Oil Pressure Dropping

[Mo]

Originally Posted by sailingchance

So, I went through all the possible areas oil could be leaking. I tightened the oil pressure screw 1.5 more complete turns. Checked the oil pressure pipe, sender, the oil fill under the mech fuel pump, reversing gear cover ( made new gasket).I also changed oil to 15W40 as suggested.

I put oil cloths down where ever I thought there might be a leak, and baby powder along the edges of the oil pan gaskets.

I ran the engine today for about an hour in the anchorage, under load going back and forth at about 1900 RPM. Oil pressure started at 40PSI which is normal. It hung around 35 PSI much longer than normal, before settling down to 20 PSI after about 45 minutes of operation. This is where she usually holds.

I checked the engine every 5 minutes, looking for the oil leak that has been dumping 3.5qts into my bilge every 5 hours. I only found a very minute (1/4 teaspoon) of a weep in a spot where the reversing gear housing meets the oil pan. it was pretty high up near the fuel pump though so it cold be just some heated residue that i didnt clean up. Regardless... it wasn't the culprit. I dont know if that means that the failure point required longer operation, or if it means I fixed the problem. Only time will tell.

When I checked the oil, I had the same I amount I started with. So that's good. It was blacker than I'd like, but I'll take.

I am heading out on a 100mile crossing tomorrow and will likely have to motor a bit. I will let you all know how it goes under longer operation. But so far so good.

Very Good Jason. Shut the engine down every 2 hrs and check your oil during the trip. Once the engine works hard it starts to use a tad...it will be less with the 15w40, but you still have to watch it. Ensure you have lots of oil with you. If motor sailing ensure the level doesn't drop and top up as necessary. See if there is any change with the leak pattern you observed when motor sailing as well.

The oil looks blacker because it has more detergent and cleans the engine...with your 30 hr oil changes you will find that, after a while, the oil doesn't look much different on removal than when it went in. Took mine about a year to notice it clean changing at 20-25 hr intervals.

I have a feeling the ball inside your oil adjustment is sticking or gunged up. Something is wrong there because the changes you have made should have made a difference on start up and idle pressure. When you get a chance you should remove it and clean it up. I think you said you did that. Need to ensure no paint or rust on the threads when the nut backs off...that nut should turn with your fingers until you lock it onto the block once you have set the pressure where you want it. If no progress from there I'd call Ken at MMI and order a new one...the old version are supposed to be the best.

I haven't see one A4 out there that hasn't used oil when used hard. Always a constant vigil on oil in these older designed engines. Check oil everytime you get on the boat and every 2 hrs underway. The switch to 15w40 will eliminate allot of oil consumption but you still need to check it. I can run mine 5-6 hrs at low rpm and doesn't use...once I get into a sea and have to use a few more HP I can be guaranteed to add after 5-6 hrs...might only be a pint, but it is what it is.

[sailingchance]

Originally Posted by Mo

Very Good Jason. Shut the engine down every 2 hrs and check your oil during the trip. Once the engine works hard it starts to use a tad...it will be less with the 15w40, but you still have to watch it. Ensure you have lots of oil with you. If motor sailing ensure the level doesn't drop and top up as necessary. See if there is any change with the leak pattern you observed when motor sailing as well.

The oil looks blacker because it has more detergent and cleans the engine...with your 30 hr oil changes you will find that, after a while, the oil doesn't look much different on removal than when it went in. Took mine about a year to notice it clean changing at 20-25 hr intervals.

I have a feeling the ball inside your oil adjustment is sticking or gunged up. Something is wrong there because the changes you have made should have made a difference on start up and idle pressure. When you get a chance you should remove it and clean it up. I think you said you did that. Need to ensure no paint or rust on the threads when the nut backs off...that nut should turn with your fingers until you lock it onto the block once you have set the pressure where you want it. If no progress from there I'd call Ken at MMI and order a new one...the old version are supposed to be the best.

I haven't see one A4 out there that hasn't used oil when used hard. Always a constant vigil on oil in these older designed engines. Check oil everytime you get on the boat and every 2 hrs underway. The switch to 15w40 will eliminate allot of oil consumption but you still need to check it. I can run mine 5-6 hrs at low rpm and doesn't use...once I get into a sea and have to use a few more HP I can be guaranteed to add after 5-6 hrs...might only be a pint, but it is what it is.

Thanks Mo! I plan to keep a very close eye on it. I was lucky she didnt seize when she dropped to zero before. Two hour intervals sounds about right. When I get to GT, I plan to pull the engine all the way out to get to the stuffing box. When I do that, I will take a good hard look at the oil pressure relief valve again and clean it up if need be. I have several parts I plan to order from ken when I get back to the states - including a new reversing gear cover. That will likely be on the list as well.

Thanks again for help and for all the fast responses. It means alot considering I get spotty internet and am hundreds of miles from any real help.

Cheers!

[Mo]

No worries....safe travels.

[Marian Claire]

SC. Glad to hear that the oil leak may be contained/slowed. A 1.5 turn in on the oil pressure adjustment should have made a big difference in your oil pressure. Sounds like it made no difference after some warm up even with the higher viscosity oil. My mechanically inclined grading contractor told me "pressure is pressure" 10/30, 15/40, water, air it matters not.
Do you have a magnet aboard? It makes extracting the oil pressure assembly easier. I am assuming you have the cone type normal in an early A-4.
My normal start up oil PSI is 60 and it slowly drops to 38 to 40 after warm up, one to two hours, at cruising 2000 RPM and 20+ at idle. The only time it drops below this "norm" is when the adjustment is not working correctly and I have to clean/dress it. If you have access it is a fairly straight forward task.
Only exception to this was when I had a pin hole in the line to the oil pressure gauge. But that PSI drop was fast. Dan S/V Marian Claire

[geekeasy]

Originally Posted by Marian Claire

My normal start up oil PSI is 60 and it slowly drops to 38 to 40 after warm up, one to two hours, at cruising 2000 RPM and 20+ at idle.

I'm having the same problem as the original poster. My engine settles at 40 PSI right after it starts up. Then sometime later it drops down to 20.

It sounds like I should follow your example and tighten the oil pressure adjustment screw such that it starts at 60. Does that sound like a reasonable approach?

Also... unlike the original poster, my water temperature goes up when the pressure drops. My engine which already runs hot starts running very hot, so I've been dropping the throttle which lowers the temperature, but does not seem to further lower the pressure.

[hanleyclifford]

The problem with adjusting for higher pressure when engine is hot is that the pressure could be very high at cold start up which is not good either. IMO low pressure developing after extended running is caused (among other things) by high bearing clearances, especially cam bearings. In any case if you cannot keep engine temperature below 180 that problem should be addressed first since oil pressure is partly a function of temperature.

[Marian Claire]

Agree with the idea of addressing the temp issue first. Get the A-4 running at normal temps and then report oil pressure #s. Dan S/V Marian Claire

[geekeasy]

Originally Posted by Marian Claire

Agree with the idea of addressing the temp issue first. Get the A-4 running at normal temps and then report oil pressure #s. Dan S/V Marian Claire

The temperature stays at nearly exactly 180, until the pressure drops when it starts climbing. But I really don't really know the causation there -- pressure drop causes heat, or heat causes the pressure drop.

In related news, my boat is out of the water now, I just removed the grated cover for the raw water intake and found out that the water intake behind it was almost completely clogged. ***?



This could perhaps make a big difference when I put the boat back in the water.

[hanleyclifford]

Originally Posted by geekeasy

The temperature stays at nearly exactly 180, until the pressure drops when it starts climbing. But I really don't really know the causation there -- pressure drop causes heat, or heat causes the pressure drop.

In related news, my boat is out of the water now, I just removed the grated cover for the raw water intake and found out that the water intake behind it was almost completely clogged. ***?



This could perhaps make a big difference when I put the boat back in the water.

You dodged a bullet. You were starving for raw water due to the clog. That looks like a 1/2" thru hull - way to small. Try replacing it with a 1" Groco and then reducing to 3/4". You'll always get good flow.

[geekeasy]

Originally Posted by Marian Claire

Agree with the idea of addressing the temp issue first. Get the A-4 running at normal temps and then report oil pressure #s. Dan S/V Marian Claire

I've run a bunch more tests. And it seems to me like it's an oil pressure issue, not a temperature issue.

I do not have an RPM meter, but if I give the engine quite a bit of throttle engine runs at 40 pressure and 180-185 degrees which seems perfect. That is for the first 45 minutes or so.

But then after 45 minutes, oil pressure gradually drops to 20 and the temperature starts climbing to about 195.

If I drop the throttle a bit, I can motor all day at 20 pressure, 180-185 temp, and 5 knots. But it would be really nice to be able to get up to hull speed.

I tightened the oil pressure adjustment valve as much as it would turn by hand. Should I try cranking it down harder from there?

Is there anything else I should try?

Thanks!

P.S. Removing the blockage from the intake didn't seem to make any real difference.

[hanleyclifford]

Your symptoms are actually classic for an engine nearing rebuild time. It takes about 45 minutes for an engine to thoroughly warm up including all it's oil. When cold the viscosity of the oil gives you the 40 psi but as the oil warms up it cannot maintain the pressure because the bearings are worn such that a lot of volume is being bled off at each station along the oil route. Look at your Moyer Marine Manual, the section dealing with the oil system. IMO it is important to replace the camshaft bearings and have the clearance set by a machine shop to .015". I had exactly the same symptons as you and this is how I solved it. Of course the mains and rods must also be within spec. In rare cases the oil pump itself can be implicated if the clearance for the gears gets too wide. Moyer Marine has that issue covered too. In the meantime if you can bring the temperature down by getting rid of the thermostat that will get some relief. Even a raw water cooled engine can run safely at 160. You can also go to 40w oil but watch your start up pressure so it does not exceed 60 psi.