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In March, my 240 started firing on 3 cylinders and making horrible noises while running. Removing the sparkplug of the affected cylinder and cranking the engine over with my finger over the hole revealed that the cylinder had approximately zero compression. A mechanic told me that the piston rod was probably broken and I would need a new engine. I was not convinced, since I could feel the piston moving when I stuck a wire down the plug hole and cranked the engine over.
A few weeks ago, I had time to remove the cylinder head. Removing it revealed 4 intact pistons running in pristinely clean bores, and a dropped exhaust valve on the #4 cylinder due to a broken valve spring. There was no evidence of the valve hitting the piston, so I replaced just that spring and the spring supporting washers. I also changed the head, valve cover, intake, and exhaust gaskets, heater hoses, valve husher rings, and timing belt, in addition to decoking the combustion chambers with a wire brush and cleaning the flame trap and collector box. I didn't replace the head bolts, since they looked fine and weren't "hourglassed."
Difficult parts of the job? A few:
Removing the crank pulley bolt. Best done with a wrench and a long cheater bar braced against something solid underhood. To remove the bolt, run the starter motor.
Loosening the A/C compressor belt. Do yourself a favor and remove the airbox to give yourself more room to turn the bolt. Ratcheting 1 click at a time is ... unfun.
Using an el-cheepo valve spring compressor from Pep Boys to remove and install valves. I had to make an adapter out of a Schedule 40 to 3/4"(?) PVC pipe adapter to reach down and push on the recessed valves. All I did was bore the wide part of the adapter out a little with a Dremel until it accepted the top washer of the valve spring. Unfortunately, it still wasn't quite long enough to allow me to remove the valve collets. So I cut a shim out of Schedule 40 PVC pipe so the washer/spring wouldn't go so far down into the adapter. You ask - why not just Dremel out a shorter length of the wide mouth of the adapter? Answer: because the wide mouth is already almost as wide as the valve washer, and if you bored out part of it, the valve washer would probably jam inside of the adapter - it needs a good "shoulder" to sit on. The collets are installed and removed through the top hole of the adapter with a pair of needlenose pliers, by the way.
So, last week, I got the car running, and everything seemed to be fine until I put the fanbelts on. When I put the belts on, the engine started making a ringing sound at idle. I removed all of the belts and the crank pulley, thinking that I had misaligned the pulley with the key and that it might be wobbling. It was fine, so I checked the other accessories. Ah hah - the alternator bearings has a bit of play in them. I left the fanbelts on the loose side with about 1/2" of play and drove the car for a week.
Well, I was driving down the shore this weekend when the ringing sound reappeared - louder then ever. This was followed by a squealing from the belts as the alternator bearings started alternately seizing and freeing up. Also, the charging light came on - all that wobbling had probably damaged something inside the alternator. I loosened the belts some more and carefully drove home, tail firmly tucked between my legs. Fortunetely, Pep Boys had a reman Bosch alternator for $135, and installation isn't too difficult. Two hours later, the new alternator was mounted, and all is good.
There were two problems with the new alternator. The first was that the B+ terminal on the alternator was very slightly larger than the terminal on the old alternator. I fixed that problem by (slightly) boring out the ring terminal on the battery cable with a Dremel. The second problem was that the alternator had a big Bakelite insulator designed so that the connections come out to the right of the car and not the left, like in our 240s. Fortunately, there was enough room to work around the insulator and run the wires out the left side, but I couldn't use the little plastic cap that fits over the B+ terminal in the original alternator. I'll either have to cover it with liquid insulation gloop, use extreme care when changing the oil filter, or modify the Bakelite to allow the cap to fit (which would void the alternator's "lifetime" warranty).
Moral(s) of the story:
Don't believe what your mechanic says without checking it out yourself.
Speaking of mechanics, don't let Lube Express change your oil. My last oil change was done by them. When I was changing the oil after reinstalling the head, I noticed that they had massively overtightened the drain plug and left out the copper sealing washer. I can't think of a better way to strip the threads in the oil pan. Can you?
Vinyl mechanics' gloves are a *good* thing!
Permatex blue non-hardening sealant is your friend on the valve cover gasket. Mine has always leaked, even after I replaced it once. I dressed the gasket with Permatex this time, and it hasn't leaked a drop since. That sealant is like Loctite in that it only hardens under pressure, so, unlike with silicone, there's no risk of getting bits of glop in your oil passages.
Creative ways of doing things (bumping the starter, PVC pipe tools) have something to be said for them
If something appears slightly broken, fix it before it breaks completely. I might have just needed a set of alternator bearings and brushes rather than a whole new alternator if I had addressed the problem completely.
Total cost was about $220 - $135 + tax for the alternator, $65 for an order from FCP Groton, $10 for oil and filter, and $10 for misc. stuff like gloves, Loctite, and Permatex sealer.
Cheers, and thanks to all who replied with advice and/or offers of new engines,
-b.
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