In article ,
Tamaroak wrote:

I recently had an oil analysis done after changing my oil before winter.
They found a significant amount of antifreeze backed up by my having to
add some during the last part of the season. It's a 1987 5.7L GMC with
closed cooling and 770 hours. It uses no oil and runs great.

I'm trying to determine the possible causes. I've heard:
1. Cracked block
2. Cracked head
3. Bad head gasket
4. Bad frost plug
5. Bad coolant pump (supposedly located on pop of the engine by the
manifold)

Any other ideas?

Capt. jeff

I would discount 4 & 5, as a frost plug doesn't lead to the Base oil pan,
and water pumps aren't Base oil lubricated, so it also doesn't lead to
the oil pan. I would first look at Head Gasket, then look at cracked
head and finally cracked block. Cracked block would not happen in the
middle of the season, unless you had a Coolant FREEZE during that time
period, Cracked head, maybe, but still very unlikely for the same
reasons, except could happen if you overheated the engine recently.
Bad Head Gasket can happen anytime, and is also not to hard to deal
with, except it will require a topend disassembly, which is also
what is required for a cracked head. Cracked block will require
a complete engine removal.


Bruce in alaska
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