Again with the oil pressure

 

My last oil pressure issue seemed to have been solved when I found the gear oiler hole had not been plugged. After plugging it my oil pressure came up to somewhere around 20lbs at idle. Since then I've installed a new oil pressure gauge line and gauge as well as a filter housing, filter and new oil lines. After doing this I found my oil pressure had dropped to near nothing at idle and maybe 15-18lbs at a much higher RPM. Does not seem to make a difference whether the engine is hot or cold, I did read in a couple of places that oil pressure loss with a warm engine seems to indicate worn bearings.

 

I have verified the lower pressure reading with a second pressure gauge. I am currently running 10W-30 with zinc additive, and the oil does not have any smell of gas. I have cracked the supply line to the gauge in the off chance there was an air pocket. As well as ran it without a gauge and its pushing oil. It is full of oil, the same oil that showed 20psi previously.

 

The engine runs pretty quiet with no knocking as far as I can tell. One thing that is an issue is the rear main seal is leaking pretty good, which I plan on replacing at some point soon. Unfortunately I do not have any other chain drive oil pumps to verify if the pump is shot or not, a few gear drive pumps but not chain drives. Although I don't think that it is the pump.

 

I feel like (hope) I've done enough troubleshooting and research to merit asking the group for help. The mind boggling part is that I had such high oil pressure before I put the filter and new gauge on and now its crap, one thing I have yet to do is to block the filter line off to see if that makes a difference. Anyhow maybe you guys can tell me what Ive missed. Thanks, Jess

 

I did think about changing oil to a straight 30 and probably will at some point in the very near future. This will be the third oil change in less than an hour of running. She should be clean at least!

Those pressures are a bit low for a rebuild, but just fine for a mid-time engine.

How accurate is your gauge? Just because it is new does not mean it is good. ADA-OMIX anyone? For a quick test put the old one back in, or better yet put in a tee & run it with both of them. (Otherwise you could be mixing apples & oranges). If they agree, your new one at least matches the old one. If they don't, that could be your problem.

Check that you have an orifice of the proper diameter either in the filter stand pipe, or in the timing case elbow. I once found a Willys with two orifices one in each placement. It had good oil pressure & the timing gears were getting lubed, so I left them both in place. IIRC, The diameter should be 0.040, but I could be wrong, so check on it.

Remember that the return oil from the filter lubes the timing chain/gears, so do not run the engine for a long time without the oil filter on line. If you do, you may be doing the bottom end sooner than you want to.

IHTH, Cpt Logger.

 

I did check with a second gauge and its showing the same. I think what I'm going to do is fab a orifice plate to put in line on the inlet filter line with a .040 hole, this will get me oil to the filter, to the chain and then create some back pressure.