What would be a good way to test the head for valve guide wear on a 300D non-turbo. I cant tell if I have bad valve seals, worn guides or both. Is the only good way to pull the head apart and wiggle the valve while its off its seat? Would head probelms contribute to very oily blowby? I plan on doing a compression test soon but I can easily start this car in when its in the 20's with no block heater. That makes me think my oil consumption is in the head. Any tips??

Your suspicion is probably accurate. If you have good compression, your rings/pistons/cylinders are probably acceptable. If your compression test proves low, do a leakdown test and listen for the exiting air. If the air is hissing from the oil cap, it's cylinders, if an intake valve you will hear it from the intake manifold and an exhaust valve from the exhaust. If you have good compression, you will hear it from nowhere and this is a strong indication that the problem is valve guides.

Another thing you can do if you know what a loose stem feels like, is to run a piston to the very top and remove a valve spring, then wiggle the valve stem. Do not remove a valve spring without the piston at the top because you could drop the valve into the cylinder requiring disassembly to retrieve it.

If you have good compression, a valve job would certainly be a worthwhile project.

Good luck,

My '84 300SD had the same problems and I did just as Larry said...when the leakdown test showed leaking exhaust valves, the head was off, and to the machine shop. The machine shop tested the head, and I needed everything but intake valves...but needed guides, seats,seals, exhaust valves and the head was milled down couple thousands. This was 20K ago, and the car runs great. The head rebuild cost me about $350.

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1983 300SD 343K everyday car
1983 300SD 285K from junk yard-tooks parts from deer car- runs great. Brothers car.
1984 300SD parts car-Hit deer
1979 300D 175K non-turbo "Doctor"
1979 300d parts car