Head bolt removal
 

1985 190D What can I do to remove the engine head bolts. They are 8mm, and my hex fits in it but is about to strip the bolt. The bolt has 12 points on it, but can find a tool for it. any ideas? I also can't find any thing long enough

Thanks

A good 12 point socket. Nothing special. With an extension about 6" long, 8 maybe.

Just get it on there good and square and clean the heads and socket of any debris first.

Tom W

Is the bolt a socket head cap screw with internal points requiring an allen style wrench or like a hex headed bolt with external points? If it is the later, the standard 12 point socket in most tool boxes will work. If it is the socket head cap screw, you will need a special socket like the hex bit sockets but with 12 points. Long ones are available in order to get above the camshaft. Bought mine from Baum Tools, but other tool sources will have them.

It needs to be like the one in the picture (attached), but longer. The only problem is I found one for $60 and I don't want to pay so much

Yeah, that is right. Sorry I misstated.

Tom W

Why does it have to be so long? I use the appropriate wrench from a set of these wrenches I bought for about $25 at AutoZone (they didn't have them as single items - I believe it was a pack of 4 or 5) to take the head bolts out of a 190E 2.3-16. Now, I damaged a bolt (one up against the firewall) by not getting the wrench in there square and having the wrench pop out before the bolt broke loose. I put the wrench into the hole, then tapped it in with a few light pops of a hammer, and then, once it was really seated in the bottom of the socket, I was careful to make sure the torque was applied "square" to the fastener. Came right out.

If you don't buy the wrench though, don't try to get the fastener out. They are in there pretty good and you don't want to mung the fastener up so it can't be removed the "normal" way. Jim

YOu have to be careful with the head bolts. The recess the wrench fits into will be filled with oil and perhaps dirt, so you have to be sure it is cleaned out well so that your wrench will seat fully. If it is not seated or you get it angled instead of perfectly straight you will have the problem that you saw.

Tom W

AAAAAAHHHHHH! NO. it is not a 12 point standard socket. it is a "tripple SQUARE" autozone has a nice low cost set for 10.00 or so. it's a 3 or 4 pack with other sizes... I second the vote to CLEAN out the bolt heads first.

I think the 190d has a slightly different head layout because I hit the same problem (on a Sunday afternoon) on the last head bolt in the center back.
The casting comes up here just a little too much for good contact.

My solution was to drive the torx head out of the socket just a little bit with a centerpunch, enough to get the length needed. It wasnt too tight and just a few taps did the job. Definitely clean the head bolts carefully, even if it takes all day, and if you round off the torx bit, grind it flat again.

this is where a breaker bar is a great tool

Yes, Clean the bolt heads out. I believe the one you're looking for is the #12 tripple square. You can also get one from the Snap On Tools truck. Mine cost about $15. In my mind, the extra $$ are worth it when the Snap On one has a tendency to be a higher quality one. Many people think that buying higher quality is only for longevity. I disagree. It's also for more precise heat treating and milling, and a lower chances of stripping the bolt heads and having a mess to get them out. That's my $.02.

You can buy the proper tool from the Mercedes dealer for about $20, made by Hazet, I think. It has to be long in order to fit through the holes for the cam bearing caps. I would NOT cheap out on this. Buy the proper tool (and not the Made In Taiwan stuff, either), clean the bolt heads, and make sure the tool is fully seated before you start really cranking with a breaker bar. You do NOT want to strip the heads on these things.

If any of the heads are damaged, REPLACE THE BOLT. They're only a few bucks each. A lot of people replace the bolts every time the head comes off, but I think that's overkill... there is a spec in the FSM, if they're within spec with good heads, I re-use them.

:scholar:

I just bought this tool before your post:( Hope it works. I figure if it is cheaply made it will strip before the bolt. I hope anyways. It needs to longer for the same reason a gsxr said "It has to be long in order to fit through the holes for the cam bearing caps."


http://www.pelicanparts.com/catalog/shopcart/TOOL/POR_TOOL_MERCED_pg80.htm

Thanks for every ones help

Here's a photo of the factory tool:

:)

http://www.w124performance.com/image...olt_driver.jpg

After a search revealed this thread I gotta ask:
What else is needed to remove the head of a 603? Can I snip the chain to free it, and then what other tips can you tell me as I've found a #20 head on a 603 in a junk yard and I'm gonna get it. :)