I'm working on my friend's 1985 300TDT (225K miles) The major complaint is that his car shakes substantially upon start-up (as if it were a cold winter start-up) and at the same time it smokes a lot too minutes after it starts up. Once he's out on the highway, it's fine. Drives well, smokes no more than any other time at highway speed. Even when the engine is warm and at idle, it still cavitates something fierce. I've done all of the maintenance on his car for the past five-years.

To summarize: it smokes a lot upon start-up with cold engine and at idle with warm engine. It vibrates a lot at start-up whether cold or warmed-up.

So far I have done: changed glow plugs (probably 20K miles ago)/ routinely changed air filter (no obstructions found anywhere-change it every 20K or sooner if necessary)/ both fuel filters every 10K miles (lately the clear in-line filter has been black with sediment, I changed it and figured he got some bad fuel, that was 20 tankfuls ago-inline filter is clear)/ran one can of Diesel Purge through system, no improvement/ adjusted valves 35K miles ago (he's 5K overdue - I doubt that's the problem, 75K overdue, maybe)/ thermostat replaced (MB brand) 18 months ago/crankcase ventilation has been checked-no obstructions found/no evidence of oil in coolant or vice-versa.

Can anyone shed some light on why this is smoking and vibrating so bad? Thanks!

[QUOTE=Boston Benz).......... (lately the clear in-line filter has been black with sediment, I changed it and figured he got some bad fuel, that was 20 tankfuls ago-inline filter is clear)............[/QUOTE]

I think you hit the nail on the head with that one. I managed to obtain some bad fuel back about Christmas. It took nearly a month of fiddling to finally get it to run smooth. The best thing that worked for me was filling up with B20 biodiesel and taking a 250 mile trip. If you don't have B20 nearby, it may take several attempts with purge. Another thing I have heard from an injector place is ultrasonic cleaning of the injectors.

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Sam

84 300SD 350K+ miles ( Blue Belle )

you changed glows recently, it sure sounds like a classic case of one or two bad glows.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I know, it does sound like bad glow plugs, but that wouldn't make sense that it idles so poorly even after 200 miles of contiuous driving. I'm almost thinking it's algae in the tank... It would be much easier to troubleshoot if it ran poorly all the time, at idle and at full throttle on the highway.

fungi to me. but the cure for that is simple. get some fungicide and try it out. what about the fuel filters? have you changed them lately?

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Gee, that sure sounds familiar!!
I've replaced injectors (twice), cleaned tank, run many different fuel sources. I've had IP timed. I've replace IP. I've had compression checked. It was fine. Thermostat replaced. New air filter. Valve stem seals and guides are fine. Valves adjusted correctly. chain stretch at 3-4 degrees. Not a BIT of blowby. No leak back from tranny line. Probably more, but that's all I can think of off the top of my head.
Be sure and let us know if you find out, cause our symptoms sound exact.
Good luck, I've given up for now.

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Yes I have changed the fuel filters recently. I'm thinking of replacing that screen in the fuel tank to see how much algae comes out. I do have a tube of Biobor Diesel Dr. too. I should try that. I'll keep all informed.

what can i get if i think i have an algae problem. i dont think i do, but then again i just bought the car, and it runs a little sluggish. i have not checked it yet. what stuff to buy to clear it out?

Unfortunately, Biobor is no longer made (was too caustic to the environment). You're best bet (I think) is to go to a marine/boat store and buy a bottle of fungicide. You add it to your full tank of diesel fuel and it is supposed to kill the fungi/bacteria in the tank. These fungi thrive in diesel fuel. Gasoline is too harsh/too hostile for bacteria to grow. Usually you get it with older diesels. I forget what causes it though, bad fuel? Don't know.

tractor or truck supply place. there is fungicide readily available. it works like a charm. i have never had to clean out physically the strainer. just put in the stuff and wait overnight and presto all is goot.

the fungus grows if there is water in the fuel. the water can come from rain, condensate or from rainwater running into either your tank or the filling station's tank.

my lovely #2 daughter once filled up my china blue 240 at a truck stop and got about a half tank of water. it was about 5 below zero and all that water turned to ice. it was a real hassle getting it all out. you have to have it in a pretty warm place for a good while to thaw out 6 gallons of water.

this one wasn't my daughter's fault!

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Interesting, that's how the bacteria form. Thanks.

I actually thought my friend's 1985 300TDT may have had a head gasket problem - although very rare on these 617 engines. It still idles really rough. It smokes a lot too (at idle). It's difficult to start too (numerous attempts on a cold start-valves were adjusted two-months ago). An oil analysis I got back today indicated ZERO coolant in motor oil. That's a good thing. My next guess is that the engine needs five new fuel injectors. Diesel Purge did nothing. Anyone have any ideas? What would cause this really rough idle and copious smoke?

If the problem occurs when the engine is first started, I would recheck the glow plugs. They can easily go bad within 20K miles. One bad glow plug will not be indicated by the idiot light, but will make the car hard starting and run rough until it warms up a little.

Right, but this also happens after the car has been driven for 200+ miles without stopping. It drives beautifully on the highway at 75 m.p.h. You pull off the highway for whatever, it idles poorly with a LOT of smoke.

The only other thing I can think of is the rack damper adjustment on the IP. See this thread:

engine shake 300D turbo

I don't know if this would explain the smoke, but it will make the engine idle rough and shake.