: Head bolt retorque method recommendation needed



Lawrence
02-10-04, 01:06 PM
Thought I should start a new thread here from this post: http://www.cadillacforums.com/forums/showthread.php?t=8051

I am going to attempt to retorque the head bolts on a 1994 STS with OEM installed heads and about 73K miles. This motor was a new OEM crate motor installed at about 35K miles, yes the first oil leak, the car now has 108K.

I know these are torque to yield head bolts. In this "attempt" should I torque to a number or additional degrees?

Any guess' as to what my chances of acheiving that torque would be?

Thanks much,

Aurora By Olds
02-11-04, 01:03 PM
Well, from the factory, the bolts are torqued to 22 ft/lbs + 90 degrees + and additional 75 degrees (if I remember correctly). If the head bolts are loose, I can almost guarantee they are stripped, unless the block has already been time-serted. It doesnt take much at all to strip these bolts out. If they are loose, I guess you could try re-torquing them, but it's a long shot....

zonie77
02-11-04, 06:29 PM
Since you are trying to stop the oil leak maybe you should gradually tighten them, then run the engine and see if you can stop the leak. If you have a beam type torque wrench (constant reading) instead of a clicker you would have a good idea how much torque you are putting on. It is entirely possible the threads are bad in which case you should grab Botboy's timesert kit if you think you would redo the headgaskets.
I mentioned I heard of this before. My friends Mercedes 6 did this. He eventually had to replace the gasket although it initially stopped with retorquing.

zonie77
02-11-04, 06:32 PM
One other idea. Get some new bolts, the 2 or 3 around the oil passage. Possibly they are fatigued and no amount of retorquing will fix them. They are not supposed to be reused anyway and retorquing is the same as reusing..

growe3
02-12-04, 01:25 AM
Re-torquing the head bolts cannot really be done without loosening then retightening the bolts in sequence. The likely results would be stripped bolt holes.

Originally you torque the M11 bolts (in sequence) to 30 Nm (22 lbs) + 90 degrees. Then turn each M11 bolt another 90 degrees.

The three M6 bolts would be tightened to 12 Nm (10 lbs).

When I replaced the head gaskets on my 93’ STS the approximate final torque for the M11’s was 120 ft lbs.

If the bolts are relaxed at all, the holes are failing; tightening the bolts won't help.

I would recommend against trying re-torquing the head bolts.

-George

Lawrence
02-12-04, 01:47 PM
What exactly is it that happens to the heads bolts on these motors? Do they stretch, rotate out, block threads deteriorate, does the gasket shrink from under them, or from the way everyone describes it, good threads simply pull straight out under normal operating. WOW!

Earlier I had assumed that the threads were damaged upon removal, which I believe still shouldn't happen unless corroded by a coolant leak, but acceptable.

So my never touched motor is just sitting there with stripped/pulled threads in the block? And all this time of driving down the road and just waiting for the heads to fall off! Double WOW!

growe3
02-12-04, 06:50 PM
It is not the head bolts. It is the head bolt HOLES.

The bolts are very tough, but have special coatings that cannot be field applied, and so they must be replaced. You get new bolts with the OEM head gaskets, the only ones to use!

The aluminum block HOLES are under a tremendous under clamping force load from the head bolts. It seems that after a while, usually around 90,000 to 100,000 miles, the aluminum seems to relax a bit, which eases the head bolt clamping force. When the head gaskets can no longer expand to seal, you will typically start getting coolant sucked into a cylinder(s).

If it weren’t such a pain to remove the engine, it wouldn’t be so bad.

-George

zonie77
02-12-04, 08:14 PM
Lawrence,
The correct answer is,,,all of the above.

The head gaskets may corrode which puts an extra strain on the bolts. The bolts are made to only be torqued once so may fatigue and stretch and the big ones is the threads fatigue and seperate from the block. When we did one many of the holes were stripped. Strips of metal came out with the bolts and this was taking them out with finger pressure. Headgaskets fail in plenty of vehicles.

Not all N*'s have this problem so there are conditions that contribute to this.

Anyway...try torqueing the bolts. You may be lucky, but if they don't tighten expect to change the head gaskets.

Lawrence
02-13-04, 01:07 PM
I am going to try a retorque today. Seems I don't have anything to loose. Not sure of what aproach to try, I'll see how they feel. I think I'll just try the single head bolt by that oil passage. As I said before, no coolant leaks or anything.

As I've watched this leak the last few days I have noticed it only leaks (pours) when the motor is cold. As it warms up, about 5 min, the leaks stops. I do mean stops, not one drop. Goes to show you how much expansion and contraction there is here. Anywhere else I wouldn't be too concerned with the leak, but as it is it puddles on the top of engine block and then runs down the back of the engine when driving, even though it is not actively leaking at this time.

I'll let you know what happens.

Thanks for all the info!


Lawrence

Lawrence
02-14-04, 12:06 AM
As expected, not as I'd hoped for, it didn't hold. All out stripped at 40 ft lbs. Out she comes for new head gaskets. Hard to beleive there were no coolant leaks or compression problems with only 35 ft lbs of torque on the head bolts. And I expect some of that 35 ft lbs was taken to break the factory thread locker.

zonie77
02-14-04, 01:37 AM
Sorry to hear it didn't work. Are you going to do heads yourself or have it done?

Lawrence
02-14-04, 04:15 PM
I'll have to do it myself. I have already started disconnecting. What a royal pain these things are. I would appreciate any tips you may have.

Thanks,
Lawrence

zonie77
02-14-04, 04:21 PM
Did you look at the thread from a few months ago on tips to do it yourself?
Do you have the factory manual?
Did you get the timeserts from Botboy?
Where are you located?

Lawrence
02-14-04, 04:56 PM
I have searched as much as I can find on this site, including one you posted "Part 1"
I do not have factory manuals yet, I may just use Alldata.
I didn't get the timeserts from botboy yet. I had asked him a question and he hasn't replied yet. The question I asked was if the kit, new, included the inserts. I thought it did. Perhaps you would know. Just wondering how much I am saving buying it used. He wants $130 plus 2.58 per insert x 20 > $51.60. A total of $181.60. New is $250? Now that I add it up I would probably buy it either way. Just wasn't sure at the time and he hadn't replied.
I am in Columbus, OH. Pretty cold here. I am trying to do it in a 2 car garage. Not sure if I'll have enough room to raise the car high enough.

zonie77
02-14-04, 05:08 PM
The kit was closer to $300. Using it once doesn't wear it out at all. You are saving at least $100 and can resell it eventually.

I think you could get it out in a garage. 8' ceiling? That would be plenty.
If you have any questions msg me today. I'm gonna be unavailable a few days.

The manual is important for cam timing and a good reference to follow when doing the removals.

Lawrence
02-14-04, 05:23 PM
Zonie77, did you do the bottom end reseal on yours?

zonie77
02-14-04, 05:38 PM
No but if it needs it now would be the time. You'll have the cradle out. Better get a dozen dishpans to keep parts sorted!

Lawrence
02-14-04, 05:48 PM
Yeah, thats what I was thinking. The thing is I don't really know if it is leaking, with all the oil coming down from the top. Thought maybe I should do it as a precaution.

Where did you place the 4x4 on the rad support, to the top of the rad or the bottom? I was hoping to leave the AC system intact. I think there is room, by taking the rad out and leaving the condensor in, to set it aside. But I don't know how that might interfere with placement of the 4x4.

Thanks for all the help,
Lawrence

zonie77
02-14-04, 06:05 PM
I cut the 4x4 to go under the radiator support. We had to pull the condensor but I have the stuff to recharge the AC. We didn't see any way to get it out without disconnecting the ac somewhere. Tape the ends of the AC lines and the fuel lines to keep crud from getting in.

The lower case seal doesn't look that bad to do but you disturb the bottom end. If you didn't see a leak there originally I'd tend to leave it. On the other hand you are doing 80% of the work to pull the engine already. Guess that isn't much help!

zonie77
02-14-04, 06:10 PM
The 4x4 is to spread the load to the outer edges where it's stronger, so cut it to fit. I think it was about 4'. I happened to have a bunch of 4x4's at the time so I used them. Possibly a 2x4 would be strong enough. The body is pretty light without the engine.

andy2175m4
08-05-05, 02:50 AM
The 4x4 is to spread the load to the outer edges where it's stronger, so cut it to fit. I think it was about 4'. I happened to have a bunch of 4x4's at the time so I used them. Possibly a 2x4 would be strong enough. The body is pretty light without the engine.


message for zonie77:

I saw in an earlier post you mentioned that it is possible to get the front head off the northstar without removing the engine from the car. I want to explore this option as I need to do a head gasket but only on the front bank of cylinders (closest to the radiator) and not pulling the engine to do this job would be great !! What's your take on this ?


thanks,

andy2175m4@yahoo.com

zonie77
08-05-05, 12:02 PM
Go for it!

The only problem I see is if the rear is ready to go (or is gone but not as bad as the front ). In that case you're gonna have to do the back the long way and you will have "wasted" some of your work.

If you are keeping the car I'd do both heads.

The timing chain!!! I believe there is a tool to lock the chains in place so they don't move/drop down. If you position the cam gears to whatever position you want, and use that tool, it wouldn't be that bad. Otherwise you'd have to pull the timing cover. No fun with the engine in the car.