I'm screwed...surprises during 1st valve job

[bigel]

Well my routine weekend valve job plans have been modified, and not by a 'little bit'.

I thought it was bad enough that all but one of the valve cover studs were backing out along with the rusted-on nuts, even though I soaked them with PB Blaster overnight! Little did I know, that was a prelude to what I would find under the driver side, lower valve cover!



It's never a good thing when parts begin falling out of the engine upon removal of a valve cover...But then I discovered that it's worse than I originally thought...there are two more, also sheared clean off, still sitting in their stud holes...



Here they are removed and placed side by side.





First, what am I looking at here.

There are four of these bolts in total, a pair between cylinder 1 and 2, and a second pair between cylinder 2 and 3. Three of the four have been flappin' in the breeze for God knows how long.

Second, why does there seem to be no adverse effect on the engine? I mean, no significant oil leaks, that is to say, absolutely no oil spots on the garage floor. No loss in compression, at least, not that's discernible to me.

Third, how bad is it?! Am I looking at something that can be rectified without an engine removal?

I am really bummed and it would appear that I'll not be driving her for an extended period of time...

[bh912e]

cylinder head studs snapped. It is common, the engine will have to come out and the cylinders will have to be removed to remove the studs and install new ones. You should count on doing a top end rebuild since you will be there....

[johnman001]

Sorry to see your pain. Some of those studs look to be snapped off close to the case threads.


Here is a stupid question that perhaps professionals could answer for me.


How did the barrel nuts get so far down on those head studs? Certainly an Allen socket wasn't used to tighten them down to the bottom of the threads like that.

Another question for the original poster:

Who last had your valve covers off and did they "tighten" the cylinder head studs while they were at it?

[peppy]

Steve, I feel your pain. I am 5 years in to fixing 2 broken head studs on a 1988 targa that had 90K miles.

I have just started the reassembly, but I am getting a 3.4.

Good luck.

[bigel]

Originally Posted by johnman001

...How did the barrel nuts get so far down on those head studs? Certainly an Allen socket wasn't used to tighten them down to the bottom of the threads like that.

Not sure, my guess is the nuts vibrated their way further onto the head studs after they had already sheared off.

Originally Posted by johnman001

Who last had your valve covers off and did they "tighten" the cylinder head studs while they were at it?

I inherited the car from a college buddy who was quite a gearhead; however, he was also very busy as an MD. He likely would have had any valve work done by a professional mechanic, so not sue about any stud tightening that may have occurred.

[Ken911]

Dilavar head studs break from chloride stress corrosion cracking. This is why they have that black coating on them. You will notice their is a fair amount of rust under that car most likely caused by in being driven on salty roads. Or just damp salt air. All it takes is for the coating to be scratched or chipped and exposure to road salt will make them snap. Stress corrosion cracking doesnt look like normal rust, stainless steel will do the same thing it will still be all nice and shiney but will crack. Once broken and with no more tension the vibration will cause the nuts to rotate up and down the threaded portion of the stud. This probably wasnt bad maintenance but age and enviroment.

[bigel]

Bump...thoughts?

[Ronnie's.930]

Originally Posted by bigel

Bump...thoughts?

There's really nothing left to think about - you must remove the engine from the car and, at a minumum, replace the dilivar studs.

[Flat6pac]

And you need to pray that you can get something on all the studs because that long one looks like it has a thread on it, above the break.
You wont know until you get the cylinders off.
Not looking at the hole in the donut, but...
Bruce

[Ken911]

Originally Posted by bigel

Bump...thoughts?

Decide now if your going to turbocharge it. Because your decision on the new forged pistons and all the other goodies you'll get while your in there will depend on it lol. It's coming out and as a minimum it will need the heads redone. Most likely new valve guides. Re-ring it if the pistons and cylinders are still to spec. Not required but might want to split the case and reseal everything and replace the bearings if you split the case. Replace the stock rod bolts with arp bolts, the stock ones are one time use any ways and a weak link in the engine. Make sure you follow Wayne's book carefuly when cleaning the cylinders for re-use other wise you could have problems seating the new rings. Most importantly get Wayne's book and ask a lot of questions in the end you will be very satisfied with the result and realize it wasn't as hard as you thought it would be. If you decide to fall off the cliff and build a monster motor like some of have here then be prepared to spend a LOT of money. Other wise it shouldn't cost too much if your careful and conservative.

[Brant]

I tore down a core once with broken studs that the previous owner kept driving for a while....

the leaks between the head and the top of the barrel ate out the sealing surface pretty heavily...

I wouldn't drive it with the broken studs. You run the risk of damaging the heads and cylinders which will add thousands to your repair bill.

[berni29]

Hi There

That is a horrible thing to find. I recently did a top end on my 993 (broken piston ring) and it was not that hard if you follow the rules and take your time. I did not split the case or disturb the rod bolts on my car. The top end was a scary enough prospect.

All the best

Berni