Ok...i'll try and explain this as best as I can.

This is a problem that has been plaguing me since the new engine buildup. I noticed that after the new engine had run a few miles last year that I was seeing wetness (seepage)along the crease where the heads meet the block. This was occuring on both sides of the engine and in both the front and the back...basically the entire length of the deck just under the head. I really wouldn't lose much (if any) coolant but I would be able to swipe a rag there and get a streak of orange and also see some that would dribble down the block and even onto the starter.

I assumed that perhaps my engine builder may not have torqued the heads down as well as they should've been, so I decided last winter to not only install some valvetrain stuff, but to re-do the head gaskets again.

Upon removing the old gaskets I really didn't notice anything out of the ordinary, maybe some dirty looking trails around some edges but that was really it. I replaced everything and torqued it all down to spec and decided to see what happened this year.

Things were great for a while, no seepage whatsoever, but the more I tuned and hit boost, the more I would start seeing it occur...just like last year.

I called both my engine builder and Fel-pro and they both agree that more than likely I am suffering from an excessive case of cylinder pressures throughout the engine and that the heads are lifting slightly enough to let compression force tiny amounts of coolant out of the sides under the heads. Perhaps I have some overly aggressive timing in a midrange area where I see 8-10psi of boost, who knows....

I have also had some people say that this type of leakage is really nothing to worry about and partly may be due to the porosity of the metal.

I plan on running a few tests to try the head lifting theory. I plan to have Jim at Speed Inc try an engine block tester to see if there are combustion gasses present in the coolant...that should tell me right there what's up.

My concern is what happens if that test comes back negative...what the hell else could be allowing coolant to escape on both sides of the block. You can physically see the wetness all along the gasket line there. The only thing that makes sense to me would be a lifting problem.

Any other thoughts or ideas?

[This message has been edited by ZBass28 (edited August 28, 2002).]

 

Did the engine block tester liquid in tube test tonight to see if we were able to detect any combustion gasses in the cooling system. Test came back negative.....

No idea where this coolant is coming from, I see absolutely zero external leaks (other than the seepage)

 

Might just have a small out of flat deck or head surface.
You can try and add a very thin layer of ultra copper silicone around the water jackets on the head gaskets.
Very thin layer.
If that don't work then odds are the heads are lifting under heavy boost.

 

What head bolt are you using? If they're old, cheap replacements or original equipment they can get "stretchy." Are the head and block deck surfaces truly flat? Are you sure?

Are you sure you're not leaking coolant up through the head bolt threads (wrong sealant, improper torque)?

If you're lifting the head under high boost then you shouldn't have any seepage if you just tool around town at part throttle for a while. Is this the case for you- only getting wet after a hard run, not after some street cruising?

Often, when combustion gasses make it into the cooling system (for whatever reason) indicated engine temps will shoot to the moon in just a few seconds. Have you noticed any such phenomenon?


[This message has been edited by Damon (edited August 29, 2002).]

 

Have you checked the coolant air bleed pipe connections on the back of the heads?
these boogers can be a pain to track down when they **** very slightly down the back of the head onto the deck/headgasketand wick along the gasket.
did you reuse the old banjo bolt seals or buy new?
Just a thought.

 

I'll try and make sure I answer everything here....

- using ARP head bolts, properly torqued and using the ARP teflon thread sealant and moly grease.

- the block was decked and the heads checked when the motor was assembled.

- definitely not coming up throught the bolts

- I have a suspicion that if I were to just tool around town and not hit boost that I wouldn't see any seepage....but I can't confirm this other than it never seeped when I was running it in the garage while tuning etc....

- I haven't seen coolant temps shoot to the moon. Might go up a few degrees on a run but nothing more than lets say 5*, if that even.

- coolant pipes on back of the head are bone dry and no evidence or leaky trails near them.

- used brand new seals on the crossovers in back (expensive little things)



[This message has been edited by ZBass28 (edited August 30, 2002).]

 

This is a long shot, but I've done a lot of reading about it and the finish of the mating aluminum and iron parts must be a certain finish in order for the graphite multi-layer head gaskets to move around but not leak. These gaskets are picky - I added a tiny amt of silicone around the water passages like the stock gaskets had (my Fel-pros didn't have the small silicone bead), and have no leaks. I almost regreted doing it but it seems to be working so far. Now if I could just seal up my darn intake!

 

i had the same problem with mine last year except it was only the drivers side doing it, when i did the cam/heads swap last year, i used gm head gaskets and head bolts, about a week after it was running i started noticing seepage right where you said, then i spun a rod bearing and had the bottom end rebuilt, i had the block decked and used felpro head gaskets along with arp head bolts, ive had no problems since the rebuild and ive got almost 10,000 miles on it now

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1995 Polo Green Z28 M6, T-Tops, Blueprinted 355 cid, 11.8:1 comp., JE Forged Pistons, GMPP Forged Steel Crank, Meziere, Star Stage 3 Kevlar, BBK 58MM, 1 3/4" Hooker LT's with Mufflex Y Pipe, LT4 Hotcam Kit, Mildly Ported Heads, K&N CAI, Flowmaster AT, QTP E-Cutout, Walbro FP, and a ton of other stuff.....

12.931 @ 109.073 w/2.084 60ft. with bad traction and clutch slipping bad through 1st and 2nd
343rwhp/348rwtq (old motor)

no new times or dyno #s with new motor

LS1 ft. brakes and LS1 DS waiting to install

 

Both times I have been using the felpro 1074 gaskets.

At the request of a few people I have added the remaining 5 cooling system pellets to my system. I only put one in after redoing the heads, and never put any in when the engine was first built. Perhaps these things are more important than I thought

 

You may want to consider either O-Ringing the block or using some Loc-Wire gaskets.



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1983 Monte Carlo, 307 Stroker, TH350, 3.73 10-Bolt - SOLD 8/19/02

Future F-Body Owner

 

Well, since we already pretty much confirmed that there is no combustion leakage pressurizing the cooling system I don't think I have to worry about o-ringing the block. There are lots of guys running more boost and making a lot more power than I am that are running just fine on the 1074 gaskets.

I have a sneaking suspicion that this may be one of the coolant passages on each side slightly seeping through because I never used those damn GM cooling pellets. I know lots of people probably don't ever use them but I assume all it would take is a few tiny imperfections in the metal or even just the normal porosity which could lead to some very subtle seepage, which is what I am getting.

Now that they are in there I'll see what happens and report whether or not it solved the problem.