Was hoping to avoid the machine shop at this point, like to make it a one day affair. Of course I will check for straightness of the head and if needed I bring it to the machine shop.

I already have the valve stem seals, they came with the elrin gasket set. Is it really necessary to get the MB ones?

If I had a choice I'd take the MBZ seals; but, already having the Elring I'd use them and be comfortable. Separate the intake and exhaust seals so you do not confuse them during the install.

Lots of good information there from the members .And wish you Jorn good luck in the repair .

Jorn pm sent..It will come in for all your needs with the W124..

Thank you so much for the link Trevor, very much appreciated.

The head gasket definitely needed to be replaced, at some places it almost fell apart. I've decided to bring it to a machine shop to rebuild the head, I think it can use some love. I'm not sure how the car passed smog two weeks ago with a head gasket like this, I got lucky I guess.

http://i662.photobucket.com/albums/u...psbgtsm7bp.png

http://i662.photobucket.com/albums/u...ps829cqaqa.png

One thing of concern is the rust in the engine, see the the coolant channels. What shall I do about that? And any tips of how to clean the pistons?

http://i662.photobucket.com/albums/u...pst1ao3dsk.png

Is it normal that bolts get this dirty?

http://i662.photobucket.com/albums/u...psgtpjin5v.png

I'd buy a copper head gasket.

For me the gasket must be a Mercedes Benz genuine part only .

yeah and they fail.There's new solutions out there.

With a head gasket failure, over heat and coolant leak, yes.

The rust in the cooling passages does not look bad. I would try to free the drain plug in the right side of the block while the head is off in case you want to flush it in the future. Stop if it feels like it is going to break. IIRC you can access the threads on the plug from both sides while the head is removed to clean and soak the threads.

The machine shop (Metric Motors) informed me that the top end has already been rebuild before and that not much was left to take off. What surprised me, because the car has only 89K miles (I have the CarFax). On top of that it's an early version of the M103 and I believe a 1990 300SE should have the later version with the improved cam. So maybe at one point they replaced the entire engine with an older engine. What year did they install the newer M103's?

They also shortened the pipe on the head to the water pump so they were able to replace the short hose, shall I leave it that way or have them install an original length pipe. I already bought a Mercedes hose, but I can see there is an advantage in leaving it short.

Got bad news this morning, the head is toast. To far corroded to make it work. The somewhat good news is Metrics has a replacement head, just a strain on the budget.

As long as there is sufficient pipe remaining that the clamp is no less than 1/4" in from the end of the hose and 1/4" in from the end of the pipe, I think it will be fine.

Good luck!