Head gasket, head bolts and other head related foolishness…

[Quagmire]

Okay, so I've rebuilt the motor in my 92 SL1 (love this little car) and have bolted down the head along with its new gasket and I have to tell ya I'm not feeling too good about this. Since the engine is out of the car, I want to make sure the head is going to stay sound before dropping the engine back in.

Having worked on a few older cars with cast iron blocks and heads, I'm having a hard time keeping faith in this head tightening sequence. To begin with, it seems to me that pre-stretching the bolts and compressing the gasket only to remove the bolts thereby un-compressing the gasket seems like an invitation for disaster. Not only that, but the bolts themselves have no washer under their heads and there's quite a bit of friction upon torquing them down, especially that last 90 degrees. Of course, this stands to reason since you've got a steel bolt threading into a blind hole in an aluminum block. The little bit of light oil on the threads doesn't seem to do much to overcome this friction/galling.

So, what do you Saturn gurus suggest I do now? Leave it, and drop the motor back in and pray? Or go buy a new gasket and bolts and try the procedure again. I have half the mind to get some hardened washers and place those under the bolt heads to alleviate some friction there and use never-seize on the threads instead of light oil. Better yet, I should get some damn studs and do what Saturn (and many other manufacturers) should do in the first place. Personally, threading a bolt into the block is a poor way to bolt on a head to begin with. Not only are you trying to clamp down the head and compress a gasket, but you've also got to overcome the friction of the threads which in the case of steel on aluminum is considerable. Besides studs give much more precise torque readings.

From my reading, these stretch bolts seem to be designed primarily to make things easier for the manufacturer during the initial assembly but are not ideal for a rebuild. Comments?

For those not familiar, the head bolt tightening procedure (SOHC) is:

- install the head gasket and then install the head bolts clean and dry. Tighten in sequence to 48 ft lbs.
- Remove bolts and coat with engine oil. Tighten in sequence to 22 ft lbs. Then tighten in sequence, to 33 ft lbs.
- Finally, in sequence, tighten an additional 90 degrees.

[johnny95sl2]

There is a reason its called a FSM the S stands for SERVICE, its not a factory assembly manual. I have done this a few times with no problems. Just follow the procedures and be happy with the results

[sl2clone]

What saturn engine are you rebuilding? My TQ sequence was 22 , 37 then another 90 degrees. According to my haynes manual.

[Quagmire]

The engine is a 92 SOHC and while I have followed the manual to the letter, torquing these bolts just did not feel right. For the last 90 degree sequence, the bolts do not torque smoothly; they are very jerky with lots of snapping/pinging noises with the wrench jumping repeatedly. Again, the procedure was followed to the letter and the bolts were lubed the second time round.

[Greg1]

Did you run a tap down the holes first? It's a torque to yield design, very common, which produces equal clamping force in the bolts. It works well with Saturns and unless they are abused, head gasket failures are rare.

[Quagmire]

Thanks guys,

Yea, I ran a tap into the holes. The block was cleaned thouroughly with degreaser and then soap and water after I honed the cylinders. I used a pressure washer on the head bolt holes and then blew 'em out with compressed air so they were pretty clean before I ran the tap.

So, are the head bolts supposed to torque down smoothly or do they go in quite hard like I experienced?

[eljefino]

Are you using a beam type torque wrench for the final 90 degrees? I'd switch to a nice breaker bar or if you're real fancy whatever goes with your angle gauge. The spring in the beam type wrenches only magnifies the normal popping and groaning one gets when doing this.

[Dr B]

my clicker torque wrench is as sturdy as any breaker bar ,plus it has rachet action so that you can really get to that angle ,to shoot 90 degrees from.
if i had a problem with flex ,could just turn the setting up to about 80
it would never flex that little click on these bolts .

[Low Saturn]

Just follow the directions. We've built several Saturn engines and all are fine.

[sl2clone]

God has chimed in. Low is the man.
Not to steal this thread , but my haynes manual didn't say anything about tightening and then loosening the head bolts. I felt about the same resistance and noise from each bolt. I sprayed them with penetrating oil before installation.
I'll admit , I didn't tap the holes out. They looked clean enough. If I kill this one then it'll be a learning experience for me.