Question for anyone running high volume oil pump on a 4.2

[rushpowersystems]

Little background here, I bought the CJ5 without firing the engine, it had about a pound of sawdust in the carburetor, figured I would just roll the dice. Pulled the valve cover and it looked like new, checked the oil drains and they were not plugged.. Pulled the pan and checked all the caps and everything was tight, and installed a high volume pump. Engine turns by hand as free as could be, and a leak down test showed the cylinders were tight. As a point I install HV pumps anytime I remove the pan, but I have never done so on a AMC 258 i6 / 4.2l .

So I start it cold and no knock, its only when I am at around 2000 RPM under load or when about to shift that I here a rod knock. Also the valve cover is overflowing with oil and I am running 80 + psi at 700 rpm, with 10/30. I am guessing I have a pressure relief spring or something has blocked the oil drain in the head, so I think I am starving the bottom end.

So has anyone ever ran a HV pump? What was the pressure vs stock?

 

[Old Dog]

I have never run a hv pump in a AMC 258 i6 / 4.2l , but I have in other engines. 80 lbs at 700 sounds like to much to me.
I think you are right in thinking your pumping the engine dry, but if you are the presure should go down to nothing too.

 

[rushpowersystems]

it’s a real stumper, I have so much oil in valve cover that it is saturating the valve guides and leaking past the gasket but it never drops past 80 psi. I am using a new gauge, wiring , sender, and have checked it with a manual gauge. I am about ready to pull the engine and rebuild the thing but I am a sucker for a mystery.

 

[Old Dog]

Sounds like a bad relief valve.
I'm guessing the gauge olny goes to 80.

 

[coldwater]

A lot of people install HV pumps in their engines, some go all out and install HV water pumps as well. I never found the practice to be a sound one when they are going onto a stock/ low rev engine. They usually just pump the pan dry. And the HV water pumps scream so much water through the system, they end up running hot. They have their place, but not usually on a stock engine. Your pressure seems hight to me, but the problem is the pan running out of oil, and stressing out the top end.

 

[rushpowersystems]

that is what makes my brain hurt, if I am starving the bottom end, then the pressure would fluctuate right? But it is solid, when I installed the pump I was under the impression that the stock pump was 40 psi. as I now understand it is 60 psi, which I would say is just right for a stock engine.

There is little doubt that it is pumping faster than the oil can drain into the pan, but what I cant get my head around here is this, the crank should get oil first, and if I am pumping all the oil from the pan, then the crank and rods would go dry and knock, but I would then loose pressure in the system, or am I missing something here?

 

[Kane]

When the pan is pumped dry the Camshaft takes the biggest hit especially the rear lobes. Also when the lifters start to lose there oil prime then you start to here valve lash noises. The valves will be the biggest indicator. I installed an HV pump on a small block and within 50 miles I destroyed a brand new camshaft because of this very issue and I never saw the guage drop pressure. I ended up buying a new cam and lifter set along with a standard volume pump. I put a high pressure spring in it and called it a day. The engine has 7000 miles on it now and runs strong. The crank gets oil first and will maintain an oil film alot better than the cam that is basically wide open on the sides. So when you get the quick knock noise and let off on the gas it has had time for the oil film in the crank to dissipate and cause contact.

 

[rushpowersystems]

There again that is what is confusing me, I have absolutely no lifter noise, on rocker noise, or noise from the top of the engine, it is from the bottom end.

I am going try the stock pump, but I am also going to inspect the oil drain backs and the crank bearings as well. If that does not work I got the winter to rebuild the engine and start fresh.