New to all this (almost)

[Baz]

Hi everyone,

I got the sailing bug last year and I recently got myself a boat - a 1971 Paceship P29. A C&C design, looking much like the Pearson 30. Very sturdy, well rigged, impeccable hull, lots a sail. Unfortunately, I haven't sailed at all with it. I did work on it in the yard for some weeks, redoing the teak rub rail, installing shore power, new battery banks, an inverter, new VHF, windex, antennas, new cushions and a spankin' new composting toilet. I bought the boat on the hard, quite a ways from home and couldn't assess in what shape the engine was in - but it looked quite clean and well taken care of.

On my first day on the water, I warmed the engine for about 10 minutes, then berthed the boat a few yards away. Oil pressure was initially at 40, then I noticed at the end it was at 20 psi. The week after, time for a second outing, I fire up the engine - which starts like a champ but, I'm new to boating, and I forget to open the water intake sea cock. After what may be 5 - 10 minutes, I realized what I have done, and open the damn thing. But the pump has lost its prime, so I shut everything down, reprime the pump, and fire up the engine again. Initial temp reading was 170, and descended to 160 in a matter of minutes (idling at 700 rpm). Oil pressure was at around 20. I waited a bit, everything looked stable, so I went out. I could easily achieved 7 knots without pushing it to hard, no overheating, but oil pressure remained below 20 so I headed back. I installed a mechanical gauge to assess the truthfulness of the installed gauge with a sending unit, using a "T" coupling. By now the initial pressure when firing up the engine is around 20-25, and it drops to 5 o 6. Throttling up does increase the pressure, but marginally. Oil level doesn't seem to change but, although I had just changed the oil, it was really black and dirty. So I changed the oil again, putting in SAE 30 instead of 10-30. I also cranked in two turns of the oil pressure screw. Upon firing up the morning after (cold engine) I got an initial pressure of 60, which dropped to 40 at idling, then to 25. I took it out, but within 5 minutes the pressure was back at around 5 or 6. I came back and noticed a clear lack of power. That's now where I'm at.

Let's see, it's not the gauges, it's not the oil pressure valve (but I still did order a new one) since the screw thing had some effect. What is left? The oil pump itself, the possible looseness of the cams. The head gasket? That would account for the loss of power, but can it really let go that much pressure without making a mess somewhere?

The thing is, I don't even know if the engine overheated enough to cause this, or if the engine was in this state when I got the boat. So, to summarize, I have some initial oil pressure which turns to close to nothing when the engine warms up, it doesn't overheat at all (staying at 120 - 130 at idle), doesn't knock, rattle or sounds funny in any way, starts every time on the first try.

I have been avidly reading this forum since the Spring, and the troubleshooting mentioned above was made possible by numerous advice and suggestions made on other threads - thanks. It is a real boon to encounter a community so dedicated to making things work - even if that thing is to other eyes but just a weird chunk of old technology.

Long live the A4!

Best,

[ndutton]

Welcome Baz,

Except for the closed thru-hull incident (think about an alarm system with the flow sensor enhancement) it sounds to me like you're headed in the right direction. I like that you're changing oil to get it cleaned up, like that you're replacing the oil pressure adjustment valve.

I'm not so sure the performance problems are related, may be a coincidence in timing (not engine timing) and it's human nature to try and connect one incident to another, make order out of chaos so to speak. For sure I'd replace the impeller, it has been severely stressed. and I wouldn't trust it.

I also don't think your oil pressure concerns are pump related unless the pick-up strainer is clogging. Gear pumps are famously reliable. I think you should continue oil changes as long as the oil appears dirty and see the regulator valve replacement and adjustment to its end before looking elsewhere.

[Marian Claire]

Another welcome. I am assuming late model with the ball and spring type oil pressure adjustment. May want to try dressing the seat and possible switching to the "old style" cone. Every time, except one, that I have had a unusual OP dressing the seat has solved it. The only exception was a pin hole in OP gauge line. Dan S/V Marian Claire

[Mo]

I'll go along with the guys. If your actual pressure (oil) was 5 or 6 I think you would be hearing a somewhat noisier engine...especially in the top end. So ensure the sending unit and gauge are not faulty...then look to the engine if need be.

[Baz]

Thanks for the welcome. So, I gather that I'm not too far off. I agree, shouldn't I be hearing nasty noises form the head at some point with only 5 psi? But I have two gauges, one with a sending unit, the other mechanical, and they both more or less agree. True, they are linked with a T fitting - so the problem could be with this specific port, meaning it still could be only a reading issue.

Meantime, I did follow another approach. More later.

Baz

[ndutton]

. . . . . shouldn't I be hearing nasty noises form the head at some point with only 5 psi?

If noises can be localized I would not expect any oil pressure related sounds coming from the head area, there's no oil flowing up there anyway. A little lower down in the valve train, yes but nothing at the very top of the engine.

Such is the nature of flatheads.

[Dave Neptune]

Gage?

Baz, good oil pressure is a very important item and due to this I would at least replace the "manual" gage. First they're cheap and they can have issues with readings~usually not~, but in this case I'd say "go 4 it".

I have seen this only twice in my many years of being a mechanic. As far as the history of the engine has it had "salt water" in the oil and sat? I have seen the oil pick up tubes rust though with just a pin hole wreak havoc with oil pressure just like on the fuel pump if a fitting is loose. The oil is far thicker and will allow far more air into the pump than if it were fuel.

If the screen were clogged the readings would be low but more steady. I've seen that far more often.

As per Mo "kiss the seat" of the adjuster and check with a new gage, I think it worth the expense. Also be sure the spring works freely in the hole so as not to get stuck.

Dave Neptune

[Baz]

I have seen this only twice in my many years of being a mechanic. As far as the history of the engine has it had "salt water" in the oil and sat? I have seen the oil pick up tubes rust though with just a pin hole wreak havoc with oil pressure just like on the fuel pump if a fitting is loose. The oil is far thicker and will allow far more air into the pump than if it were fuel.
Dave Neptune

Interesting. I figured oil pump failure would be a rare occurrence.

I'm now looking to acquire another A4, so I can always have one at the ready. My season is over, might as well plan for the next ones. I jut found this salvaged "Moyer Marine rebuilt" (it has the sticker) - looks a bit worn out, and it doesn't have the newer water pump, it still has the one with the grease cup. I would like to assess how old is this "rebuilt". Would anyone happen to know when MMI started using their own cupless pump in their rebuilds?

[Administrator]

...when MMI started using their own cupless pump in their rebuilds?

I think it was about 9 years ago, give or take.

Bill

[Dave Neptune]

Check first

baz, a failed oil pump is rare and not often seen unless it gets fed chunks from something else failing. The pick up tube and or plugged screen just feed the oil to the pump. I am just suggesting a possibility here.
Your likely culprit is the adjuster possibly sticking. As I said I'd get the gage to confirm and futz around with the adjuster a bit. The senarios I suggested are very rare and should be considered after the gage and adjuster futzing.
Didn't mean to mislead just tossing out an idea.
I'd look and futz a bit before picking up another engine.

Dave Neptune

[Sony2000]

Baz, you may have the oil pressure adjuster that is the problematic one of the two that were installed in the Atomic 4.
I have one available in Montreal, as well as a water pump with the grease cup, that was recently rebuilt including the high output cam.

[Baz]

I had an interesting chat with Ken at MMI today. Although admittedly rare, it seems like my actual symptoms could indeed be the gear oil pump. So that's it, my season is over and I have my winter hobby. Regardless of this particular - and quite serious issue, there must be a ton of other ways I can make this 40 year old engine feel better. I just received the manual...

Sony2000: I'm in Sherbrooke. Good to know that another afourian is not too far away.