300td head swap in progress/downward spiral, questions...

So I posted awhile ago here asking about my 300td with a thrown rod - so, I scored a running 300D for cheap (both are 85s), pulled both motors, and am about to put a good one together. The good motor from the 300d is a ridiculous oily mess, so I was planning on replacing anything that resembles a gasket, including dealing with the upper oil pan.

Here of course, is where we get to the downward spiral part - can the upper pan be removed without trashing the rear main seal? Also, I don't really want to pull the crank, but I would be insane to have it torn down this far and not replace the rear main seal, right? It is fairly oily back there, but it doesn't look like its from the main, mostly from those balls knocked into the ends of the oil galley, or from farther up... Then of course, if I do pull the crank, it seems silly not to just go ahead and rebuild it, which I was trying to avoid.

I was going to plastiguage the bearings just to see, but was hoping to avoid further expense

So what's the collective advice here?

Thanks all!

[rwthomas1]

Re-sealing/re-gasketing an otherwise sound engine is a prudent thing to do. Since you have it apart and out of the car you might as well. Changing the rear main seal is a good idea too, provided you don't have to pull the crank to do it. Look at it this way: If you don't re-seal it then the engine will likely leak oil once you install it in the car. If you do re-seal it then it has a much higher chance of not leaking. RT

[t walgamuth]

you might find that the bearings are worn and this is why the oil is seeping out everywhere. the seals wont hold it if the bearings are shot. hopefully this is not the case, but better to find out now than later after putting all that work in it and having to re-pull it.

ask how i know to advise this.

it was a 64 lincoln and i didnt bother to guage it and it had to come back out. and they werent easy in those lincolns.

tom w

[Diesel Giant]

Since its out of the car, replace every seal you can get to. Its so easy to work on the engine on an engine stand and not in the car. I would also drop in a set of rod and main bearings whil you are at it.

[signalredcoupe]

Exactly what I'm considering. I've pulled my engine for a minor restoration & mainly because at 290,000, I know it needs a timing chain & I found it to be leaking out the rear portion of the head gasket. I've bought the entire gasket set. I don't like the fact that the upper oil pan has no gasket. What would be the best sealant?
According to the manual, the crankshaft must be pulled to change the rear seal I suppose because it simply cannot be pulled out around the crank? Didn't ruin mine by removing the pan. I would hope to just loosen the mains only- to provide relief? I know I'm going to wind up pulling the crank, buying new bearings which I probably don't need. Simply plastigauging th bearing is cheap. Cost of bearings isn't that expensive. Messing with the pistons is.
Also, those knocked in balls at the rear of the block can be removed & substituted for plugs according to the manual if they won't seal properly.
Sounds like we're in the same boat. I'm interested how it turns out for you.
Paul central FL
1984 300CD red/black

[Diesel Giant]

Hey take some digital pics of the work you do.

[Pete Burton]

You might want to compression check it first. If the compression is lousy, just resealing won't get you a really good engine. OTOH, good compression should give you confidence in the rings and liners. New pistons are expensive. With the engine on a stand, removing the crank isn't all that hard, and you can check the journals and all the bearings. Good chance the crank won't need anything. With 248K on mine, all my journals were well within specs for new.

[t walgamuth]

the lower end seldom is worn out. but it is worth checking it. it it is shot then everything else is too including such things as the oil pump. plastigage and compression test it to be sure of what you have.

tom w

i already pulled the head and its on the stand...

[Pete Burton]

Then you can try to make an assessment via liner wear and ring gap. For some reason, cyl #1 seems to have the most problems. After removing the crank, push #1 piston down and out. (you'll have to remove the oil sqirter to that cyl first. See if the rings are free and check the gap between the ring width and piston ring grooves on both compression rings. You can take a ring off (carefully, of course) and reinstall in the bore to check end gap. I'd think you could accept values just a small amount beyond the rebuild limit in this case, but that's your call.

Background - I got an 85 300TD w/ a thrown rod, got a running 300 parts car (also an 85) and proceeded to make one. Last time I posted, I was going to check out the bearings on the parts car motor, which ran quite well (I drove it home, very smooth) - One of the bearing shells had a crack in it, so I pulled the crank, new rings and bearings and blablabla later, it's all back together w/ the head from the wagon and back in the wagon.

So last night, I crank it over w/ the stop lever on the inj pump down until I get oil pressure, prime the inj pump, then try to fire it up. No go, cranks fine, no signs of life, but I figure its cold out (20 degrees) and the rings are brand new - I plug in the block heater, go inside to warm up for an hour and come back. Turn the key and it fires right off. BUT! (always a but...) it surges kind of wildly, and I have to keep my foot on the gas to keep it going. If you start it w/out a foot on the gas, it will rev to 1500rpm and die immediately. If you keep your foot on it, it will rev between 1000 and 2000rpm, as soon I take my foot off the pedal, it dies. It will restart immediately, but behaves the same. Lots of black smoke. Sounds beautiful though, and runs smoothly, except for the surging. If it was a gasser, this would be a mixture problem, most likely, but this is my first diesel. Advice? The car has been sitting at least 2 years, the tank registers full, though the fuel in the prefilter looks kind of dark... Though I thought diesel didn't really go bad? I am using the IP and injectors from the donor motor, which was running fine prior to me taking it apart...

Thanks to all for the advice so far!

[t walgamuth]

get some fungicide and kill the fungi. after sitting overnight change the filters and fire it off. very good chance it will be fine.

good work so far.

tom w

tom w and others -

i replaced the filters and poured some fresh diesel into a cup, wedged it in the engine compartment and ran the supply and return lines into it, primed it again, and fired it up. it is better. but not at all right. less smoke, a little less surging, but still a lot of black smoke. it seems to consume a large amount of fuel, the cup holds about a pint and doesn't last more than 5 min or so at most. you have to lay on the pedal pretty heavily to keep it running, if you rev it up to 1800+ rpm, suddenly, you need much less pedal to keep it running at the higher speed and it doesn't surge. it sounds fairly smooth, but much too harsh, not quite sure how to describe the sound. the other thing i noticed is that it takes a lot of cranking to get it to fire if you let it sit for say 10 min or so. i had it running, then was fixing some leaks on the return lines from the injectors (all better), but then i had to crank for 30+ seconds to get it to fire up again. then, once its going, if it dies, it will restart immediately - is something leaking down?


also, i was wondering if this could be the result of my inj timing being off? the pointer that indicates degrees on the balancer was all bent and useless on the motor when i got it, so i bent it back and did my best to set it correctly at TDC when the head and oil pan were still off - it couldn't be off more than a degree or two though, i don't think... BUT, also when i was installing the inj pump, i was having a terrible time getting the beginning of delivery right - if i set the crank at 24deg before TDC of the compression stroke and installed the pump w/ the wide spline aligned w/ the mark, delivery would begin like 200+ degrees away. i installed the pump w/ the spline aligned and the crank at 0 deg BTDC of the intake stroke, and it seemed ok, in that when i cranked it around to 24 degrees BTDC of the compression stroke, i would get fuel. but this is clearly not what is stated in the manual... also, i set the timing w/out holding the lever at the full load stop, does this matter?

thanks all!

This is an engine w/ new rings and bearings - the original head from the wagon, and a block from a 300D. The engine still will not run without holding the pedal down significantly, though it does not surge about 1500 rpm anymore. Above 1500 rpm, it runs pretty smooth but sounds very harsh. Lots of black smoke at all engine speeds. Under 1500 rpm, it wants to die unless you nearly floor the gas pedal and it will come back up. No air cleaner, crankcase vent on top of the valve cover is open. Both supply and return lines run into a jar in the engine compartment w/ fresh fuel. The fuel seems to go away *fast* - approx 1 pint is gone in a few minutes. This seems like an awful lot to me... Per the drip method, injection timing is ~25 degrees BTDC of the compression stroke. I pulled the injectors, two looked wet on the bottom, some threads here said that this might indicate a leak? I swapped them for two others I have, no difference. I am using the IP and now 3 of 5 injectors from a car that I drove home and was running fine. The head is the original from the wagon, which died of a thrown rod. Any thoughts? I said in another post that I am not convinced the pointer for the timing marks is completely accurate, but I cannot believe it is off more than a couple of degrees either...

[300SDog]

On fiddling with IP timing did you ever discover a point where smoke changes from Black to Blue? I believe thats where you want the timing to be.

But with switching heads the valve timing can also be off. I'd check the TDC mark on the crankshaft pulley with that on the camshaft too.