hmmmm, it is supposed to be 70 here this weekend with some much needed rain.

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Jim

Pretty nasty. It should be real evident where the problem is once the head is off.

It is going to take multiple flushing to get all this mess out.

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Jim

Your problem should be the back left (viewing from the front) of the head like most everyone else (you'll see why when you get head off). You may also have some coolant leakage trails at #3. New head gaskets are reinforced where these typically push oil into the coolant passage...back firewall, passenger side. The trick after doing the head cleaning and resurfacing it is getting the head bolts torqued correctly. You'll probably need to do it a couple times after running. Otherwise...back to the drawing board.

W124 FSM section 03-7021aw provides a piston protrusion spec for the 601/2/3 series. 0.74-0.96 front and rear for a "new" block, 0.96-1.16 for a machined block. It doesn't provide a fore-aft variance spec which would be nice to confirm bent rods before refitting the head.

If you go deeper into the engine, it's pretty obvious to see from piston skirt wear if any rods are bent -



Note the bright patches on #1 and #6. Main and rod bearings on this block were withing installation spec, not just service spec. I'm tearing into another block with similar bright patches on #1 and #2.

Sixto
87 300D

Jim, a friend's 1991 350SDL suffered from high oil consumption due to bent connecting rods that result in oval cylinders. Once you pull the head measure the cylinders to be sure they are perfectly round. My friend had his indy buy a new block/internals and install his bolt-on accessory items for a mere $8,500.

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Fred Hoelzle

Pictures from today. Pulling timing chain cover tomorrow.

Note the discoloration on the top of #2 piston versus 1 and 3.

It looks like the gasket failed between the timing chain cavity and the #1 cylinder.

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Jim

It is quite obvious by the very minimal amount of wear on the oil pump chain tensioner that the oil has been changed in this car regularly. At 238k miles it has the least amount of wear that I've seen on one.

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Jim

Even the main tensioner looks good. Are you sure it hasn't been apart before? Does it have an old or new style vacuum pump?

Sixto
87 300D

You know I thought the same thing in regards to the oil pump chain tensioner. I'll look at the vacuum pump to see if it has been updated.

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Jim

Have you checked piston protrusion?

Sixto
87 300D

Not yet. I was going to spend some time on the block tomorrow.

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Jim

There is ~.300mm difference in the gap between the front and the back of the piston. I called and discussed it with the owner and he said he was using a qt every 400 miles so we're going with the 3.0 liter.

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Jim

The FSM says to measure the vertical protrusion of the piston.

Sixto
87 300D

I did. I just shot these pics like I did to show the difference. One rear protrudes ~.605 and the front is ~.300.

I think I'm going to tear it on down.

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Jim

Jim, the differences in piston gap and piston protrusion indicate bent connecting rods and oval cylinders. I would consider that block toast. From what I have read there is insufficient cylinder wall thickness to increase the bore size. No sense in tearing that engine down unless you want to confirm the bent connecting rods.

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Fred Hoelzle