what could cause 2 sister cylinders to have low compression?
12-07-2006, 07:51 PM
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what could cause 2 sister cylinders to have low compression?
Like the title says. I looked at a possible motor buy today and it sounded like it ran fine, has a few leaks that will need to be fixed (rear main seal/oil pan gasket), and water pump looks like it started leaking.
This is in a running car so i heard it on, and sounded normal.
The thing that worries me is the compression test that we did. It read 180-155-180-155. I was kinda shocked to see that much of a difference. Spark plugs looked fine, there was no smoking coming out of the exhaust.
Any ideas? Any recommendations?
The car was a 98 Honda Civic Ex 5spd with 165k miles on it.
-Shane
This is in a running car so i heard it on, and sounded normal.
The thing that worries me is the compression test that we did. It read 180-155-180-155. I was kinda shocked to see that much of a difference. Spark plugs looked fine, there was no smoking coming out of the exhaust.
Any ideas? Any recommendations?
The car was a 98 Honda Civic Ex 5spd with 165k miles on it.
-Shane
12-07-2006, 07:53 PM
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I'm pretty sure the oil pan gasket will NOT cause a decrease in compression numbers..unless the rings are bad. With that said, either 2 of the pistons have leaky piston rings OR you have a leaky headgasket (that's not quite blown yet).
12-07-2006, 07:57 PM
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Re: (Syndacate)
Oh i wasn't stating that the oil pan gasket or rear main seal were causing the compression leak I'm stating that those need to be fixed 
.
I'm really trying to avoid headgasket but if its gotta be changed it'll be changed
Anything else that could cause those numbers?
-Shane
.I'm really trying to avoid headgasket but if its gotta be changed it'll be changed
Anything else that could cause those numbers?
-Shane
12-08-2006, 03:37 AM
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Re: (Eyal 951)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eyal 951 »</TD></TR><TR><TD CLASS="quote">how are those sister cylinders? I'm not seeing the correlation aside from possibly being one after the other in firing order.</TD></TR></TABLE>
I don't think anybody is...but we know what he means by him telling the compression #'s across the board so I guess it's just better to let it go :-P
At OP:
Yeah, there is something else, like I told you in my post, it could also be the piston rings.
I don't think anybody is...but we know what he means by him telling the compression #'s across the board so I guess it's just better to let it go :-P
At OP:
Yeah, there is something else, like I told you in my post, it could also be the piston rings.
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12-08-2006, 08:09 AM
#8
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Re: what could cause 2 sister cylinders to have low compression? (vtecn8ive)
Low compression could come from a couple things. Piston rings, valves not seating correctly or bent, valve seals failed.
Valve seals would be the easiest to change without removing the head gasket.
Valves would require lifting head and new head gasket but I doubt it is the valves unless the timing belt snapped. If the water pump is leaking than possible time for new belt as well.
Valve lash could be out of adjustment causing valve not to seat at the right times.
Could be a few different problems. Does the head tick while idleing/running?
165k on a poor maintained vehicle could boast numerous problems.
Good luck.
Valve seals would be the easiest to change without removing the head gasket.
Valves would require lifting head and new head gasket but I doubt it is the valves unless the timing belt snapped. If the water pump is leaking than possible time for new belt as well.
Valve lash could be out of adjustment causing valve not to seat at the right times.
Could be a few different problems. Does the head tick while idleing/running?
165k on a poor maintained vehicle could boast numerous problems.
Good luck.
12-08-2006, 01:27 PM
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Re: what could cause 2 sister cylinders to have low compression? (sauceja)
I thought they were considered sister cylinders oh well sorry about that.
I did not notice any ticking.
the motor seemed to run perfect. No smoke, no idle problems, No noticeable leaks besides the ones already stated, motor i clean.
But the numbers are just freaking me.
I did not notice any ticking.
the motor seemed to run perfect. No smoke, no idle problems, No noticeable leaks besides the ones already stated, motor i clean.
But the numbers are just freaking me.
12-08-2006, 02:55 PM
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Re: what could cause 2 sister cylinders to have low compression? (Jim Truett)
how much do leakdown test cost and where do you get them done at?
-Shane
-Shane
12-08-2006, 05:33 PM
#12
Re: what could cause 2 sister cylinders to have low compression? (vtecn8ive)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecn8ive »</TD></TR><TR><TD CLASS="quote">how much do leakdown test cost and where do you get them done at?
-Shane
</TD></TR></TABLE>
Good question. I have my own leakdown tester so I have never needed someone else to do it. Just call some local shops and ask if they provide that service and how much it costs. If you have an air compressor, you can get a leakdown tester for anywhere between $50 and $175.
-Shane
</TD></TR></TABLE>
Good question. I have my own leakdown tester so I have never needed someone else to do it. Just call some local shops and ask if they provide that service and how much it costs. If you have an air compressor, you can get a leakdown tester for anywhere between $50 and $175.
12-08-2006, 06:24 PM
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Re: what could cause 2 sister cylinders to have low compression? (Jim Truett)
Someone on another board i was asking said it could be Cam Timing.
Is this possible? wouldn't it affect all 4 cylinders and not just the 2?
Is this possible? wouldn't it affect all 4 cylinders and not just the 2?
12-08-2006, 07:11 PM
#14
Re: what could cause 2 sister cylinders to have low compression? (vtecn8ive)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecn8ive »</TD></TR><TR><TD CLASS="quote"> wouldn't it affect all 4 cylinders and not just the 2?</TD></TR></TABLE>
Yes.
It's the piston rings, valve seats, or headgasket. Personally I would assume the valve seats are slightly pitted and leaking.
Yes.
It's the piston rings, valve seats, or headgasket. Personally I would assume the valve seats are slightly pitted and leaking.
12-08-2006, 07:18 PM
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Re: what could cause 2 sister cylinders to have low compression? (Jim Truett)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett »</TD></TR><TR><TD CLASS="quote">
Yes.
It's the piston rings, valve seats, or headgasket. Personally I would assume the valve seats are slightly pitted and leaking.</TD></TR></TABLE>
Agreed... Though I'm not gonna state what I think it is, IMO it could equally be any one of them.
Leakdown test is needed...blah :-\
Yes.
It's the piston rings, valve seats, or headgasket. Personally I would assume the valve seats are slightly pitted and leaking.</TD></TR></TABLE>
Agreed... Though I'm not gonna state what I think it is, IMO it could equally be any one of them.
Leakdown test is needed...blah :-\
12-08-2006, 07:25 PM
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Re: what could cause 2 sister cylinders to have low compression? (Syndacate)
Leakdown test will be done if the guy goes lower on the motor 
12-08-2006, 07:37 PM
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Re: what could cause 2 sister cylinders to have low compression? (vtecn8ive)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecn8ive »</TD></TR><TR><TD CLASS="quote">how much do leakdown test cost and where do you get them done at?
-Shane
</TD></TR></TABLE>
You can build your own. Check the FAQs at the top of the forum.
-Shane
</TD></TR></TABLE>
You can build your own. Check the FAQs at the top of the forum.
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