Can Head Bolts 0n a 380sl be Loosened & Re-torqued?

[daimlerdude]

Well, now that I discovered that the right head gasket on my 380sl is leaking oil, I'm wondering whether one or more of the bolts or heli-coils that should be holding them in, might have loosened up over the years, and if so, whether loosening and re-torquing the bolts could possibly correct the leak.

I came across a website dealing with Saab's aluminum head engines that states "To address an external oil or coolant leak from the cylinder head gasket when no engine overheating or other running complaints have occurred, it is only necessary to retorque the cylinder head bolts. Cylinder head removal and gasket replacement is not necessary in most cases."

According to this site, all the head bolts should be loosened (in reverse of tightening order) and re-torqued to 90 degrees beyond the original 60NM, which is the same torque that MB specifies. But I'm hesitant to do this until I can be sure that it's not going to make the problem worse.

So, I was wondering if any of you guys ever did anything like this.

Thanks in advance.

DD

[Strife]

Why do you think it's leaking. Many, many times this is really a valve cover gasket leaking in a manner that looks like a head gasket. Of course, if you have oil in the coolant or coolant in the oil, that's another story.


Specifically, absolutely do NOT use that advice. Firstly, the head bolts on that engine are non-stretch; secondly, unless your engine had been properly rebuilt in the past, there are no helicoils/timeserts in the block. If you were to do what you are contemplating, I'm virtually certain that you would strip the threads out of the (aluminum) block, which, of course, would be VERY bad.

[daimlerdude]

Originally Posted by Strife

Why do you think it's leaking. Many, many times this is really a valve cover gasket leaking in a manner that looks like a head gasket. Of course, if you have oil in the coolant or coolant in the oil, that's another story.

Specifically, absolutely do NOT use that advice. Firstly, the head bolts on that engine are non-stretch; secondly, unless your engine had been properly rebuilt in the past, there are no helicoils/timeserts in the block. If you were to do what you are contemplating, I'm virtually certain that you would strip the threads out of the (aluminum) block, which, of course, would be VERY bad.

I thought and was hoping that the oil was coming from the valve cover gasket. So I replaced that. But when I got under the car, ran the engine, and looked more closely, I could see that it was coming from the head gasket.

I realized after I posted my last message, as you did, that the procedure that Saab listed for re-torquing the head bolts on their aluminum head engines was for stretch bolts, which the 380 doesn't have.

So, I'm thinking that I'll just loosen and re-torque each bolt one at a time using the specified tightening sequence (from the inside out), the same way Roncallo said he re-torqued the head bolts on his 560. As the block was helicoiled when I did the valves several years ago, I am thinking that re-torquing to the specified 60NM, and maybe a little beyond that, won't strip the threads. And if that doesn't correct the leak, I'll just have to replace the gasket, which I would have had to do anyway.

But thanks for the concern and taking the time to prevent me from making a big mistake.

DD

BTW, do you or does anyone else out there happen to have an 8mm U-body or off-set dogleg driver for 116 or 117 head bolts they'd like to sell or rent out for a short time? If so, please email me. Thanks

[oldsinner111]

you can only do it with a copper head gasket,try searching gasket Works for better gaskets for Mercedes

[daimlerdude]

Originally Posted by oldsinner111

you can only do it with a copper head gasket,try searching gasket Works for better gaskets for Mercedes

AFAIK, nobody makes a copper head gasket for the 107. And with all due respect, what is your basis for asserting that you can only re-torque copper head gaskets?

If you search "re-torquing head gaskets" on Google, you'll find many posts that suggest doing this anywhere from 30k-100k miles to prevent head gaskets from developing leaks, or before changing leaking gaskets on many cars, none of which have copper gaskets. And genuinesaab.com/psi/files/headretorque.htm explains how to do this for the SAAB 9-3 which also has an aluminum head, but doesn't have a copper gasket>

If, however, you can support your assertion in some way, I'd like to hear it.

[meltedpanda]

I would not do that , too risky , Im with Strife on this one..

[daimlerdude]

Originally Posted by meltedpanda

I would not do that , too risky , Im with Strife on this one..

Thanks for the concern, Panda. I listen closely to anything you or Strife has to say about things. But I also listen closely to what Roncallo has to say, and he said that he successfully re-torqued the head bolts of his 560sl in this thread: benzworld.org/forums/r-c107-sl-slc-class/1405722-replacing-head-gasket-86-560sl.html. And his block wasn't helicoiled, whereas mine was.

So, I'm thinking that if it doesn't work, I'll just have to replace the head gasket, which I'd have to do anyway.

DD

[DieselPaul]

You're loosening, and retorquing to factory specifications, I do not see how that could pull the threads out. If the factory torque will rip the threads out of the block, so will replacing the headgaskets and bolts. However if you decide to grossly over torque yeah that could damage threads.

Just keep in mind the gasket may actually be bad and this may do nothing. If you're willing to accept the "risk" I think its worth a go before you tear the motor down.

As for the copper headgasket thing, that's apocryphal.

[meltedpanda]

thanks for that. Diesel P said it the best so far. If your willing to accept the risk.
I guess my thought is that a gasket of that age , no matter if the head is tourgued to spec ,that is leaking , most likely will continue to leak, perhaps even worse (with new pressures??) .
I also have some not so good expereince with helicoils, but that is another discussion
But
Nothing ventured --- nothing gained
Good luck , let us know how you make out