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The fun continues. Low compression in Cylinder #1
J3ff
Member Posts: 4,058 ✭✭✭✭✭
From day 1 my mechanic friend said that the engine didn't sound 100% right. I also have ALWAYS smelled a heavy gas smell at the dock. It's been through three mechanics in 5 years, and only the last one noticed the plug last year seemed off on one of the cylinders.
He replaced it and we kept an eye on it. Finally doing a compression test while it was cold.
Hoping it comes up when warm doesn't sound sensible to me. Going to run one when it's warm one of these days.. assuming it's going to be lower than the rest when warm. Kicking myself for not doing this test when it was under warranty for the 2 years after it was bought!!
It tops out at 35mph ish.. Wonder if this is why it wont hit 40, wouldn't do it with the 20p 4 blades and wont do it with the 22's either..
Where would you start assuming it's lower than the other cylinders when warm?
He replaced it and we kept an eye on it. Finally doing a compression test while it was cold.
Compression test
1) 90psi 2) 156psi 3) 157psi 4) 161psi 5) 154psi 6) 158psi 7) 151psi 8) 153psi
Compression average (147psi) * Note that testing was done with engine “Cold” and that cylinder #1 may come up when warm.
I ran some carbon cleaner in cylinder #1 in hopes of improving the compression
Remove and replace spark plugs
Spark plugs in fair condition, besides cylinder #1 (STBD/Rear). Has small rust and deposits throughout electrode
Hoping it comes up when warm doesn't sound sensible to me. Going to run one when it's warm one of these days.. assuming it's going to be lower than the rest when warm. Kicking myself for not doing this test when it was under warranty for the 2 years after it was bought!!
It tops out at 35mph ish.. Wonder if this is why it wont hit 40, wouldn't do it with the 20p 4 blades and wont do it with the 22's either..
Where would you start assuming it's lower than the other cylinders when warm?
Post edited by J3ff on
Comments
the rust on the plug is a dead givaway- you need to adjust your valves- it isn't seating. hopefully it's just an adjustment issue... it could be a spring issue... it could be a seat issue... it's likely a lifter rod issue. holding 90 on a dry cylinder, though, it seems it would be an adjustment. the exhaust valve is the culprit.
by the way- #1 is port front.
check the seat of the rocker to the pedestal... pull and roll your lifter rods across a flat... there should be zero wobble... the concern here, under scrutiny because of the rust, is the cylinder ingested some water and enough to bend the lifter rod ever so slightly, and because of the valve doesn't seat fully.... which is an easy fix.
warm up your engine and then pop off the valve covers... leave one bank covered and tune the exposed valve springs... i can never recall (it's one of those things i try not to commit to memory as that will get me in trouble every time) but i think it's turn to no rattle, and then a quarter turn more... but don't hold me to that for all that's holy- reference it.... torque specs are just a thing- it gets you close- every engine and cylinder will be slightly different- valve springs just ain't that precise... there will be as much as a pound of torque delta across a bank every time. it's a messy but it's a simple job.
i bet you discover a slightly out of true lifter rod... IF you do, get a scope on that cam lobe and look for scoring just to be careful. again, though, the lifter rod is the most likely issue.
PC BYC, Holland, MI
Thank you all for your advice, have read it all and am talking to the mechanic about it, including all of your advice. As far as when it happened who knows, but it isn't a recent development it seems.
This is from the water test when the engine was being "broken in" - straight from the invoice 8/29/2016
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First of all, the tach has always been 300-400 rpm off of reality (verified by Vessel view mobile)
This test was done with stock 3 blade 22p props on it. Does 5100 rpm sound right for 34 mph?
Seems to me that 5100 - 5200 rpms at 34 mph is completely not accurate seeing how it just did this with 4 blade 22p's on it..
Down here in the keys another shop did the same thing in less than 18. Wish I had known I was dealing with con artists up in the N.E.
Go Steelers!!!
I agree & that wire harness is not a Rinker part, which they should know. Also, they should know what wires are for what if they deal with this stuff every day.
Dream 'Inn III -- 2008 400 Express
Go Steelers!!!