think i got a leaky HG

[malloynx]

ok here is the deal. i got about 6k on the rebuild and the motor is running fine. however i think i'm losing a bit of coolant at a very small rate. i had the overflow throw up once; so i burped the system and all seems to be fine. however; when i turned the car off the other day i saw small bubbles coming from the overflow bottle. this points to exhaust gases.

i had the block and head machined very smooth and i'm running ARP head studs with a cometic 1.4mm headgasket. i DID NOT retorque the studs and i don't believe i followed ARP's instructions on the strech factor.

should i attempt a retorque?? what is the proper way to do a retorque?? loosen 1 stud at a time?? please help

 

[johnathan1]

stretch factor??? Whats that??

 

[GotBoost?]

What boost have you been running? How many pound-ft of torque did you use on the head studs? I would run a compression check right now (write down the #s), then retorque the head studs (i recommed 85-90 lbs, following arp's instructions), change the engine oil and top off all fluids, then run a second compression check and compare to the first one. If the numbers got better, drive it on stock boost for the first 500 miles, and check those fluids (and the condition and quality of the engine oil) at least daily. If the numbers in the second compression test are no different, you might have to do it all over again. Other feel free to chime in.

 

[malloynx]

anyone else?? IJ you out there?

 

[lagged]

first off do a leak down test or cooling system pressure test. that will tell you FOR sure if you have any leaks. no guessing games. then you can try torquing down the head some more.

 

[jtamulis]

Why does no one listen to me. Mike I told you to retorque your HG, and so did
MK3Brent . Yes, one at a time, in the proper order.

 

[johnathan1]

what torque does everyone recommend for ARP studs, and a stock hg?

(Sorry, Don't mean to threadjack...)

 

[malloynx]

what i'm asking, is do i loosen them all first or what>> WHAT IS THE EXACT WAY TO DO IT.

 

[supra90turbo]

Just as it says "retorque" so, just re-torque them down in the correct order of course, no loosening necessary.

 

[cnewingham]

yes you do lossen or you dont get a correct reading. You back them off a 1/4 turn and then retq it doing only one at a time in tq sequence.

 

[lagged]

yes you do lossen or you dont get a correct reading. You back them off a 1/4 turn and then retq it doing only one at a time in tq sequence.

yes.

Just as it says "retorque" so, just re-torque them down in the correct order of course, no loosening necessary.

no.

 

[IJ.]

anyone else?? IJ you out there?

Malloy: Sorry popped in late last night then hit the sack... zzzZZZzzz

I retorqued mine after finding advice in a Cometic PDF about using "new hardware" and the need to retorque.

I back crack the nuts then pull them back to spec in the torque sequence.

As long as it doesn't have a huge combustion leak into the cooling system it might pull back down and seal.

My "guess" here is you'll find a couple of loose ones when you do it in the middle, I did! <fingers crossed it seals>

Did you use Brake Quiet when you installed it?

 

[jetjock]

As IJ points out, you can't correctly retorque a fastener without first breaking the original preload. As for "stretch", it's referring to how some fasteners used in critical applications must be tightened a certain amount into their elastic region. Unless one has the gear to measure it (expensive) it's usually done by measuring angular displacement of the fastener beyond a specified torque.

 

[cnewingham]

I am going to use copper spray on my mhg just as a reasurence cause it never hurts if used properly.

 

[shaeff]

cnewingham, i'd use permatex brake quiet, as it cant melt and get all into the coolant circuit. that's what i used. works great!

edit: i know you said if used properly, but why chance it at all?

-shaeff

 

[JustAnotherVictim]

I'm with shaeff on the brake quiet, no resurface and no problems yet

 

[GrimJack]

Malloy, try the block test as well. If that comes back clean, it will be a load off your mind.

 

[malloynx]

thanks fellas, i will give that i try today. also when i loosen each one, i still need to do about 3 passes to get to my desired torque. i know this stuff, but i guess i'm looking for a little reassurance

 

[shaeff]

mike, when i re-torqued mine, considering they're at 90ft lbs, i didnt loosen them enough to do three passes to get them back up that high. i just cracked mine loose, and re-torqued them.

-shaeff

 

[TONY!]

If I had to know for sure if I had a BHG, I would:

1) Do a block test on it.
2) Next I would burp the system and try to get all the air out of it.
3) Then I would do as upgradedsupra mentioned: put a container (such as a soda bottle) in the engine bay and have the overflow tube run into it.
(If you are losing coolant, that will show you the proof of where it is going.)

Sorry lagged, but I definitely do not think that a compression test will tell you for sure if you have a BHG.
It sure as hell did not tell me of mine that I had for some time, although mine was an intermittent leaking one--as I suppose all start out as.

You want to catch a BHG when it is just starting.
That will be when it is an intermitten leak or only leaks under high combustion pressures (high boost).
In my opinion, by the time a leak down test will tell you for sure what you have, you have already risked your head to warping and other problems that can come from overheating.

I don't think there really is a 100% accurate test.
I have read some stating the block test is not as accurate as others, but I think the block test along with the 'soda bottle in the engine bay' trick would be the most accurate way of knowing what you have.