Ford NAA Distributor/Oil pressure problem

   / Ford NAA Distributor/Oil pressure problem #1  

tmajor

Platinum Member
Joined
Oct 9, 2007
Messages
704
Location
NE PA
Tractor
2010 MF 1529, Woods ZTR MZ1952, National Mower sickle bar circa 1963
Hi,
I just changed out my NAA distributor with a used one. Tractor starts and sounds good. While taking it for test spin, I noticed that it didn't seem to have any oil pressure. It never did have terrific pressure, especially when warm ... but it did have some.

According to the manual, the distributor can't be fully seated, unless the end of the dist. shaft drops into the oil pump slot. Is this for sure?

I didn't compare the length of the shafts, but assumed it was correct, as I believe the NAA was the only dist. with a straight tang on the end to fit into a slot in the oil pump. Plus, it was represented as a NAA dist..

Thanks, Tom
 
   / Ford NAA Distributor/Oil pressure problem
  • Thread Starter
#2  
The distributor won't seat fully, until the shaft drops into the oil pump slot.

After checking the distributor shaft length, and finding it to be correct, I tested the oil pressure gauge, which seemed OK. So, at this point, I'd say the oil pump has gone south.
 
   / Ford NAA Distributor/Oil pressure problem #3  
odd that it would just up and die while setting.

Normal procedure is to investigate rapid drops in oil pressure, vs gradual ones which are usually wear, etc. going from some, even if not great, to nothing sounds odd.

I'd pull the oil pump and inspect and check the relief valve.

what was your oiul pressure before failure?

most 134/172 engines I see that are not worn slap out usually make good pressure 40-55psi. My most worn 172 engine will make 40 psi cold, and 28 hot idle.. and it's been run hard and put away wet long before I got it.

post back

soundguy
 
   / Ford NAA Distributor/Oil pressure problem
  • Thread Starter
#4  
Like I said, it has never had good or uniform pressure ... I'd guess, 30 lb. was about max, when cold, .. maybe 10lb. when hot. The guy I bought it from, said the pressure had always been low.

I've got a new pump on the way, but I'll look things over, when I get the pan down.
 
   / Ford NAA Distributor/Oil pressure problem #5  
that's dismal for a OHV red tiger engine... I'm not sure I've ever seen a runner with that low of pressure...

check the pump pickup tube as well..
 
   / Ford NAA Distributor/Oil pressure problem
  • Thread Starter
#6  
I think, I've discovered the problem.

This morning, after breaking two studs off, while removing the pan, I got the pump removed. I didn't see anything wrong, until I took a look at the check valve or pressure valve, which ever it is. The valve was half way across the hole. Not being familiar, I tried to push the piston back with a screw driver, which didn't do anything. Then I removed the cap and spring, applied some WD-40 and played around with the piston. Finally, I was able to tap it in further, but it was tight! Eventually, I got it worked out of the pump body. The piston was a little varnished, but I noticed a pretty significant, 1/2 moon wear ridge, which would correspond with the pump hole, on the piston. I don't know why it froze fast ... whether it was the varnish or whether the wear ridge had gotten turned a bit. Regardless, it was frozen in place.

I can't imagine, the changing of the distributor, having anything to do with the oil pressure issue. :):)
 
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   / Ford NAA Distributor/Oil pressure problem #7  
at least now you know!

soundguy
 
   / Ford NAA Distributor/Oil pressure problem
  • Thread Starter
#8  
I received the oil pump today ... it seemed to take longer to get here, than I expected.

It seemed to be short one gasket for the pick-up tube to oil pump, ... I made that. When I got the pump in place, I couldn't get a wrench on the rear nut to tighten. I had to pull the pump back out and grind some of the casting back, more like the original equipment. After that, it pretty much went together OK ... drive shaft to the distributor was a little snug, mating up.

Ready for the test! I was told to crank the engine over a bit, without starting, to prime the pump and get some pressure. That didn't seem to do the trick, so I fired it up. It probably took 30 seconds for the pressure to start to climb. Warm, at decent RPM, it has about 42 lbs. and about 20 lbs, at a real low idle.

So, I believe, it's ready to go. :)
 
   / Ford NAA Distributor/Oil pressure problem #9  
dang.. still low at idle.. I'm surprised.. those engine usually make better pressure than that... even worn..

soundguy
 
   / Ford NAA Distributor/Oil pressure problem
  • Thread Starter
#10  
The NAA has run good this summer, with the exception that the water pump went south.

As I was brush hogging, I noticed quite a few hayseeds stuck on oil on the right side of the engine. I haven't examined it carefully, but I believe, oil may be coming from the distributor to block connection. I thought maybe, there should be a gasket between the dist. and block, but I don't see any such part or application.

Like I said, I didn't examine it carefully, but the oil was pretty far forward and spread toward the back of the engine.

Anybody had this problem or know anything about it and it's cure? Would a gasket under the dist. mounting be any problem?
 
 
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