compression test results what do they mean?
Thread Starter
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Laughing Gas
Joined: Aug 2008
Posts: 804
Likes: 0
From: Staten Island,hamilton ny
compression test results what do they mean?
#1 couldnt get adapter in
#3 250
#5 150
#7 390
#2 330
#4 340
#6 320
#8 300
something tells me this isnt good?it the worst possible time for it ,so with my luck i am guessing new motor time? am i right?
#3 250
#5 150
#7 390
#2 330
#4 340
#6 320
#8 300
something tells me this isnt good?it the worst possible time for it ,so with my luck i am guessing new motor time? am i right?
Posting Guru
Joined: Oct 2007
Posts: 2,225
Likes: 1
From: Farmington, Minnesota
Was the engine up to temp as much as it can be when tested? #7 is a respectable number. I think you don't want more than a 20% variance. Doesn't look super promising, what led you to want to do a comp test?
Thread Starter
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Laughing Gas
Joined: Aug 2008
Posts: 804
Likes: 0
From: Staten Island,hamilton ny
yes and the codes and rough idle and smoke,its killin me right now,just did injectors cups starter,front wheel bearings and brakes and rotors and alternator i really dont like this truck right now
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
I hear ya bud, Stinky put me in a thunk for the longest time... but I didn't have low compression to drive the stake through him.
I have to ask because I didn't know myself - you cranked at least five times on each cylinder to get to peak compression? I'm grasping for hope here.
I have to ask because I didn't know myself - you cranked at least five times on each cylinder to get to peak compression? I'm grasping for hope here.
Thread Starter
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Laughing Gas
Joined: Aug 2008
Posts: 804
Likes: 0
From: Staten Island,hamilton ny
i tested them twice and cranked til it wouldnt go any higher got the same numbers,i also made sure the adapter was bottomed out,this is the last news i wanted and i had to be sure.The real bitch of it is this is my only vehicle,i now have no vehicle ,my job is 200 miles away,i am in central NYS near syracuse it is cold (low 30's for highs) we have snow and are getting more and i have nowhere inside to do it.Macnamara's law strikes again.
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Fleet Mechanic
Joined: Jul 2005
Posts: 1,800
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From: Southern Colorado
I would add some oil (2 tablespoons of 10wt. or ATF) and retest (at least the low ones) wet. You may still need a rebuild, but you'll know if it's rings or valves by doing this.
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Lead Driver
Joined: Sep 2005
Posts: 9,399
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From: Norco,CA
Really sucks. I must of missed something but why the injector cup change? On the low cyclinders can you here where the air is goings? Pull the oil cap off listen there and in the intake and exhaust. Or is it just leaking around the adapter for the test.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Postmaster
Joined: Apr 2012
Posts: 2,613
Likes: 8
From: North Georgia
Eh... 150# on cyl5 is way beyond a missing crush washer.
The rings or cylinder wall is probably toast on #5.
I dont see anything in your sig...
Tuner?
Curious why so many dusted motors are showing up lately.
The rings or cylinder wall is probably toast on #5.
I dont see anything in your sig...
Tuner?
Curious why so many dusted motors are showing up lately.
Thread Starter
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Laughing Gas
Joined: Aug 2008
Posts: 804
Likes: 0
From: Staten Island,hamilton ny
just installed dp f6 tuner with new injectors in september changed cups 2 weeks ago,and i did check all bolts immediately before compression test and swapped a different injector to #5 with new o rings and copper washer ,and compression tested twice i am pretty confident the numbers are accurate,the question now is where do i get a new motor?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Junkyard or look at craigslist for someone parting out a wrecked vehicle.
I'd keep it plugged in in the mean time to aid in cold starts. A few drops of oil and re-check the compression is a good idea. If it's rings, you may get by with just a rebuild kit, but 150 is kind of low for just rings.
I'd keep it plugged in in the mean time to aid in cold starts. A few drops of oil and re-check the compression is a good idea. If it's rings, you may get by with just a rebuild kit, but 150 is kind of low for just rings.
Posting Guru
Joined: Oct 2007
Posts: 2,225
Likes: 1
From: Farmington, Minnesota
just installed dp f6 tuner with new injectors in september changed cups 2 weeks ago,and i did check all bolts immediately before compression test and swapped a different injector to #5 with new o rings and copper washer ,and compression tested twice i am pretty confident the numbers are accurate,the question now is where do i get a new motor?