420 engine compression tests
420 engine compression tests
I recently noticed a small amount of white smoke coming out of my oil filler tube so since we are having some warm then cold days in Pennsylvania I figured it was condensation, especially since I haven't been using my 1956 420 much lately. So I did a cylinder leak down test and a compression test so I could sleep a little easier at night. I had around 113 pounds of compression on the front cylinder and around 110 pounds on the rear cylinder. I checked for oil in the coolant and there was none, and there is no sign of any water or foam in the oil. The leak down test showed a 35% loss in the front cylinder and about a 38% loss in the rear cylinder, both readings were in the low loss side but 40% begins the moderate part of the gauge, there was a lower amount of compressed air coming from the dip stick and the filler tube. The oil pressure gauge always reads HIGH and there is never seems to be any loss of power, no white smoke coming out of the exhaust, it always starts up instantly. There seems to be a small amount of water/condensate on the inside of the oil filler tube cap while it is running. Also I was about a 1/2 quart overfilled in the engine so I drained it out. Which it did seem to smoke less. I also set the valve clearances on all 4 valves. I'm thinking everything is pretty normal for the age, although the piston rings are somewhat worn. Am I thinking correctly or am I missing something? All opinions are greatly appreciated. Thanks for your time in advance!
Last edited by notmeu on Wed Feb 13, 2013 9:04 pm, edited 1 time in total.
1956 JD420, gearmatic 8a winch, custom 6 way blade and FOPS.
- DukeofDeere
- 1010 crawler
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- Joined: Wed Oct 26, 2011 7:12 am
- Location: Hudsonville Michigan
Most Debuque tractors should read full if you pull the dipstick very soon after shutdown.
If you wait longer it will read one quart over full due to the filter can draining down.
If this machine has some temp fluctuations from change in weather there will always be some moisture in the crankcase that will take some running to evaporate out. (White steam) nothing unusual. Newer engines have the crankcases breather going back into the air cleaner then carb to burn it off.
The close readings sound very good on your compression test!
Sounds like a strong machine.
Duke
If you wait longer it will read one quart over full due to the filter can draining down.
If this machine has some temp fluctuations from change in weather there will always be some moisture in the crankcase that will take some running to evaporate out. (White steam) nothing unusual. Newer engines have the crankcases breather going back into the air cleaner then carb to burn it off.
The close readings sound very good on your compression test!
Sounds like a strong machine.
Duke
Last edited by DukeofDeere on Wed Feb 13, 2013 9:11 pm, edited 1 time in total.
- DukeofDeere
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- Location: Hudsonville Michigan
'56 420 oil filler condensation
I also have a 56 420 and to eliminate the moisture problem I went with a 180 thermostat and a jute bag over the rad for winter operation, they should be run at the top of the temp range to eliminate the condensation in my opinion
- DukeofDeere
- 1010 crawler
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- Joined: Wed Oct 26, 2011 7:12 am
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A lot of the time you will have moisture in the breather cap and pipe, but not in the engine itself. You have hot air escaping the engine through the pipe and breather which are cold, so it condenses there.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
That makes sense Lavoy, Does the compression tests sound good? I cannot find any information online, or in the service manual.Lavoy wrote:A lot of the time you will have moisture in the breather cap and pipe, but not in the engine itself. You have hot air escaping the engine through the pipe and breather which are cold, so it condenses there.
Lavoy
1956 JD420, gearmatic 8a winch, custom 6 way blade and FOPS.
- DukeofDeere
- 1010 crawler
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- Joined: Wed Oct 26, 2011 7:12 am
- Location: Hudsonville Michigan
In my neck of the woods with all the temp fluctuations there is almost always condensation certain times of the year.
Spring project at my uncles with 40+ antique tractors in cold storage is to open the crankcases and transmissions and drain off the condensation. Usually a cup or more before clean oil comes from around the threads of the drain plug.
Compression test is really good.
Being that close to equal is great.
If I remember right 120- 130 is perfect.
Duke
Spring project at my uncles with 40+ antique tractors in cold storage is to open the crankcases and transmissions and drain off the condensation. Usually a cup or more before clean oil comes from around the threads of the drain plug.
Compression test is really good.
Being that close to equal is great.
If I remember right 120- 130 is perfect.
Duke
You are within 10% difference, and the overall numbers is good.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
- Paul Buhler
- 350 crawler
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checked my notes, and my 420 has compression of 110 on #1 and 115 on #2. I used an inexpensive rubber cone type tester, so numbers may be off somewhat, but it gave me an idea of the balance between the cylinders. Paul
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
Thanks Paul. I'm surpried that the compression isn't more of a published data for the 420, either in the manual or service manual. If it is I surely missed it!Paul Buhler wrote:checked my notes, and my 420 has compression of 110 on #1 and 115 on #2. I used an inexpensive rubber cone type tester, so numbers may be off somewhat, but it gave me an idea of the balance between the cylinders. Paul
1956 JD420, gearmatic 8a winch, custom 6 way blade and FOPS.
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