Oil Pressure Adjustment

[roadnsky]

I would welcome any comments or suggestions from Don or anyone else who has had oil pressure issues.

Jesse-
As I don't see that you've gotten an answer to your original question, I'll give you a quote from Don in the meantime...

Erratic Oil Pressure
"As our technical service reaches more and more Atomic 4 owners, I suppose it's logical that we would eventually run into a few of the "leftover" issues that bothered tech service folks at Universal in their later years. Erratic oil pressure in late model engines was one such festering issue in the late 1980's, and it continues to show up on our plates today as well.

There are, of course, the few cases of loose electrical connections (or short circuits) between the sending units and gauges, but for the most part, indications on gauges have been real, and the late model spring and ball type of regulating valve has been the culprit.

Problems in late model regulating valves almost always relate to the fact that the spring-loaded ball doesn't always seat squarely over the orifice in the block, through which oil is being supplied by the pump. It's interesting to note that Universal tried several different sizes of balls during their later years, in an apparent attempt to steady out the regulating valves; however, it is not at all clear that either of the two sizes they tried made any significant improvement in the function of the valve.

In many cases, as the threaded part of the valve is turned in (clockwise) to increase oil pressure, the spring arches slightly so as to press against the side of the ball. This side load causes the ball to move more to one side of the orifice which allows more oil to pass through, instead of less. This is how you might get a slight decrease in pressure, while turning the adjustment in, in an attempt to increase oil pressure.

Other symptoms of regulating valve problems include oil pressure decreasing as RPM increases (another manifestation of the ball moving off center) and low oil pressure which doesn't respond normally as the adjusting bolt is turned in. This problem is sometimes caused by a regulating spring that has worn thin by rubbing along the inside of the threaded hole into which the adjusting bolt is installed.

I'm not sure that we would ever have come to this conclusion on our own, but one of the good Universal technical service folks put a bug in our ear back in the mid 1980's to the effect that early model regulating valves, which were built around a spring-loaded pointed shaft instead of a spring loaded ball, tended to provide much more consistent control. Below is a photo showing the inside of each type of valve.

In the event that you might be facing oil pressure issues that do not respond to normal adjustment (35 to 40 psi fully warmed up at normal cruise, and 20 psi or so at idle), you might want to consider the regulating valve found in the overhaul section of our online catalog before taking on any heavier maintenance on your engine. Many overhauls have been headed off by the installation of this "early model" style of valve.

Another significant aspect to the problem of regulation relates to the fact that the orifice in the block is not always perfectly centered with the centerline of the threaded shaft.

The effect of this misalignment sometimes causes oil pressure to take a nose dive during an adjustment, as the threaded shaft nears the end of its travel and forces the ball (or even the pointed shaft of early model valves) off to the side of the orifice in the block. In these cases, it's usually necessary to use the regulating valve seat dressing tool shown in the specialty tools section of our online catalog to bevel the orifice slightly, bringing it into alignment with the shaft or ball."

You can read the entire posting here (http://www.moyermarine.com/oil_pressure.htm)

I do agree that maybe you might need to do the seat dressing to attain the 35-40 psi you're seeking.

[hanleyclifford]

pressure relief valve

Tom - I would like to get your reaction to an item, if you are willing - go to www.mcmaster.com and check out item #4704K32. Others feel free to comment too.

[hanleyclifford]

beyond adjustment

Jerry - Thank you for putting that info on screen as it may be of benefit to owners with adjustment requirements. The greater issue, however, lies in the case where the adjuster is "two blocked" or run all the way in and still satisfactory pressure cannot be had. I have mine shut completely, and I even threaded and blocked the "dump" hole, yet low pressure persists. This is the scenario some of us are dealing with. The external Indigo adjuster requires constant attention, and I am seeking an alternative.

[roadnsky]

Hanley-
Understood. I was just trying to make sure Jesse felt he got some attention too.
He might get what he needs by re-dressing the seat as Don recommends.

The other "topic" that you and Tom are discussing is certainly got our collective interest.

[hanleyclifford]

Jerry - I agree that Jesse should do everything possible with the stock adjuster before going as far afield as I have gone. In fact I believe Don Moyer has suggested that the early type adjuster can be installed in late blocks and might perform better.

[sastanley]

Jerry, I too, have read that from Don many many times. I just bought the Indigo oil filter kit, with which you apparently remove the ball/spring regulator. I was just about ready to try the needle/cone style early model dohickey, but coupled my Indigo oil filter kit with my Indigo prop purchase instead.

If I ever get my boat back in the water, I'll report back. Time will tell.

[thatch]

Re: pressure regulator

Hanley,
That regulator, (#4704K32) looks to be well suited to our oil systems. Based on some of the comments about stock A4 oil pressure adjuster woes, I'm pretty sure that it will do a more stable job of pressure control, at least in some cases. Your approach of cooling the oil via a seperate pump, lines and heat exchanger is probably the best way to to get rid of some of the heat that this engine/transmission combo creates. I mention the transmission because there is one bearing in particular (the thrust bearing) which is capable of generating a considerable amount of heat by itself. Although the water and oil systems are seperate, they work hand in hand at keeping the overable package under control.
Tom

[hanleyclifford]

moving afield

Tom - I am going to order that regulator and we will test it. As far as the original problem with Jesse, after studying the two regulators side by side in Jerry's post, it almost seems obvious that the early style is superior based solely on its capability to control the spring as well as the better shape of the seal, cone to seat. If Jesse is to make a move on this, I think he should get the change over kit to early style; always try the simple solution first.

[67c&ccorv]

Tom - I would like to get your reaction to an item, if you are willing - go to www.mcmaster.com and check out item #4704K32. Others feel free to comment too.

I think(?) that the 4704K32 is a "pressure relief valve" and would not operate like the oil pressure regulating valve does in our A-4's.

Anyone else

[hanleyclifford]

regulation or relief?

Good thought - Let's put this question to the platoon: is the stock adjuster that comes with the engine a "regulator" or is it a "relief valve"?

[thatch]

"nice catch"

67C&CCorv,
Actually the correct terminology for the A4 oil pressure control valve, along with other automotive oil control valves should be "pressure relief valve". They all work on the principal of using spring pressure to hold a ball, piston or some type "pointy thing" like the early A4's have in a hole until oil pressure builds enough to collapse the spring preventing pressure from building beyond a certain point. Most automotive oil systems use a very accurately machined piston in a bore controlled by a well fitting spring to control pressure, not just a ball bearing and sloppy fitting spring like the later A4's have. This could explain why the oil guages in most autos react very smoothly compared to, at least, my A4.
Tom

[MikeB.330]

I have a late model MMI exchange engine that I purchased from Don a few years ago. It does in fact have the early model, "pointy thing" type pressure relief valve. Before I purchased some other type of regulating valve I would for sure try the early model A4 relief valve. Once the engine was broken in and a final adustment made, I have rock steady oil pressure.

Mike

[Don Moyer]

Relative to loss of pressure as oil thins over several hours of operation, we've traveled down many, if not all, of the same paths as the rest of you (and a few others as well) with minimal success. Through the simple process of elimination, we finally came to suspect the performance of the oil pump itself.

The challenge in measuring oil pump performance is that the pump is built into the rear main bearing cap from where it feeds directly into the pressurized oil system, making it impossible to measure its output independently from the rest of the oil system. We therefore had to construct a bench testing apparatus on which to mount the bearing cap and route the pump’s output through a channel to a manual control valve, and then to a flow measuring chamber. This set-up enables us to measure the flow rate of a pump at various pressure and RPM settings totally independently of the rest of the pressurized oil system.

We didn’t have to perform many tests to see that performance varied greatly between pumps, even between those which passed the gear backlash and end play specifications of Universal. Moreover, when we installed one of the poorer performing pumps in a test engine on our dynamometer, we were able to duplicate the symptom of decaying oil pressure over time – even in an engine with otherwise pristine bearing clearances.

Bench testing pumps separately from the rest of the engine also enabled us to identify wear within the housing (including the holes in which the shafts turn) as the biggest factor in reduced performance. In fact, since the bearing cap is mounted in plain view on our test stand, you can watch oil literally pour out of the clearances between the shafts and housing.

We now perform a test of the oil pump on every engine as it comes into our shop for rebuilding, and if the performance doesn't meet a certain low threshold, we remachined the housing to accommodate new oversized gears and shafts which we have locally manufactured. We are planning to introduce these oversized oil pump gears in our online catalog in the near future for our do-it-themselves rebuild customers in cases where oil pressure is a concern.

Don

[67c&ccorv]

I don't see any oil collecting in the bilge. I do seem to be burning a bit of oil, but the amount has dropped to less than one quart between oil changes. As I noted, I don't let the oil get below the add mark on the dipstick.

Burning 1 qt of oil between oil changes is a lot of oil - I would start looking for other causes for the erratic oil pressure.

[67c&ccorv]

we are planning to introduce these oversized oil pump gears in our online catalog in the near future for our do-it-themselves rebuild customers in cases where oil pressure is a concern.don

dibs!!!!!!