Im a firestarter, a twisted firestarter… that’s how I feel, like taking a match to it all.
All was going so well. I had the engine heads on last night, ready to time up the chain etc.
After the above last nights update, a message was soon posted which changed my mood from mildly cheerful to one requiring the use of a straight jacket.
It had not occurred to me at all, but a member on the 500E forum noticed that the insides of the piston bores were not finished correctly for an “alusil” block.
The finish that the first engine builder guys did for me is a traditional hone which leaves a cross hatch pattern as you can see in the above pictures.
Apparently these blocks require a special three of four stage honing process which ends with a final hone using silicon paste which totally smooths the inside surface of the cylinder walls. This, it seems, is imperative unless I want to scrap my engine.
Thanks to the eagle eyed members who spotted this error.
After I read this post, I quickly started researching. I found many (two) old videos, made in the days of Beta Max cassette tapes, showing the process.
Ze German guy explains it best. I didn’t understand a word but the video says it all.
This process is specific to Alusil bores and narrows it down considerably to M117, M119 and some others that used these blocks, if we confine to Mercedes. Porsche and some others also used these.
As these blocks are pretty much indestructible, we have never had to rebuild bottom end on one before and not many other garages have that I have spoken to.
After all if you have a problem with bottom end on M119, you would probably just buy a second hand engine for next to nothing. Unless it’s a 500E and the blocks aren’t readily available.
It became clear that No1 engine builder was not aware of this required process. It was done now but luckily I haven’t started the engine and no damage has been done. Decisions to be made.
I then experienced various psychological states.
Around 11pm last night I was in denial. There must be a reason why they honed it this way. Maybe it will be fine. How much difference can running some special grease through the bores for a minute actually make?
I woke up feeling regret. Dad always told me that I shouldn’t touch things that weren’t broken. It’s my way to keep going until I’m satisfied. This block should probably have been left as it was. Possibly just new piston rings would have sufficed.
The sandy finish inside the bores before we started the work, is exactly what we are now looking for.
Then came acceptance.
My plan to have the engine built today and possibly in the car over the weekend was out of the window. It dawned on me that I would never be happy to just suck it and see. Even if the engine started up and didn’t smoke, it would bug me every time I saw the car.
This morning I spoke to all of the local engine builders. Out of five calls, only three knew what I was talking about. Only one has ever had the equipment to do it and no longer has it now due to lack of demand.
I spoke to other engine builders further out. After several calls only one company I found still does this work. Not local.
So at 10am this morning I undid all of last night’s work. Removed heads and stripped the block down again. So very frustrating.
Got it loaded and is currently being driven to Engine builder No 3.
My biggest worry now is that this builder will decide there is not enough cylinder left to hone and it needs liners. I don’t want to go down this road if possible.
They say they are very busy and could take up to two weeks to turn around.
Ah well, I guess I now have time to sort out that headlamp wiring.
Thanks again to those who spotted the problem and posted. Very much appreciated. Now where is that voodoo doll.
