Here is what I know:

1. 1985 300CD California edition
2. 250k Miles, all service records since new, well cared for, zero rust!
3. Runs great, a little smoke on full acceleration
4. Has significant coolant leak on right rear corner of head (lose about 4 oz every drive), Gasket or cracked head?
5. Compression: 380, 320, 290, 360, 330
6. The # 3 intake valve has too much play in the valve-guide
7. Not doing this job myself, I have a Mini Cooper in full restoration and no way I am equipped to do two major projects at once. I thought I was done fixing this Mercedes!
8. Labor to remove, reinstalled, & tune whole engine is $5000
9. Full rebuild from Metric Motors is $9000 with freight
10. Labor to remove, reinstall, & tune cylinder head is $6000
11. Cylinder head rebuild is $4000 with freight

Note that the labor to remove and reinstall a cylinder head is greater than the labor to remove and reinstall the engine!

I am thinking I should go ahead with a full rebuild for two reasons. First, it guarantees the engine will have all fresh gaskets, so no rear main seal or other leaks to worry about for a few years. Second, the shops that do this work will soon disappear so better to get my "lifetime" car finished now than later.

The bummer is that I will have way more into this car than it is worth, but when was that ever not the case?

You can also:

1. Get a used engine and put it in.

2. Sell the whole car and get a different one

Itīs not cheap to own one of these cars if you have to rely on shops to do the work

Adding #3 to christuna's list...confirm that the coolant isn't getting into the oil and,

#3 Add just enough stop leak to stop the leak, then drive and enjoy the car for many many miles.

Good luck!!!

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

I love the 300CD, not a lot of them around, at least good examples.
Seen some premo one`s listed for $12K on up. Seen some in the PNP`s
beat to crap...too bad.
I saw this listing on CL guy posted the picture as he is looking for one.
Beautiful one, it is what we all dream of having.....not the one`s we are

driving now.


https://sfbay.craigslist.org/nby/cto/d/petaluma-want-to-buy-mercedes-300cd/7278904725.html


When I was a kid, the 55 - 57 Chevy`s were called "Hard Tops" w/o the door

post. The CD is in this category, though MB calls it a Coupe. Both classy
vehicles.



You are kind of in a pickle restoring one and need to fix the other. Those

are kind of low # on the engine.


Where are you in Ca.? I saw this one on the Redding CL, a running parts
car for $800 with 253K miles. Something to think about.

https://redding.craigslist.org/pts/d/redding-300d-turbo-diesel-running-parts/7281938737.html


Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Used engines are still plentiful. I'd get one check compression, get it running on a stand and if good, install. Make sure that you can't buy a car in the same condition as yours with a good motor for $1000.

The only reason I spend money on the car that I painted is it's been in the family since new and I want it to be a nice daily driver with everything working and looking good. Time moves on and projects need to be completed which means - nothing comes in unless something goes out. I hate it. Good deals are everywhere but take up too much space.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I agree with sugar bear's suggestion. In fact I did the Barrs Leaks radiator sealant about 5 years ago on my E 300 D, which sealed up the head gasket very well. I have had to add just a bit more once or twice, but I am happy with the repair. I understand that head gasket leaks are common on this engine so another engine may well have the same problem develop.

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'97 E 300 D

it's not too difficult to replace the head gasket on these engines

Pick n Pull Oakland had 300CD on the block for piecing out about a year ago. Dang the body looked good, interior not horrible. It got picked hard in a hurry. A tad depressing.

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1986 300SDL, 362K
1984 300D, 138K

It all depends on how you want to use it .

A good used engine plus installation is good but as you mentioned, will still need lots of fiddly little rubber parts to stop leaking .

For $5K an honest indie M-B shop should be able to do a top notch complete rebuild .

It's the small things, hoses and so on that really make the end difference .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

It's not the easiest one either.

you need an engine crane to lift a 617 iron head. Unless you're lifting weights or something.

then you have to know how to set both engine timing and injection pump timing.

OP has a loose intake valve on #3 (where the low compression is)

He could probably get away with a used cylinder head and be under $400 all in if he did his own work.

lots of good responses most of which are correct. Get a good used running engine with compression and preferably oil analysis as well if you can. Replacing engines is child's play with these cars. You get to replace other parts at the time while you are at it like mounts and driveline components which are easy to access. You might want to get a tranny while you're at it as its the next to go. If you have unlimited money it doesn't matter what you do. Spend it and support the slobs toiling in the shops. This site is primary for people who can fix their own and want to keep a great design going.

What is wrong with #3 intake valve? Is the guide worn and the valve stem is loose OR is the guide loose in the head?

If the guide is loose in the head I wouldn't drive it. If the guide is worn and has clearance between it and the valve stem you could drive it forever. Your compression #'s are not horrible. Was a wet test performed? If the rings are good consider doing a top notch valve job, new timing chain, vacuum pump, nozzles and hoses etc. The problem with a used motor is that it may not be as good as what you have. Don't consider a used engine without a compression test

Good luck! Post some pics of the car.

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

https://om617rebuild.com/

made by a friend

As someone mentioned earlier, really depends on what your end goal is. If you’re just trying to string it along and keep it running, use that Bars stop leak and crud up the cooling system.
If you’re keeping the thing for your end all, be all lifetime car, fix it properly. Using that stop leak crap is not really a fix.
If you’re in NorCal, find DieselKraut and he’ll get it fixed right for a lot less than $5k

I had a similar situation, head gasket was leaking oil externally, still making good compression, smokes a bit when hard into boost.
I pulled the head, albeit following a Peachparts tutorial, had it professionally rebuilt for $500. Dropped it back in and all head gasket probs are no more

I put the motor at TDC 1 before pulling the head and affixed a bungee cord to the T chain to stop it from moving. No need to retime anything, just slip the cam gear back on, exactly where I marked it before pulling. Hardest part was dealing with a little 10mm nut/bolt that affixes the turbo support bracket to the block - super bad access

Point of the story is.... for less than $700 and 3 evenings of tinkering, it now has new valves/guides where needed, T chain tensioner, HG, valve stem seals, and new gaskets for the turbo/intake/exh system.

Your block is probably still good and flat. You can get a machinists straight edge for cheap and can measure how far off it is. Given good lubrication and cooling, the lower end lasts a super long time, and can operate decently when worn out. If your valves aren’t super bad, wouldn’t be surprised if your smoke is caused by something else, like the turbo.

The engine was pulled out and sent to Metric Motors in LA. Inspection on tear down revealed:

1. Badly needed a valve job
2. Coolant leak was caused by corrosion forming a low spot on the block
3. Main bearings were shot
4. The fuel pump timing device had to be replaced
5. The camshaft had to be replaced

So it turns out the block had to be removed and resurfaced to fix the leak. The bill for the complete rebuild at Metric motors was $9300 plus tax and shipping to San Diego. The total comes to $10,270. It is pretty shocking how fast they rebuilt the engine. It only took four weeks. Now I have to get the engine back in the car.

I will post some pictures when we have the engine on the hoist.