1978 300d Cyl Head availability & $$$$
 

Hi Folks,
I'm currently looking at a 1978 300d that may have a cracked cylinder head.
(maybe?? - head gasket replaced 1 yr ago, - currently some oil in coolant, loss of power)

Worse case situation, I'm assuming a cracked cylinder head - or maybe a warped cyl head. I thought since the head gasket was already replaced - perhaps there are other issues?(other than the head gasket being gone again)

If it is the cylinder head - can the crack be fixed? (welded)

If I need another cylinder head what would be the availability & cost??

Thanks in advance for all your help!!

Aivars Berzins

A couple years ago I replaced a head on a 1980. The head is slightly different than yours since it had the pencil glow plugs, but at that time a new bare head was $800. I ended up putting on a rebuilt head with new valves, milled flat, checked for cracks, no welds, and guaranteed for one year for around $800. Cracks can be welded, but personally I would get a head that has not been welded, especially on a diesel.

Another reason for oil in the water is that the cylinder block may not be flat and may need to be milled. This would require disassembly of the engine, and you would not know until you took the head off and checked with a very straight edge.

Used heads should be readily available for the 300D.

another way i've seen oil get into the coolant is through an oil cooler...

A cracked cast iron head is kinda rare. More likely it's a head gasket problem again. MB changed their head gaskets several times. The new ones are NOT to be exposed to air until they are ready for immediate use. Be sure to let it rest and follow the directions shipped with the new gasket.

You could certainly have other problems but if it didn't freeze or overheat, it's probably a head gasket.

FWIW: MB wants you buy new style (use them once) stretch bolts. I like the early hex drive type and they work just fine. Simply torque them down in proper sequence to their original specs. I do re-torque them at the 1,000 mile oil change and final valve adjustment.

Or you could get the newer stretch bolts.

DON'T get your block or head surfaced unless you have one helleva gap under the straight edge. A light pass with a DA to remove gasket crap is all that is usually necessary for iron. The hatching gives a good grip for those new, more pliable, head gaskets too. If you have them surface cut, you will find out why Mercedes sells those offset camshaft sprocket keys :eek:

Thanks for all the good advice!!

Aivars Berzins