oil presure

[20/2]

Hi all
I have a 20/2 listerold, runs fine but oil presure drops of now and again, then engine knock a couple of times , then is ok again, does anyone know what pressure these engines should run at at say 400 rpm? has anyone had a problem with oil pumps?

[dieselgman]

What make 20/2 and how is it configured? Primary lubrication is via splash, not oil pressure. The function of the pump is to lift oil to the upper splash-sump and feed main bearings.

These typically don't push much more than a pulsating 10 psi anyway.

dieselgman

[dieselgman]

400 rpm sounds very slow for a 20/2. You may experience issues with getting sufficient oil splashed to upper components at this speed.

dieselgman

[akghound]

Sounds to me like the engine may be low on oil. However, I do wonder what the knocking sound is. Are you still on the original cam? Do you have dippers on the rods? If you do have dippers the knock most likely is not from the rods. Hummmmm what's knocking?
Ken Gardner

[rf]

I had a similar problem with my 12/2... it was a sticky pump plunger, polished the plunger and honed the bore.

Rf

[cujet]

I spend an awful amount of time with my twin's oil pump. It was so poorly machined, that, after disassembly and inspection, I'm sure it would not have worked. I ended up making some cheezy tooling to lap the ball seats. Plus I had to re-machine the fittings, so they would actually seal. Plus the piston was very roughly finished, as was the bore. I think it took me a week to get the pump to a condition that was "OK".

Certainly, the plumbing was not airtight and it would have been very difficult to prime.

It makes about 5PSI max. But moves plenty of oil.

[20/2]

Hi all
 thankyou for all your very interesting replies.
I run this engine in a narrow boat. with revs between 200-600 rpm. (2mph-6mph on the canal).
so the low oil pressure could be due to any of your replies.
The engine has run for approx 30 hrs since new, so i will give it a bit more time then if problem does not go away, i will strip down pump spring valves etc, and keep you all updated. thnks

[SHIPCHIEF]

Cujet's neighbor Rocketboy had a twin which lost oil pressure. He documented his engine progress on his website for a while.
If I recall corectly, his oil pump piston return spring had broken. Like into several pieces. It's easy to check.
I guess he posts under Listerboy now? here's a link to the relevant page.
http://www.listerboy.com/lister5.html
After cludging around on the site some more I would say that powerannand owns it? ,,Still, it's got the original story and is worth re-reading.

[ronmar]

Could be that the pump plunger is sticking in the down position, and the knocking you hear is the cam bumping it instead of the plunger following the cam?, or it is a little sticky, and the knock you are hearing is the pump plunger popping up against the cam.  That would be one thing that could cause a knock that comes and goes.  It would also explain it coinciding with the oil P comming and going. 

Agree with all the above, Slow crank speed = lower dipper velocity and possibly insufficient splash lube to the internals.  But if it was a rod knocking, it would start and continue to knock:)  Also, not much real oil pressure, it moves the volume, but dosn't make much pressure.  I also had to do quite a lot to my 6/1 pump.  The pump on the 6/1 I have with the deep sump is actually below the oil level so no real issue priming, but The balls didn't seal, and it took quite a bit to get the seats lapped so it would pull enough suction to move a good volume of oil.  If I were contemplating slowing one down that much, I would definitely look into some supplementary oil pump to put oil where it MUST get for long and healthy bearing and ring life.  It would also allow for some oil filtration... 

[dieselgman]

I have no doubt that the knock mentioned is not directly related to supposed oil pressure (or lack thereof). Those oil pumps are marginal at best.

dieselgman

[buickanddeere]

  Makes a belt driven PS pump from a vehicle, a full flow filter and some tubing look like a good substitute for the plunger/spring thing.   

[dieselgman]

The newer air-cooled Listers 1950's up through the 1990's used reciprocating or cam lobe driven pumps as well (very reliable)... however, they are very high precision and built with highest quality hardened steel where needed. This is generally not the case for the Indian Lister clone copies of same.

dieselgman

[Don_Edwards]

I was about to start a new post but I see I'm not alone. Lost oil pressure, or should I say flow, out of the blue. I knew a rebuild was in my near future so I topped it up with synthetic oil and hoped for the best after the pump repair. A radiator fan failure finally finished it. It will have an overheat alarm before it ever starts again. 

One thing I did was use Viton check balls to make sure it gets a good seal. One of my original check-balls looked like it was made with a hammer and I stumbled upon the Viton balls in McMaster looking for replacements.

[dieselgman]

check balls are not the high-wear item... the iron seats they fit into generally take the wear and tear. If you replace the steel balls with viton, you may have a performance issue because gravity is a factor in making the pump work. The balls must fall under their own weight, if the weight is altered there may be an issue. Be careful!

dieselgman

[Quinnf]

For what it's worth, when I was putting the PS Beta Test engine back together and I took apart the oil pump, I decided then and there that pump was NOT going to be used without some work done to it.  The machining on the pump was poor and the springs were wound out of what looked like bobbie pins.  I seriously doubt they were spring steel.  A pump failure could let your upper sump run dry, ruining your engine.  I wouldn't trust it to keep the upper sump full, so I filled the lower sump so it overflowed into the upper sump and maintained oil level that way.  That engine is sleeping in a crate in my groj now.  When/if I ever put it into service I'll adapt the lower oil intake port in the crankcase to take an oil sight glass so I can keep an eye on oil level without taking the door off. 

I second the power steering pump idea.  I also have a bronze Oberdorfer gear pump that I picked up at a marine surplus place that I could belt off the shaft to filter oil and feed the upper sump, if I want to do that.  But consider just overfilling the lower sump.  Remember, a wise man (George Breckenridge) once said, "If it isn't part of the design, it can't fail."  Keep it simple. 

Quinn