simms minimec P4696 leaking oil

[Jhinschen]

G,day fellas.

Got a bit of a Query regarding a minimec P4696 on a 1964 NP Super dexta.
Short story is when under load, a fair amount of oil (not Diesel) leaks out of a small threaded hole on the rear of the pump. I believe this is supposed to be a vent for the cambox. This means everytime I do my prestart checks I am having to top up the oil in the pump.

Am I able to put in a copper pipe with a banjo bolt or brass fitting and direct the leaking oil back in the filler cap (which is also threaded) without causing any problems.

I don't mind stripping the pump if necessary however I am in the middle of planting and need to keep it working.

Cheers Joel

 

[Majorman]

There should be a banjo bolt and a pigtail pipe there. The pipe allows the oil/diesel level in the cam box to remain constant and keep the main parts of the pump lubricated. Diesel will leak into the cam box as it is supposed to do, then reach a level with excess going out through the pipe onto the ground. You really need that pigtail pipe.

 

[Jhinschen]

Thanks Majorman. Putting a pigtail on it is not a problem, but I am a little concerned about the amount of oil I am having to top up with every day. As I said before when working hard she spits a swag of oil out of the vent hole, about 100ml.

 

[Majorman]

The only oil that should be in the pump is about 1/3rd of a pint in the governor housing, the rest should be diesel that dilutes the oil down. This is normal. The leak is usually from the pump into the governor housing through the seal. You should not be having to put oil in there and oil from the governor should not be leaking out of the pigtail pipe. Are you sure you are not overfilling it with oil? There is little chance of engine oil getting in there but diesel could get in through a faulty diaphragm in the lift pump.

 

[560Dennis]

Did you get it fixed ? Was wondering how you were doing With this project.

 

[Jhinschen]

Gday fellas. Long story short, to keep the old girl working I put a 5/16” unf bolt with a copper washer in the vent hole on the rear of the pump. I then drilled and tapped the filler cap and using a 1/8” Bspt thread and tail I attached a crankcase breather so that the governor compartment does not over pressurise. My reasons for doing this are that I need to keep her working, the parts to make the pigtail are not readily available over the counter in my area and this time of the year everything here is shut down. I have attached a couple of photos. So far I haven’t had any issues. I still check the pump oil level on every pre start check and the oil level has remained constant.

Cheers

 

[Majorman]

There is no way that pressure could build up in the governor area anyway, it is only a weight device spinning in a small amount of oil and diesel. However by blocking the rear vent, diesel is going to build up in the cam box and possibly damage the seals that keep the two areas apart. I still would suspect leaking lift pump diaphragm if you are getting a lot of liquid build up in the cam box.

 

[Jhinschen]

Sorry majorman, my blunder. I meant pressure in the cambox not the governor. The oil level is currently remaining constant, neither leaking out or increasing due to excessive Diesel. The lift pump is new. Cheers fella

 

[Majorman]

OK, no problem but you have put a breather on the governor and sealed the cam box if you have blocked the pigtail pipe outlet. The ywo compartments are separate.

 

[Jhinschen]

I think the seal between the two is probably already buggered, thus why the oil was getting shot out of that vent. If there’s any build up of Diesel now it will just run back into the oil compartment and get drained when I do my start up check every morning. It’s not ideal, and I will get it fixed properly but until then I got millet to plant and need to keep her going. As I mentioned earlier we are remote and the luxury of a fully serviced town nearby doesn’t exist, so improvisation is what keeps our wheels turning. That’s farming.

Thanks all.

 

[Majorman]

OK, I understand. The pump is one of the most expensive items and not the sort of thing you can work on without special tools. I worked on those pumps when I was training at our dealership and at Fords and you have to be like a surgeon if you do not want to ruin it.

Are you in Oz? Where abouts?

 

[Jhinschen]

That’s right , Australia mate. Located in the western Burnett area of central Queensland. It’s about a 4 hour drive one way to the nearest major town which is Maryborough and even then parts are limited. We used to have a lot of Machinary wreckers and old fellas with tractor grave yards which was handy. But the scrap steel fellas cottoned and cleaned most of them out.

Anyhow, thanks again

 

[Dieseltech]

OK, no problem but you have put a breather on the governor and sealed the cam box if you have blocked the pigtail pipe outlet. The ywo compartments are separate.

The cambox is also part of the governor at the drive end on Simms pumps, all ONE area for the oil/diesel leakoff supply. The Older American Bosch Pumps had SEPARATE cambox and governor ends, and were oiled separately with a seal inside to keep the oil levels apart. Ford Simms pumps were not separate.