I am getting ready to torque the head bolts on my 89 300 TE and have some questions about this procedure.

I have the head gasket and head on the car with the bolts finger but the shop manual says to torque them to 50 (or 55) nm while the sheet that came packed in the gasket set says to torque them to 75 nm before doing the two half turns on the bolts.......I don't know if I should stick to what the manual says or if there is a reason that this head gasket says to torque to 75nm (or is that just for another model)?

The manual also says to oil the head bolts and any part of the bolt that comes in contact with the head...... Can I use never seize on the threads and mating surfaces instead or should I stick to the oil?


any advise, opinions, or help would be greatly appreciated.

It is important to clean the head bolt holes in the block first. But I can not get into that.

I know on the M104 engines you torque them to the 55nm. Waite 15 minutes then you stretch the bolts by turning them 90 degrees. Wait another 15 minutes and stretch them another 90 degrees. Put a mark on each rocker so you don’t get lost as to where you left off. When your done each rocker arm should have three marks. One for when you torqued it, then one for each time you stretch it. I used some of my daughter’s nail polish. Oppppps! That's not spec. Buy new bolts and washers and it is important to apply oil to the threads and just under the head.

shhhhhhhhhhhhhh.............................It's ok, I managed to get the bolt holes cleaned out and and no one ever has to speak of that again?




the M104 and M103 procedure sound the same, I wonder if there is a reason that the 75nm and then the two 90 degree turns was specified in the instructions with the gasket I received.



And as far as that non spec nail polish you used.......... be careful or your engine might blow up

In the 1989 MB TDM...M103 head bolt torque is listed as 70Nm with 2 stages of 90deg angle of rotation. Threads & shoulders of bolts lubricated with oil.


TDM=technical data manual

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M.B.DOC thank you for the info....... Maybe I should should have started some physical fitness training before doing this kind of work.

Thanks, M.B. DOC its good to know the two engines are different.

dka-66, Yea, its a lot of work and you will break a sweat. Maybe that's why they give you the 15 min breaks. LOL

Also, just thinking if my engine blows...then I can fix that exsessive .00085 gap on my head gasket. Strange how things work out for the better. LOL

ehopkins, I enjoyed those 15 minute breaks and the head in now torqued correctly......That first 90 degree turn was not that bad but I swear I was saying a little prayer for each bolt on that second 90 degree go 'round. I was just worried a bolt was going to break or the threads would strip.

have you started rebuilding your engine to get rid of that excessive gap yet?

I know exactly what you mean about twisting a bolt to much. I think that's where most of my sweat came from.

Haven't started the rebuild yet, want to see if it blows. Highly unlikely though. I’m doing the front brakes tomorrow. Had a little intermittent squeak that soon turned into a big intermittent grind. I was thinking it was the right rear but turned out to be the right front.

And here I thought it was the nearly hundred degree weather in Houston, TX that had me sweating

Good luck on the engine you'll need it...... also (and for real this time) good luck on the brake work, I always love how brake issues or suspension trouble can feel or sound like the problem is something different or on the other side of the car.


As for me the work the work continues on getting my girl back together, I still have the oil pan, timing, covers, manifolds, and all those unimportant things like belt tensioners and the water pump left.

DKA, yeah, that last 1/4 turn is really scary.
By the way, did you get the head resurfaced?
I have this obvious theory about why the 103 gaskets begin leaking oil and water at the corners: the head is aluminum and the block is iron. So, when that long head heats, it slides along the gasket at a different expansion rate than the block. If the head is really smooth, it doesn't abrade the gasket as quickly. My original gasket weeped oil at the right front, and water at the right rear. Upon removal it was obvious why, the gasket had just been chewed up on those outer corners. I had the head really smoothed, and so far so good (10 years) on the rebuild.

DG

DG, The head was not warped but the guy I took it to did smooth it out really nice, If the work he did is as good as it looks I will have a really nice top end... I thought my gasket looked a little chewed up as well and I was wondering if someone took the head off and set the head on a dirty, gritty shop bench and that is the way it was put back on (with very little cleaning that is)