Melling Oil Pump Spring Pressure

[Joe L.]

Re: Melling Oil Pump Spring Pressure

I am with Duke on this, especially if you have your engine rebuilt by someone else.

The casting thickness has nothing to do with the quality of the gears and tolerances.

I have NEVER seen a broken case yet and had to look at a number of STOCK pumps to find one that didn't look new inside or measure out bad.

They actually use this type (positive displacement pump ) in factories that pump every thing from abrasives to water.

I hate to say this here but every apprentice that builds engines and has to turn the page in the book to do so buys an oil pump rather than open up his own SIMPLE pump (4 screws) and look inside. Oh yes I forgot, there is a pin that holds the spring in.

The stock pump is so powerfull it needs a by-pass to RELIEVE the pressure or it will take the babbit of the bearings.

The people that manufacture pumps will paint a doom & gloom picture of what could happen if the pump went bad. They want to sell pumps.

Well the worst oil pump I took out in the 50 or so years was pumping oil. You have to really wear one out to stop the by-pass from working. All you will see is low pressure at idle.

Now if you are going to run your vette around the track all day at 5K+ then look into a better pump and oil pan, and bearing clearances.

GM did put HP/HV pumps in some of their HP engines BUT remember that it had to be PRODUCTION to race in STOCK events. Why the large gas tank fill on our vettes? To fill the tank faster at the track. NO not at the pump.

Some pumps that fail we all hear about are usually not pump failures but PUMP DRIVE failures like the 5/16 hex Ford shaft drive or just run out of oil.

I took the pan off a 64 impalla at the Chevy dealer and the W/O read "replace oil pump Pressure intermittent". There was about 4 qts of jello looking oil and 1 QT of oil that the pick-up sat in. The dip stick read full.

Cleaned the old jello oil out, looked at the gears and re-installed. Pan gaskets only. The pump was operational for the condition of the engine.

look inside one once , SIMPLE. I have a shelf full of oil pumps given to me by guys that were afraid to look inside and purchased new ones.

DOM

DOM------


GM never used a high volume oil pump in any PRODUCTION Gen I or Gen II small block. They did use a "high pressure" pump in most mechanical lifter small blocks, but never a high pressure.

They did use a high volume pump in some big blocks, though. The first to get one was the 1969 ZL-1. They didn't use one again until the Gen V big block was released.

[Joe L.]

Re: Melling Oil Pump Spring Pressure

All------


I'd like to make a clarification to my post #29 in this thread. I'll have to do it here separately since I can no longer edit that response. In that response, I said that GM never used an oil pick-up screen configured like the one I pictured in that response for PRODUCTION or SERVICE, except, possibly, an L-88 application. I should have said they never used an oil pick-up screen like the one pictured in that response for PRODUCTION or SERVICE of any BIG BLOCK engine. I failed to make that clear in the response since I figured the response only dealt with big block engines but that may not have been clear in what I said.

More on this later in a new thread I'll start.

[Bruce W.]

Re: Melling Oil Pump Spring Pressure

Tim, I have a 283 fuel injected engine. oil pressure was to high for PV. 45lbs at idle 60 when driving. I pulled the pump and found it was a high volume, high pressure pump. I replaced it with a standard pump from corvette central. That brought the pressure down to normal limits at idle when warm but still runs at 60 lbs when driving. I ordred from the dealer a pump spring part #3814903 which is what is suppose to be original. Before pulling down the pan again I checked your post and you indicated that the correct spring should be 2 7/8" with 21 coils. This spring is 2 1/4 " with 23 coils. It is from GM with part #3814903. BTW it doesn't matter what weight oil I use, pressure is the same. Engine probably has only 200 miles on it. Could it be that it just has tight clearances? At this point don't know what to do? appreciate your help. Bruce