Sometimes LT5 will drive you nuts!

[secondchance]

I have been chasing mysterious coolant loss since early March. Eventually I ruled out (at least for now) head gasket failure because I don’t see any exhaust contamination in the coolant and coolant is disappearing as opposed to being pushed into the over-flow bottle.
Then two weeks ago my battery died on me suddenly and wouldn’t hold the charge. I took it back to the Sears and replaced it with a new Sears Die-hard but still wouldn’t hold the charge – dreaded parasitic loss! While checking the coolant level in the expansion tank I heard a faint whirr of electric fan coming from AC evaporator housing. Turns out my HVAC fan controller has failed and failure was such that, even with the ignition turned off, HVAC fan was running at low speed constantly – fixed!
One day I am driving back home from work and I noticed bluish smoke coming from my exhaust. At first I thought it was coolant steam but I could smell the burning oil. After some thought I remembered when I drained my oil catch can about a year ago, after dropping in my mini-stroker, catch can had this gooey, almost caramel like, mix of engine oil and coolant resulting from coolant getting into the cylinder. Theorizing that he same goo must have entered the PCV valves on its way to the catch can I removed both PCV valves. Sure enough driver side PCV valve was clogged shut. Cleaning out both PCV valves seems to have cured oil smoke from the exhaust.
Finally, after much thought and failure to track down where the coolant was getting into the intake despite multiple plenum pulls and inspections, I ran a bottle of coolant dye as I drove to WAZOO HQ last Saturday. Coolant was drained and plenum removed carefully to minimize coolant spill over the injector housing. Once the plenum was removed black light revealed thin line of coolant glowing along the bottom edge of #1 cylinder secondary intake/IH gasket and not as pronounced but the same the same in the #2 cylinder – both facing the coolant port on injector housings.
Permatex, Form-a-gasket #1 (fast drying/hard curing sealant) was used to reassemble the injector housings to the heads after quick check with aluminum straight edge. I had a bit of fiasco mistaking kinked throttle cable for a vacuum breach (2,000 rpm idle) resulting in unnecessary removal of plenum followed by starting the motor before torqueing the plenum bolts (fatigue induced stupidity). During this process (and reuse of plenum gaskets) I may have damaged plenum gaskets because I am still getting some coolant seeping into to driver side bank (most likely #1 or #3 cylinder).
I have a new set of plenum gaskets coming from Jerry’s and hopefully replacement of plenum gaskets will cure this issue once and for all.

Thank you Jim for your never ending support & help!

[XfireZ51]

Yep. And if the IHs are ported there's an even greater possibility of coolant being sucked into intake. I used Permatex #2. No worries now for 3 years.

[secondchance]

Yep. And if the IHs are ported there's an even greater possibility of coolant being sucked into intake. I used Permatex #2. No worries now for 3 years.

Any thought on using Permatex #1 or #2 around the coolant ports on IH top to bottom surface of the plenum?
Any thoughts on doubling up on plenum gasket?

[XfireZ51]

Any thought on using Permatex #1 or #2 around the coolant ports on IH top to bottom surface of the plenum?
Any thoughts on doubling up on plenum gasket?

My plenum is blocked off so no issue there. I tried a thicker gasket and that made it worse. The coolant seems to burrow through the gasket so the thinner the better. Also installed dry aside from Permatex #2. Also would NOT use FlatOut gaskets.

[5ABI VT]

I have been chasing mysterious coolant loss since early March. Eventually I ruled out (at least for now) head gasket failure because I don’t see any exhaust contamination in the coolant and coolant is disappearing as opposed to being pushed into the over-flow bottle.
Then two weeks ago my battery died on me suddenly and wouldn’t hold the charge. I took it back to the Sears and replaced it with a new Sears Die-hard but still wouldn’t hold the charge – dreaded parasitic loss! While checking the coolant level in the expansion tank I heard a faint whirr of electric fan coming from AC evaporator housing. Turns out my HVAC fan controller has failed and failure was such that, even with the ignition turned off, HVAC fan was running at low speed constantly – fixed!
One day I am driving back home from work and I noticed bluish smoke coming from my exhaust. At first I thought it was coolant steam but I could smell the burning oil. After some thought I remembered when I drained my oil catch can about a year ago, after dropping in my mini-stroker, catch can had this gooey, almost caramel like, mix of engine oil and coolant resulting from coolant getting into the cylinder. Theorizing that he same goo must have entered the PCV valves on its way to the catch can I removed both PCV valves. Sure enough driver side PCV valve was clogged shut. Cleaning out both PCV valves seems to have cured oil smoke from the exhaust.
Finally, after much thought and failure to track down where the coolant was getting into the intake despite multiple plenum pulls and inspections, I ran a bottle of coolant dye as I drove to WAZOO HQ last Saturday. Coolant was drained and plenum removed carefully to minimize coolant spill over the injector housing. Once the plenum was removed black light revealed thin line of coolant glowing along the bottom edge of #1 cylinder secondary intake/IH gasket and not as pronounced but the same the same in the #2 cylinder – both facing the coolant port on injector housings.
Permatex, Form-a-gasket #1 (fast drying/hard curing sealant) was used to reassemble the injector housings to the heads after quick check with aluminum straight edge. I had a bit of fiasco mistaking kinked throttle cable for a vacuum breach (2,000 rpm idle) resulting in unnecessary removal of plenum followed by starting the motor before torqueing the plenum bolts (fatigue induced stupidity). During this process (and reuse of plenum gaskets) I may have damaged plenum gaskets because I am still getting some coolant seeping into to driver side bank (most likely #1 or #3 cylinder).
I have a new set of plenum gaskets coming from Jerry’s and hopefully replacement of plenum gaskets will cure this issue once and for all.

Thank you Jim for your never ending support & help!


I applaud you on diagnosing and getting it all sorted out. Itll be a good feeling once its all done. Many people would have paid half the value of the car at a shoppe trying to trace those symptoms and probably not even have it repaired right. :cheers:

[secondchance]

I applaud you on diagnosing and getting it all sorted out. Itll be a good feeling once its all done. Many people would have paid half the value of the car at a shoppe trying to trace those symptoms and probably not even have it repaired right. :cheers:

Thanks for the encouragement. It's pretty bad when one realizes that of so called professional mechanics only few really know what they are doing.

[Paul Workman]

In my experience, damn few shops are worth a damn on most cars, leave alone an LT5. I don't know about y'all, but I support the Registry BECAUSE of this site and the people and expertise they bring to this particular car.

[Dynomite]

I have been chasing mysterious coolant loss since early March. Finally, after much thought and failure to track down where the coolant was getting into the intake despite multiple plenum pulls and inspections, I ran a bottle of coolant dye as I drove to WAZOO HQ last Saturday. Coolant was drained and plenum removed carefully to minimize coolant spill over the injector housing. Once the plenum was removed black light revealed thin line of coolant glowing along the bottom edge of #1 cylinder secondary intake/IH gasket and not as pronounced but the same the same in the #2 cylinder – both facing the coolant port on injector housings.

Permatex, Form-a-gasket #1 was used to reassemble the injector housings to the heads

That is some very interesting professional diagnostics for sure :thumbsup:

Yep....Jerry take note.......another Permatex Guy :D

I use a bit of Permatex on all gaskets holding back coolant.

[secondchance]

In my experience, damn few shops are worth a damn on most cars, leave alone an LT5. I don't know about y'all, but I support the Registry BECAUSE of this site and the people and expertise they bring to this particular car.

Thanks to the Net Registry I met up with WAZOO guys. Without the WAZOO I would never have had access to hydraulic lifts, all tools (some custom fabricated by Phil), wealth of knowledge and generous help and support of great group of friends. Now I own a ZR-1 I never thought I could AND able to maintain it.

Net Registry and the WAZOO gave me a car, a great hobbby and terrific group of friends! Who needs a stinking dealer shop?!

[dredgeguy]

Thanks to the Net Registry I met up with WAZOO guys. Without the WAZOO I would never have had access to hydraulic lifts, all tools (some custom fabricated by Phil), wealth of knowledge and generous help and support of great group of friends. Now I own a ZR-1 I never thought I could AND able to maintain it.

Net Registry and the WAZOO gave me a car, a great hobbby and terrific group of friends! Who needs a stinking dealer shop?!

I will certainly agree with you. Our group has talent and would give you the shirt off their backs. I recall Phil driving 1.5 hours for a Wazoo day and then driving home and back (3 hours) to get a part and tool we needed to fix my car. Then going home at almost 10pm. 6 hours of driving to help me out. Just a fantastic group. I said it before and will say it again, anything happens to my Wazoo brothers, bye bye Z and hello Toyota;)

[Kevin]

I wish everyone had access to a group like wazoo or fbi. These cars will drive you to the absolute edge of reason. Vac leaks, coolant leaks, current draws....Without the registry and the net before it i'd have sold this car years ago

[secondchance]

I said it before and will say it again, anything happens to my Wazoo brothers, bye bye Z and hello Toyota;)

Oh! Bite your tongue. Never a Toyota... Seen one too many growing up in Korea - South Korea that is.

[secondchance]

I wish everyone had access to a group like wazoo or fbi. These cars will drive you to the absolute edge of reason. Vac leaks, coolant leaks, current draws....Without the registry and the net before it i'd have sold this car years ago

Kevin. Don't forget. These cars are 20 to 25 years old. Considering the age, these old girls are doing quite well!
I still remember meeting my first red/black 91 at Sports Chevrolet in Silver Spring, Md in October 1991. Took her out for a spin and hopelessly fell in love. Totaled her on I-4 in Florida back in 1996. Drove BMW 850i for 4 years but couldn't get ZR-1 out of my system. So, I picked up a 94 in 2000. It took me 15 years to bring her youth back and then some. I may get old but my Z is getting younger, better and stronger - I just love it!!!