Need tech specs 1991 190-2.6 head bolts - PeachParts Mercedes-Benz Forum

pepprdog · #1 12-10-2008, 04:24 PM

Where can I find specs for MBs on line?
I have about every MB factory book made from 1965 to 1986 but since I retired I have gotten just a few , mostly CDs and Haynes. I don't work on many cars anymore but it seems that every one I get is one I have no information on. Living in a very rural area makes getting anything difficult unless I can get it through the internet/satellite.
Right now all I need is the max length of the head bolts but a quick resource for this kind of info would be greatly appreciated..........

slk230red · #2 12-10-2008, 10:48 PM

Quote:

Originally Posted by pepprdog

Where can I find specs for MBs on line?
I have about every MB factory book made from 1965 to 1986 but since I retired I have gotten just a few , mostly CDs and Haynes. I don't work on many cars anymore but it seems that every one I get is one I have no information on. Living in a very rural area makes getting anything difficult unless I can get it through the internet/satellite.
Right now all I need is the max length of the head bolts but a quick resource for this kind of info would be greatly appreciated..........

According to the information I used when I replaced the head gasket on my 2.3, if the length of the head bolts on a 2.6 exceeds 108.4mm, the bolts must be replaced with new stretch bolts.

wbain5280 · #3 12-11-2008, 12:41 AM

They're cheap, buy new ones. I did for my 300SE's valve job.

S-Class Guru · #4 12-11-2008, 06:52 PM

Yeah, I think I paid about $40 AT THE DEALER for new bolts.
None of my old ones were stretched past 108.4, but when you are torquing to 70 NM, then turning an additional 180 degrees, you want that warm feeling that one of those suckers isn't going to break!
Torquing those head bolts that far was one of the scariest jobs I ever did to a car.

DG

pepprdog · #5 12-12-2008, 12:12 PM

Thanks guys, I have new bolts but when I read the max of 108.4mm and these measured 114.17, I can see why the exhaust side bolts could have been removed with a 1/4 inch wrench set .......they were REALLY loose.
So it's 70Nm and 180 for the 2.6 - 103........

S-Class Guru · #6 12-13-2008, 08:33 PM

The length measurement is taken from the end of the bolt up to the seating surface below the head. I think you may have been measuring the overall length including the head & flange of the bolt. It's unlikely that your original bolts are out of spec (longer than 108, if measured as above), but as we said, it's a good idea to use new ones.

Yes, the torque process should be:
- Be sure bolts are clean and oiled. Oil the contact surface under the bolt head and on the cylinder head surface. Clean the bolt holes of course.
- start with the middle bolts (lower, then upper) and work forward and back equally to the front and rear bolts
- 1st pass approx 35 NM (just to be safe).
- 2nd pass 70 NM
- 3rd pass - 1/4 turn (90 degrees) Use an 18 inch breakover bar.
- 4th pass - another 1/4 turn. (grunt).

That last pass will scare you, they get hard to turn.
If anything acts strange, like not torqueing evenly, you may be galling the surface of the head. Stop, remove the bolt and check.
Some like to use an angle guage, to accurately get the 1/4 turn, but if you very carefully align your wrench handle you can approximate 1/4 turn very closely.

cheers,
DG