Been getting misfire codes for quite some time. Took to mechanic today. He checked sensors, injectors, etc.. Did compression test. Told me the 2 cylinders that have been throwing the code 4 and 6 have low compression. 75 lbs. vs 125 lbs in other cylenders. Said rebuilt time. 5.2 with 209,000 miles. He thought it was cracked head but couldn't confirm without tearing down. No oil in coolant no coolant in oil. No loss of either except maybe uses 1/2 quart of oil between oil changes every 3k miles. Does all this sound right. Anything else I should look at thats less expensive. Comments appreciated.

 

From my searching looking for my transmission trouble solution Ive found that the magnum engines have problems with the cylinder heads cracking, dont remember where but it will cause loss of compression but not fluid leakage. However with as much compression as you've lost having about a 1/2 quart of oil seap past the rings where its worn is highly probable.

 

Cracked heads can be confirmed with a leakdown test. However, at 209k I would probably just drive her until she quits, then park her out back for spares.

 

Did the mechanic also test the compression in those two suspect cylinders
'wet'
which means that a tablespoon of motor oil was poured down the sparkplug hole
and then the compression test repeated?

if the wet compression number is a lot higher than the 'dry' compression
then it indicates the rings in those cylinders have problems
and you essentially have no other choice than to rebuild
.... although you can 'band-aid' the problem with an oil additive like
Restore or Rislone

http://www.atvconnection.com/Feature...e-Restorer.cfm

but since you have two suspect cylinders
that more probably indicates a blown head gasket
which is common in the back cylinders near the firewall
on Magnum V8s

I don't know your budget and money situation

If it were me i would have the engine rebuilt at 209,000 miles with this problem,
or buy a shortblock plus new Edelbrock Magnum cylinder heads

if you are on a tight budget
consider doing a wet compression test
and even better
an air leakdown test where you can listen
for where the leakage is actually going,
to see if you might 'get lucky'
and find a blown head gasket as the cause
and then make this repair yourself
for less than about $150
not counting your labor

it is also possible that 'hard carbon' deposits
at the valve seats can cause low compression readings,
as can similar hard carbon deposits sticking the piston rings

it might be worth treating the engine with a $7 spray can of
official Chrysler Combustion Chamber Cleaner
before doing the
wet comp test plus the air leakage test
and perhaps using 16 gallons of gasoline that has had added a
$21 can of Yamaha 'Ring Free' additive:

http://www.usboatsupplies.com/mm5/me...gory_Code=AYOI


good luck