Oh for Pete's sake!

Who is Pete anyway?

So that *&^%$! 240D...

Trent turns out to have gotten himself in over his head and has everybody mad at him including me. The 2 hoses I really needed for this car turned up but they're wrong, both for a gasser, not even close to what I needed.
I finally got some standard heater hose and crammed it into place. Really crammed it since its supposed to be bigger at one end than the other. The other little hose I took to the parts store and they let me look around until I found one that was close. What I bought is too big but it should do short term.

So I get it all assembled and guess what? The friggin thing bubbles coolant out of the radiator again...


ARRRGH! The boys on the Mercedes list (okiebenz.com) came up with a bunch of cockamamie theories but have finally settled into thinking its probably a cracked head or block.

Angie is going away this weekend so I think I'll make one last ditch effort and re-torque the head bolts. Its possible they've stretched a little since I've had the engine running. Unfortunately thats a bit of a PITA because the cam has to come out of the way. I intend to zip tie the cam to the chain so the timing can't shift, we shall see what we see...

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...

HEAD GASKET!

When we last left our hero his 1978 Mercedes-Benz 240D was down for the count with a failed head gasket. What to do, what to do? Call out the troops of course! Saturday three of my good Mercedes friends came over and the four of us got to work.

I started before the others arrived, at about 7:30am I started by pulling the washer fluid bottle, radiator, hoses and radiator shroud plus the air cleaner and its hoses. Finally I disconnected the battery. My friend Fred arrived and we had breakfast. While we were eating Dimitri and Dwight arrived, with our team assembled we went back out and really got going. The air conditioning compressor gets moved out of the way but not removed. Mercedes recommends pulling the power steering pump out of the way but I didn't want to deal with the mess so we just pushed it out of the way, same for the oil cooler. With the front of the engine exposed the fan and its pulley get removed, all the belts are now out of the way. The thermostat housing comes off, then the injection lines, glow plug wiring.

Throttle linkage injector return lines and injectors which leaves the valve cover.

With that removed we see the cam shaft, timing chain and lifters, and Dwight's finger :)

Getting the head off and not screwing up the timing was one of our top goals so we spent a lot of time mucking about. It turns out you cannot leave the top sprocket on and remove the head, don't even bother. Fortunately as long as you maintain tension on the timing chain you can lift the head off without changing its alignment on the bottom end. A couple friends are helpful there.

So pull all the head bolts, put them in a piece of cardboard to keep them ordered.

The pull the head, its not super heavy but a helper here is a great idea, an engine lift would do the job too but is probably overkill.

Now clean the mating surfaces of the head and block real good. We scraped with razor blades to get a good clean surface, then ran a wire brush in the drill over them to be sure. We also cleaned all the headbolts good with a wire wheel. These are the hex head bolts which can be reused, unlike the later type which are torque to yield. Fred measured bend in the block, its slightly banana shaped which is normal. Mine is between 0.003 and 0.004 which is well within spec.

With everything cleaned a coating of Hylomar on the mating surfaces:

Thats some interesting stuff, it ate right through my gloves...

Re-install the head and torque it down. Theres a procedure for that of course...

Tighten, tighten some more, wait 10 minutes, tighten some more. You end up at 100Nm, a good long torque wrench is nice.

The rest is reversal of dissassembly which of course leaves out all the fun. Getting the timing chain back together was a bear, we probably wasted an hour on it. First we got the sprocket on but forgot the top guide, then we got the sprocket on backwards. FINALLY we got everything on and in the right orientation, I spun the engine over with a ratchet a couple times to prove it was all going in the right direction and nothing hit or made bad noises. Dwight and Dimitri had to head home, I can't blame them, they both drove many miles to be with me. Fred bless his soul stayed until the bitter end. Finally at 10:30pm we fired the engine up. Of course with no fuel in the injectors it was a tough start but with Fred working the primer pump and me cranking the starter it fired to life. Sounded weird which I realized later was the lack of air cleaner. I backed the car out of the garage and buttoned it down for the night.

I haven't had time to put in the radiator so I can run it up to temp and know for sure the head gasket fixed the problem but I'm pretty confident. If it weren't raining I'd be out there right now. Maybe tomorrow night...