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#Post#: 77563--------------------------------------------------
2.25L compression
DIR By: Donk
Date: October 19, 2013, 8:03 am
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Does anyone know what would be the minimum acceptable psi
compression reading for a 2.25L engine? donk
#Post#: 77578--------------------------------------------------
Re: 2.25L compression
DIR By: puddlejumper
Date: October 19, 2013, 10:01 am
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Not sure if there is a set minimum figure but I would be wanting
around 100psi as a minimum for a fit engine and even scores
across all cylinders
No doubt wiser folk than I will be along soon to tell me I am
talking bollocks
Above assuming petrol engine, needs to be a lot higher for a
diesel
Doug
#Post#: 77583--------------------------------------------------
Re: 2.25L compression
DIR By: smackitwithanammer
Date: October 19, 2013, 11:45 am
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With a low compression head on a petrol 40psi is good.
#Post#: 77615--------------------------------------------------
Re: 2.25L compression
DIR By: guest13
Date: October 19, 2013, 3:00 pm
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As new figures for a petrol should be 145psi for a 7:1
compression ratio engine
A 8:1 should be 155-160psi
Drop more than 10% your engines getting worn (but beware some
compression testers aren't very accurate so look what the
tolerance on it is)
By the time you've lot 20% the engines due a major rebuild
#Post#: 77635--------------------------------------------------
Re: 2.25L compression
DIR By: v8bobber
Date: October 19, 2013, 5:06 pm
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Those figures seem a little high to me.
I know official workshop manual states 125psi for a 7:1 and
thats hot with the throttle held open (300 rpm or something)
From past experience it's no so much the drop in pressure but
the difference between the cylinders which should be within 10%
ideally.
When i put my 86" back on the road the pressures were about
105-110 and runs perfectly.
Dave
#Post#: 77643--------------------------------------------------
Re: 2.25L compression
DIR By: smackitwithanammer
Date: October 19, 2013, 5:57 pm
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Meant 140. Mine had 130-135 and was good
#Post#: 77646--------------------------------------------------
Re: 2.25L compression
DIR By: Donk
Date: October 19, 2013, 7:35 pm
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I have 100psi (cold) across the pots. Probably drop a bit when
at operating temp? The engine has lost heaps of power etc.
Yeah, time to park it and look into costs for a rebuild. I need
the donk reliable. Looking at 30%+, drop from spec which is
substantial to start with, it feels fairly easy to turn the
engine over by hand when warm, under cranking it sounds like
theres hardly any resistance.
Think Ill remove and fit the engine myself but leave the
reconditioning to the pros.
For pistons, rings and bearings and other engine components are
there suppliers that should be avoided? Wheres the best place
to get engine components? I know a top engine reconditioner who
has all the machining equipment. He recoed an engine for me
about 7 years ago and it has been great. Still is but I
wouldn't know where he would source parts for this exercise.
cheers donk
#Post#: 77655--------------------------------------------------
Re: 2.25L compression
DIR By: FenTiger
Date: October 20, 2013, 3:43 am
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Now try a wet compression test with the throttle wide open.
(Squirt of oil down each pot) Then report findings. You may just
get away with a head rebuild....
#Post#: 77670--------------------------------------------------
Re: 2.25L compression
DIR By: Donk
Date: October 20, 2013, 6:22 am
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yep will do. Prob tomorrow.
I will expect compression gain across the pots but should be
relatively even. If compression fails to rise within a nominated
% of the other pots it would indicate either broken ring(s),
head gasket and/or valve leakage, maybe even a leaky sleeve.
Pull out the leakdown tester, TDC valves closed on the pot,
connect shop air, and listen and look for escaping air from the
cylinder in question. It will be leaking down substantially my
guess through the crankcase but might get some air through the
other orifices and radiator. id be jumping for joy if I could
fix the head and get psi back. donk
#Post#: 77671--------------------------------------------------
Re: 2.25L compression
DIR By: Donk
Date: October 20, 2013, 6:32 am
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--- Quote from: FenTiger link ---
>
> Now try a wet compression test with the throttle wide open.
(Squirt of oil down each pot) Then report findings. You may just
get away with a head rebuild....
>
--- End Quote ---
remember some years back did a compression test and got a low
read in one pot. Splashed a Tbls of oil in and rechecked and got
about 6psi higher. Thought it was just a valve but it was broken
rings later found. I find the leakdown tester helps with the
diagnosis. donk
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