1998 EFI 225 Compression

[davidm]

I am negotiating the purchase of a 1998 or 1999 Mercury EFI 225. The compression readings provided indicate all cylinders show compression between 95 and 100 psi. Is this acceptable? Are there other questions I should ask? Thank you.

 

[gss036]

Re: 1998 EFI 225 Compression

I think I would asking how they did the compression test. About equal pressures are what you look for but I think that 95-100 is about 15%+ too low. But, then again determine how the tests were conducted.
Maybe a more experienced person can jump in here with some advise.

 

[Don S]

Re: 1998 EFI 225 Compression

This is directly from the OEM service manual

COMPRESSION All Models – Using a fully charged battery, throttle shutters wide open and cylinder block warm
110 – 135 psi
(753.3 – 924.5 kPa)
Variance between cylinders should not exceed 15 psi (102.7 kPa)

 

[davidm]

Re: 1998 EFI 225 Compression

Thank you both very much for your help. I will use the information you provided.