# Best way to tell if a tractor engine needs overhauled



## FarmerCline (Oct 12, 2011)

I have just now started to do some work on the JD 4020 I bought last winter. We have replaced the tires and rims and had to repair an internal hydraulic leak. I bought this tractor with the understanding that it had a complete engine overhaul done by JD 1000 hours ago. The little bit I have worked this tractor it just didn't seem like it had much power. This week we had the tractor put on a dyno and it would only make 80hp and had almost as much blowby as it had coming out the exhaust. I'm now being told that it needs to be overhauled. If it does need overhauling this makes me think I was not told the truth when I bought it. I am somewhat mechanically inclined and can do many repairs myself but I'm kind of in the dark on this as I have never done any engine work so I'm not really sure what to look for as indicators that an engine needs rebuilt.

Hayden


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## urednecku (Oct 18, 2010)

I'm no mechanic either, but with that much blow-by I tend to agree. Just because somebody turns wrenches for a JD dealer does NOT mean they are a "mechanic"!


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## Orchard6 (Apr 30, 2014)

Assuming it's a diesel, have the injection system looked over first, make sure everything is up to par there. Check compression too.
What has the tractor been used for for the last 1000hrs? Sometimes if a tractor doesn't get used hard the rings take a long time to seat. Also there have been cases where oil will glaze the cylinder walls from lack of heavy use. Try running it as hard as you dare for a few days and see if it gets better.


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## hog987 (Apr 5, 2011)

[quote name="Orchard6" post="142138" timestamp="1407699863"]

Assuming it's a diesel, have the injection system looked over first, make sure everything is up to par there. Check compression too.
What has the tractor been used for for the last 1000hrs? Sometimes if a tractor doesn't get used hard the rings take a long time to seat. Also there have been cases where oil will glaze the cylinder walls from lack of heavy use. Try running it as hard as you dare for a few days and see if it gets better.[/quot

Another thing that can happen under light use is a build up of carbon. So the valves might stick open a bit. Poor spray from injectors. Rings dont seal right. But a good work out doing heavy work helps with all of this.


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## FarmerCline (Oct 12, 2011)

It is a diesel. I don't really know how it was used the past 1000 hours......it was supposedly being used to make hay. And yes just because they work for a dealership doesn't mean they are a good mechanic.....some are very good others not so much. I'm starting to wonder about how the person I bought it from cared for it as when I changed the hydraulic/transmission fluid the filters had been in there so long they had collapsed. The fluid didn't have any metal shavings but was nasty dirty.


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## endrow (Dec 15, 2011)

Maybe there definition of the word complete is a bit gray


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## Nitram (Apr 2, 2011)

Complete overhaul depends on what the definition of is is....sounds familiar?


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## panhandle9400 (Jan 17, 2010)

*You can pull a oil sample and have it checked , they can tell you what is wearing inside engine. The blowby is the 1st signs of problems / internal wear. Bet it has weak compression too. Did you buy it from a dealer or a jockey ? If they dont have paperwork on repairs I do not trust them. 4020's are good tractors , what year model is it ?*


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## FarmerCline (Oct 12, 2011)

panhandle9400 said:


> *You can pull a oil sample and have it checked , they can tell you what is wearing inside engine. The blowby is the 1st signs of problems / internal wear. Bet it has weak compression too. Did you buy it from a dealer or a jockey ? If they dont have paperwork on repairs I do not trust them. 4020's are good tractors , what year model is it ?*


 I bought it from a farmer who was supposedly a friend of the original owners who supposedly had the overhaul done. The guy I bought it from did not have any paperwork and I took his word for it. When I bought it I thought it was in pretty good shape but the more I get into it the more little issues I find. I will have the compression checked. Would an oil sample still be worth doing since I just changed the oil before putting it on the dyno? It is a '71 powershift.


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## Farmerbrown2 (Sep 25, 2018)

Pull the pan off and pull some bearings this will tell you how much wear there is on the bottom end. If somebody didn't change some bearings along the way . I would also suspect the injection pump or injectors so if you are going to overhaul it try this first . If this tractor sat a lot fuel could definitely be the issue . I know, just did a pump and injectors in my 4020! If it was mine I would go this route does it use oil mine will use 2 quarts every 100hrs. has some blow by and I would not overhaul it. Next thing is if they didn't change hyd. filters they most likely didn't change engine oil either . Plain and simple dirty oil will ruin anything[ i.e. the motor ] may take a while to get that glaze off the sleeves . I see 71ps fix it rite and it will last another 40 years.


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## Orchard6 (Apr 30, 2014)

It's not uncommon in my area to have a tractor with a neglected hydraulic system. Most don't understand how they work or they they need regular service. As long as the oil is on the stick they're A'OK! 
I would probably try to get at least 50 hrs on the engine before I sent an oil sample in. 
It may be possible that a ring has broke or stuck and is causing the blow by issue as well. Thats why I'd get the compression tested to see if one hole is lower than the rest.
How does it start? If the blow by is that bad and you think it is weak it would make me think that it would start rather hard and possibly need the nose candy (ether) even on mild days.


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## FarmerCline (Oct 12, 2011)

Orchard6 said:


> It's not uncommon in my area to have a tractor with a neglected hydraulic system. Most don't understand how they work or they they need regular service. As long as the oil is on the stick they're A'OK!
> I would probably try to get at least 50 hrs on the engine before I sent an oil sample in.
> It may be possible that a ring has broke or stuck and is causing the blow by issue as well. Thats why I'd get the compression tested to see if one hole is lower than the rest.
> How does it start? If the blow by is that bad and you think it is weak it would make me think that it would start rather hard and possibly need the nose candy (ether) even on mild days.


 When I bought it last winter it was very hard starting and it did concern me a bit but it was very cold weather so I wrote it off as that. Unless it is very warm out it is still a bit hard starting but not to the point of having to use ether.....I have never been a big fan of using it.


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## MT hayer (Mar 1, 2014)

That is a typical 4020 to not pop right off. They take some wind up before fire. I certainly wouldn't tear into it just yet. Most older tractors will have some blow by when worked hard. As long as the oil pressure stayed up when you had it on the dyno, you should go hook on to a plow or a loaded hay truck in a soft field like mentioned earlier and burn the dust off the manifold.

I would take the fuel down to a 1/4 tank and put a bottle of Stanydyne summer treat in. Yes the whole bottle to clean the fuel system. I would run it 20 hours or so hard and then change the engine oil filter. Just the filter. This will clean the engine up and you can cut it apart and look for any shiny stuff. Take note of the oil use if any and let us know


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## Tx Jim (Jun 30, 2014)

As has been stated a "compression test" will determine if engine needs pistons & sleeves. I'd suggest to check cyl head valve clearances before compression testing.


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## shortrow (Feb 21, 2012)

All of the above. Hope it works out for you, that's a good tractor you've got. Just needs tlc.


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## NDVA HAYMAN (Nov 24, 2009)

Hayden, you have received some good advice from these guys. Go thru the process to check everything out cause a 71 power shift has some good value. Can you find out from the farmer, the previous owners name and get the rebuild paperwork to see if it was really done?


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## FarmerCline (Oct 12, 2011)

NDVA HAYMAN said:


> Hayden, you have received some good advice from these guys. Go thru the process to check everything out cause a 71 power shift has some good value. Can you find out from the farmer, the previous owners name and get the rebuild paperwork to see if it was really done?


 I doubt it.....the previous owner supposedly passed away a few years back and he bought the tractor right after that.


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## askinner (Nov 15, 2010)

Could have actually had a rebuild, but it may have gotten hot some time afterwards, and grabbed a piston, which will need a head off job to check out. If it's been used lightly, and carboned up, brake fluid is the best decarbonizer you can get, it will deglaze and free up any stuck rings.


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## hog987 (Apr 5, 2011)

askinner said:


> Could have actually had a rebuild, but it may have gotten hot some time afterwards, and grabbed a piston, which will need a head off job to check out. If it's been used lightly, and carboned up, brake fluid is the best decarbonizer you can get, it will deglaze and free up any stuck rings.


I have used break fluid to condition belts but have not heard of this. Do you just mix it in with the fuel or take the head off and soak the parts?


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## askinner (Nov 15, 2010)

hog987 said:


> I have used break fluid to condition belts but have not heard of this. Do you just mix it in with the fuel or take the head off and soak the parts?


No, you pull the injectors, and tip it in the pots and let it soak for a couple days. Apparently it's the best decarbonizer you can use. Just make sure you get the remainder out of the pots, and change the oil afterwards, and give it a good work out.


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## siscofarms (Nov 23, 2010)

If your still working the problem here It very well could be the rings and the easiest way to do this is the hard pull like some have suggested but put a few gallons of filtered burnt oil or transmission fluid or some bio diesel in the tank . Fuel is so "DRY" now you really don't get any lubrication anymore . Truthfully this probably isn't gonna help a 1000 hr supposed OH but that's what we do with fresh engines here . Plus I make bio diesel so it gets burned a lot anyway .


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## R Ball (Feb 26, 2013)

We've used brake fluid and automatic transmission fluid down the carburetor in older motors to help clean them up.


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