Rebuilt 964 engine not making oil pressure

[Moriartyhlms]

Yeah, we have the same theory that the pump is just made move liquids, and so the dry pump was just cavitating with air on both sides. The Rothsport check valve itself seems to work just fine, and I am going to reinstall it; I really like how it prevents smoke on start ups when the car sits.

[stownsen914]

Well, good news that the engine ran well! It's still a little strange that this didn't sort itself out with the Rothsport valve in place. Maybe it needs to be primed to work properly? You might want to verify oil pressure while cranking again once the valve is back in place.

[pmax]

Originally Posted by Moriartyhlms

Yeah, we have the same theory that the pump is just made move liquids, and so the dry pump was just cavitating with air on both sides. The Rothsport check valve itself seems to work just fine, and I am going to reinstall it;

Congrats on the successful resolution !

Originally Posted by Moriartyhlms

I really like how it prevents smoke on start ups when the car sits.

The flip side is a delay in oil pressure buildup on startup ?

[spyerx]

Originally Posted by Moriartyhlms

Quick update: this week I was able to get normal oil pressure to register after removing the Rothsport check valve, so it certainly seems like that was the root problem. My buddy and I actually got the engine started yesterday, but quickly noticed that the fuel return line was leaking...which means I get to drop the engine again today. Engine sounded good though for the brief time it was running. Thanks again to all for your help..

Congrats. Gotta see it when done!
I ended up replacing all my fuel lines. All of them.
Before we installed the motor back we pressure tested all the long lines. Both the pressure and return had mild seepage. Ugh.
Thst was a 2 week delay getting the parts.

[Walt Fricke]

All the more reason to squirt some assembly lube into the pressure side oil pump gears before putting the second case half on as a matter of routine.

[Richey]

When changing oil on a car with the Rothsport check valve , i always pressure the oil tank a little after filing with oil to push oil past the valve , you can hear the oil flowing . The oil pressure gauge always registers immediately after starting .

[Moriartyhlms]

Hello, just wanted to give everybody another update on this:

I just put the check valve back in my engine, and it seems to work fine.

If I had to guess, I think the oil pump doesn’t generate enough suction while cranking to open the check valve and that’s why I was having the oil pressure issue that kicked off this thread. That said, when reinstalling the valve today, I tried real hard (and made a big mess) to prime the line full of oil between the check valve and the pump...in case that made any difference.

On a related note, the engine has turned out really good and stronger than expected. I documented everything here on the other forum.

Thanks again for everybody’s help.

[r lane]

That check valve has to have fluid on both sides or it or it doesn't work. Cannot have it installed on a dry motor. Bob