Jim My Dad used light to look for uneven surfaces. I was only eight years old so I don't remember all the details or results but he was a full time mechanic all his life and this was a routine. He had a tail light bulb soldered to a twisted pair. He dropped it into each spark plug hole, threw a rag over it, got under a tarp to eyeball.
We used light tables to check flatness of carbon seals for jet engines but that was a tad more sophisticated than what Dad did. Harry Watkins Newton, MS 86 SDL Silver 85 300D Euro 86 SDL Gold 81 240D manual trans ----- Original Message ----- From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" <[EMAIL PROTECTED]> Sent: Tuesday, January 03, 2006 10:28 AM Subject: Re: [MBZ] OT: Genset > I found my 18" Starrett rule and my feeler gauges. I wiped down the > head and block and went looking for warpage. Using the 0.004" gauge > (limit is supposedly 0.006") I walked all over the head, both > directions, and nowhere did the feeler even begin to come close to > fitting under the rule. Ditto the block. > > I next calipered the head gasket, which is 0.068" thick. The old > gasket is about 0.070" thick, less of a difference than I thought > based upon handling them. > > Next I placed the head on the block sans gasket. I had some real > trouble getting it to sit flat, it looked like there was some > interference from the locating dowel pins. I was able to use three > head nuts to pull it down on that (away from the pushrods) side, then > I removed the nuts. It looked pretty good by eye, and probing all > around it with my 0.004" gauge it only wanted to nose in a bit in some > places, and only slipped in at one corner of #1, which is not one of > the places I was seeing leaks. > > Looking at all the studs I found no place where there were > insufficient threads protruding. So _that's_ not it. > > So, from yesterday's list I'm only left with surface roughness as a > potential culprit, and that seems unlikely to be responsible for such > widespread leaking, especially as the gasket is a rubberized (?) one. > It seems pretty grippy, unlike the old 2-layer metal one. > > Sigh, no real smoking guns. I suppose it is possible that the > business with the dowel pins could have been responsible. If the head > got started clamping down while it was not seated flat to begin with > it could have gotten 'trapped' at a bad angle and leaked, even though > it looked OK by eye. > > The current plan is to put it back on again but this time paying more > attention to getting it flat before I start torquing the nuts down. > If it leaks again the plan is to remove the head and use that spray-on > copper gasket sealant I bought yesterday. If _that_ doesn't work > I'm not sure what I will do. > > -- Jim
