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Tue Feb 05, 2008 6:42 pm

Recently put a 2L 914 in my Thing. All clearances were to spec, etc., but oil pressure sucked. Replaced case w/a Type 4, added a Melling oil pump. Pressure is OK, but not great. When oil temp is low pressure is good, ~60psi.
At 220 deg, pressure drops to 30 @ 2000 rpm, 10psi @ idle. Heard these engines just plane have poor oil pressure, why?

Tue Feb 05, 2008 7:51 pm

I'd say your oil pressure is better than just "OK" - Factory specs on the wear limit for oil pressure is like 28PSI at 2500RPM and oil temp at 158 degrees. And that's with straight 30W oil. Yours is loads better than that! 10PSI at idle on a hot engine is fine. Really high oil pressure is just a waste of horsepower anyway.

Wed Feb 06, 2008 12:41 am

cecil wrote: Recently put a 2L 914 in my Thing. All clearances were to spec, etc., but oil pressure sucked. Replaced case w/a Type 4, added a Melling oil pump. Pressure is OK, but not great. When oil temp is low pressure is good, ~60psi.
At 220 deg, pressure drops to 30 @ 2000 rpm, 10psi @ idle. Heard these engines just plane have poor oil pressure, why?

Did you check to see how the Melling pump matched up with the T4 case? Sometimes you need to bore out the feed and output galleys on the case to match the high output pumps. I had this done when I built my 2056 last spring.

Are you are you sure the sender and gauge are accurate as well? Did someone check your crank and rod clearances? Bore straight? The 2.0 main bearing journals are prone to issues. Always best to use a 1.7 or 1.8 case when rebuilding, as they're the same case but are subject to less stress. Not a big deal as long as the case was inspected and came back as straight.

These motors aren't prone to low oil pressure. Do you have a pressure light along with the gauge? Does it ever flickr on at idle?

Wed Feb 06, 2008 1:00 am

He said he had 10PSI at idle with a hot engine, I'd hope there wasn't any flicker on the oil light! - as the idiot light doesn't come on til around half that pressure.

Wed Feb 06, 2008 1:09 am

glutamodo wrote: He said he had 10PSI at idle with a hot engine, I'd hope there wasn't any flicker on the oil light! - as the idiot light doesn't come on til around half that pressure.

I hope not either! I just don't trust gauges or senders unless they've both been tested to be accurate. The idiot lights tend to be pretty full proof in my experience.

Thu Feb 14, 2008 8:33 pm

The problem is more than likely the Melling pump. It is cast iron and the case is aluminum.The thermal expansion rate of these two metals is dissimilar.Put a stock pump back in it, and my guess is that problem will be gone.If you insist on that heavy,power robbing melling pump,then the way to make it work is to chuck it up in a lathe and machine it for an O-Ring,so that when the engine gets hot there is no oil pressure bleeding from the pump into the crankcase,Tim.

Fri Dec 02, 2011 8:43 pm

in my type 4 2000cc installed a 1829 maxi pump 1 CB performance (more diameter holes) ........engine cold 40-50 psi...but hot only 20-25 max at 3000 rpms!!!