No oil Pressure Reading

[stevep]

Hi all -- Late model A-4 that ran fine last year with steady 40 lbs oil pressure at cruise. This spring, when recommissioning, engine started up fine but had very low oil pressure reading with original oil pressure gauge. Yesterday, when starting, oil pressure reading was normal but then dropped bask to almost "0" and stayed there. So, today, I installed a new oil pressure sending unit and gauge from MMI, and had the same disappointing results. When I turned on the ignition key, the needle flickered but did not move further when the engine was started. And, I have verified that the engine has adequate oil. At this point, my next (and last step) is to run a wire directly from the sender to the gauge and see what happens.

I would really appreciate any and all advice on what to do to try to resolve this problem, including your thoughts on whether I am facing a engine rebuild or replacement.

I may have reached the limit of my do-it-myself ability. So, any recommendations for an Annapolis MD area A-4 mechanic also would be appreciated. Thanks
Steve

[hanleyclifford]

Try taking the oil sender unit off the block and cranking without ignition. See if you get a good flow out of the hole.

[stevep]

Oil pressure problem

Thanks very much for your quick and to the point suggestion. Very little oil flow out of the opening and there was a sound resembling broken glass from inside the engine when I turned it over. I removed the oil pressure regulating screw and didn't see a ball and spring (the screw had a protrusion at one end) and I didn't know how to determine whether the spring and ball might still be in the engine because I can't see into its hole. Any next steps?
Steve

[sastanley]

Steve, if your 'regulator' has a point on one end it is the older style which is highly coveted. I think it seats directly and eliminates the ball (or rather the ball/spring/bolt mechanism was introduced later & some people feel it is an inferior design.)

Here is a pic of Moyer's kit:


Sorry you don't have oil pressure..I'd be worrying about damaging the engine at this point with further running..it sounds like the gauge is probably working just fine. I don't have much solution for that..'broken glass' doesn't sound promising. Maybe a spun bearing or something.

[hanleyclifford]

There is a possibility someting is wrong with the regulating device. If so it would be good news. Try to get whatever you can out of that oil regulating assembly whether it be ball, cone, spring (perhaps broken?). Have a magnet handy in case you drop someting into the bilge. Post a picture of the results.

[stevep]

Lack of oil pressure

Well, I removed the oil pressure regulator (see picture) and extracted the spring and ball with a magnet. Don't know if the recess contained washers or any other parts. Two other things -- the oil in the pan is pristine and as clean as when I poured it in from its containers; and I didn't hear the broken glass sound when I started the engine and check the oil pressure (that remained close to "0"). Any further suggestions would be greatly appreciated. Thanks
Steve

[stevep]

Huge picture

Very sorry for the very large size of the picture. What do I have to do to not repeat this mistake.
Steve

[sailhog]

Steve,
There's a simple procedure in the Moyer Manual that involves inserting a section of brass tubing into the oil pressure adjustment and turning it about so as to knock free any crud. I don't have the manual on me, but someone will chime in on the matter.... Hope all turns out well.

[hanleyclifford]

The ball riding on the end of that spring is what regulates the pressure. If someting is preventing that ball from resting on it's seat the result would be a bypass and "dump" of all your oil pressure. Moyer Marine sells a tool to dress that seat and dislodge any crud that may be on it. The fact that this problem developed suddenly without any apparent mechanical problem suggests a blockage that may be correctable.

[stevep]

Loss of oil pressure

thanks, again. I will order the tool tomorrow and give it a try. If that doesn't help, is there anything else I can/should do?
Steve

[hanleyclifford]

While you have the ball and spring out of the engine try putting the oil sender back in at the front hole, laying a clean towel under the regulator hole and cranking the engine (no ignition). You might get lucky and something nasty might pop out of that hole.

[stevep]

No oil pressure

Well, so much for plan A. No oil pressure at all still, so it looks like the engine must come out. I spoke with Will Sibley last night (a very nice man). He thought that the oil pump could be the culprit and I now agree. So, a couple of new questions. How can I determine whether my current head and other components will be suitable for a "short block" rebuilt engine? At a minimum, I plan to use my recent Balmar alternator and my new raw water pump. How can I determine whether I should reuse the current cylinder head, manifold, etc. Secondly, what pieces can I remove from the engine while it is still mounted to lighten it for lifting and removal? Thanks in advance.
Steve

[hanleyclifford]

I think you are getting ahead of yourself here. Wait until you get the engine out and have a look. You may not need a rebuilt engine. OTOH you might but have a look see before ordering anything. Before lifting the engine out of the boat I always take off starter, alternator and manifold with hot section attached. Before starting the disassembly, if you have the time it might be a good idea to pressure test the engine cooling system for 20 psi. If the first test fails, remove the manifold and test it separately. If it passes, become suspicious of the block and/or head.

[stevep]

No oil pressure

Well, the oil pressure issue forced me to examine and consider the overall condition of the engine -- the side water plate is beginning to leak and there is considerable blow-by. I do appreciate your suggestion to be cautious before over-committing to more than I may really need. Thanks
Steve

[edwardc]

... How can I determine whether my current head and other components will be suitable for a "short block" rebuilt engine? At a minimum, I plan to use my recent Balmar alternator and my new raw water pump. How can I determine whether I should reuse the current cylinder head, manifold, etc.

I recently went the "short block" route from Moyer. They build-up their rebuilds as late-models, even if it's an "early model" block. Assuming you have to go that way (and its not yet clear you will have to), your late-model head, manifold, pump, alternator, and distributor should fit fine.

One "gotcha" to watch out for: There are different styles of accessory drives for the early-models, and the late-models. They differ in the location of the distributor clamp-down hole. On the early-models, it's on the accessory drive; on the late-models, it's on the block. It's possible to end up with an early block, a late accessory drive, and have no place to screw down the distributor clamp (don't ask how I know this!). It's not fatal, merely annoying, as you then have to drill & tap the block to accept the distributor clamp screw. Moyer will do this if you warn them when you order.