New Head Bolts ? 126 chassis V-8 ? HELP?
 

I am about to torque my right head after a rebuild (and new head gasket/cam/followers/valve seals/) on my '85 380 SE.all the bolts are in ,but not tight.I was about to torque them,but am now confused about weather I need new head bolts or not because of "Stretching"?Everything came apart no problem,all bolts looked great I cleaned all threads and used motor oil on the threads before I installed them.Do I really need new bolts?Is the problem when I torque them ( thread damage?).Any input greatly appreciated.

Why risk it?
 

Another poster (MikeV) recently refurbed his MB head as well and used the old bolts. Guess what? He's getting antifreeze in his oil.

Yes they do stretch as I've heard and if it were me I'd never risk having to take apart my engine again because I didn't spring for a set of $1.50 head bolts.

Good luck in whatever you decide~

Paul

____________________
'91 300E, 206k miles

Headbolts
 

Barndoor,
The aluminum block engines don't use torque to yield(stretch)bolts.Look at the torque specs. The bolts that will break if stretched too many times are torqued at a 90 deg. angle of rotation.Your biggest concern is if the threads pull out of the block.At some point MB switched to a special alloy bolt to prevent this.If your bolts are a bright metal color, you're fine.
Good luck,
Peter

Bolts are Bright metal!
 

so,you're saying that my car does not use "Stretch Bolts"?
they are bright metal,almost chrome.I am getting confused?
thanks!:confused:

I Dont Have Stretch Bolts!
 

Ok,
after looking at the CD repair manual,
I have determined that my car doesn't use the stretch bolts.
I did look at the manual under a diesel engined car,they are saying to replace those bolts because of stretching.
So.......................................................
I guess I'm ready to torque!

Barndoor,
That is correct.The technology is fairly new.The specs for a torque to yield bolt call for an initial low torque with a torque wrench. Then with a regular flex handle turn each bolt 90 deg. of rotation. Some specs call for waiting a few minutes and rotating another 90 deg.These bolts have a special necked down area which actually stretches with each 90 deg.After so many streches they will break;american and rice burner manufacturers say use new ones each time.MB gives you specs to measure the strech to determine if the're still usable.At any rate you don't have stretch bolts.If you have the upgraded bolts, you should be fine.Also if you want sticker shock, check the price of new bolts,and you need 36 of em.Hope the explanation helps.
Peter

Thanks Peter!
 

you know,looking at these bolts ,I thought they couldn't be cheap!
They are beautiful!
I love the term rice burner!
Life is too short to drive a japanese car!
they are BORING!
anyway,
I appreciate the help!
Now,I need the newton meter to Foot pounds conversion?

Just for future info! If you see a spline headed (head) bolt then it is a stretch bolt! If it is a reqular allen then it isn't a stretch bolt.
Convert Nm into ftlbs by multipling by .7, ie; 70Nm would be 49 ftlbs.

or you could use this handy site for conversion:


http://www.megaconverter.com/

MB DOC
 

Thanks for the reminder about the way to diferentiate between the two types of head bolts;I had forgotten that.I was also trying to provide a little education.I was told that if you give a man a fish,he will eat that day.If you teach a man to fish he will spend the whole day in a boat drinking beer! Joke. Joke.Anyway you're explaination makes it very clear.Thanks.
Peter

Thanks you guys!
autozen,I was about to order new head bolts this morning,until you logged in with your much needed information!
Thanks to everyone!
I didn't get the heads torqued today,other things came up.
But I hope to get this thing together this week,
I WANT TO DRIVE IT!
which is the BEST motivation to get a car fixed!