Last summer, I needlessly adjusted the valves and IP. Upon start up, I had a bad miss. I wasn't able to rectify the problem and took it to a MB specialist.

The diagnosis was that #4's compression was down 100 psi from the others. (#350/#350/#350/#250 - all wet numbers). I had been tracking the dry compression with a Harbor Freight gauge over the years and kept getting #290-300 dry. Not the end of the world, but not a spring chicken, either.

Now the miss is pronounced, smoking profilic, and oil consumption is greatly increased.

It was operating fine prior to adjusting the IP, but perhaps the long periods of cranking to bleed the air from the lines finally caused something to give way.

It also didn't help that, years ago, the alternator seized (meaning no water pump) and I limped it to the garage with an elevated temp gauge. It would stand to reason that #4, being the farthest from the radiator, would see the highest temp and possible sleeve warpage.

This is the second engine rebuild my car has seen.

In 1979, the original owner damaged their oil pan and continued driving on a dry engine until it threw a rod out of the engine block. The second owner installed a new short block and *did not* make any modifications to the head (no refinishing). I've spoken to the second owner and he verified the story that the receipts told.

That was 130,000 miles ago.

Today, I'm working with the MB specialist to get a quote for a rebuild.

I don't like playing these types of guessing games because, until you open it up, you have no idea what to expect.

At a minimum, I'm looking at new bearings,rebuilt vacuum pump, gaskets, rings, head reworked, and possibly new sleeves (#4, in particular). But, with 130k on the short block and ~ 190k on the head, what is the likelihood of needing new pistons or valves?

What else can I expect to replace? Estimated cost in parts (labor will probably run $1500)?

Timing chain, water pump, injectors, and IP were all replaced/refreshened up within the past 15k.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.

The pistons might be fine. They need to be measured. Valves might be good too, they'll need to be looked at. I did a 115 240 about 20 years ago. I think the parts were somewhere around 2K?

Did you check the valve clearance now?

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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 double and triple checked the valve clearance before buttoning it up.

The mechanic verified as well.

It has been burning oil since I bought it almost six years ago. What it doesn't burn is dripping from the rear main seal. I did go through about a quart between 500 -1000 miles depending on the driving conditions, with more being consumed after long bouts of highway driving.

I'd been postponing an inevitable rebuild, anyway. It's time to bite the bullet.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.

Is the rest of the car worth what you'd put into a rebuild? It might make better economic sense to drop in a good used resealed long block. What does Metric want for a good as new 615 these days?

Sixto
83 300SD

A quart every 500 miles isn't too bad. It's when you're up to adding two quarts per fill-up when there's a problem. I've seen the OM615s last over 120,000 miles after reaching the quart every 500 miles stage.

I'd recommend you just check/add oil at every fill-up, and otherwise enjoy the car! That engine may still have some life in it.

Previous to the miss, it was 500 miles/quart.

Given that it's winter, I haven't driven it enough recently to know what the current usage is. However, I suspect it's much more than that.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.

I had some rust repaired, added new rockers, and the car painted 5 years ago.

If it wasn't worth saving I'd have junked it.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.

Oh, I see. Yeah, if it's more than a quart every fill-up/500 miles, then it's rebuild time.

Might be able to do an engine swap too if you'd prefer the cheap route - you could look for a badly rusted or crashed 220D or 240D with an engine with suitable compression to swap in.

Being a '74 240D the engine is a OM616.916. I bought a rebuilt OM616.916 for the '73 from Metric almost 10 years ago, to replace the dead OM615. It was about $5000 then. Current price is about $2K more:

220D/240D

Not sure what cost to rebuild it yourself would be, but I'd guess about half that.

Thanks.

I found another source that would rebuild mine for $3600 plus freight.

As I said, it's a guessing game until one tears into it. I gave as much info as I could to get a sense of what parts might be salvageable and what might need replaced.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.

The other angle of my point is $3600 could buy a W115 240D in all around better shape than yours or a suitable replacement. It might cost as much to ship an engine as an entire running car. I'm not nudging you in this direction, just suggesting a point to consider.

Sixto
83 300SD

Finding a nice 115 today is like finding a unicorn. They are so rust prone they probably will rust in Arizona!

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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.

Air could be put into the cylinder to confirm where the compression leak is located i.e., rings, intake and/or exhaust valves. Both the oil burning and the low compression could be in the cylinder head which has never been rebuilt. The block only has 130K but it was overheated. 250 psi wet indicates rings that are really shot or normal leakage on a valve that needs resurfacing.

At 130K the bearings may be excellent, the valves at 190K can often be refaced, guides you'll probably need a few. Pistons probably ok except #4 but that is a guess until it's opened like you said.

Good luck!!!

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

Indeed. Someone recently posted in the Vintage section a link to a Bring a Trailer auction for a W115 240D that went for $5000. The car was a repaint with non-original cloth upholstery on the seats.

http://www.peachparts.com/shopforum/vintage-mercedes/382764-bring-trailer-featured-w115-240d-manual-auction.html

Perhaps W115 values are on the rise as they become more rare and people start to appreciate their place in M-B history. It also seems there is a fair amount of interest in the chassis amongst younger folks looking for an older M-B who want something besides a W123.

If the car is nice and you like it it's probably worth the rebuild, especially if you're looking long term. You've already done the body work, sounds like. How's the interior? Suspension? I'd be attached to it after all the effort invested so far.

As for re-using your recently replaced parts (timing chain, water pump, IP) - Whoever builds your engine might not want to offer a warranty because of the "used" parts. You'd just have to communicate and come to some kind of agreement with the builder.

And FWIW I'd put in a new oil pump.

I was sitting here wondering if the compression numbers done in a static fashion where bad enough to cause your missing symptom. The return tube from the vacuum pump does not have oil in it either? Common oil burning problem on these earlier engines.


At running or dynamic rpm the effective cylinder compression comparisons may be different. Your oil consumption is very excessive for the lower blocks expected normal condition at that milage as well.


Almost sounds like the overheat was so bad the piston rings may have lost their tempering. Anyways I would be tempted to get a newer 616 engine to get away from your type of injector pump. A little more horsepower as well after about 1981?


I believe you can still find really solid 616 engines still out there. The newer engines with minor modifications go in pretty easy. You just have to be pretty selective in what you choose as a used engine.


Otherwise I would pull the head and have a look at the crosshatching and general bore conditions.There are things here that do not add up properly.


Do not neglect the simple check of backing off each injector line when the engine is missing to locate the cylinder that is not firing properly. I would want things nailed down a little better before deciding on a course of action.