compression check and head studs?

nostatic · nostatic's Garage

Can compression and leakdown be used as a diagnostic for broken head studs? I get the feeling from reading archives is the answer is "no", but I figured I'd ask directly. If the engine has good even compression and low leakdown, can one feel OK about the studs, or is pulling the valve covers the only "gold standard"?

rstoll · 07-25-2002, 06:41 PM

Valve covers have to come off. Put a wrench on those nuts! OUCH!

TimT · 07-25-2002, 07:07 PM

Can compression and leakdown be used as a diagnostic for broken head studs?

yes, and no.. you can have bad compression readings and leak down readings with perfectly good head studs,

you can also have great compression readings, and leak down readings, only to break a head stud the next time you start the engine..

nostatic · nostatic's Garage

Quote:

Originally posted by TimT
you can also have great compression readings, and leak down readings, only to break a head stud the next time you start the engine..

Well, I can't do anything about that (ie the future), but I'd like to know if I have one broken *now*. So can you get good numbers with a currently broken stud?

APKhaos · 07-25-2002, 08:21 PM

Quote:

So can you get good numbers with a currently broken stud?

Oh yeah, sure can. The only way to be sure is to wrench on those nuts. You only have to drive one and hear the head 'bark' under throttle to realise that the good studs really hold the head down until combustion pressures get high enough to flex the head - way higher than a compression test.

Its a good investment, and not doing this check is really not worth the risk. You deserve a good car, and we really want to see you happy.... no, really!

marcesq · marcesq's Garage

I would second Robert's advice. It is easy to pull the lower valve covers and hit the barrel nuts with a hex wrench just to make sure.

You don't want to do that 3.6 conversion any sooner than is needed!!

Wayne 962 · Wayne 962's Garage

I would pull the valve covers off to check for broken ones, but I would not recommend putting a wrench on them. Rust can get in there and create a nasty situation.

What if one breaks? Can the owner of the car sue you for rebuild costs? Possibly...

-Wayne

curtisaa · 07-25-2002, 08:34 PM

THAT IS NOT TRUE FOR A 3.0 L CAR... If the studs are broken ( not loose) the head studs will basically fall off. You guys, are just too paranoid about this process. If a head stud IS broken, when the head cover is off, the stud (bolt) will basically come out wih a socket..simple as that...... There is NO hisssing when a "cold start" is tested ( this would only be the case from a earlier car)..... You guys are giving Todd, ALL this junk mail about "whAT IF'S".I'm sure Todd's wrench will the "knowledgable" "NOSTATIC" good info...

jeez..let the guy do his thing.....believe me Todd is very good, and he DEFINITELY knows his sh** !!!

speeder · 07-26-2002, 12:29 AM

I say pull the lower VCs, how much are a couple of gaskets? If one is broken, it will be laying there in the galley. BTW, my car has like-new compression in all cylinders, including the one w/ the broken stud. Sure wish I'd done the VC thing, not just compression check. As far as will one break in future, who knows? If overall engine health is excellent, (like mine), you can always JUST replace lower studs, which is what I will do. Good luck, keep us posted!

Doug Zielke · 07-26-2002, 04:53 AM

Broken Dilivar head studs on older 3.0 and 3.2 motors are a given.
Bet the farm on it. When it happens, fix the motor and continue to drive.

NS: If you are a chronic worry-wart, you shouldn't own a 20 year- old Porsche.

Wayne says: "What if one breaks? Can the owner of the car sue you for rebuild costs? Possibly... "

Only in America.