How much can a bad oil seal effect compression
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How much can a bad oil seal effect compression
How much can a leaky oil seal effect compression.
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Re: How much can a bad oil seal effect compression
if your talking about crankshaft seals on a 2 stroke, you won't see a difference in compression. Compression only checks piston rings, cylinder condition and head gasket.
To properly check if an oil seal is bad you need to perform a leak down test. This test is very cumbersome on a 2 stroke. There are other tests which people claim work to test crank seals which I have little to no faith in. One is spraying carb cleaner around the suspect seal while the engine is running and listen for a change in rpm. Personally I think the seal has to be real bad for this to work.
If you do have a bad crank seal your engine will run lean . You may notice eratic or high idle, bogging, white looking spark plug, gas/oil seapage from the seal area.
To properly check if an oil seal is bad you need to perform a leak down test. This test is very cumbersome on a 2 stroke. There are other tests which people claim work to test crank seals which I have little to no faith in. One is spraying carb cleaner around the suspect seal while the engine is running and listen for a change in rpm. Personally I think the seal has to be real bad for this to work.
If you do have a bad crank seal your engine will run lean . You may notice eratic or high idle, bogging, white looking spark plug, gas/oil seapage from the seal area.
Re: How much can a bad oil seal effect compression
I mean oil seals not crank case seal. If they do not effect compression then I guess something is bad in my top end. Will this http://cgi.ebay.com/ebaymotors/REPLACEM ... arQ5fParts fit my 86 Honda aero50?
Oh and my engine does not run I am working on getting it running has very little compression.
Oh and my engine does not run I am working on getting it running has very little compression.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
That linked piston fits your motor. The oil seals will not affect compression, most likely rings are bad.
2001 Honda Elite
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.
Re: How much can a bad oil seal effect compression
Well time to take that head off then.evilone wrote:That linked piston fits your motor. The oil seals will not affect compression, most likely rings are bad.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
Good idea, hopefully you won't need a piston.
2001 Honda Elite
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.
Re: How much can a bad oil seal effect compression
Fingers crossed.evilone wrote:Good idea, hopefully you won't need a piston.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
You need to bone up on your 2 stroke theory. A 2 stroke pressurize the mixture in the crankcase and then feed the mixture into the cylinder UNDER PRESSURE. So a bad crank seal will effect compression. How much depends on how bad the seal is, but it will lower it for sure.mopar4u wrote:if your talking about crankshaft seals on a 2 stroke, you won't see a difference in compression. Compression only checks piston rings, cylinder condition and head gasket.
To properly check if an oil seal is bad you need to perform a leak down test. This test is very cumbersome on a 2 stroke. There are other tests which people claim work to test crank seals which I have little to no faith in. One is spraying carb cleaner around the suspect seal while the engine is running and listen for a change in rpm. Personally I think the seal has to be real bad for this to work.
If you do have a bad crank seal your engine will run lean . You may notice eratic or high idle, bogging, white looking spark plug, gas/oil seapage from the seal area.
You also do not need to preform a leak down test to check the case seals, a leak down test only checks the cylinder and rings. You pressure and vacuum test a two stroke crankcase to check the seals. You car guys need to stop applying 4 stroke stuff to these 2 strokes.
Bear 45/70
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
Re: How much can a bad oil seal effect compression
Bear45-70 wrote:You need to bone up on your 2 stroke theory. A 2 stroke pressurize the mixture in the crankcase and then feed the mixture into the cylinder UNDER PRESSURE. So a bad crank seal will effect compression. How much depends on how bad the seal is, but it will lower it for sure.mopar4u wrote:if your talking about crankshaft seals on a 2 stroke, you won't see a difference in compression. Compression only checks piston rings, cylinder condition and head gasket.
To properly check if an oil seal is bad you need to perform a leak down test. This test is very cumbersome on a 2 stroke. There are other tests which people claim work to test crank seals which I have little to no faith in. One is spraying carb cleaner around the suspect seal while the engine is running and listen for a change in rpm. Personally I think the seal has to be real bad for this to work.
If you do have a bad crank seal your engine will run lean . You may notice eratic or high idle, bogging, white looking spark plug, gas/oil seapage from the seal area.
You also do not need to preform a leak down test to check the case seals, a leak down test only checks the cylinder and rings. You pressure and vacuum test a two stroke crankcase to check the seals. You car guys need to stop applying 4 stroke stuff to these 2 strokes.
Very rarely does a bad seal show up on a compression test. Compression tests are done to check the top end.
I'm not a car guy, I work and ride on snowmobiles all winter.
Perform a leakdown test/pressure test (whatever you prefer to call it) from the intake, not from the spark plug hole. Block off the exhaust. http://www.duncanracing.com/TechCenter/ ... sstest.pdf
Re: How much can a bad oil seal effect compression
I beg to differ with you. After 25 years as a 2 stoke mechanic, I can tell you that a bad crank seal sure as * will show up on a compression test. But then having been a factory certified 2 stroke mechanic makes my experience null and void according to you. I was doing crankcase vacuum and pressure test 20+ years ago, what were you doing?mopar4u wrote:Very rarely does a bad seal show up on a compression test. Compression tests are done to check the top end.
I'm not a car guy, I work and ride on snowmobiles all winter.
Perform a leakdown test/pressure test (whatever you prefer to call it) from the intake, not from the spark plug hole. Block off the exhaust. http://www.duncanracing.com/TechCenter/ ... sstest.pdf
Bear 45/70
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
Re: How much can a bad oil seal effect compression
Well I will be taking them engine off the scooter tomorrow and bringing it down onto the work bench so I can work on it easier.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
The piston is toast and I don't know about the cylinder it doesn't have any gouges out of it but it does have like a bump on it in one spot looking form the bottom or the top you can see it sticking up a little bit. Will post pics later.
Last edited by toad772 on Mon Aug 09, 2010 3:46 pm, edited 1 time in total.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
Making new thread with pics
Last edited by toad772 on Mon Aug 09, 2010 5:26 pm, edited 1 time in total.
PS3 it only does everything.
Re: How much can a bad oil seal effect compression
Makes sense.Bear45-70 wrote:A 2 stroke pressurize the mixture in the crankcase and then feed the mixture into the cylinder UNDER PRESSURE. So a bad crank seal will effect compression. How much depends on how bad the seal is, but it will lower it for sure.
2001 Honda Elite
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.
1995 Yamaha Jog
1994 Yamaha Axis
I can't believe
that cop put me
in the backseat
when I clearly
called shotgun.