Barely Broken in 1991 240 with a Seized Cam Shaft. How Should I Proceed?
 

Hi everybody. A friend of mine has a 1991 240 with 92K that is in really good condition. Unfortunately, the car has sat for the better part of a year only being started periodically after his mother had become too ill to drive. His only complaint about the car was that it would sometimes shut off while it was being driven. He was able to start the car about a month ago and allowed it to sit and run in the driveway for about an hour (the car wasn’t actually driven only because it is not registered). The next time he tried to start it, he was unable to as it would crank but it would not start.

After having the car towed to a local mechanic, he was told that his cam shaft was seized and that he needed a new engine. After attempting to turn the cam myself with a 13mm socket and ratchet, I discovered that it is indeed seized (as a side note, the mechanic cut the timing belt he says so that he could check to see if the cam would turn while cranking. Couldn’t he just have removed the oil cap and looked in the hole in the valve cover?). At any rate, the mechanic said that a seized cam shaft occurs as a result of low oil pressure.

I know that the cam shaft is seized only because I attempted to turn it myself, but I am suspicious as to how it became seized after the car was successfully started so recently. I suggested he refuse the engine replacement, tow the car home and allow me some time to get some advice. He agreed. My questions are; what can I do to free the cam shaft and where should I go from there? Once the cam shaft is free, I figured I’d start with the basics… a good and thorough tune up, throttle body cleaning, pump checks, injector cleaner, fuse box cleaning, CPS change and all the other things I’ve done to my own 240 to get it running. Thanks so much everyone for all your help. I look forward to hearing from you.

I'd replace the cylinder head. I wish I still had my old one here that was good. There are no cam bearings...the head itself provides the cam journals. You COULD put bearings in it, but by the time it is all said and done, you'll have less money in a good used replacement head. I'd pull the oil pan, and check for metal shavings. While the head is off, look at the cylinder walls for scoring. If it's deep, the engine IS indeed done. If light, you could do an overbore and rebuild it.

^This. At the very least, a replacement head and cam. A cam with reduced oil pressure and flow might not seize at idle for a period while it's grinding away at the aluminum journals. Swapping a complete head is 3.5 hours...with swapping components is 4. Double that if all the valves are lapped. It can be done faster but those are shop hours and cover things like broken studs and so forth. Find out the labor rate per hour and do the math. Of course check the cylinders while you're there. If your mechanic is in the 21st century, he'll have a bore scope and can pull a plug and check the walls w/o puling the head. Cutting the belt? Not really something we do but face it, if the cam seized it was ruined anyway. The car takes the 530 head, quite common. A good used one can be had for $150 or less, shipped to your door.