99 maxum scr 2400

[99maxum211]

i just purchased a 99 maxum 2400 scr
the engine hasnt ran for 3 years. the engine starts.we did a compression test test results as follows
cyl 2 160
cyl 4 150
cyl 1 150
cyl 3 100
cyl 5 120
cyl 7 135
cyl 6 155
cyl 8 155
the previous owner always over heated as from what i was told
do you all think its worth trying to get the compression up with mystery oil and just see if i can loosen all cylinders or just buy a new motor.
also i went to check the condition of the riser and manifolds and found like a dot of oil inside is that a concern?
im also replacing the riser and manifolds any way.
what do you also think of sierra riser and manifods or stay with merc cruiser
i have to many people in my marina in my ear. i would like some advise please

[mmwjr]

I would perform a leak down test on the odd bank cylinders. This will tell you if the compression is low due to a leaky intake valve, exhaust valve, or between cylinders (head gasket). It may just need a head gasket or valve job. Serria makes good products and I have used their exhaust components before without any issues. Do you know why it overheated? Bad impeller,... ? Not that it makes any difference but is this a 5.0 or 5.7 engine?

[99maxum211]

The old owner was a hack...not to sure why every story was conflicting..don't know what to believe.
I have a 5.0

[mmwjr]

Originally Posted by 99maxum211

The old owner was a hack...not to sure why every story was conflicting..don't know what to believe.
I have a 5.0

Did it overheat when you ran it? I would use a handheld IR temp sensor and take reading at various spots. I still recommend a leak down test. When running does water come out the two idle ports on the sides of the exterior transom assembly?

[shrew]

If the engine hadn't run in 3 years, I would have started with mystery oil before I attempted to turn the engine over initially. Condensation and time do horrible things to the rings and the cylinder walls.