Saturday, June 1, 2013

240D repairs continued

Guess I should bring you all up to date on the saga of my 240D.
When we left our intrepid heroes the team had successfully replaced the head gasket on the 1978 Mercedes-Benz 240D. The next few days I was busy and didn't have any chance to work on the car so it waited patiently for me to give it a longer run. I finally snuck in an hour, got the radiator and hoses and whatnot installed and ran the car for awhile. It sounded good but as usual (for me anyway) there were air bubbles in the cooling system that made the temp go higher than I like. Of course just when I gave up and shut the car off a big bubble popped out of the radiator and the coolant level dropped considerably, typical...

Anyway then we were on our yearly spring trip to camp where it rained almost the whole week, so no car wrenching.

Upon our return I ran the car some more and make some tentative runs around the neighborhood. I really hate idling the car in the driveway waiting for it to warm up and putting the engine under load warms the cooling system much more rapidly. That seemed to go pretty well until I discovered the upper radiator hose was leaking. This could in part be attributed to the old hose clamp but considering all the work we've put into the car thus far I didn't want to take any chances so I ordered new hoses from my local CarQuest. They were cheap enough (under $30) and they had them the next day. While I was at it I changed the oil. I figured any bits of schmutz or whatever that we had dislodged during the head gasket job would have worked through to the oil filter (or would be suspended in the oil) by now and it would be a good idea to get it all out of the engine.

New hoses in I had to do the bleeding the coolant dance which is actually considerably easier after this job as I only lost about half a gallon of coolant in the process. With the engine temp stabilized I took a couple more rides around the neighborhood before I decided it was time to head out on a longer ride. This longer ride gave me the opportunity to put some speed on and I'm pleased to report that the engine seems to perform better than it did in the past, especially the recent past. Unfortunately after about 5 miles there was a strong smell of burning oil and I figured I'd better turn back. Good thing as when I got home I discovered a truely massive oil leak. This engine has always leaked some oil somewhere above the alternator but now it was really bad. I searched around with a light and decided the leak had to be coming from the timing chain tensioner.

The timing chain tensioner does exactly what it says it does, keeps the timing chain tight. Its a spring with a hydraulic dampner of some sort that uses engine oil to damp the movement of the spring. It has to come out when you pull the head and if I remember correctly we originally tried to just unscrew the spring which doesn't actually work, you have to pull the whole assembly. Unfortunately it would appear we left it loose.

Unfortunately for me the timing chain tensioner lives behind the AC compressor. This in itself isn't a big deal but the bottom front bolt for the AC compressor bracket lives behind the water pump pulley. The water pump pulley lives behind the fan and since I wasn't removing the radiator to get the 4 bolts that hold the fan out requires working between the radiator and its shroud in a way my wrists and elbows just don't want to bend.
I managed it all in about an hour, the tensioner cap was loose (very loose, like turn with your fingers loose) so I tightened it and got everything back together only to find that I'd trapped the alternator/water pump belt behind the water pump pulley. Theres a little gap there just big enough to allow you this mistake without (fortunately) harming the belt.
That was it, I was all in, my back was killing me from hunching over so long and I was sweaty and tired so I quit for the night...

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