113 heads, and '91 F-Body's but those don't have the restrictors.

Longer length intake bolts go at the front and rear to accomodate the retainers.