4020 1969 valve cover gasket blow out

sfi3213

New User
Need some insight on what to do now. I was plowing with my 4020 tractor, and I noticed starting to smoke from the front of the tractor, and smell like oil burning. I creaped it back up to the barn, and parked it under a shade tree and let it set there for about 75 minutes at idle. When I shut it off, the drivers right side valve cover gasket exploded. Sound like a shotgun blast going off. Why? what should I look for? How do I proceed? Thanks in advance for any help
 

The only thing I can figure is that the crankcase vent tube is plugged-up....it comes out of the rear of the valve cover.

If something was wrong...why did you idle it for better than an hour??
 
(quoted from post at 16:58:01 06/12/17)
The only thing I can figure is that the crankcase vent tube is plugged-up....it comes out of the rear of the valve cover.

If something was wrong...why did you idle it for better than an hour??

I was always taught to never shut an engine off if it has been working hard, but to let it cool down.
 
Letting an engine idle for a bit is just fine but doing so for more then an hour is a waste of time and $$ and fuel. 5-10 minutes is all that is needed. As for the gasket blowing out sounds like the crank case vent is clogged up so you get high internal pressure in the engine and so the weakest gasket blows out
 
(quoted from post at 17:39:55 06/12/17) Letting an engine idle for a bit is just fine but doing so for more then an hour is a waste of time and $$ and fuel. 5-10 minutes is all that is needed. As for the gasket blowing out sounds like the crank case vent is clogged up so you get high internal pressure in the engine and so the weakest gasket blows out
Thank you for your comments; Hopefully I will get out of work at a reasonable time and start taking things apart. Thanks again
 
Better the valve cover gasket blown out than
the rear main seal!! Make sure you take the
breather tube off, instead of trying to blow
it out or rod it out while it's still
attached to the engine.
 
Gas or diesel?

If it built pressure from a clogged breather, the pressure would have built slowly, and found somewhere to go, like pushing out the dipstick. It would have also built the most pressure under working load, not idling.

Was there any loss of performance prior to the oil blowing and smoking?

What I have seen happen is a gas engine with gas in the crankcase igniting with an explosion. But I've only seen that happen once, and that engine had been driven so hot it melted a hole in the piston, ignited down through the cylinder and blew the valve cover off!

Can you provide any more details?
 
(quoted from post at 03:27:54 06/13/17) Gas or diesel?

If it built pressure from a clogged breather, the pressure would have built slowly, and found somewhere to go, like pushing out the dipstick. It would have also built the most pressure under working load, not idling.

Was there any loss of performance prior to the oil blowing and smoking?

What I have seen happen is a gas engine with gas in the crankcase igniting with an explosion. But I've only seen that happen once, and that engine had been driven so hot it melted a hole in the piston, ignited down through the cylinder and blew the valve cover off!

Can you provide any more details?
This is a diesel tractor, no loss of performance, but oil started dripping out from under the valve cover closest to the drivers seat and on the drivers right side of engine.
 
Steve, correct me if I'm wrong, as I am not a JD guy, but doesn't a 4020 have a screw on oil fill/dipstick? Otherwise, yes, you're right, have seen some dipsticks popped out/blown out from high crankcase pressure

Ross
 
Did the 1969 4020s still have an air pump driven off the timing gears like the older ones? If the crankcase breather was plugged could that pump generate that much pressure, or would it back vent into the intake manifold?
 
(quoted from post at 01:21:34 06/14/17) Those breather tubes can be a bugger to get out, as they get stuck near the bottom.
Isn't the breather tube the one in the top of the valve cover?
 
Comes up out of the valve cover, then turns and goes down along side of engine, on down through a hole in the block/casting. When I got mine, someone had cut the tube off just above the hole in the block. Apparently crud builds up there, and it can be difficult to get out.
 
(quoted from post at 10:51:51 06/14/17) Comes up out of the valve cover, then turns and goes down along side of engine, on down through a hole in the block/casting. When I got mine, someone had cut the tube off just above the hole in the block. Apparently crud builds up there, and it can be difficult to get out.

Mine does everything you wrote, but does not go through the block...... it attaches to the side of the engine and you can see the hole tube. nothing goes through the block
 

Pull the vent tube and clean it out..pull the valve cover, clean it up and glue a new gasket on..reassemble and run
 
(quoted from post at 00:52:31 06/15/17)
Pull the vent tube and clean it out..pull the valve cover, clean it up and glue a new gasket on..reassemble and run
Will do. I guess the only other concern I have is maybe the oil cooler, and if it warrants taking apart and checking for obstructions or restriction? When I took the vent cover off it was machine screws. Is there a inch pound factor when reinstalling or just nice and snug?
 
(quoted from post at 05:30:38 06/15/17)
(quoted from post at 00:52:31 06/15/17)
Pull the vent tube and clean it out..pull the valve cover, clean it up and glue a new gasket on..reassemble and run
Will do. I guess the only other concern I have is maybe the oil cooler, and if it warrants taking apart and checking for obstructions or restriction? When I took the vent cover off it was machine screws. Is there a inch pound factor when reinstalling or just nice and snug?

Should have 1/4" bolts(7/16" socket) with special contoured washers. I clean the valve cover spotless clean and glue the new gasket onto the cover with weatherstrip adhesive and let it dry for sometime.

Then I install all the bolts and washers...tighten the bolts from the center out to the ends snug. Even tighter if the valve cover is 'banana' shaped(warped).
 

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