Looking to possibly purchase an '87 300D.

I've read things in the past about the infamous cylinder head failure on these 603 motors, which makes me VERY, VERY, VERY nervous about even thinking about one of these cars.

What advice do you guys have for me? Will the heads on these cars ALWAYS crack? Or are they alright as long as they are never overheated?

Is exact-brand MB Coolant absolutely necessary in these motors? Would the phosphate-free Pentosin coolant be fine?

Lastly, I read somewhere that MB Transmission Fluid was the only tranny fluid that should be used in a Mercedes. Is this accurate?

What other advice can you give for potentially purchasing the 1987 300D?

Thank you!

No, they will not always crack on their own. 90%+ of the time it involves overheating. They CAN crack on their own without overheating, as can a cylinder head on any engine in the right conditions.

Zerex G05 is a good alternative to MB branded coolant.

Any off the shelf Dex/Merc ATF will be perfectly fine.

Spend the money for a prepurchase inspection by a qualified Mercedes mechanic before you buy it.

Where are you located?

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

There are literally hundreds of #14 heads still in service
I own 2 of them. My theory is that people neglect to keep their cooling systems in order AND there is a known weakness in the thermal switch atop the head that turns on the electric fans when AC is on. There should have been a relay to carry the current, instead the sensor switch carries all the fan current and the contacts burn out. Also the later models switched to a lower temp sensor, it can be considered an update worth considering.
You will want to find out if there is still a trap-oxidizer (Nasty Trap Oxidizer!) in place on the exhaust? It is a contributor to engine failure for sure! Fortunately there is a free dealer replacement under warranty if it hasn't been done (they can tell you by looking at the VIN # on their national computer files whether or not the NTO "Factory Campaign" has been done.)

The things I have seen is cooling systems with deposits in the radiator that reduce cooling efficiency, coupled with a non-working AC radiator fan, and even the fan on the water pump not spinning properly because the fluid leaked out of the thermo-clutch, all these factored into a hot summer drive will overheat the system, boiling water in the head and the result is possibly a cracked head. Headgaskets also can be a contributor when they start leaking, and another thing is thermostats that stick closed (ask Greasybenz about that!) you see there are several small things that can cause the head to fail, even a new style head wouldn't be immune.
I also suggest having a potential car inspected by a mechanic who knows these engines.

The item I worry about on 603's is the vacuum pump. The old style pumps (and some believe a few of the new style one before they were upgraded) are a real bugger if the bearings come apart and spew into the timing chain it's a recipe for a disaster (as in new pistons, valves, cam shaft, etc even a new block if it locks a piston hard enough, I've seen that too) so definitely get a pre-purchase inspection or else plan on replacing all the above if you buy the car!
DDH

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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!

I've got the original cylinder head on our 87' 300sdl and it's got over 308k logged on the odometer.

It has no signs of a cracked head or compression in the cooling system.

I also take good care of our cooling system like new antifreeze, w/pump, radiator, and stat.

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87' 300sdl

My 87 has the #14 head with 180,000. I looked at an 87 with 365,000 miles on a #14 head. Both had the latest model vacuum pump, both had signs of a radiator replacement and both had the belt tensioner replaced. All are important on a 603.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

I have an 84 300cd-t(123 chassis). does my engine have the same head that you are all talking about?

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coupes are cooler than sedans
84 300cd-t 305k
84 caddilac eldorado 43k
87 shelby GLHS 84k
86 dodge daytona shelby 112k
77 buick lesaber sc 74k
all coupes

No, you have a 123 Chassis with a 617 engine with a cast iron head. No issues with heads on these.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

Thanks buddy, i took a second look at the thread and realized it said 6cyl. i appreciate the quick response though.

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coupes are cooler than sedans
84 300cd-t 305k
84 caddilac eldorado 43k
87 shelby GLHS 84k
86 dodge daytona shelby 112k
77 buick lesaber sc 74k
all coupes

Any way to tell if the vacuum pump is the "latest/updated" version?

What makes them "updated"?

Thanks!

If the car is in good exterior shape, interior shape, and everything functions as it should coupled with at least some service records- GO FOR IT! I love mine to pieces and Hans has treated me only the best. It's a very quick diesel when you get on it, sounds nice, and gets awesome fuel mileage (coming from me when my firebird gets about 9mpg). The ride is second to none comparing it to my 82 300D. Seriously, get it if it looks good man

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.:1982 300D "The Ambassador"- R.I.P:.
.:1987 300D 3.0 "Häns"- Current Whip:.
.:1967 F85 Oldsmobile "Grandpa"- Show And Go:.
.:1991 WS6 Firebird Trans-Am "Blackbird"- FOR SALE:.

My 87 300d has 373,000 miles and the original #14 head. No signs of problems yet. The transmission is also original. Mine had all records since new and was very well maintained.

I have about 230k on mine with no problems to date...with the engine. If you are looking to buy one of these, see if the evaporator has been replaced and check the rear suspension. It seems I have replaced just about every piece of rubber on this car in the past 3 years. The car is very fun to drive, I just get tired of working on it. My experience should not deter you though. I bought mine cheap and as the saying goes...The most expensive car you will ever buy is a "cheap" Merecedes.

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

Diesels need diesel coolant, Zerex G-05 is the only alternative I know to the M-B stuff.

If the head is good, treat it well and don't worry about it. Will a head ever crack if not overheated? I don't think there are enough of these 20-year-old cars around in the hands of the original owners to prove that their car has never been overheated, ... I overheated my first '87 300TD in '89 when a hose blew on the freeway (defective).

Many theories, not enough data to say. I have two #14 heads with no problems, ...

They're a great car if in good shape, expensive as any Mercedes-Benz if neglected or abused.

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Gone to the dark side

- Jeff

The 722.6 transmissions require specially formulated ATF. I don't know if it's available in the aftermarket.

The 722.3 and .4 transmission use plain old Dexron III. For kicks, read -

http://www.peachparts.com/shopforum/showthread.php?t=201529

W124 300D radiators are a maintenance item. Replace it every 5 years before the plastic gets brittle and fails.

Someone asked about the vacuum pump -

http://www.peachparts.com/shopforum/showthread.php?t=182725

Sixto
87 300D - 210K miles on #14 head