OM603 Cylinder Head 1987 - PeachParts Mercedes-Benz Forum

vwnate1 · #1 08-30-2015, 08:29 PM

I'm new to these 6 cylinder engines , my Brother bought one and now it's weeping coolant at the right rear corner of the cylinder head / engine block joint .

He says it needs a new / different head ? .

We shouldn't have the original head planed ? .

Casting #'s I should look for and where are they , etc. ? I know some here have gone through this already .

TIA , I'm in So. Cal. if any good shops or links etc.

jay_bob · #2 08-30-2015, 09:30 PM

I would pull the head first and see what you got before shopping for a head. May just be a breach in the HG.

But to your point there were several casting numbers in the 603. The standard from 87 was the #14 and these are known to fail. From what I have read they tend to fail - cracks between the valve openings, or valve to pre-chamber opening is the usual failue mode - usually as a result from overheating.

There is a #17 and then a #22. I think the 22 was used on the 3.5 L for the 350SD/S350 of the early 90s.

*still rolling along on my #14 head....

vwnate1 · #3 08-30-2015, 09:54 PM

Thanx Jay ! .

I thought to pull it apart for a looksee first too but it's _his_ car , I assume you know how that goes....

.

So , where to look for the # 14 ? .

Under the rockerbox or externally ? .

TIA ,

mannys9130 · #4 08-30-2015, 10:15 PM

There is a part number stamped on the head near the injectors and intake. The second or third group of numbers will be 14, 17, 22 and that is what's being referenced. I agree to take the head off first, but if it's a #14 you might just replace it while it's off. Some believe the #14 is so brittle it might crack from the first heat cycle after being removed and replaced.

Replacing the head with a #22 gets you angled injectors, so understand that the injectors and prechambers will be different than a 17 or 14. If you replace the head with a 22 and use the revised head gasket, you won't have cracked head issues or leaking oil gallery issues (that's the other issue with these heads).

dkveuro · #5 08-30-2015, 11:01 PM

Mercedes increased the gasket deck thickness on the later heads due to field reports of gasket failure. ( like yours. ) #14 heads are not rigid enough, reason for increased thickness. However not all failed.

Mercedes has gasket face to valve cover measurements for the heads and must not be machined if already at limit, as it reduced deck rigidity and alters chain/cam/crank timing.

These dimensions can be found at StarTek site.

zu! · #6 08-31-2015, 12:09 AM

Here you go. It's right under the air horn as its called. Mine looks like it's a 17, but it's really a 14.

Sent from my iPhone using Tapatalk

vwnate1 · #7 08-31-2015, 09:57 AM

And I THANK YOU ALL VERY MUCH ! .

Now I have a starting point .

A Month or three ago we found an OM603 in a Junkyard , the car was clean but wrecked , my Brother commented ' maybe I should buy this engine ' as he was worried he'd have this exact issue .

The turbo and other engine accessories had all been stripped off but they only wanted $250 for it fan to flex plate .

Onwards , always onwards .

treetops · #8 08-31-2015, 09:14 PM

Check the casting # on the junk yard engine. I got a #17 head complete(valve cover to bottom; cam, sprocket, valves, tappets...etc and injectors) for 150 plus pressure testing for another 200 or so. It tested fine, true, not warped and had enough material to be machined if need be. Not too bad comparing to prices on the web or new.

If it works out, cheap insurance.

vwnate1 · #9 08-31-2015, 10:22 PM

That Junk Yard car is long gone ~ here in Sunny So. Cal. , they rotate 'em out of the rows in about two weeks even if untouched

.

I looked at it to - day and , sure as shootin' , we've got the # 14 casting head so now I'm ' On The Hunt ' for another one .

I sure hope I don't get suckered into doing the head job , I have a yard full of dead vehicles right now .

Like older Mercedes diesels ? ?CHEAP? (as in scrap value) ? looky here : https://www.kenporterauctions.com/vehicle_listing_temp.asp?auctionid=367&searchval=Automobiles

TO-MORROW FOLKS ! .

vwnate1 · #10 11-19-2015, 09:31 AM

First allow me to say THANK YOU to the several Members who PM'd me with good used # 22 heads

.

@ $700 each they were a bit over my $ range .

So , back to my local Pick-A-Part Junk Yard I went and found another 1987 300SDL with the same color paint and upholstery , it had been rear ended by a semi so I was able to buy the # 22 cylinder head complete , the rocker box and oil pan all for $35 , I hied the head off to my Machine Shop who tested it , touched up the valves and installed a full set of the up graded valve step oil seals , it's all buttoned up and running fine again .

Whew .

Got the entire job done for under $1,500 .

I have a few 'photos if anyone cares....

daw_two · #11 11-19-2015, 11:01 AM

Please post pics --- I like to see what other forum members are doing.

Hit Man X · #12 11-19-2015, 03:28 PM

Just FYI to anyone else, there are No 15 and No 18 heads around too... I have owned both.

mannys9130 · #13 11-20-2015, 01:28 AM

#18 or up is considered a definitive fix for the cracking. The older castings are still prone. #14 is the worst for sure.

cho · #14 11-20-2015, 02:56 AM

Quote:

Originally Posted by Hit Man X

Just FYI to anyone else, there are No 15 and No 18 heads around too... I have owned both.

#20 also...I have one

.

sixto · #15 11-21-2015, 04:34 PM

Quote:

Originally Posted by mannys9130

Replacing the head with a #22 gets you angled injectors, so understand that the injectors and prechambers will be different than a 17 or 14. If you replace the head with a 22 and use the revised head gasket, you won't have cracked head issues or leaking oil gallery issues (that's the other issue with these heads).

To clarify, #17 through #22 castings use inclined injectors and a slightly different set of injector lines though injector lines for vertical injectors can be bent to fit (if you dare). I don't recall reading that #17 and later castings have less propensity to crack than #22 heads. From what I've read, the big difference in #17 and later castings is oil journal geometry ahead of the #1 combustion area but #22 castings and the latest head gasket part number can still leak.

Personally, I wouldn't pay more for a #22 casting over a #17 all else being equal. Personally, I wouldn't reinstall a #14 casting that shows to cracks. Torquing the head could stress latent cracks into... uhh... post-latency.

Sixto
83 300SD