Did compression test..
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Postmaster
Joined: Jun 2003
Posts: 4,191
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From: WA
Did compression test..
Before I start doing some upgrades to my 351M, I wanted to see if a compression test showed any glaring problems.
I did the test after driving awhile, then letting the engine cool down a little.
1st pass dry. 2nd pass dry 3rd pass wet
Cyl 1 125 psi 145 165
Cyl 2 125 PSI 143 162
Cyl 3 122 PSI 137 147
Cyl 4 122 PSI 140 155
Cyl 5 131 psi 142 165
Cyl 6 112 psi 125 140
Cyl 7 150 psi 153 170
Cyl 8 150 psi 150 160
Looks like #6 is always low. 7&8 show oil burning on the plugs, maybe enough to make them semi-wet always? I do get the puff of blue on starting after it sits.
Watching the guage as I cranked it, the pressure always went over 100 on the first revolution, then built up from there over a few more cranks.
Anything stick out here? I assume my valve guide seals are leaking. Does #6 warrant further investigation?
Thanks for any help!
I did the test after driving awhile, then letting the engine cool down a little.
1st pass dry. 2nd pass dry 3rd pass wet
Cyl 1 125 psi 145 165
Cyl 2 125 PSI 143 162
Cyl 3 122 PSI 137 147
Cyl 4 122 PSI 140 155
Cyl 5 131 psi 142 165
Cyl 6 112 psi 125 140
Cyl 7 150 psi 153 170
Cyl 8 150 psi 150 160
Looks like #6 is always low. 7&8 show oil burning on the plugs, maybe enough to make them semi-wet always? I do get the puff of blue on starting after it sits.
Watching the guage as I cranked it, the pressure always went over 100 on the first revolution, then built up from there over a few more cranks.
Anything stick out here? I assume my valve guide seals are leaking. Does #6 warrant further investigation?
Thanks for any help!
Thread Starter
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Postmaster
Joined: Jun 2003
Posts: 4,191
Likes: 0
From: WA
Did compression test..
Originally posted by Torque1st
#6 may have a leaking valve. Did you check with a vacuum gage b4 you did the compression test? The engine looks to be in generally poor condition, sounds like rebuild time to me.
#6 may have a leaking valve. Did you check with a vacuum gage b4 you did the compression test? The engine looks to be in generally poor condition, sounds like rebuild time to me.
