Head Gasket vs. IH Gasket Failure

[wutanec]

I don't drive my 90 ZR1 too often but when I do start it up in the morning, there is some white smoke coming out of the tail pipes and I do smell coolant burning, it goes away once I drive the car for a bit.
automatically I was thinking "uh-oh, the head gasket" but then after searching the forum, I feel like it could be IH gasket as well.

Here is a rundown of symptoms.

* Engine seems to be healthy and runs well
* The car runs hot but never overheats - seems to be normal based on forum feedback (Planning to get a Haibeck chip)
* White smoke coming out of the tailpipes with sweet smell, not so thick, it could be mistaken for condensation (but the smell gives it away)
* The smell and smoke goes away after the car warms up
* Oil seems to be clean without any sign of contamination
* There is a pool of coolant right above the driver side valve cover gasket (attached image)

I know it is not possible to accurately diagnose a problem without actually testing the car but I would really appreciate some opinions based on the history with these cars. I did not really budget for a head gasket job when I got this car lol. So I am hoping y'all tell me it is the IH gasket as that seems to be a job I could take myself

[Paul Workman]

More likely one of the IH gaskets is leaking near the 1-3 cylinder runners or the 2-4 runners. I'd do the easy stuff first, and pull the plugs, looking for the one(s) that are either wet with coolant or extra (i.e., steam cleaned) white. And, if any of the cylinders I mentioned indicate coolant, breathe a sigh of relief! Jerry's to the rescue!

The web between the coolant and the 1&3 and the 2&4 runner(s) is quite narrow - especially if the top end has been ported.

I replaced the plenum gasket three times (with nearly the same mileage as you have now) on my Z before (1) switching to the gasket from Jerry's Gaskets, and (2) applying 3M gasket adhesive to the plenum gasket around the coolant ports on the IH side of the gasket.

Also!! Try re-torquing the bolts holding the IH to the heads. (I found several of mine were loose) In fact, I put BLUE Loctite on the threads to keep the bolts from loosening again.

Unless the motor has been overheated at some point, the head gasket is not likely. So, unless you are experiencing the coolant spilling out of the over-flow reservoir or bubbles flowing out of the return lines in the reserve tank, the IH gasket(s) are not where coolant is getting into the cylinders.

As for the location on the cam covers you've indicated finding coolant, it is more likely it ran down the lip of the cam cover, down from the cross-over manifold gaskets near the front of the motor.

Too early to say, but my money would NOT be on the head gasket yet.

[Ccmano]

Originally Posted by Paul Workman

More likely one of the IH gaskets is leaking near the 1-3 cylinder runners or the 2-4 runners. I'd do the easy stuff first, and pull the plugs, looking for the one(s) that are either wet with coolant or extra (i.e., steam cleaned) white. And, if any of the cylinders I mentioned indicate coolant, breathe a sigh of relief! Jerry's to the rescue!

The web between the coolant and the 1&3 and the 2&4 runner(s) is quite narrow - especially if the top end has been ported.

I replaced the plenum gasket three times (with nearly the same mileage as you have now) on my Z before (1) switching to the gasket from Jerry's Gaskets, and (2) applying 3M gasket adhesive to the plenum gasket around the coolant ports on the IH side of the gasket.

Also!! Try re-torquing the bolts holding the IH to the heads. (I found several of mine were loose) In fact, I put BLUE Loctite on the threads to keep the bolts from loosening again.

Unless the motor has been overheated at some point, the head gasket is not likely. So, unless you are experiencing the coolant spilling out of the over-flow reservoir or bubbles flowing out of the return lines in the reserve tank, the IH gasket(s) are not where coolant is getting into the cylinders.

As for the location on the cam covers you've indicated finding coolant, it is more likely it ran down the lip of the cam cover, down from the cross-over manifold gaskets near the front of the motor.

Too early to say, but my money would NOT be on the head gasket yet.

I agree 100%.... the lower IH gaskets are one of the most overlooked causes of both coolant and oil burning issues.
H

[jss06c6]

Agree as well..here are a couple of pics of the head showing the proximity of the coolant passage to the intake runners.. this is also one of Jerry's IH gaskets.. look closely and you'll see some coolant remaining in the head..IMG_20180622_072557032.jpg1529535838959_adobe.jpg

Sent from my XT1585 using ZR-1 Net Registry mobile app

[Marc Haibeck]

The liquid in the first picture is most likely oil leaking from the rubber PCV vent tube grommet. Coolant would come from the area adjacent to cylinder number one. The cavity forward of the puddle looks dry.

[wutanec]

Thanks so much for the feedback guys. I think I am going to tackle this job, it wouldn't hurt to replace all the gaskets under the plenum. What are some of the parts that I should order in advance in case something breaks in the process other than the gaskets? is there a good diy on the forum somewhere that I could follow?

[Paul Workman]

Originally Posted by wutanec

Thanks so much for the feedback guys. I think I am going to tackle this job, it wouldn't hurt to replace all the gaskets under the plenum. What are some of the parts that I should order in advance in case something breaks in the process other than the gaskets? is there a good diy on the forum somewhere that I could follow?

Marc Haibeck has produced a number of articles, including a video on pulling the plenum - dos and don'ts along with how to.

Jerry's Gaskets can supply you with whatever gaskets you need (AND anything else too that might need, e.g., secondary vacuum circuit and actuators, coils, starter, etc.)

[wutanec]

With this condition, would it be imperative that I park the car and not drive it until the issue is resolved? Or would it be okay to drive it for a few miles here and there?

[TX '90 ZR1]

I agree with Marc about the fluid you are seeing comes from the PCV elbow. I had the same issue. It is hard to track it to the elbow, but just change it. I'll speculate you will find the lip on the elbow is deformed. Jerry's Gaskets has these.
I would hesitate to operate the car with a coolant leak into the intake. It will not get any better on it's own and could very well get worse.
Last thing you need is to fluid lock a cylinder and have to deal with all the problems this will cause.