220D, low temp., low compression, what now?

[Zeppo2K2]

Hi, 'new to the forum, great reading the posts.

I'd like opinions on a 1973 220D I purchased off eBay (a mistake I won't do again). I had the car shipped to L.A. and driving it home 200 miles I found: temp. gauge broken, no heat from heater, radiator at ambient temperature. The car was from FL, so the heater was not missed I guess. With a new thermostat, the temperature comes up to normal, but it badly smokes (blue) for about 5 minutes after a cold start. It takes about 3 or so minutes of cranking and glowing to start after sitting for a night (60 degrees). After starting, it is rough running for a few minutes until nice and warm.

It is now stored, but I'd like to get it on the road.

Compression shows, in order 1 - 4: 280, 160, 190, 280. Records with the car show an engine "rebuild" 30,000 miles ago, new pistons, rings, timing chain and valve job on head.

So what to do? Purge? Italian tune-up, lot's of them? (I'll probably get a ticket before it warms up with all the smoke.) Any ideas as to what running cold by previous owner would do to the engine?

Thanks in advance, Ron

[TMAllison]

I would think you ought to have more compression that that.

Adjust the valves and check your glow plug resistance. Suspect both need addressing.

[kerry]

X2.

[300SDog]

Check valve clearances first before doing compression test otherwise results aint to be entirely believed.

Normal glow/start-up time for primitive gorilla knob system is about 3-5 minutes, sounds like you aint glowin the plugs enough - hence crankin the engine way too soon. Yer first old-world diesel I presume? It aint nothin like modern diesels when it comes to startup ritual. Back in '73 these were not start and drive away cars but had to be warmed up. And primitive glow system is excruciatingly slow by modern standards. Thats 3-5 minutes just to glow the plugs you understand.

Meanwhile all diesels run rough to some degreee until warmed up, again check valve clearances and injector pop as referrenced below before worrying about rough cold performance. Otherwise you're outa yer mind tryin to diagnose engine condition of pistons, bores etc based on coldstart rough running. Start-up smoke/ unburnt fuel is also normal, though common culprit of incomplete combustion can be injector pump timing too.

My advice is change all filters, adjust valves and get injectors pop tested on yer newly purchased 220D. THEN decide how it runs after you're mastered the art of patience required in 3-5 minute glow/start and 10-15 minute warm up ritual. Otherwise weakness of the 220D is commonly worn out injector pump seals for never having it's separate oil sump monitored and oil changed. Worst case scenario there is $6-800 pump rebuild.

And rebuilt longblock (30k miles ago) oughta hopefully last another 70-90k miles if half-assed done correctly. Though personally am someone who believes old diesel shortblocks caint be properly rebuilt at all. Oughta opt for new factory shortblock instaed, says me. Question of pistons, rods and crank perfectly blueprinted and ballanced at factory that provides MB diesel longevity, procedure that rebuild shops caint replicate. I'd rather have an original decent running engine with say 250k miles than one thats been rebuilt.

Otherwise how's rest of the car? If its' got manual everything including sunroof plus excellent original paint then reconnoitre '73 220D to have immense long term classic value that shouldnt dip below $2500 USD with nowhere to go but up in value. 114/115's are hot ticket item right now, most of em doubled in value over the past 3 yrs. And question of massive upholstery, wing windows and pre-steelworkers strike German sheetmetal make pre-73/74 exceptional years for classic MB's better than 1974-'79.

[Zeppo2K2]

Thanks for the replies folks, I'll give some more background on the car.

The valves were adjusted before the compression tests. Also, I tried placing oil into one of the low cylinders, and it seemed to up just a bit. I did change all the filters.

I think I have experience to evaluate the car correctly. Let me give a bit of my background: I purchased a '74 240D in Germany at the factory, drove it over there, shipped it here, drove it, sold it 2 years later. In March '06 I decided to find a 220D, and this smoking car was my first venture back with M-B since '76. I have 5 now, 3 are parts cars, one my daily driver, and it starts and runs great. So I do have a bit of experience with these cars, but the idea of removing the head, and going deeper is scary.

Back to the car that smokes. When started, the column of blue smoke out the back is as large are the car! And to start it, you really run the starter for minutes. I did swap injectors with one of the parts cars, and no change for the smoking car, and the parts car still runs fine. (This is a car I purchased for $300, no air cleaner, no oil changes, but engine still has great compression, go figure. The intake area and butterfly were caked with filth.)

So I'm wondering if something happened to the smoking car from running cold. Like carbon on the valves, or on the rings, causing compression loss. And blue tells me it is burning engine oil badly, so maybe the valve seals too?

And in answer to 300SDog's questions, the car is in fair condition. Manual windows, no sunroof, repaint but over dents, a bit of rust, no leaks, rubber mounts including "A" arms replaced. The seller told me it had leather interior, no dents, and smoked "a little". When it got here, it had MB Tex (good condition, but not leather), dents in roof and hood - rust hole in floor - a surprise for me, and the smoking issue that is huge. The seller did give me some money back, but the shipping costs made this a bad deal.

I can't figure out what to do with this engine, maybe swap it for the "dirty" engine with great compression (I drained its oil, put a few gallons of diesel fuel in, pulled injectors, and spun it for a few minutes, let it drain for a few days, and now that thing is clean. But I don't trust it.)

BTW, 300SDog, I tend to agree with you, it is probably difficult to rebuild a diesel block correctly from what I've read. So maybe it was not the cold running that caused the compression loss, but just a poor rebuild.

Thanks in advance for any ideas you folks may have.

Ron

[dkveuro]

Not to rain on your parade...but the compressions should be better than 350 psi at sea level. Ideal compressions would be 425 and higher, depending on the engine speed the starter can generate. Your engine has 21 to 1 compression ratio.

I have found that nearly all Mercedes diesel engines respond very well to a new set of second oversize rings in otherwise used pistons and bores.

IE: If the bore is standard, a 2nd oversize set of rings, file fitted to each bore bring the compressions up to 400 psi plus. Cold engine starting at these levels is quick and nearly smokeless.

I file fit the rings in the lower part of the bore were there is little wear to 0.008" thou. On VW diesels I can get down to 0.006" thou end gap.

This, after I have the pistons media blasted clean.

The Mercedes diesel also responds very well to porting....the 5 cylinder turbo head is very restrictive. ...but this does not apply in your case.

The OM615 is a simple motor to work on..... has a chain driven cam easy to remove for head or block work.

Swinging the motor out along with it's transmission is a 4 hour job if you have a engine crane.

It's suggested to remove the cylinder head first, so the engine is held while you undo the head bolts which can be tricky out of the car.

The I/P is easy to set too and don't be frightened of loosing the i/p timing as the chain cannot slip over the i/p sprocket due to a plug in close proximity with the chain/sprocket.

Mercedes sells advance/retard cam keys still so setting the timing is a matter of getting the correct key.
Crank assemblies are nearly indestructable and often show little wear after 250,000 miles.

Gaskets are available and only basic tools are required to do most work.
Any competent machine shop can install valve guides should they be required.

[300SDog]

Silk purse outa sow's ear - ye gotta be crazy thinkin rework the rebuilt engine instead of swappin yer reliable parts car engine in there. And new subframe bushings plus A-frames count for alot with 115 suspensions. At best salvage cyl head from the 'build reconnoitring useful item when original parts car longblock hits 350k+ miles.

And I agree with dkveuro that new oversize rings is the only rebuild procedure an original factory ballanced Stuttgart engine oughta ever need. Morons go ape rebuilding these things with "new" imballanced pistons, i dunno why. Meanwhile Deves of Sweden makes aftermarket soft-metal rings specially designed for tired high mileage factory blueprinted Mercedes engines keepin original ballanced pistons, rods and crank intact.

Otherwise yeah it's gospel truth that 1973 and earlier 220D are considered better cars than '74-76 series w115. Buncha factors: German steel workers strike forced MB to import rustprone Russian and Italian steel for sheetmetal circa 73-79. And then there was "safety" lunatics abolished flamable seat glue in '74 that gave old models better upholstery. Plus outlawed corner vent windows for blocking peripheral vision of driver, can ye believe it?

Arguably 1974 was beginning of the end when it came to automobile craftsmanship. Now if it was 1968/69 4-spd 220D with manual sunroof then I'd like to own it myself - reconnoitre $5k USD for one of them in excellent original condition.

[vox_incognita]

Originally Posted by 300SDog

And I agree with dkveuro that new oversize rings is the only rebuild procedure an original factory ballanced Stuttgart engine oughta ever need. Morons go ape rebuilding these things with "new" imballanced pistons, i dunno why. Meanwhile Deves of Sweden makes aftermarket soft-metal rings specially designed for tired high mileage factory blueprinted Mercedes engines keepin original ballanced pistons, rods and crank intact.

Why`s that? I vaguely remember a forum thread saying different weight categories of conrods used in one engine(I don`t remember whether on any or only om617)
On the other hand ,the manual says:"in one engine,all connecting rods are to be of the same weight category"
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/615/03-313.pdf
...crank,flywheel and vibration damper balanced as a set....

Or the above statement only refers to 5 -cyl engines???

[pdxwaker]

I think blue smoke indicates oil getting burned... does it also let out a puff of smoke between shifts? You might look into valve guide seals.

If you plan on keeping the car, upgrade the glowplug system to a parallel style. This is amazingly simple with the 220d gorilla knob... just replace the glow element in the salt-shaker with some solid copper romex (12 or 10 guage?), replace the plugs with the correct parallel versions, and put heavy guage wire between the plugs instead of the rigid resistive elements. Also, remove the GND strap from the final plug at the front of the engine. This is a sub-$100 upgrade that will make starting quite a bit easier and reduce warm up times. No relay is required.