another thing necessary to use the #17 casting will be injector lines, the old ones aren't shaped properly.
FWIW, my two #14 heads keep on purring! I did have them surfaced and valve jobs at around 250K miles (each)

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

so the 350sdl head can be put on a 3.0 603 turbo? Just seems weird to me. I guess its the stroke thats longer on the 3.5, and not the bore. Does this head not crack? Is it a different alloy?

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1981 300SD 512k OM603

The heads were reinforced in the water jacket for the turbo engines, and then further starting with the #17 head. That's the biggest difference. On the #22 head apparently the oil channel in front was changed to prevent oil leaks.

Since the head is flat, there is no difference in mating surface for the 3.0 and 3.5's larger bore, so it does not affect the combustion chamber. I do have some reservations regarding power though, the 3.5L had less power, and its head has different injectors, larger pre-chambers, etc for emissions reasons, it might be why the 16% larger engine has 10% less power, so putting a 3.5L parts on a 3.0 might decrease power, possibly even less than the 3.5L's power.

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Gone to the dark side

- Jeff

Folks, while you can swap all those parts, you do not NEED to swap the prechambers, injectors, lines, etc if you put a newer head on an older car. The ONLY possible snafu is that some of the newer (#17-up) heads don't let the old vertical prechambers fully seat, causing pressure leaks. This is a 50/50 shot... some people report problems, others do not. I was one of the "lucky" ones, and I had the problem when installing my 1987 prechambers into a new #22 head. My solution was to machine a couple of mm from the lower edge of the prechamber body... problem solved. See photo below.

Additional photos of my 603 head replacement are at this link. Metric Motors, a major MB engine rebuilder, is the place who told me the 50/50 percentage, based on their experience. They machine the head, instead of the prechambers, since they have the equipment to do so... I did not, so I did the prechambers instead (much easier).

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Dave
Boise, ID
Check out my website photos, documents, and movies!

Jeff, I believe the reason the 603.970 3.5L put out less power was because it was artificially limited by the injection pump calibration (133hp @ 4000rpm). If it was allowed proper fuel delivery, power should be normal. This restriction was removed for the 603.971, which returned to the same 148hp (@ 4000rpm) of the 3.0L, but added 15% more torque. If it was allowed to rev to 5000rpm, with slight IP tweaks, I bet the power level would be higher. Both make 228-229 lb-ft of torque at 2000-2200rpm, btw; compared with 201 @ 2400 for the 3.0L.

Note that all the 603 turbos use the SAME camshaft, so that may also be part of the reason the larger engine has the power curve shifted down somewhat. The 3.5L would have benefitted from a slightly hotter cam, at the expense of low-end torque... but MB's goal was torque, not HP, which is why they left the cam alone.

Finally - the alloy of all the heads is the same, AFAIK, the only difference was in the design of the castings. I have only heard of one or two newer (#17-up) heads actually cracking, and generally only under extreme circumstances. So while they can crack, it's extremely unlikely, as long as engine temps remain below 120°C and the coolant level is normal.

I called a machine shop years ago and talked to them about 603 head repairs. They said they had repaired several with no comebacks and sounded knowledgeable about the problems. I may have posted a link.

Some people may not 'fess-up about repaired heads for fear that it would affect the resale value on their car and make them look like a hack. I would try it in a heartbeat.

If you are on a tight budget, and can find a shop capable of doing a weld job at the right price, it's worth a try. But I wouldn't want a #14 head on a car that will be pushed past stock power limits... if you intend to max out the IP or install a Myna pump, a #17-22 head is almost a requirement.

That's not the way I would approach this. I would look for a shop that specializes in welding cylinder heads. I would probably choose a shop that does aircraft heads. The one I mentioned before wanted about $400 at that time.

At the time I could buy a used engine for $500 so I wasn't going the welding route anyway.

I agere, a shop that specializes in aluminum head repair is really the only way to go. But at $400, when a #17 can often be found for a few hundred more... it's a tough call, unless you're fixing the car to sell it.

That's what I mean. You can buy a whole engine or a whole car for less than a new head, with a little luck for less than a used head.

The only way I would go for a new head is with a totally pristine car, and a totally pristine car probably wouldn't need a new head.

I haven't been reselling cars lately, when I did I bought them in nearly perfect mechanical shape, but needing cleaning.

I don't agree with the whole car for less than a new head. Usually, unless it is a wreck or close to it, '87s go for closer to $3500. Add to that the usual repairs and tweaks to make it "perfect", and you have a substantial investment above the $1700 - $2200 for the head casting.

Changing cars and the great unknown is a pain and a gamble, fixing the one you have many times makes more sense. I looked for a year for the right car with the right colors, options, condition & history, ... then I made it better. If the head leaked, I'd consider a 14 head, I bought one for just that reason.

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Gone to the dark side

- Jeff

Talking about a parts car, not a replacement car.

Ahhh, got it. I've seen those for fairly cheap.

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Gone to the dark side

- Jeff

So the day has finally come, I pulled the head on my 603 tonight and sure enough, before a thorough cleaning, I can already see cracks in three of the chambers.

There is a 92 300SD in the junkyard- I'm told its a #17 casting, I vaguely recall others using the 3.5 heads on the 3.0 blocks. What all was necessary to swap to make it work? I'll probably go out and pull it for my car since I did find one very tiny crack in the other #14 head I had pulled from the yards coming from the #4 prechamber.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

WOW that is shocking, 2 cracked #14 heads.
Well let me be the first to welcome you to the OM603 cracked head club.

The #17 head will work for you car. I can't remember when they switched from straight to angled injectors, but I think that is the only change.

How much can you pick up the head for?

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


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