Let’s play advocate of the devil and reflect back on the options.
1: New RMFD engine.
2: Full rebuild.
3: New cylinder head on the current engine block.
4: Repair cylinder head on the current engine block.
5: S/H engine.
Given the fact that I could not see any visual damage during the inspection of the block, it may very well be possible that it is in a fine condition. I am not that naïve to think that a visual inspection is enough to determine usability. With other words, that can only be decided after a specialist inspection. IMHO, measuring the M88 engine block is what any machine shop can do.
If the pistons measure well within specification and the bores are OK, I can do with replacing the main-bearings and con-rod bearings including the required machine work of the crankshaft (if necessary). If any of the pistons measure out of specification, IMHO all six of them have to be replaced.
I have summarized the visual damage rather well I think. Add to that; I have the advantage of knowing that member Robinson bought a S/H head from a well-known Dutch breaker to repair the engine of his E34S HD91 model a few years ago. I hope Robinson doesn’t mind that I post a picture of that cylinder head that was taken shortly after he received it.
I knew that he complained about the condition of that cylinder head and tried to get his money back or at least have it replaced with a good cylinder head, but to no avail so he decided to use it nonetheless. He recently attested in this thread that that head failed and needs to be replaced after 40k km.
With other words, leaving the cracks unattended is naïve and stupid. A befriended mechanic helped me with removing the valves using his special tool and he said that he has seen a lot of such damage on a wide variety of road cars and that the machine shop doesn’t object to them. Well I do, at least for this engine.
Let’s revert back to the combustion chamber of the cylinder head of my E28S. The green arrows point to the cracks that are similar to Robinsons example. The yellow arrow doesn’t point to a crack, but the combustion chambers of cylinders #2, #3, #4 and #5 have a crack at that point. Only the combustion chambers of cylinders #1 and #6 doesn’t have them. I assume that the coolant channels are larger at the front-and rear side of the engine.
The red arrow points to a crack that I just discovered during the analyses of the high-resolution version of that picture. Given the fact that Udo specifically mentioned cylinder number six and all the other cylinders don’t have any damage at the same spot, I think that this is the crack that he meant in his phone conservation. But when looking at the detailed pictures, I must admit that all combustion chambers have this damage to a more or lesser extent. Although the high resolution pictures provide some detail, my Sony DSC-F717 is not an adequate tool for doing so. It simply lacks the capabilities to capture microcontrast level such as a DSLR with a decent lense can do. Retaking these pictures, but then with my Nikon D70 and 70-200VR/2.8 lense will provide for much more detail into the microcontrast level, but may be academic. Would be a nice experiment though. It certainly has a usable macro range.
I am playing with the thought of having it send to the machine shop to have it analyzed and pressure tested. This doesn’t break the bank and will achieve objective results. Provided that it tests OK at that point and ALL the cracks can be repaired reliably, why not repair this head, and fit a complete new valve train ?
If that particular crack cannot be repaired reliably to my terms and conditions, then it is off course game over. A new head with a new valve train (option ) still is significantly cheaper then a RMFD engine , but only if the current engine block can be reused. Off course, I need to budget for bearing replacement etc. I have the feeling that this will end in an investment that comes close or exceeds the cost of a RMFD engine, the worst case scenario.
Camshafts are visual OK and resemble that of what can be expected for a 95k mile engine. The Timing chain, the sprockets, the guides and the oilpump for instance must be replaced, but those don’t determine the cost. The chain guides are worth zooming into though.
The chain guide in the head is hardly worn at all. I assume that it has been replaced.
The wear patterns in the lower chain guide (engine block) are much deeper. This probably is the cause of the distance of the OT mark on the vibration damper and the OT mark on the timing chain cover. More importantly, this proves that the lower chain guide has never been replaced and the chain also not.