FRporscheman

I just replaced the head gasket on my 968. I've done a 968 HG before and at least 4 on 944s, so I'm familiar with the entire process.

I usually put the head washers on, then drizzle oil liberally onto the studs, then put on the nuts, and start torquing. This time, while looking up the torque angle numbers in the Manual, I also read "lightly oil the threads" - so I put my finger into a quart of oil and rubbed it onto the threads, and repeated. Then I put on the (dry) washers and nuts, and started turning. The 15 ftlbs was easy and felt right. The 60 degrees felt fine. The 90 degrees felt ridiculously hard, and on 3 or 4 of them it got really easy to turn about halfway in. It scared the living daylights out of me. It felt like I was turning the stud and stripping the block or something.

I just went and bought a beam-type torque wrench to check the torque on each nut. I have about 40-45 on 4 nuts and the other 6 have at least 60-65. Those six feel really tight and wouldn't budge, so they might even have more torque than what I read. But the 4 that were looser would still turn when I got up to about 40 while trying to check them.

I really am too scared to bolt it up and start it. I want to know if I should have oiled the washers and that is causing my issue with weird feelings while turning? Or is the turn angle method just stupid? This is the first time the HG was ever changed, so this is the first retorque ever. I definitely don't want to even think about changing my head studs.

Am I being paranoid and is this OK? Or should I take it apart, order a new HG, and just torque it to 15-37-66? Or can I undo one nut at a time, oil it up more, and try again?

V2Rocket

maybe the looser feeling ones are getting to a well-oiled spot on the threads...?

KuHL 951

Do you know how many times those head bolts have been re-torqued? That comment about them getting real easy to turn half way through doesn't give me a good feeling. That's what I like about ARP studs; completely re-useable, no stretch, torque value only, no torque angle. I had issues with my BMW using torque angle specs after a HG failure and had a moderate oil leak. Checked them with a TQ wrench and found the same variations as you but only on two of them. I backed everything off again and used 3 step torque only, finishing at 85 ft-lb, never leaked again.

FRporscheman

V2 - my brother suggested the same thing. Or maybe when they got easy to turn, oil finally hit the washers and made the nut easier to turn.

Steve, this is the first time the head studs/nuts are being retorqued. On your BMW, you backed off all the bolts and tightened them again, on the same headgasket? I always thought a headgasket is trashed once the head is loosened. Did you back off the bolts one-by-one or all at once?

I just went out to stare at it and mope. I noticed one of the loose nuts had less stud sticking out above it. Almost a whole thread. So I tried to tighten it with the beam torque wrench, and it went up from about 42 to 50, and when it got to 50 it keeps turning. This was only like 10 degrees, if that counts.

Legoland951

I would clean the threads with steel brush or the nuts. By the time I install the nuts, they can be threaded all the way down to the end by hand (without head on) It may cost you a little though since you are not supposed to reuse head gaskets. I never use the angle method and torque my head nuts to 85 or 90 ft lbs or torque using snap on dial indicator torque wrench. Clicker types are very often "very inaccurate" according to research done by some aftermarket hardware companies. I anti seize everything from threads, nuts, and washers since I am looking for consistency as that is the only thing that matters to the surface of the head, not how much angle is turned. I know there have been lots of discussion on this but I absolutely believe that just about any consistent torque above 60 is better than inconsistent readings. Lubricant only improves consistency.

m42racer

Don't panic. It's probably nothing at all. You may have fallen victim to the typical issue with Loctited studs in the block.

The factory glues the studs into the block. Nothing wrong with this if the torquing is done before the Locktite is cured. Once the Loctite goes off, retorquing can be an issue. You could break the glue and the stud could turn until friction overcomes the turning movement. These studs should be tightened with angle not torque as angle overcomes friction. 90 degrees is 90 degrees always. Ft/Lbs can change with friction.

This is what I would do. Loosen each stud one at at time and remove any that are loose in the block. Check that there is no block material coming out with them. If no studs are easily removed, then leave well alone. Then coat both sides of the Washer with oil and the nut with oil. Now torque the nut to 45 Ft/lbs. I would guess if the threads in the block have been compromised, you will not be able to reach this torque number. If all torques down OK, then loosen again and do the angle method. Draw a line across the stud after the nut is installed and check where the line is after doing the required angle. It is quite normal that you may see different amounts of torque on each stud. friction is controlling this. Do each stud one at a time, in the correct sequence. Have faith that the angles given have been well tested and if all is well in the block, the studs will tighten up as required. These Head studs can be stretched more than once. As long as you have not exceeded their yield, they will return to their original length and can be stretched again.

I think the studs are turning in the block and this is why you are having different these issues.

FRporscheman

m42racer, ack , that's not what I wanted to hear! I don't want to take out any studs. I will if I need to, but I want to do everything possible before going that route. I used angles on the last 968 I did, and it's held up fine. But while turning the nuts it felt fine, consistent, and as one would expect. This one felt really strange. I don't get it though - the other one has 230k miles and felt good, this one has 180k and feels bad?

Lego, I agree, the angle method seems silly. How can it claim to be better when it's still based on an initial torque of 15 ftlbs? I also believe consistency in clamping force is key for the head. That's why I was double checking the torques on the nuts with the beam torque wrench. The only thing is, a torque reading is not an accurate means of measuring clamping force, and neither is an angle. In the end, I've done many HG jobs and never with a problem, and the only thing I changed this time is how I oiled the studs, so I'm just stuck on that.

billthe3

Which 968 is this that you're working on? Your mom's? Just wondering...

FRporscheman

The red one, the '95. It's been a solid, bulletproof motor so far........


I went and drew a line on each of the 4 funky studs. I watched the line to see if it turned while I tried loosening and then tightening the nuts, and they did not turn. Therefore I believe the studs are not turning (thank God). But the problem remains that on these 4, once the nut gets to about 45 or 50 ftlbs it just keeps turning. So I believe the studs are just stretching too much. I've only taken a couple classes in continuum mechanics but if a material continues to deform (stretch) under constant force (turning the nut) isn't that plastic deformation (bad crap)?

Or am I crazy and should I just be happy the studs are not stripped and close it up?

KuHL 951

Arash, I used the new HG that leaked and it held. I'm not saying it's the right thing to do. I did not want to pull the head a 3rd time after finding bad machine work on the first head repair resulting in bad compression and 1 leaky valve on the second replacement head. I drained coolant and just reversed the TQ pattern until all were hard finger tight. The two studs near the area of the leak were 10-15ft-lb lower than the adjacent ones using a clicker TQ wrench by increasing the set point 5lbs until it wouldn't click. These were on well oiled studs and hardware. I was willing to gamble and won that time since it's been about two years now. There is a sealant material on the BMW gasket that needs to heat up and I don't think the engine ever got hot enough to do that before I saw the leak.

Your last statement about the marked studs not turning but the nuts continue turning without increasing effort seems odd to me though.

FRporscheman

This whole thing seems odd to me. I mean I'm sitting here pulling out some of my hair because of this problem, and I'm pulling out the rest of my hair because I'm not really sure why I'm pulling out my hair.

What will happen if I fully undo one nut, oil it gratuitously, and re torque it in stages?

Rock

Stretch it, like its a birth squeeze

billthe3

I would be afraid that untorquing a single nut might potentially be enough to cause the head to warp or crush the gasket in some way.

If you think the didn't get the nuts torqued down all the way, shouldn't the head gasket still have some crush left in it to allow for the retorquing? I think I'd just pull them all back and apply a lot of oil and then retorque and see what happens.

FRporscheman

I pulled the bad nuts one by one, added oil, and started torquing. With a snap-on clicker torque wrench. I started with just one, and got that one torqued to 70 ftlbs. I went 15-36-55-70. Then I went after the other 3 one at a time. These 3 are at the far back all next to each other. I loosened one to where it just started to become easy to turn back, then torqued to 15, and repeated on the rest. Then I did all 3 together at 36-55-70 with 15 min waits in between. It worked thank God. Dodged a bullet.

Is 70ft lbs enough?

Screw that silly angle bullsh**. I'm sticking with the tried and true torque method and a good ol' clicker.

FRporscheman

LMAO!