I have a 1977 450SEL that overheated and blew both head gaskets. I have removed the heads and taken them to a shop to get them checked. They are reporting that the heads have 0.015 inch warp (which translates to 2.03 mm) also they are saying that the heads are below minimum thickness. I checked the engine service manual and they allow 0.08 mm (0.003 inch) of warp. The from "new" head thickness reduction allowed is 0.25 mm (0.010 inch). While the manual says that "a slightly distorted parting surface will adapt again to cylinter head when tightened" in section 01-418, I am concerned that the amount of distortion measured is more than "slightly".

Any thoughts or guidance would be appreciated. I really don't want to spend a significant amount on the car due to the body having some corrosion issues.
Thanks,
Lee

0.015" (0.38 mm) is a lot of warp. I'd look for a set of good used ones.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

first, you must remember why we do this... many of the folks
here go out and buy new heads, new pistons, new cranks and
they just load up and spend big bucks... but that is not why we
are here.... I hope your using a good economical machine shop.

have them grind the heads as low as there willing to go and then
go out and buy a copper head gasket... in fact you may not even need
to have them leveled with the copper head gasket....remember the copper head gasket is thick and it may give back to room....

my ignorance but are the heads alum? if so often they can be straightened. my machinist has a jig for bending them. he puts them in it and puts them in an oven overnight. often they can be straightened enough to not need planing.

the copper head gasket also is an option ... after straightening, if the compression is too high or a clearance problem is there.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

First, I forgot to mention that I was not sure on the unit conversions, sort of a long day yesterday and I did not take the time to validate my conversions.

Second, Yes, the heads are aluminum. I had not thought about the straightening. What temperature does your machinist use for the overnight heating?

Anyone know what alloy the heads are cast from?

Third, I did not think about a copper head gasket. Any idea on where to find one?

Thanks to all for you inputs.
Lee

anyone who has the tools to do it should know the temp. on the copper gasket, i dont actually know if such an animal exists for a benz. no personal knowledge.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Tom,
I asked about the temperature because I have a background in metallurgy. For aluminum alloys, if too high of a temperature is used, it will weaken the alloy.
Lee

Understand the metelurgical concerns...

I'm not sure the relieving temp- but it has become an industry practice to straighten. Think of a VW head or some other(TR 7) where the camshaft rides in the head. If the headwarps, you loose camshaft brg alignment. I've seen them REALLY BAD (ala TR-7). It was noticable doing a compression test by the un-even sound of the engine.
Just find a good machineshop which does a lot of head repairs.


Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E