My 1989 745T died tonight.
I was crusing about 55 when I started hearing some noise like valve clatter
I saw a little smoke coming from the rear and about that time the engine quit.
I lifted the hood and there was smoke coming from under the intake manifold about where the oil breather is located.
It appears the oil was coming from the dipstick tube; but...
yesterday I removed the oil breather for cleaning and replaced it with a new o ring. It didnt appear to be leaking when I checked it.

I tried to restart the engine with some help, with the oil filler cap off and saw the cam turning normally and all belts were in place.
However the starting noise was different and it wouldnt fire. One cylinder maybe?

One more clue, maybe...
I have been losing oil from the cap and discovered a broken seal which I replaced today. That was the reason for the oil breather cleaning.

I don't know when the timing belt was changed but it was checked recently and passed..

I think the oil issue is separate from the no-start problem but not sure
Any help would be greatly appreciated

Check the dipstick now. I hope you didn't have a major oil dump that caused your engine to quit internally speaking.

If you oil on the stick...that's good, then I would go after the Timing idea too.
--
'75 Jeep CJ5 345Hp ChevyPwr and two motorcycles: it wasn't Volvos safety , it was Longevity that sold me

There is no such thing as 'checking a timing belt and it passed.'
A perfectly good appearing belt can shear or fail the next time you run the car...the only thing that means anything is time in service. OK, number of starts might play a part if you only run a mile down to the train station, but you get the idea.

You can pop the top timing cover and put the engine at TDC on compression #1 cylinder and check the timing mark on the camshaft sprocket.

If after replacing seals your leaking oil in different places, your engine is not breathing properly, and most likely till you find the plug it will find other areas to leak out, you do not have a Fire Trap on the tubo models but you do have a hose and oil catcher box, check to make sure the oil hasnt crusted the hole where the rubber pipe going from it to the turbo pipe isnt clogged or close to it. thats probly your best bet with pressue causeing seals to go. now your seals just could be woren out and in need of replacement too.

Rotate the engine to TDC (observe crank pulley or remove #1 plug, look for top of piston travel) and remove the top timing cover. Your timing mark should be right on. If not, it should be noticeably off. I guess it's possible the cam seal leaked oil, making it easier to slip a tooth by lubing the belt up. Inspect for oil in the cam cover when you look at the timing marks. On a 740, the mark for the intermediate shaft is unimportant.
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Rob Bareiss, New London CT ::: '87 244DL/M47- 221K, 88 744GLE- 202K, 91 244 181K, 88 244GL 145K

Your coment: "On a 740, the mark for the intermediate shaft is unimportant. caught my eye. I a getting ready to change the timing belt on my '90 240 and later this summer my '87 740. I thought the intermedite shaft provided a counterbalance for the crankshaft to keep vibrations down. If this isn't true, what is the purpose of the intermediate shaft?

TIA
Dan

I've wondered about that myself also. I do know that on those models that had a distributor on the side of the block near the front was driven by that shaft.
Hence it had to be timed with the crank and cam.
John