JD 8430 hydraulic fluid in crankcase Help!

murrwill · May 13, 2022

We have an old 1978 JD 8430 and have discovered hydraulic fluid is going in to crankcase. We are new to the John Deere world. Bought 3 yrs ago for cheap horsepower but now we have a problem that none of the young techs in the area seem to have answers for. We don't have the capability or the knowledge to split a beast like this on the farm.
Any suggestions would be appreciated
Thanks

This post was edited by murrwill on 05/13/2022 at 03:55 am.

Tx Jim · May 13, 2022

My guess is engine rear seal is allowing hyd oil from Perma-clutch housing to move forward into engine crankcase. IIRC one needs to R&R engine to replace rear engine seal. I had that happen on my JD 4255 many yrs ago.

tim s · May 13, 2022

There is a sump screen in the bottom of the clutch housing, first place to look,, when that screen clogs the clutch housing fills up with oil and it forces oil through the rear main seal,, next step is it will blow the timing hole plugs out on the right rear of the block,,making a large mess, Over time the clutch plates will start flaking off, this plugs the screen.Clean the screen, change the engine oil,,run it and keep an eye on it,,,strong chance it will be okay for a while.

casecollectorsc · May 13, 2022

Find the trans. breather and make sure it is clean...could be building pressure and forcing oil thru the rear seal.

murrwill · May 13, 2022

(quoted from post at 04:53:29 05/13/22) Find the trans. breather and make sure it is clean...could be building pressure and forcing oil thru the rear seal.

Where would I find this?

murrwill · May 13, 2022

(quoted from post at 04:53:29 05/13/22) Find the trans. breather and make sure it is clean...could be building pressure and forcing oil thru the rear seal.

Where would I find this?

murrwill · May 13, 2022

(quoted from post at 04:53:29 05/13/22) Find the trans. breather and make sure it is clean...could be building pressure and forcing oil thru the rear seal.

Where would I find this?

Tx Jim · May 13, 2022

Breather is located on top of hyd oil filler pipe on rear trans case cover

WNYBill · May 13, 2022

Real main seal. Our old 420 makes oil and loses hyd fluid. Start using #10 oil in hyd and just cycle it. Drain crankcase and fill
hyd. We have been doing that for a couple of years, cycle a qt or 2 about once a month. For some unknown reason it has stopped doing
it. (the little guy in there discovered we didn't panic, so he quit screwing with us}

Bill

murrwill · Oct 27, 2022

Thanks the screen was plugged however we cleaned screen replace hydraulic fluid started it up and within 2 mins the crankcase was full again. At wits end. Nobody around my area has any answers

buickanddeere · Oct 27, 2022

(quoted from post at 14:51:22 10/27/22) Thanks the screen was plugged however we cleaned screen replace hydraulic fluid started it up and within 2 mins the crankcase was full again. At wits end. Nobody around my area has any answers

Only two minutes ?

murrwill · Oct 27, 2022

Yes very quickly

murrwill · Oct 27, 2022

You would think if it was a main crank seal oil would be leaking our as well from engine and that doesn't seem to be the case

wore out · Oct 28, 2022

(quoted from post at 05:04:49 05/13/22)

(quoted from post at 04:53:29 05/13/22) Find the trans. breather and make sure it is clean...could be building pressure and forcing oil thru the rear seal.

Click to expand...

Where would I find this?

There is a hose that connects the clutch housing to the back half of the tractor, as the other poster said, the actual vent is through the fill cap at the rear.

Fitting 4a or 4b screws into a port in the planetary output bearing holder (Key #23 in the drawing below).

As I'm sure you know, the clutch housing is a ''dry sump'', oil is scavenged by one half of a dual gear pump located in the front left of the hinge area.

One section of that pump supplies clutch operating oil (drawn from the back half of the tractor) and the other section returns oil from the suction screen in the clutch housing to the rear half of the tractor.

murrwill · Oct 28, 2022

Sorry im not sure what the pics are telling me?
Is there something i should be looking into with that hose?

wore out · Oct 28, 2022

You ASKED how the clutch housing is vented, and I explained that.

It certainly wouldn't hurt to look at the vent hose between the front and back of the tractor, but I highly doubt that could cause that much oil to wind up in the wrong place.

I would verify that the clutch housing scavenge pump IS returning oil to the back half of the tractor, you could disconnect the hose from the back half and hold it over a bucket while a helper CRANKS the engine over with the starter.

murrwill · Oct 28, 2022

Sorry I'm not a mechanic. Just a farmer trying to figure this out. What are you saying with the diagrams? Is there something I should be looking for there? Is there something that could be the cause of my problem?

murrwill · Oct 28, 2022

Ok thanks for the help. Sorry I didn't get notified of this response so please disregard my previous post

wore out · Oct 28, 2022

Don't worry about the parts drawings I posted, as I said, I posted them to answer your ''venting'' question, but that is more than likely NOT your problem.

Did you understand what I posted about the ''scavenge'' pump, and the hose that carries return oil from that pump to the back half of the tractor?

murrwill · Oct 28, 2022

I think so but would you have more info on identifying it? What side of the tractor would it be on?

used red MN · Oct 28, 2022

(reply to post at 00:55:21 10/29/22)

ttps://partscatalog.deere.com/jdrc/navigation/equipment/65881 I will suggest obtaining a servic...ce-manual?_pos=4&_sid=a405cf07c&_ss=r

used red MN · Oct 28, 2022

(reply to post at 00:55:21 10/29/22)

ttps://partscatalog.deere.com/jdrc/navigation/equipment/65881 I will suggest obtaining a servic...ce-manual?_pos=4&_sid=a405cf07c&_ss=r

wore out · Oct 29, 2022

(quoted from post at 11:11:39 10/28/22) I think so but would you have more info on identifying it? What side of the tractor would it be on?

Below are a couple photos of the hinge area of my 8630 showing the hydraulic lines connecting the front and rear of the tractor.

AFAIK, your 8430 should have a similar setup, but I'm not 100% sure and I don't have an 8430 nearby to verify that it's exactly the same.

In each photo the line that carries oil scavenged from the clutch housing to the rear half of the tractor is the upper hose of the group of four, and is hose clamped at each end.

View of LH side of hinge area/

View of the RH side of the hinge area, the hose at an angle in front of the 4 grouped hoses is the vent hose between the halves of the tractor.

JD 8430 hydraulic fluid in crankcase Help!

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