IH gasket coolant leak w Pics
 

For the past several weeks I was noticing a bit of white smoke coming from the exhaust. It went away once the motor was warmed up and I had
attributed it to the new MagnaFlow I had installed. But there was a bit of a coolant smell tho. However, I did a WOT run and then the smoke really came out. SO, off came the plenum. =Jeff= and I did a coolant pressure test as recommended by Ccmano and karterdon, and we saw coolant dropping into the #4 primary runner coming from between the cylinder head and the IH. I had used .030" gaskets when I did the P&P this winter.
I think that's too thin to hold up. Now replaced with .060" from FlatOut Racing. Motor runs much stronger when firing 8 cylinders. :dancing
While I was at it I blocked off coolant passages at the IH/Plenum interface
Pics below:

http://i187.photobucket.com/albums/x...antleak026.jpg
http://i187.photobucket.com/albums/x...antleak027.jpg
http://i187.photobucket.com/albums/x...antleak028.jpg
http://i187.photobucket.com/albums/x...antleak029.jpg
http://i187.photobucket.com/albums/x...antleak025.jpg

Re: IH gasket coolant leak w Pics
 

Good to know! Mine has had the same gasket from FO since March with no trouble. Installed mine dry this time.

The ones I've taken apart seem the bolts could use a retorque. Was planning on checking torque of the IH this fall.

Re: IH gasket coolant leak w Pics
 

Any pictures of that? What did you do to block it off?

Was the I/H to head gasket a GM one?

Re: IH gasket coolant leak w Pics
 

Bob,

He might be talking about HOTB Issue #10, Apr 07 that Locobob wrote. Great article and I followed step by step to do mine too.

http://i78.photobucket.com/albums/j8...1/DSC00825.jpg

Re: IH gasket coolant leak w Pics
 

Bob,

Sorry didn't take pics, but its the IH coolant passage that mates with the plenum passage to the TB. Found on either side between primary #4 and secondary #2, primary #3 and secondary #1 runners. I used a 1/8 NPT countersink socket head plug. Drilled out existing hole with 21/64" bit, then tapped with 1/8 NPT tap. Got all at ACE hardware. I put a bleeder valve on the passenger side coolant tube using the same bit and tap.
The I/H gasket I used were from Flatout Racing. Only this time I used a .060" rather than a .030".

Re: IH gasket coolant leak w Pics
 

How come whenever something odd happens -=jeff=- name is always close at hand??????

Re: IH gasket coolant leak w Pics
 

Informative Thread :thumbsup:

Re: IH gasket coolant leak w Pics
 

Cause I am the second set of eyes.. LOL

Re: IH gasket coolant leak w Pics
 

Psst, I told you to pull the injector housing :D

Re: IH gasket coolant leak w Pics
 

:worship: I am not worthy. :worship:

Re: IH gasket coolant leak w Pics
 

These damn guys from Hawaii..... Showoff!!!!!

Wow that is what a Z motor should look like, PERFECTO!!!!!!!

Re: IH gasket coolant leak w Pics
 

Hawaii:

http://www.youtube.com/watch?v=fK6jJaHf80M

LGAFF
92 ZR1
#234

Re: IH gasket coolant leak w Pics
 

Yep it is almost too sanitary!!
We all need our LT-5's to look that pretty :thumbsup:

Re: IH gasket coolant leak w Pics
 

I've been looking at the pictures and offer the following personal observations for consideration.

1. Looks like your inj housings are ported.

2. Does NOT look like the gaskets match the porting very well. Significant casting shift occurs frequently in the plenum, injector housings and even the heads. When porting is done properly, it also port matches to the companion part. Unless the parts are (a)properly set up and shallow bored & on a CNC to OEM specs or (b)scribed to an OEM dimensionally accurate template for hand porting, mismatch can occur.

3. The gasket used show quite a bit of distortion around the bolt holes, possibly an undersized coolant hole and fairly significant port mismatch on the adjacent port where the leakage occurred.

4. The LT5 was produced with incredibly precise tolerances throughout, including flat surfaces.

5. A 0.030" thick gasket is more than adequate to seal if it properly matches the parts and manufactured with the proper materials.

6. By scaling the ports in the photos, the gasket web in the leaking area is about 4.25mm wide, assuming a 36.5mm gasket port diameter. By comparison, my gasket which is 36.5mm port dia & made to OEM spacing specs is 6.0mm wide.

My Summary: I think the gasket area between the coolant hole and port hole is too narrow. Assuming (1) the port work was done using OEM center to center port spacing dimensions and (2) a "ported" gasket made to OEM drawing spacing specs, the fault would lie with the gasket not fitting properly.

In my old days (and they're old!) we port matched using the gasket and scribed a transfer to the intake & heads to port match so the ports would line up when assembled. It didn't really matter much if the gasket was off, as long as we used the same gasket manufacturer. Today, with the LT5, tolerances are tighter and porting complicates the issue. When I started making LT5 gaskets, I used GM engine drawings as a reference for dimensions and consulted with the best & most experienced LT5tuner/builders. It was a good education.

Problem Analysis: The gasket used is not made to the proper dimensions and is made from paper. I do NOT think the problem here is due to the 0.030" gasket thickness. Gasket thickness required is ONLY relative to the irregularities of component surfaces.

Solution:
(1) Always make sure port work is done to engine manufacturers dimensions and not to gaskets used as a template.
(2) Use correctly dimensioned gasket made from quality material.

Just my 2 cents worth.

Jerry

Re: IH gasket coolant leak w Pics
 

Thanks for the comments about my pic posted. The down side is I still don't have it running yet and my project keeps going and going. I am just going to get all my mods done before bringing the Beast out. I could not have done it all without the help off all here. We sure do have a great community and it helps to keep the ZR-1 alive. =D> :handshak:

Re: IH gasket coolant leak w Pics
 

HAWAIIZR
Great looking engine!
Can you give us the details on the paint finish?
What silver did you use?

Re: IH gasket coolant leak w Pics
 

Dom - It almost looks as if something was pinched between the IH and the gasket?? In your Pic it appears that there is a mark in the IH??:icon_scra

Re: IH gasket coolant leak w Pics
 

Jerry,

I appreciate your $.02. The IHs I had were already ported but to 34mm. I opened them up to 36-36.5mm. However, the Plenum was matched to the IH and then the cylinder head to the IH. The gaskets were from FlatOut Racing based on their 36mm template. I did trim gaskets to match as close that I could while leaving material where I thought it needed it.
However, good tips for next time. So far, my repair is holding.

Re: IH gasket coolant leak w Pics
 

Dominique,

If you have the injector housings off again in the future, let me know & I'll send you a set of plenum & injector housing gaskets on trial. The gaskets are made to OEM engine specs for port spacing, have 37.5mm port size for the plenum & 36.5mm for the inj hsngs. They should make a pretty accurate template to check the porting location accuracy.

The material I use for plenum & injector housing gaskets has a fully cured nitrile butadiene rubber binder for maximum fluid resistance. It has excellent sealability in a variety of environments and flange conditions. I'm certain this material has superior resistance to the paper gaskets you're using.

If you use the gaskets and like them, you can pay for them. If you don't, toss them and forget about it. Hopefully, you won't incur any more coolant leaks.

Take care,
Jerry