This site uses cookies to maintain login information on FarmallCub.Com. Click the X in the banner upper right corner to close this notice. For more information on our privacy policy, visit this link: Privacy Policy
NEW REGISTERED MEMBERS: Be sure to check your SPAM/JUNK folders for the activation email.
Low compression and valves
Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
- Ronny Bailey
- 10+ Years
- Posts: 719
- Joined: Thu Oct 23, 2008 2:38 pm
- Zip Code: 77802
- eBay ID: ronnyb.east.texas
- Tractors Owned: 1938 Farmall F-20
Grandpa's '49 Cub #82289
194x Gibson Model D
1953 Allis Chalmers CA - Location: TX, Bryan
Low compression and valves
Reading Larry's post, I noticed a lot of folks think his low compression (40#) is probably related to the valves.
I understand that if they don't seal, you can't get good compression.
If this is a valve problem:
The fact that all four cylinders have the low readings must mean that each has at least one valve with a bad seal.
Is this unusual? It seems to me the likelihood that all four would have valve problems would be kind of remote.
I read that the engine hasn't run for about 20 years and some valves were stuck.
I was just curious about this and thought I'd ask.
After the valves on mine were loose, I chipped away a lot of carbon off the valves and seats.
Used an old vacuum cleaner while doing it so nothing would fall into the engine.
Haven't done a vacuum test on it, but it sounded good at the LA Cubfest when it was running.
I understand that if they don't seal, you can't get good compression.
If this is a valve problem:
The fact that all four cylinders have the low readings must mean that each has at least one valve with a bad seal.
Is this unusual? It seems to me the likelihood that all four would have valve problems would be kind of remote.
I read that the engine hasn't run for about 20 years and some valves were stuck.
I was just curious about this and thought I'd ask.
After the valves on mine were loose, I chipped away a lot of carbon off the valves and seats.
Used an old vacuum cleaner while doing it so nothing would fall into the engine.
Haven't done a vacuum test on it, but it sounded good at the LA Cubfest when it was running.
Ronny
“If it ain’t broke, I haven’t 'fixed' it yet”
“If it ain’t broke, I haven’t 'fixed' it yet”
-
- 10+ Years
- Posts: 1631
- Joined: Fri Dec 22, 2006 6:28 am
- Zip Code: 37743
- Circle of Safety: Y
- Location: Tennessee East
Re: Low compression and valves
Ronny you are right about a 'bad seal' on each valve. I would rather think it is a carbon problem. Carbon is not selective. It can cause valves to stick or nor seat and hold rings tight. Just put a pint or so of kerosene in the oil and run it under load for a few hours. You will be surprised how much dissolved carbon will drain out . You can do this until the oil looks more like oil and not hurt anything.
47 Cub (Glenda)
52 Super A
62 Cub (Genie)
43 H
42 M
In all things know which way the wind is blowing.
52 Super A
62 Cub (Genie)
43 H
42 M
In all things know which way the wind is blowing.
- Lurker Carl
- Cub Pro
- Posts: 3970
- Joined: Mon Feb 03, 2003 9:54 am
- Zip Code: 16685
- Circle of Safety: Y
- Location: PA, Todd
Re: Low compression and valves
A rich fuel mixture left unchecked over years of operation, as will worn rings, will create the carbon deposits on the exhaust valves that result in poor compression. So will disregarding regular maintanence. A too hot combustion temperature will erode the valves and seats. Worn valve guides can cause the valves to rest off center on the seat. Rust could be a culprit with an unused engine.
I'm not a big fan of diluting the crankcase oil with any solvents that are meant to "clean out" particles within the engine. The Cub engine can not efficiently remove these particles from the oil because only part of the oil flowing from the pump is routed through the filter. The rest of the crud-laden oil makes it's way to the various bearings throughout the engine. Engine deposits are best left alone or physically removed when the parts are dismantled.
I'm not a big fan of diluting the crankcase oil with any solvents that are meant to "clean out" particles within the engine. The Cub engine can not efficiently remove these particles from the oil because only part of the oil flowing from the pump is routed through the filter. The rest of the crud-laden oil makes it's way to the various bearings throughout the engine. Engine deposits are best left alone or physically removed when the parts are dismantled.
"Chance favors the prepared mind."
- Louis Pasteur
"In character, in manners, in style, in all things, the supreme excellence is simplicity."
- Henry Wadsworth Longfellow
- Louis Pasteur
"In character, in manners, in style, in all things, the supreme excellence is simplicity."
- Henry Wadsworth Longfellow
-
- 10+ Years
Re: Low compression and valves
For cleaning up the carbon without adding solvent to the oil or anything mechanical, My Dad and I like to do this process when we get a new, used motor.
We use Lucas fuel treatment. Use your favorite brand.
With the engine running at high idle, slowly squirt the lucas directly into the throat of the carb. It will start to load up and blow white smoke and probably spit some carbon out the exhaust. Stop squirting before it dies and let it clear out.
Do it again. The third time, squirt enough in the kill it. Choke it right down till it dies. Turn it off and let it sit overnight, so that it has time to desolve what is left of the carbon in the cylinder, rings, and both intake and exhaust valves.
When you restart it, it will smoke the white smoke, but will clear up and should hep your compression problem.
We use Lucas fuel treatment. Use your favorite brand.
With the engine running at high idle, slowly squirt the lucas directly into the throat of the carb. It will start to load up and blow white smoke and probably spit some carbon out the exhaust. Stop squirting before it dies and let it clear out.
Do it again. The third time, squirt enough in the kill it. Choke it right down till it dies. Turn it off and let it sit overnight, so that it has time to desolve what is left of the carbon in the cylinder, rings, and both intake and exhaust valves.
When you restart it, it will smoke the white smoke, but will clear up and should hep your compression problem.
- Lurker Carl
- Cub Pro
- Posts: 3970
- Joined: Mon Feb 03, 2003 9:54 am
- Zip Code: 16685
- Circle of Safety: Y
- Location: PA, Todd
Re: Low compression and valves
dshawz wrote:Do it again. The third time, squirt enough in the kill it. Choke it right down till it dies.
Be very careful when adding liquids into the air intake of any engine, it can create a hydraulic lock up. It's a proven method for instantly destroying an engine.
"Chance favors the prepared mind."
- Louis Pasteur
"In character, in manners, in style, in all things, the supreme excellence is simplicity."
- Henry Wadsworth Longfellow
- Louis Pasteur
"In character, in manners, in style, in all things, the supreme excellence is simplicity."
- Henry Wadsworth Longfellow
- ToddW
- Cub Pro
- Posts: 2293
- Joined: Tue Sep 02, 2008 3:46 pm
- Zip Code: 54911
- Tractors Owned: -
1951 F-Cub
1960 Yellow Loboy
Despeeder, FH Rototiller, / FH York Rake, FH plow, 152 Disk plow, Woods brush mower, Wagner Loader, Grader Blades, 23-A Disc Harrow. Spike tooth harrow
FORD JUBILEE with Sherman 12-speed
1953 Ford F-100 Jubilee
Cadet 108 with mower and snow thrower -Cadet 1650 with deck and thrower - Circle of Safety: Y
Re: Low compression and valves
I've read posts here in the forum about running the engine briefly with 1/2 pint kerosene added to motor oil to clean the crud out. Wouldn't this be a good idea to try to improve compression and remove deposits
Last edited by ToddW on Sun Mar 22, 2009 9:28 am, edited 1 time in total.
-
- 10+ Years
- Posts: 1631
- Joined: Fri Dec 22, 2006 6:28 am
- Zip Code: 37743
- Circle of Safety: Y
- Location: Tennessee East
Re: Low compression and valves
Don't run the engine with kerosene only! A pint or so with the oil will do the trick. A few minutes will not work either. A few hours is needed for the kerosene to do it's work.
47 Cub (Glenda)
52 Super A
62 Cub (Genie)
43 H
42 M
In all things know which way the wind is blowing.
52 Super A
62 Cub (Genie)
43 H
42 M
In all things know which way the wind is blowing.
- ricky racer
- 10+ Years
- Posts: 6334
- Joined: Wed Sep 12, 2007 8:40 pm
- Zip Code: 49120
- Circle of Safety: Y
- Location: Niles / Buchanan, Michigan
Re: Low compression and valves
A simple way to see where compression is lost is to induce compressed air to each cylinder and see where it leaks from. You can use the threaded end of a compression tester on many brands or make an adapater from an old spark plug that you can attach an air hose to and induce regulated compressed air into each cylinder to see where it's leaking. If you hear air coming out the exhaust, it's leaking past the exhaust valve. If you hear it leaking out the carb, it's leaking past the intake valve. If you hear it leaking out the crank case filler pipe, it's leaking past the rings. Once you know where it's leaking, you'll know what you have to do to "Get-R-Done"!
1929 Farmall Regular
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub
-
- Team Cub Mentor
- Posts: 20370
- Joined: Fri Jul 02, 2004 9:52 pm
- Zip Code: 65051
- Circle of Safety: Y
- Location: Mo. Linn
Re: Low compression and valves
On one cylinder both valves are open for about 15 degrees of crankshaft rotation. Depending on where a 4 cylinder engine stops in the combustion cycle it is possible to have a valve open in at least 3 if not all 4 cylinders. An engine sitting for 20 year - gonna have problems.I noticed a lot of folks think his low compression (40#) is probably related to the valves. I understand that if they don't seal, you can't get good compression.
The fact that all four cylinders have the low readings must mean that each has at least one valve with a bad seal. Is this unusual? It seems to me the likelihood that all four would have valve problems would be kind of remote. I read that the engine hasn't run for about 20 years and some valves were stuck.
More than likely had problems before it was parked.
Grammer correction.
Last edited by Eugene on Wed Mar 18, 2009 8:28 pm, edited 1 time in total.
I have an excuse. CRS.
- ricky racer
- 10+ Years
- Posts: 6334
- Joined: Wed Sep 12, 2007 8:40 pm
- Zip Code: 49120
- Circle of Safety: Y
- Location: Niles / Buchanan, Michigan
Re: Low compression and valves
Eugene brings up a good point. In my earlier post I should have stated that each cylinder needs to be checked on it's compression stroke.
1929 Farmall Regular
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub
- Ronny Bailey
- 10+ Years
- Posts: 719
- Joined: Thu Oct 23, 2008 2:38 pm
- Zip Code: 77802
- eBay ID: ronnyb.east.texas
- Tractors Owned: 1938 Farmall F-20
Grandpa's '49 Cub #82289
194x Gibson Model D
1953 Allis Chalmers CA - Location: TX, Bryan
Re: Low compression and valves
Good info! Here's another question:
I've noticed that it's usually recommended that you remove all the spark plugs when using a compression checker.
Why is that?
I've noticed that it's usually recommended that you remove all the spark plugs when using a compression checker.
Why is that?
Ronny
“If it ain’t broke, I haven’t 'fixed' it yet”
“If it ain’t broke, I haven’t 'fixed' it yet”
-
- Team Cub Mentor
- Posts: 20370
- Joined: Fri Jul 02, 2004 9:52 pm
- Zip Code: 65051
- Circle of Safety: Y
- Location: Mo. Linn
Re: Low compression and valves
Example. On a 4 cylinder engine, the 3 cylinders not being tested will compress the air/fuel in the cylinder - slowing the number of rpms the engine is being cranked over by the starter. This may or may not effect the reading on the cylinder being tested. High compression engines, this will definitely make a difference. C-60 engine - not so much.Ronny Bailey wrote:Here's another question: I've noticed that it's usually recommended that you remove all the spark plugs when using a compression checker. Why is that?
Actually, I done the compression test both ways. I'm looking more for even readings, in the satisfactory range. On a well worn engine it won't make any difference in the readings.
I have an excuse. CRS.
-
- 10+ Years
- Posts: 318
- Joined: Mon Feb 25, 2008 8:16 pm
- Zip Code: 44483
- Circle of Safety: Y
- Location: OH
Re: Low compression and valves
I have to agree with Lurker you don`t have a full flow oil filter & all that sludge will go through the bearings. Plus you can bend a rod if you put a licquid in the combustion chamber.
- Corky's Cub
- 10+ Years
- Posts: 2453
- Joined: Thu Mar 08, 2007 12:57 pm
- Zip Code: 30607
- Tractors Owned: Just One:
1957 Farmall Cub
"Corky"s Cub" - Location: Georgia, Jackson County
Re: Low compression and valves
Eugene wrote:Example. On a 4 cylinder engine, the 3 cylinders not being tested will compress the air/fuel in the cylinder - slowing the number of rpms the engine is being cranked over by the starter. This may or may not effect the reading on the cylinder being tested. High compression engines, this will definitely make a difference. C-60 engine - not so much.Ronny Bailey wrote:Here's another question: I've noticed that it's usually recommended that you remove all the spark plugs when using a compression checker. Why is that?
Actually, I done the compression test both ways. I'm looking more for even readings, in the satisfactory range. On a well worn engine it won't make any difference in the readings.
Eugene's got it...and there's another problem that might not be so pronounced on the cub...on bigger engines, if you constantly run un-burned fuel through the engine by turning it over, it can cause premature wear on the valve guides and rings and make the engine run smoky way before it's time.
Corky
I found this old Cub, Forgotten and Forlorn,
With pistons and valves frozen and worn.
Help from my buddies on Farmallcub.com,
And an engine from Ralph, (37’s the one),
Now ole Corky is running and back to life,
Much to the surprise of my dear, dear wife!
With pistons and valves frozen and worn.
Help from my buddies on Farmallcub.com,
And an engine from Ralph, (37’s the one),
Now ole Corky is running and back to life,
Much to the surprise of my dear, dear wife!
- Winfield Dave
- 10+ Years
- Posts: 3558
- Joined: Thu Apr 22, 2010 2:31 pm
- Zip Code: 17953
- Tractors Owned: ......Almost enough.
N3NIK - Circle of Safety: Y
- Location: PA, Middleport (Schuylkill County)
Re: Low compression and valves
Earlier this week I was reading some posts here about using a vacuum gauge to help diagnose engine issues.
Maybe this would be of some help?...It seemed to identify different problems by the gauge reactions.
I haven't done it....just sharing.
Maybe this would be of some help?...It seemed to identify different problems by the gauge reactions.
I haven't done it....just sharing.
Dave
"More gold has been mined from the thoughts of men than has been taken from the earth." -- Napoleon Hill
"More gold has been mined from the thoughts of men than has been taken from the earth." -- Napoleon Hill
Who is online
Users browsing this forum: No registered users and 35 guests