Blown head gasket on the #2,4,6 side----just take off both heads and
replace head gaskets and intake gaskets. Also with heads off you can look at
valves to see if any is burnt and if you have high milage(over 100K) just do
a valve job at the same time and problem is solved
TimR
----- Original Message -----
From: Jack <jack@california.com>
To: <dakota-truck@buffnet.net>
Sent: Sunday, May 14, 2000 1:51 PM
Subject: DML: Compression test on '87 Dakota 3.9L
> I just finished a compression test on an '87 Dakota 3.9L V-6 and got the
> follow results:
>
> #1 197 psi
> #2 184 psi
> #3 195 psi
> #4 190 psi
> #5 204 psi
> #6 165 psi
>
> First off, the results seems high across the board. Haynes manual says
> at least 100 psi and no more than 25% variations between cylinders.
> Technically speaking, the above results are within the parameters for
> normal readings. The two cylinders with the lowest reading are adjacent.
>
> The crux here is that I am dead certain that the engine is leaking
> combustion gases on the power stroke from one or more of the cylinders
> into the coolant system and that coolant is leaking into one or more of
> the cylinder chambers on the intake stroke. The reasons that I am
> convinced of this is:
> #1 The engine looses coolant with no evidence of an external leak.
> #2 After running to warm up and then cooling down, the coolant in the
> reservoir reeks of gasoline.
> #3 The pressure at the upper radiator hose feels abnormally high. After
> running awhile and then shutting down, the high pressure forces coolant
> up through the rad cap and into the reservoir tank.
> #4 After warm up, with radiator cap off, I see bubbles in the filler
> neck after slightly revving the engine.
> #5 After running for a while, the temp gauge fluctuates between hot and
> normal as coolant is lost and circulation becomes erratic.
>
> I have decided to remove both heads and have them rebuilt or exchange
> them for rebuilts. In preparation for this, I bought a pressure tester
> to do a static compression test and got the results posted above. I can
> easily modify it and perform a leakdown test as well, but that will have
> to wait until next weekend.
>
> Can anyone comment on the readings that I got? Do they seem high? Any
> and all comments welcome.
>
> Thanks, Jack
>
>
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