JD 4239 engine.

L8R · May 11, 2020

I am working on doing a major engine overhaul on a 4239 John Deere engine. I am seeing that there is a high ring and a low ring overhaul kit and how do I know which one I have?

Tx Jim · May 11, 2020

Welcome to YT
Is the engine a naturally aspirated or turbocharged? Where are you sourcing your pistons/liners? Do current pistons have any markings on them?

L8R · May 12, 2020

(quoted from post at 14:22:24 05/11/20)
Welcome to YT
Is the engine a naturally aspirated or turbocharged? Where are you sourcing your pistons/liners? Do current pistons have any markings on them?

Thanks Jim! It is naturally aspirated and I am wanting to purchase from Canadian Tractor Parts Direct. https://www.canadiantractorpartsdi...at mean and how do I know which size I need?

Tx Jim · May 12, 2020

IIRC if rod/main brg inserts aren't standard size the brg halves will be marked on backside of brg with 0.010 or 0.20 or 0.030. Be sure to re-install caps in same location that they were removed from.

Determined · May 12, 2020

(they are asking about standard rod and main bearings. They give other options of 0.010, 0.020 and 0.030 for sizes. what does that mean and how do I know which size I need?)

If the engine was previously repaired or overhauled it would be common practice for a machine shop to have cleaned up any scoring or wear on the bearing surfaces of the crankshaft by machining it to a smaller size, how much smaller would be determined by the depth of the damage on it.

The only way to know will be to first find the crank specs for your engine then with the proper micrometers measure the crankshaft you have.

If for example a machine shop removed .020 of material to clean it up then a .020 oversized bearing would be required.

jimtrs · May 12, 2020

(quoted from post at 08:47:13 05/12/20)

(quoted from post at 14:22:24 05/11/20)

Thay are asking about standard rod and main bearings. They give other options of 0.010, 0.020 and 0.030 for sizes. [b:e97e243cd4]what does that mean and how do I know which size I need?[/b:e97e243cd4] [/url]

Click to expand...

Absolutely no offense meant.....

if this is your first engine rebuild, and if this is a John Deere 4-239D Diesel, do you feel qualified to rebuild this engine?
Not my first choice to cut my teeth on.

Precise measurements are needed to determine if crankshaft grinding is needed, then to specify bearing sizes. Lots of other critical stuff. Might be best left to a machine shop.

miangus · May 12, 2020

You got some good advice. I would at least take that crank to a machine shop if you are not experienced. Take the head with you, that work requires a machine shop. Make sure the mains and rod caps are marked, they must return to the locations they came from. Also take note of piston direction. You have a manual right? I don?t know about that particular engine but getting the cam an Injection pump timing on a 203 Perkins would be quite the adventure with out a manual. Can you find a friend that can provide advice and consul. You know the guy that can read that vernier gauge on mic.

L8R · May 12, 2020

If for example a machine shop removed .020 of material to clean it up then a .020 oversized bearing would be required.

Thanks! The engine was not opened up before so the crank was not previously ground. The reason we started on this is because the previous owner said the engine has a "rattle". We found 2 broken bolts in the clutch that may have been the issue, but we expected to find something loose in the engine. There is nothing so far and the engine looks very clean and nice inside. Very slight wear marks on the bearings. I want to measure the crank and rod bearing journals. the manual says to measure at 3 different points in case there may be irregular wear.

L8R · May 12, 2020

Make sure the mains and rod caps are marked, they must return to the locations they came from. Also take note of piston direction. You have a manual right? I don?t know about that particular engine but getting the cam an Injection pump timing on a 203 Perkins would be quite the adventure with out a manual. Can you find a friend that can provide advice and consul. You know the guy that can read that vernier gauge on mic.

Thanks! Glad for all the good advice. Yes I have an engine manual and yes we did mark all the parts so far. I was thinking it will be an adventure even with a manual

but my boys and I are doing a project so at the least it will be an "experience". I will see if I can find a local machine shop that can do cranks & heads. our thing is to take it apart and get it back together with sound parts in it. [/quote]

jimtrs · May 12, 2020

Thanks! The engine was not opened up before so .....

Boy if I had a dollar for every time someone said that, I could take some time off

The only way to know that for sure is if you owned the machine since new. A lot, most, machines especially older ones worked hard in their day. Common for farm tractors to need rebuilds every 5 years, or less. I've seen diesel engines need rebuilds with less than 2000 hours and some not needing a rebuild at 20,000 hours. All depends on how it was used and maintained.

Very slight wear marks on the bearings.

Completely normal, after even a short amount of run time

I want to measure the crank and rod bearing journals. the manual says to measure at 3 different points in case there may be irregular wear.

Takes quality precision instruments, and the knowledge of how to use them.
There will always be uneven wear, on the pistons, on the cylinders, on the crankshaft, rod journals, etc. This is due to the thrust side of all these components taking the brunt of the power stroke.

buickanddeere · May 12, 2020

The highest compression ratio is desired for winter starting .

ben brown · May 12, 2020

reliance engine parts off a hyper engine kit that the top ring is closer to the top as are then new jd engine have. cost more i did one on my 3020 and its working out good most my customer don't want that kit as it cost more now on the light side after i read all the post of all the do this and don,t do that i probably have to closes my shop get a manual pay attention to how it come apart you be ok also you take a few pic as you go as a reminder you get repair manual off e-bay or a I-T manual

L8R · Aug 1, 2020

(quoted from post at 15:04:04 05/12/20) Make sure the mains and rod caps are marked, they must return to the locations they came from. Also take note of piston direction. You have a manual right? I don?t know about that particular engine but getting the cam an Injection pump timing on a 203 Perkins would be quite the adventure with out a manual. Can you find a friend that can provide advice and consul. You know the guy that can read that vernier gauge on mic.

Thanks! Glad for all the good advice. Yes I have an engine manual and yes we did mark all the parts so far. I was thinking it will be an adventure even with a manual but my boys and I are doing a project so at the least it will be an "experience". I will see if I can find a local machine shop that can do cranks & heads. our thing is to take it apart and get it back together with sound parts in it.

/quote]

Thanks again, everyone, for the helpful advice. The engine is back in the tractor and we have been using it for a few weeks now.

Kansas4010 · Aug 2, 2020

Thanks for the update.

JD 4239 engine.

L8R

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Tx Jim

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Determined

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