Oh Geesh!

[CC57]

Getting the car ready to take to the track tomorrow and ... what's this?! Water leaking out of the 2nd head stud from the rear on the Dart Aluminum head above #8.

 

AAAArrrggg!!

 

OK, I'm no engine expert. What's y'alls prognosis; thread sealer not holding, blown gasket, cracked head, ....?

 

Thanks for your analysis.

 

 

Now, where's that bottle of Jack Daniels....

[racer61]

if its just leaking from around the bolt, id say just reseal the bolt. As long as there is no water in the cylinder or in the oil then the gasket and head are fine.

[CC57]

Firs of all , thanks for yrou reply.

 

Now that I've stepped away and the heart rate has gone down a bit, I'm attempting to analyze the situation.

 

Couple of questions:

 

1) What's your thought of draining some of the water out of the radiator and checking to see if there's any oil in it. See if the water looks fairly clean. I figure this might help me figure out if there is a bigger problem or not. Yours or anyone's thoughts on this?

 

My concern is, are there internal studs (under the valve cover, under the intake manifold) that are leaking too, but I can't see them.

 

2) Keeping in mind ths is an aluminum head on a high compression (~13.5:1) engine, can I just remove one stud, apply the sealant, and retroque? Or do I need to back off the nut on all the studs and retorque in the proper sequence?

 

Thanks again

[jwmbishop]

Pull both valve covers and all spark plugs - put 15-20 lbs air pressure to the water system and look for seepers.

 

If you have not yet run it then you can very safely remove just the one stud/nut and reseal. However if you have run it you should back em all off to at least 30 lbs, change and then retorque (be sure to back off the intake bolts first - they will cause the gasket layers to "scuff" if not). But first lets make sure you ARE using washers (I have seen many people not - disaster waiting to happen), and of utmost important - the studs are bottomed out on the block! Also inspect the spot face at the top of the head bolt hole - this is a place I have seen to be a problem quite often - the washer should have a nice flat surface to lay on - many times this becomes funnel shaped from heat cycling and removing and replacing the head!

 

draining a little water won't tell much - the oils floating at the top. use a cardboard strip to dip into the radiator - the oil will show if its there. Besides that its most likely to have water in the crankcase than oil in the water. Pull the oil plug and let a quart out into a glass jar - the first quart will show any water.

 

this is the one issue that I don't like about studs vs bolts. But keep in mind either way the space from the block surface to the underside of the torque washer is a void - it hurts nothing to have too much goop in there. I like using non-hardening permatex brown - if you do get some in the oil areas it washes into the oil and should cause no problems. Seal the threads AND washer bottoms - wipe off any excess after torqueing. Be sure to retorque after a heat/cool cycle- unless gasket manufacterer says specifically NOT to.

 

edited to add: If this engine was running fine and now suddenly has a leak - you may have a crack - there are five bolts (assuming chevy) around each cyl (sharing two beween cyls), the shortest one is at the very bottom and is the one you can see with the valve covers on - I have seen stock heads (never a Dart) crack the boss there from over torqueing - or over heating. Generally a blown head gasket will happen up at the top shared bolt. I can't recall ever seeing a blown gasket at the bottom - but anything is possible.

[CC57]

draining a little water won't tell much - the oils floating at the top. use a cardboard strip to dip into the radiator - the oil will show if its there. Besides that its most likely to have water in the crankcase than oil in the water. Pull the oil plug and let a quart out into a glass jar - the first quart will show any water.

 

Good point about the oil floating on top. Heck, I shoud have known that based on watching all the media coverage from the Gulf spill.

 

I will say this, when I opened the radiator cap and looked in it, and stuck a finger in it, looked clear, felt ok. And for what it's worth, when I did drain some water into a bucket, it looks fines (liitle bit of discoloring from block rust I would assume).

 

As far as draining some oil into a jar, the only down side on that test that I can think of is this car runs on Methanol, so there is always a bit of moisture apparent in the oli during oil changes.

 

edited to add: If this engine was running fine and now suddenly has a leak - you may have a crack - there are five bolts (assuming chevy) around each cyl (sharing two beween cyls), the shortest one is at the very bottom and is the one you can see with the valve covers on - I have seen stock heads (never a Dart) crack the boss there from over torqueing - or over heating. Generally a blown head gasket will happen up at the top shared bolt. I can't recall ever seeing a blown gasket at the bottom - but anything is possible.

 

6 races on this engine since freshening. And yes, it is a Chevy and it is the one of the bottom studs. 2nd from the back, #8 cylinder. I'm going to discount overheating. Car is very cold blooded (I run 1 165 degree thermostat in it) and race temp usually is around 205 - 210.

 

JW, I sincerely appreciate your reply. Keep 'em coming.

[jwmbishop]

Bottom stud I would just reseal and pressure test. The majority of your flame kernal pressure is on the top three studs - some builders even use a stretchier bolt on the bottom row to reduce burnelling at the flame ring of the gasket - but again - pressure test after you have sealed the threads just to make sure nothings going in or out of the combustion chamber!!!!

 

And as you mentioned freshening I would ask what gasket you used. the felpro blue is not the best choice for alum high comp - but many grab it anyway. Any good composite rebuilder gasket will work as you want to torque cold run to warm and retorque - then run to operating temp allow to cool completely and final torque. The felpro blue takes this expansion "capture" step away - retorqueing is NOT a good thing with it!

 

With alum expanding more (in terms of speed of expansion/contraction rather than dimension) than cast iron it is best to cycle them into place. the caveat of course being except when torqueing with a jig that gets them all at the same time (like production assembly) then its a one time and done deal. But most of us don't own that kind of expensive equipment!

[jwmbishop]

On the topic of overheating I have seen them come in with 210 on the highest temp but still had all the stress cracks of over heating. I had a 350 bridge and tunnel between 4-6 and it never went over 200. But was so lean it fried the gasket flame ring.

 

You can have a good cooling system that handles the therm transfer well - but running combustion temps that are well above the safe range. Typically not with alchy tho - with alchy one jet size too lean goes straight past mild overheat to damaging hard parts - while with gas usually two sizes are the "safe range". And since the "sweet spot" that we play with when making altitiude or air density responses is a three size range you can see how much more unforgiving alchy is.