Compression Test?
03-13-2008, 12:06 AM
#1
Registered
Thread Starter
Join Date: Feb 2005
Location: Southern Marylend
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Compression Test?
I'm looking to buy a 2001 Wellcraft Excalibur 260 and found a nice example online with low hours and a 502/415/B1. The boat is out of state so I had a Mercruiser rep come down and to a mechanical survey. He stated the following:
"ALL MECHANICAL POINTS OF INTEREST ON THE 502 MPI BRAVO PACKAGE CHECKED OUT GOOD .ALL OIL LOOKED GREAT NO SIGNS OF WATER IN FUEL ENGINE OIL OR OUTDRIVE OIL
COMPRESSION ALSO IS IN STANDARD RANGE CYLINDERS ARE ALL IN SPEC.
(1) 160 PSI (2) 165 PSI
(3) 160 PSI (4) 160 PSI
(5) 165 PSI (6) 160 PSI
(7) 160 PSI (8) 160 PSI
RISER AND MANIFOLDS ALSO LOOK TO BE IN OK SHAPE . ALL OIL ARE IN NEED OF CHANGING ENGINE AND OUTDRIVE. "
I'm very confused at the compression readings. At std atmosphere of 14.7 160 psi suggests 10.88 compression ratio. Mercruiser says the 502/415 is 8.75. I would have expected compression around 128 psi. Maybe less considering cam overlap. I did an internet search on compression tests on similar 502s and numbers were in the 125 psi range
What's up? Am I being scammed?
Cheers!
"ALL MECHANICAL POINTS OF INTEREST ON THE 502 MPI BRAVO PACKAGE CHECKED OUT GOOD .ALL OIL LOOKED GREAT NO SIGNS OF WATER IN FUEL ENGINE OIL OR OUTDRIVE OIL
COMPRESSION ALSO IS IN STANDARD RANGE CYLINDERS ARE ALL IN SPEC.
(1) 160 PSI (2) 165 PSI
(3) 160 PSI (4) 160 PSI
(5) 165 PSI (6) 160 PSI
(7) 160 PSI (8) 160 PSI
RISER AND MANIFOLDS ALSO LOOK TO BE IN OK SHAPE . ALL OIL ARE IN NEED OF CHANGING ENGINE AND OUTDRIVE. "
I'm very confused at the compression readings. At std atmosphere of 14.7 160 psi suggests 10.88 compression ratio. Mercruiser says the 502/415 is 8.75. I would have expected compression around 128 psi. Maybe less considering cam overlap. I did an internet search on compression tests on similar 502s and numbers were in the 125 psi range
What's up? Am I being scammed?
Cheers!
