W124 Diesel Aluminum Heads.(87 300D) - PeachParts Mercedes-Benz Forum

Carrameow · #1 07-28-2004, 03:43 AM

I like my 87 300D a lot and now I am thinking of getting rid of my Volvo 940 Turbo, a good car, but it eats gas. I was thinking of running a pair of 87's for the Family, because the W124's almost pays for itself in low fuel consumption. Before I do so, i heard the W124 Diesel is not the same bear as the W123 and its Aluminum head cracks. Is this true? If it happened, could the head be fixed? What factors accelerate head cracking?

md21722 · #2 07-28-2004, 08:43 AM

All original 1987 heads were flawed from the factory. MB redesigned them about 5 times thru the early 90's. Head gaskets were also redesigned several times. Factors that accelerate damage seem to be lots of city driving and having the trap oxidizer installed for a long time. The standard test seems to be to check the upper radiator hose for pressure. If there is high pressure the next morning after using the car, there is some sort of problem - either head, or head gasket. Irratic temperature problems also will show up. It might get hot around town or at low speeds but cool down on the freeway. There is only 1 case I know of where a 603 had symptoms of a cracked head & no cracks were visible when the head was pulled. Every other case I know of involves a cracked head.

The head casting # is near the #2 injector. Number is an MB part number i.e. "603 xx 14 01" for an original head. "17 01" is the first casting that solves the original problems.

Regards,

Carrameow · #3 07-28-2004, 09:11 AM

Should i be R and Ring my Trap Oxidizer ? Will that prolong head life?

md21722 · #4 07-28-2004, 09:17 AM

You shouldn't have one.

If you do, call the dealer and they'll install a new exhaust system from downpipe to tailpipe and a replacement pipe for the trap oxidizer. Free of charge.

There was a "service campaign" to remove them.

Regards,

P.E.Haiges · #5 07-28-2004, 10:16 AM

Too bad there wasn't a "service campaign" to R&R the defective aluminum heads.

P E H

goldenbear · #6 07-28-2004, 10:41 AM

Carrameow,

Note that if you have the original head it doesn't mean that it WILL crack. I know upwards of a dozen OM603 owners with the original head, one of them is shooting for 500k mi by the end of this year (currently at 472k mi). Just watch your temp closely and don't allow it to overheat. Replacing the trap oxidizer should be a priority.

Christophe · #7 07-28-2004, 07:22 PM

Just got my 124 300TD and it still has the original "...14" head with 170km. Car runs strong, no overheating and no presure in the radiator. As previously stated, not all the oringianl heads are bad but if the engine is overheated at some point in its life, the old heads can crack. Not like the old 123 iron-heads.

Love the way this car drives!

goldenbear · #8 08-02-2004, 04:07 PM

Looks like I jinxed myself. The day after I posted to the reliability of the original heads, when properly cared for, not overheated, etc., my car appears to have manifested a head crack in normal operation and began showing symptoms on Friday.

Tirebiter · #9 08-02-2004, 04:53 PM

Are there no after market cylinder heads to cure the problem?

I know a man who replaced his Ford Aerostar heads several times before he found a set of German made steel replacement heads that cured the problem.

I like the way the 603s run but I am unwilling to depend on a vehicle with inherent problems like that.

goldenbear · #10 08-02-2004, 05:02 PM

Quote:

Originally posted by Tirebiter
Are there no after market cylinder heads to cure the problem?

I know a man who replaced his Ford Aerostar heads several times before he found a set of German made steel replacement heads that cured the problem.

I like the way the 603s run but I am unwilling to depend on a vehicle with inherent problems like that.

It is strongly recommended to ONLY use a genuine Mercedes replacement head. I don't know that an aftermarket head exists.

Regarding its dependability, I've had the vehicle for 4 1/2 trouble free years with no car payment. The car turns 18 next month. I have absolutely NO problem spending $2-3k for another couple hundred thousand miles. Otherwise, the vehicle is showroom and I look forward to driving it for many, many years. The 126 fits me perfect and IMO, along with the 124, is the pinnacle of Mercedes engineering excellence.

gsxr · #11 08-02-2004, 05:47 PM

Quote:

Originally posted by Tirebiter
Are there no after market cylinder heads to cure the problem? I like the way the 603s run but I am unwilling to depend on a vehicle with inherent problems like that.

Mercedes redesigned the head 5 times. The cure is to install a newer version. The 1986/87 models in the USA all came with a #14 head. You need to install a #17 or later head and it should never crack again unless severely abused (I don't think I've ever heard of a cracked 17+ head.) The latest version, if you buy a new head, is #22. No need for an aftermarket steel head.

Best bet is to buy a 300D/TD/SDL that comes with the updated head, after a previous owner has already had the problem and fixed it. These are kinda rare but they do pop up from time to time...

dieseldiehard · #12 08-02-2004, 06:30 PM

An area of caution to the DIYer who buys a new (-22?) version aftermarket 603 head, there are reports of some precombustion chambers that fail to seal where a lip extends out in the opening where they go, regardless of how tight the ring is tightened it hits the ring and won't bottom. The solution is to machine the lip off in the recess or, as GSXR has described, machine the flange on the PC chambers.
I believe OE heads have no problem in this regard. I would hope the aftermarket heads do not have the upside down "Y" in the casting.
If you need the name of the machinist that supplied me with this info, send me a PM, I'll dig up contact info (BTW it is DeGroff's Head Shop in Northridge, CA)

I was considering a new head as I went into a top end reman on my '87 300DT but my -14 head had less than normal corrosion and was just slightly non-flat so I had it pressure checked and skim cut and (knock on wood) its running fine ever since. Seems like the head hasket was leaking that is all.
Also, the PO had the trap oxidizer recall performed early on. I think that is one culprit, and stop and go driving in hot weather might be another contributor to head failures. Not all #14 heads have failed you know. The car has 257K mostly freeway miles showing and still a great looking and running car.

gsxr · #13 08-02-2004, 07:39 PM

The prechamber issue affects some newer heads - possibly #17 or #20 as well, definitely some #22, since it happened to me. Metric Motors says they find it on maybe half the new 603 heads they buy when rebuilding 603's. Some need machining, others don't. Apparently the design spec changed on the newer heads for the angled injector prechambers or something. Only way to know is to insert the p/c with the head off, measure protrusion, then insert a shim of known thickness (say, 0.5mm) and measure again, the difference should be 0.5mm - if not, you need to machine & repeat the measurements until they come out correct. Or after the head is installed and you get the nice "puff puff puff" when cranking (like I did!), yank the p/c's, machine them, and reinstall!

gsxr · #14 08-02-2004, 07:40 PM

FWIW, Marshall Booth also thinks (as do I) that a city-driven 603 with a trap oxidizer heavily contributes to the cracking later in life. Freeway driven cars, and/or those who had the traps removed as soon as the TSB came out, have the best chance of survival.

Carrameow · #15 08-02-2004, 08:06 PM

My 87 was going to replace my 85. I'm glad I didnt sell it and I will probably repair the 85 engine/ replace it.

I've sunk a lot of money ( for me) into a Timing Chain, Struts, Alternator, Water Pump, AC., Tires for the 87

I start a new job with a 3 hour round trip commute pretty soon....