Low Oil Pressure Continues

[tartan30cirrus]

I have turned in my regulator MANY turns (no threads showing behind nut now) and, while the engine does not seem to stall due to too low oil pressure at cruising RPM, the pressure is still only ~20 psi or just under at cruising RPM (1600 +) and the engine is fully warmed up.

Should I redress the reg. valve as laid out on pp5-4 through 5-5 in manual? Or is something else at work...how worried SHOULD I be? The engine is brand new afterall and I do not recall this issue last fall.

Upon start up, when cool, the pressure starts higher than it has been (was 35, now 45) and is 35 psi or so for a good 15 + minutes at cruising RPM before engine warms fully and iit drops to 30 then just above 20 psi. At idle it drops to 10 or less and the engine stalls.

Looking forward to replies. TX in advance.

Cheers,
Clint Chase

[bcooke]

If the pressure goes up when you screw in the regulator then I would say the regulator is working.

Since you believe everything was fine last fall I would consider the oil quantity and type the most likely culprit. Did you replace the oil this spring? (aways a good idea.) An engine at rest accumulates oil in the sump so the level in the sump (and pump inlet) comes up while sitting. Once the engine is running, more of the oil is held in the internal passages. Maybe there isn't enough oil in the sump to supply the pump once the oil is up where it belongs.

If the wrong type of oil is used or has become contaminated the viscosity may be too low, making it harder for the pump to build up the pressure. You didn't try dumping in some of that 5w-30 oil did you? As the oil temps come up the oil could be acting like a 5w oil which is pretty thin and hard for an oil pump to work with given the design tolerances of an A4.

If the engine stalls at idle and the oil pressure indication is low I would believe the guage reading and worry about siezing the engine. You could try a direct reading guage attached to an available oil port but until you do don't assume a faulty indication and keep motoring along. Engines don't run long without oil. Trust me on this. And don't ask me how I know...

-Britton

[tartan30cirrus]

Hey it's Britton from the Plastic Classic Forum. Cool. Well, since this post I swapped in a new regulating valve that Don sent to me on warranty. The "new" one is actually the old-style regulator, the plunger type. I used a redressing tool to improve the seat and installed. Made no difference. So I put in a direct reading guage and wham...pressure was 60 at cold but comes down while engine warms. Now, the max pressure I get at cruise with a warmed up engine is about 30psi, a big improvement -- 15-20 psi at idle. The engine was shutting down earlier when the OP dropped below 10 and OP switch turned the fuel pump off. That gave me a slow steady shutdown. Fixed that shutdown. I am pretty darn sure I have straight 30W oil in there but may do an oil change if I can't get OP up to 40 psi @ cruise.

Now I have YET ANOTHER PROBLEM...when I went to check if the guage was screwed into the pressure port tight enough I broke the fitting at the threads. Now I have a couple/three inches of nipple sticking out of the block and have to figure out how the heck to get it out so I can get my sender or mechanical guage back in! See my post under general interest if you have some ideas for me.

TX for your thoughts.

Cheers,
Clint

[tartan30cirrus]

I'd like to get my OP up 5-10psi at max warm...I would like to try a slightly stiffer spring in the regulator...have heard of a couple people having success with this either on this s ite or the Sailnet site. What size/# spring should I try?

Also, my warmed up OP is 25-35 depending on if you look at the mechanical or electronic gauge. My cold pressure is as high as 70 psi...it drops to 40-50 with in 5-10 min of motoring. Does this cold pressure seem too high?

Cheers,
Clint
One happy A4 guy this summer...finally!

[Tartan27]

I too am having similar oil pressure problems with my late model. More on that later...
For now, I have a simple, dumb question: is adding more oil, of a higher viscosity, an acceptable temporary solution to get me from a transient (expensive!) mooring back to my home marina? Will it actually raise the oil pressure to an effective level? I am going to install the "old-type" regulating valve, inspect for minute leaks, etc., when I get home, but for now need to get motoring asap.

My OP was 50+ after starting when I turned the valve all the way in a few weekends ago, but goes to 5 or less after an hour of running. Each time I run the engine, starting pressure is a little lower, and it approaches zero sooner. Hence I'm left adrift with no wind and entering the nearest available harbor.
Thanks.

[Don Moyer]

The most important question is: What is your oil pressure at your normal cruising RPM? We're told by the engineering community that an engine can tolerate oil pressure down to 10 psi per 1000 RPM.

If your oil pressure drops below 10 psi per 1000 RPM, you could try a 40 weight oil on a temporary basis, but increasing oil viscosity is a short-lived remedy for a serious oil pressure problem.

Don

[Sony2000]

Just above the oil pressure regulator is the head of a screw bolt. Why was it included in the design of the block? Can I use the hole for a direct reading pressure guage?

[Carl-T705]

never disregard a faulty gauge. I bought a Corvette engine one time because the owner claimed the oil pressure went to zero when the engine warmed up. He decided it was bad bearings because when the engine was warm it dragged turning over with the starter. I gave him $25.00 for it. He bought a new engine put it in the car and same problem..... Turned out it was a bad oil pressure gauge AND a bad starter. Always do the simple (cheap ) stuff first.

[hanleyclifford]

Just above the oil pressure regulator is the head of a screw bolt. Why was it included in the design of the block? Can I use the hole for a direct reading pressure guage? Actually, that is a 1/8" NPT plug unless it has been altered. It is an excellent place to read oil pressure.

[Sony2000]

On my test bed I'm using a water pressure gauge as an oil gauge behind the flywheel. Once in the boat I'll transfer it. The engine rests backwards down below, and that section is visible from the cabin and the cockpit.