730 diesel no oil pressure

Plowboy34

New User
Hello. Thanks for any help at all. First off I have a 730 that I am the second owner of. The tractor has been sitting for 5 years from bad wiring harness. I rebuilt that and got it going again. Changed oil and coolent. After driving it down to my barn I was almost there and it started smoking white and gotten hot. Smelled like coolent. So I pulled the head. Couldn't tell where it was blown on the gasket so I put new gaskets on and everything back together and went to start it up to warm it up to tq the head and thin I noticed it had no oil pressure at all. Now I am lost. Any help will be appreciated!
 

How long did you roll it over without fuel and without compression? Does the oil pressure gauge function? Was there frozen water in the oil and twisted the oil pump drive coupling?
 
How long did it run after you changed oil? Did it not have oil pressure immediately after you changed oil? Or just since you pulled the head?
 
(quoted from post at 19:27:18 02/07/17) How long did it run after you changed oil? Did it not have oil pressure immediately after you changed oil? Or just since you pulled the head?

I would say not over 60 seconds I fired it up to make sure I had the wiring right. Thin I changed oil and it had pressure thin drove it 300yards and the white smoke and it got hot. Now i put the new head gasket on and it has ran for a couple minutes and no oil psi. I pulled the gauge off and nothing is coming out of the line after running for 60 seconds.
 

Running 60 seconds with no lubrication and full load on bearings ?
Why are you not cranking it with the compresssion released and the fuel in the zero delievery position to trouble shoot the oil pressure ?
 
Check the line going to the gauge all the way down to the source. The gauge line on my 630 was plugged with a piece of stray blue silicone a couple of years ago. It's a fluke occurrence but it can happen.
 

Running 60 seconds with no lubrication and full load on bearings ?
Why are you not cranking it with the compresssion released and the fuel in the zero delievery position to trouble shoot the oil pressure ?[/quote]

Yeah I am now but how long should it take turning it over should I start having oil pressure?
 
I would guess I've turned it over for a
couple minutes. Took the over off of the
bottom of the oil pump and the two gears in
there are not spinning. So it's looks like
my next step is going to take the fly wheel
off and timing cover and check out the oil
pump gear. Hopefully I didn't get in over my
head here....
 
I don't think those diesels have the oil pump coupling ? Too bad for him as that would be a much easier fix.
 
Anything can be fixed. Get the JD service book if you don't already have it. It's very detailed. By the time you're done you'll understand the tractor better. Just take your time.

If it's electric start, it's easy enough to pull off the starter, govenor, and crankcase cover and
look down inside. You should be able to see the top of the oil pump, at the bottom of the flywheel side. It's driven by some bevel gears. From there you can figure out if it's something in the pump that let go or if it's the drive gear. If it was in the pump you won't have to take the flywheel and timing cover off.

When I first read this, I thought you were saying that you ran it out of oil. But now that I read it again, you were trying to do initial start up after putting the head back on, and noticed the pressure not coming up, correct?

I have a 720 diesel that I've been straightening out off and on the last few years. I keep running into problems like you, and then eventually figure them out. These diesels are sometimes pricey to fix, but it can be done.

If you do pull the flywheel, be very careful when reassembling so that crankshaft endplay is correct and the flywheel is tight. The service book tells you how in detail. This is critical. Maybe you already knew that.
 
I just bought the book and it does go very in depth. I already pulled the flywheel but now I have a buddy who is going to help me pull the governor and look down in there and see what we find. Thanks for the help!
 
Just a note that if you pulled the flywheel it would be smart to use new bolts in the flywheel when you go back together. Bob
 
Don't pull the governor as all you will see is the top of the main case. Drop the oil pump and check for sheared key in the beveled gear. I f that's ok pull the big left housing to see if the oil pump drive is ok . You best find an old diesel mechanic because you could find a big can of worms . This is no job for a wannabe mechanic .
 

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