bigturboz28

Just put in a new set of MLS 5 layer head gaskets with copper spray. Have boost capped at about 7-8 lbs to find my issue. Tune at 0 psi is 12.5:1 at 2 psi it drops to 11:1 and stays there all the way to 8lbs. Timing is set to 16 deg. Not spraying meth. TR6 plugs gapped to 0.03". Heads torqued to 90ft-lbs. Car never even comes close to overheating. For some reason it will blow a little coolant out of the overflow (i.e. lifting the heads??) when I get into boost. After which it will seal back up and not use any coolant at all. The only thing I can think of is too much backpressure, because I put the stock cats on my exhaust, which is otherwise two 3" pipes. I am second guessing it because when I am in boost both 38mm wastegates are open to atmosphere, so i would think that would get rid of any "extreme" pressure in the downpipes.

<edit> cars made about 650 rwhp @ 6000 rpm on a mustang dyno at 7lbs.

Any Ideas?

CamaroSS19

iTrader: (24)

Stupis question but your using head studs right

trans2000am

iTrader: (49)

thats some big numbers for such low boost

ajrothm

We have this problem on our turbo busas ALL the time..... 9 times out of 10, either the head or the block is not 100% true. Studs, MLS gaskets(we use Cometics) and the head torqued to 65 ft lbs(stock is 45lbs) and that "usually" holds up to about 24lbs of boost (400+rwhp)....BUT the head and deck has to be straight. Boost likes to warp heads and decks.

bigturboz28

Yea, it has head studs. Block was new and heads ground flat. The boost controller took a **** and the boost spiked to 20+ psi and blew a couple liters out of the rad cap. Can ran fine after but i decided to replace the head gaskets anyway (heads and deck looked good, but I did not have them reground). Now after the head gasket replacement, it pushes water at low boost levels. Assuming it is not the deck and head surfaces, what else could it be?

trans2000am

iTrader: (49)

you retighten the studs your surpose to after a couple miles on the first torque down

Mr.MartyStone

iTrader: (12)

That's probably the problem in assuming everything is fine. When you put that much pressure inside the cylinder due to detonation you create extreme cylinder pressures. Sounds like the heads aren't true. Pull em and check, asides from the fact that the tune is off or the gaskets are done, that is the only thing it really can be.

Nate

bigturboz28

Yes, I retorqued them, none of the nuts moved - all were good.

Any comments on the backpressure?
I guess a crack in the head could do the same thing, comments?

stevieturbo

when re-torquing...its wise to slacken off, then re-torque. ( one at a time of course )


Are you overfilling the cooling system ??


Ive passed a little water on 2 occasions with my current 5 layer MLS.

But HG integrity is 100%, and I havent even re-torqued....ever.
Thats a few months now, and a fair few runs up the track.

I log pressure in the cooling system, so its easy to spot if a gasket might be leaking.

bigturboz28

Yea I have read about it happening once or twice, but this is every time. So basically no boost until I can figure it out. If I have to pull the heads again, so be it, but, I do not want to pull them only find nothing wrong with the gaskets (as they seal 100% as long as I have no boost).
Any other insights are welcome.

sr71

iTrader: (17)

is the engine still in the same form you got it from Jason in?

bigturboz28

sr71,

No, the engine I got from Jason had all sorts of problems, the main bearings failed shortly after I got it (which took out the crank/cam/pistons - BTW it did not have the hellfire rings on pistons as advertised either - FYI), the block was clearanced incorrectly and the rod bolts were smashing into the block, it was a total right-off. I ended up having to build a brand new short block - which as you can understand was very frustrating, since I saved for so long for the first one. I spoke to Jason about it, but he just stopped returning my calls / PM's - he not did offer or do anything for me. I was really disappointed in the way he handled the situation - because he seemed like a nice enough guy on the phone. This is an entirely different discussion, which if you can get Jason to call me back on / PM me, I would really appreciate!

But back to my other issue, any input on my ??head lifting?? at low boost problem?

stevieturbo

Your problem isnt the gasket...thats for sure.



So could be clamping related....or deck/head surface issues

crashly

agree with most posts here.
we run std felpro head gaskets , #1010 , with up to 30 psi , twin gtk 550's , 355 cubes, with water, BUT 100 % meth fuel
no problems...
sounds like the machine work on the block and heads is no 100 % true, and with a bit of detination, the head gasket leaks...

think about it... if all surfaces were spot on and true... no leak..

hope you find the problem

cheers
ash

bigturboz28

Thanks for the input.

Jake@EPP

You mentioned the boost ran away once on a run up to 20+ psi. Im guessing it rattled and lifted the head, the hg is probably toast. Yank the heads and test for true on the block surface and the head, if thats good then put a new set of gaskets on and give it a shot.

Boosted One

iTrader: (6)

Ever figure out your problem? I would guess something cracked when the boost spiked. Is there any way you can warm the motor up, then presurize the radiator/coolant system? There is a tool just for doing that.

Frank