4020 Rocker Arm Cover Gasket and Valve Adjustment Questi

mtb34 · May 17, 2023

Had a leaking valve cover gasket on 1965 4020.

Pulled it and ordered a new gasket from Deere.

New gasket is cork/rubber (R49866) ... Old gasket just rubber (R32593).

Someone used sealant with rubber gasket but no instructions for sealant on the cork/rubber. I thought they didn't need any.

Any thoughts?

I just used petroleum jelly on the cork/rubber for my top transmission cover.

Also on valve adjustment manual shows .018 for exhaust and intake but I thought I saw a post awhile back where people mentioned something a little looser.

Thanks.

Muir hill 101 · May 17, 2023

On cork I use Indian head or hi tack Ive got one that
wont seal without a little silicone . I didnt know Deere
had a rubber gasket

Mike M · May 17, 2023

I am not sure on that gasket ? Seems like I used to get the rubber ones and also had to get new bolts
too for those over the original cork type ? Can't remember what was different about them ? I always
coat cork rubber gaskets with a very slight amount of silicone gasket maker.

JIM MN · May 17, 2023

Glue either gasket to the valve cover.. The first gaskets were cork with flat-blade screwdriver screws.. Then Deere went to a rubber gasket and they offered fastening screws that had a hex head so you could tight down the valve cover tighter; with the rubber gasket ....

tomstractorsandtoys · May 17, 2023

I wish Deere would throw out all those cork valve cover gaskets and give us something better like the newer
tractors use. Tom

JD Dave · May 17, 2023

You can get by with very little or no sealant on the gasket. Less is more. No gobs of anything that can get down into the engine. The valve adjustment: follow the directions in the JD
manual to a tee. Works every time.

mtb34 · May 17, 2023

Thanks for the suggestions.

I will go with the .018.

The valves are way out of tolerance at the moment.

I feel bad I didnt look at them sooner.

The tractor is still a little new to me and I am fixing alot of things on it.

Attached a picture of the old gasket. Cant believe the part number is still visible.

JD parts site says it is superceded.

matthies · May 17, 2023

And you know you adjust half of the valves at tdc, then rotate engine to tdc again, adjust other half and you are done.

Muir hill 101 · May 17, 2023

They have never sent me anything but cork Just replaced two this spring . so. What part number is the rubber gasket

Fixingfarmer · May 19, 2023

While the mechanic in me says dont bother putting anything on because it should be easily removed the farmer says if I didnt adjust the valves on it my entire lifetime before I had it open...if you dont want it to leak what I would do is put a little aviation gasket maker on both surfaces picking the first one you want glue. It will need to dry a bit but it stays softer than most other things when it comes time to remove it. Believe it or not sisu engines use to this day a cork gasket on their lower pan gasket. Combine that with a
round rolled edge and about a hundred Allen head bolts of two different sizes the only way you wouldnt have a leak and still be able to get it off easily when they dumped the front dampener into the radiator in 1000 hours was to use that product.

4020 Rocker Arm Cover Gasket and Valve Adjustment Questi

mtb34

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Muir hill 101

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Mike M

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JIM MN

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tomstractorsandtoys

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JD Dave

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mtb34

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matthies

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Muir hill 101

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Fixingfarmer

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