Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 01-04-2006, 01:42 AM
Registered User
Join Date: Jan 2005
Posts: 2
Question rocker arm bolt (6) loose!!

After loosing almost all of the engines power and having such a rough running engine I thought this was an electrical problem. It turned out to be much more than that after I decided to investigate even more...

I am currently faced with 6 bolts that have stripped out of the rockers that go onto a head of a 1988 mercedes 300e. I have since cleaned everything up . Almost ready to begin my thread repair with the engine and head in car. After having read many previous posts on this subject most of my questions have been answered...those that Im unclear on or am seeking advice on are the following..
1. I am planing on helicoiling all the threads while I'm in there. I found a helicoil that is a selflocking (when a bolt is in place) as opposed to the free standing inserts most parts store sell... has anyone used these???. (I think 12mm length will work better than the 6mm length but will measure first before ordering).. a engineer from an aviation bolt manufacturer told me that these helicoils are better for my application with aluminum since they will insure the threads dont spin out with heat and vibration .yet can be removed if necessary with extraction tool when bolt is removed..

2. Are the torque specs for these rocker arm bolts 15ft/lbs or 13ft/lbs.. i have seen both mentioned in posts..(8mmbolt-1.25 pitch)
I was told that to properly torque these bolts with this insert that I need to add an additional 3-4 foot pounds to over come forces from the expansion ring in this helicoil as the bolts are I will be using a torque wrench for shure..

4.Should I have 2 diagonal alignment tube guides per rocker assembly? I need to find a new one, The one currently that is in one of the rockers has its side chipped. Can the one in the Rocker that is chipped be taken out it looks to be a pressed fit? the other two on cylinder #6 are out and loose?

5. Can I still use these bolts if they look visualy ok or can i easily get upgraded bolts mentioned , chromoly I think they were called?

6. Lastly I am planning on using a 21/64 bit . Do I need a short length.. Will I have the space needed with a drill on cylinder #6 and the firewall? Is it ideal to use a 8.25mm bit ?(this is slightly smaller than a 21/64 bit.)

sorry for so many questions I want to take my time and do the strongest best repair my first time with this. Any opinions or tips are appreciated. Dave
Reply With Quote
Old 01-04-2006, 09:08 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153

Installing heli-coils with the head on is not a good idea UNLESS you isolate the area & have a shop vac to suck away the debris as you drill & tap.

WE use Time-serts instead of heli-coils as they "hold" better. A 8mm kit comes with all of the needed tools except the drill motor.

Make sure to use NEW bolts 8 x 70 MM that are 10.9 hardness.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator
Reply With Quote
Old 01-04-2006, 09:49 AM
t walgamuth's Avatar
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 33,042
are these

adjuster bolts you are talking of?

i thought an 88 would be hydraulic.

and if so how expensive would it be to buy new rockers?

and come to think of it how the heck did they get stripped?

tom w
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual. It still needs upholstery redone...I also have a 427 Cobra replica with an aluminum chassis.
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 04:27 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page