techs, do you lube M103 head bolts?
 

If so, what do you use? Motor oil? Assembly lube?

Thanks,
Sixto
95 S420
91 300SE
87 300SDL
83 300SD

I use a light coating of ATF. Some others use WD40 ect...
DR.D

WD40 is too light. Any oil will do, I personally would not use ATF, it is too light, but will probably be okay.

Good luck,

Head bolt lubrication...
 

Hi there,
I have always used chassis grease to lube both the threads and the shoulders of the head bolts. This allows for very consistent head torque measurment. In over 35 years and over a dozen engines or more I've never had a problem. It's especially important to use some kind of grease or anti-seize when the bolt is going into threaded aluminum. If you don't it might not come back apart again.
By the way, here's a tip for removing bolts that have broken off in a head or block - use a mig welder to build up the broken piece to a height that you can weld another bolt on the built up piece. Then very carefully back out the bolt. The welding causes enough heat so the bolt or stud usually comes right out with little effort.
Another tip is to ALWAYS chase the threads in a block using a tap, before installing the head. This will help ensure a consistant torque, and if the hole has oil or antifreeze in it, it will help get rid of it.
Here's another tip, and an important one. If you use a silicone sealant, like RTV, etc., be sure not to use too much. I've seen some very shoddy jobs where engine passageways were actually plugged by silicone sealant. The way I prefer to do it is messy but works well. Apply a small amount on each side of the gasket surface, then work it in with your fingers, removing any excess material. It really doesn't take much at all to do a great job of sealing. Make SURE that the surfaces to be sealed are absolutely clean and DRY. The RTV will not seal if there's any oil or water on the surface to be sealed. Also, don't use it where it is exposed to gasoline - it will dissolve in short order. It is good for sealing oil and water, not gasoline.
Regards,
Richard Wooldridge
'82 300D/4.3L V6
Etc...

I run the bolts through a die, tap out the holes in the block, clean the bolts in solvent and blow dry, then use motor oil on the threads, and after oiling, let them sit on paper towels to remove excess oil. make sure you get oil on the bottom of the bolt head (the contact surface to the block), and MOST important is to use air to blow any oil, antifreeze, or what have you, out of the holes in the block. Make sure you measure the bolt length after removing them to make sure they aren't stretched beyond what's allowed.

Gilly

Gilly,

Since you joined, let me ask this - why does the W124/M103 shop manual (01-1450 ref 01-1050) say torque to 55Nm, 90-deg, 90-deg and the W126/M103 shop manual (01-450) say torque to 70Nm, 90-deg, 90-deg? Are they not essentially the same engine? I don't have access to a W201 shop manual so I don't know what it says.

Thanks,
Sixto
95 S420
91 300SE
87 300SDL
83 300SD

I couldn't get M103 work instructions to come up on my 124 disc, some disc problem. I did check to see what the torque spec would be on an M119 motor, and came up with the 55nm, 90-90 torque spec, so maybe you were looking at the wrong engine.
I verified that it's 70nm, 90-90 on the 126 chassis and also in the 201 chassis, I'd use 70nm, 90-90 on it.

Oh great :confused: ,I just did my head last weekend and MY 124 disc said 55Nm,90,90. That's what I did , hope everything will be OK.

Kyle
It should be OK. I'm curious where/how you found this spec.
Here is what I'm trying to do to find it and the problem I have:

I tried finding it using your car as an example, so i selected a '88 300CE, then selected the "confirm" button on the following screen. Selected "engine manual", then selected "mechanical and combustion manual" (the other 2 choices were LH injection and cruise control). The screen I get next only offers these choices:
07.3 KE injection
09 air cleaner
14 intake and exhaust manifolds and emission control
15 electrical
30 accelerator control
47 fuel system
49 exhaust system

technical modification
modification notes
programmed repairs

I tried doing this with several different 103 engine-equipped vehicles with the same results. No selection for group 01 like there should be.

Gilly

Hi Gilly, you should get a choice between the mechanical and combustion manuals.The sections you mentioned are in the combustion manual.If you have a problem with the program/disc try opening it from Adobe.Sections 01, 03, 05, 13, 18, 20, and 22 are in the mechanical manual.These discs have their weird little ways sometimes, I couldn't open section 7.3 until I downloaded Adobe 5 . I won't worry about the torque on the headbolts though, thanks.

Someone told me it's in section 01-1450 so I went straight to the PDF in the Engine\103 folder. No toruque specs in 01-1450 which sends you to 01-1050. Could be that the index sends you somewhere else but I had the same trouble as Gilly coming at it with a W126 CD mindset.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

I guess I'd be worried that the specs Kyle is getting is actually for a V8, like a 400E, as the spec he has matches what I come up with if I research the bolt torque as a V8 model.

Gilly