Oil filler cap dances pretty strongly and it blow out a good amount of smoke and uses oil. Starts right up in all temps and has good power. Car has 210 k and had top emdrebuilt maybe 5kago. So how long can it last ?

If it starts right up in the cold the engine is good. As long as its not consuming an unreasonable amount of oil it can last another 100K miles.

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1984 300D Turbo 200K

Does it matter checking blow by when it’s warm vs. cold?


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When you are topping off oil weekly or sooner, it's time to bite the bullet and find another motor and swap it. Just do the math on oil, it aint cheap and motors are couple few hundred, maybe more shipped. If you're up to it a motor swap is a weekend job. Doesn't hurt to refresh the clutch while it's all apart.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

How long can it last? Probably as long as you can stand it. The smoke/smell and oil consumption will probably get to you long before the engine is actually "done".

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Hmmm....I would look at oil leaks and valve seals first?

Personally, I think the oil cap test isn't much of a test on a diesel engine as the crankcase ventilation is different than a gas engine.
https://www.youtube.com/watch?v=1ajChDRzku4
He talks mostly about turbo diesels but the NA has some of the same issues.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Are you saying excessive blow by is not from cylinder rings and piston wear?

I'm saying that the oil cap test is not a very legitimate test for checking blow by on a diesel engine due to crankcase ventilation and little vacuum produced. Compression and leak down checks are much more reliable.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I agree that the oil cap test is silly. I think it gets repeated too much on "Craigslist tips" sorts of threads and has strangely become this end-all-be-all "test".

If you actually do have a lot of blow-by then you might look into Marvel Mystery Oil as a way to fix a stuck rings problem. It definitely worked for me (really helped with the compression/cold starting), but also unplugged a few leaks in my old gaskets, so the oil comes out on the driveway instead. But the gaskets are relatively cheap and easy compared to rings so I'll take it.

Do some research and decide for yourself though.

-Rog

Agree that a compression test and a leak down test are the way to go. Also agree to try something like MMO with a couple of short interval changes then drive it hard uphill and coast it downhill to work the rings back and forth in case they are stuck.

At 210K on a 240 checking the timing chain for stretch would be in order, seen a few of them break.

Do you know what valve seals were put in and were any guides replaced? Did the oil consumption start after the top end was done? What oil is being used, diesel rated and weight? Is there oil in the air cleaner...= bad vacuum pump.

Curious... was this run WVO?

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I will check records that came with car about rebuild. I’m going to put breather hose in plastic bottle and drive it to see how much oil collects. Valve guides usually produce smoke on startup，I don’t have any

No wvo, air filter good

I tend to estimate the basic 616 engine condition partially on oil consumption. Anything below a quart every say one thousand miles is not that bad to me. During highway use.

The piston speed is higher on the 616 engines at highway speed. Than the 617s. So most use some or more oil than in city driving. So check your oil when highway use is involved. Actually a practice that is being lost to time is checking the oil at every fill up. To me it still is a very good ideal especially on an old car.

Oil consumption can usually be reduced in the warmer weather by running straight 40 weight diesel oil as well. Doing so may even reduce ongoing wear a little. As I was typing this I assume straight 40 weight diesel oil is still available. I have not seen it at some places in the last few years. Another indicator is what the hot oil pressure is at idle. Staying up at two bar is good. Or close to it. Of course this is partially dependant on the viscosity of the oil. Idle rpms etc.

Running straight 40 weight is what was recommended when these cars were new. Except in really cold weather. There were no multi grades. Or they were new to the scene.

I have actually experienced the oil consumption reduced to about half. When going from 10-30 to straight 30 many years ago. On a gas car. Also it will reduce blow by. On other cars I have used this approach there was always some improvement. Also have a look for oil leaks on your engine.

As suggested already. Miracle mystery oil is cheap. A container in the oil pan with the next oil change may or may not help. It is worth the attempt though in my opinion.

A quart in the fuel tank as well should do no harm. It does seem to have an effect of loosening up the piston rings in certain instances. Of course if the rings are totally free already there would be no improvement. Last but not least do not go over the mandated oil change intervals with these engines. If sludge has accumulated in the engine over the years. The miracle mystery oil will also help to reduce it.

The old timers used to always say never run less than 40 weight base oil in diesels. Based on too many issues that had occurred with earlier diesel engines doing otherwise. Not only because I eventually became an old timer as well. I tend to agree. It is a real shame that on all too many of these older diesels reasonable oil period changes where ignored as they aged. Once the oil additives wear and the soot accumulation grows high it becomes abrasive in nature.

Years ago I took apart some Mercedes gas engines with very high miles on them. It always amazed me that the cylinder wear was so neglishable you could still see all the original honing marks on some of them. I just figured the owners had changed the oil regularily. Do not forget to examine the hoses that go to the oil cooler for general condition and seeping. If either one fails the engine in most cases will become toast.

Most failures seem to occur when the weather warms up each year. We should be seeing at least a few posted on site all too soon. They present such a disaster if they fail you have to be proactive. Waiting for failure is really not a sensible option. Many of them may still be the original over thirty year old hoses. When the oil cooler is in operation the oil is at least 200 degrees and the hoses are under high oil pressure. They had to be high quality to last this long under those conditions. Most will eventually fail at highway speeds.

I have at last found a source of new hoses made by the original company for some of these engines. They may be an exclusive to this one supplier. He claims he has them made by them for him in Germany. Remember as well to check the clearance between the engine belts and the one cooler hose. The can cut into the oil hose if the engine mount is sagged..