Oil pressure goes down to nearly 0 when hot
 

Hey guys,

thanks for all the information in this forum, I learned a lot so far!
I bought a Helms 30 with an Atomic 4 in it about 2 weeks ago. The problem I have with it is that the oil pressure goes down to nearly 0 (under 10psi) when the engine is hot (it barely changes when changing the revs). The pressure is too low in forwars, neutral and reverse. The temperature goes up to 190 degrees, too. The oil pressure is good whe the engine is cold, though. I already changed the oil to SAE30 (I don‘t know which oil was in it as I bought it). The low oil pressure doesn‘t seem to affect the running performance. I tried to adjust the oil pressure screw, too, but it barely made any difference at all.
The next problem I have, but what I don‘t want to discuss right now (I only write this for your information or because these two problems might? correlate), is that the engine doesn‘t rev to more than 1200rpm in forward gear, neutral and reverse are good.

I‘m desperate right now and have no idea where this could come from. :confused:
Thanks for your help/rescue and br
Max

You have numerous issues going on.
First thing I would do is confirm the gauge reading to be accurate. Test with a mechanical gauge.
Second thing I would do is determine if the engine is RWC or FWC. 190 degrees is far too hot for raw water, minerals and salt will slowly clog all the cooling passages. If the engine is RWC that temp needs immediate attention.
Third thing I would do is see if the running gear is clean, 1200 RPM is barely off idle.

I don‘t have a mechanical gauge right now but I can get one at Pep Boys. Do you know where I can connect the mechanical gauge to?
The engine is FWC, so the temperature should be okay, I guess.
How can I see if the running gear is clean?

One more thing I forgot to mention: As the rpms go up (to 1200) the propshaft starts vibrating and making klacking noises (not too loud).

BR
Max

Second question first: You need to swim under there and look.
If you are in Maryland you won't be in the water for long!

I had a look at the prop right now and there were some very small barnacles but removing them didn‘t make any difference.

"the engine doesn‘t rev to more than 1200rpm in forward gear, neutral and reverse are good."

Can you give us some more info, RPM in neutral, in reverse? Is your A-4 a direct drive? What size prop are you using? A optical tach may help verify your tach readings.

If the oil pressure gauge proves to be correct I would try dressing the oil pressure adjustment. Not hard to do if you have access and know what to expect.

Dan
S/V Marian Claire

Thanks for all your fast replies!

The engine revs to over 3000rpm in neutral and reverse. The A-4 is a direct-drive. Is the oil pressure adjustment the oil pressure screw with the spring and the ball? I tried to adjust this screw and it barely made any difference. The spring and the ball look good (I had them out today).

The spring and ball set up have had issues. The area that the ball contacts needs to be smooth. I just know that when my OP adjustment did not produce changes dressing the seat worked. I have the old style cone type. I think MMI makes a tool for this and may loan it out??? but I have had good results using a improvised method.
Good to hear that you have access to that area.

Dan
S/V Marian Claire

3000 RPM in reverse is very hard to believe! Is the shaft turning? Is it moving water around the boat? If you're getting 1200 in fwd, you should get maybe 1600 in reverse - same shaft and prop. Perhaps another issue for your list..

Doing some more thinking, and I'm not getting a good feeling about this. Let me ask - did you do a sea trial on this boat before you bought it? How was the engine running during the sea trial?
a) No oil pressure is NOT good. Might be the gauge (hopefully) - worst case the bearings are gone (and perhaps other things with them).
b) 190F is OK for a glycol cooled engine running hard. At 1200 rpm, you're NOT running hard and temps shouldn't be so high. Do you have a thermostat installed? If you have an IR thermometer, try to get inlet/outlet temps for the engine and heat exchanger. Are you only reading the electric temp gauge? Where is its sensor (the location at the front of the head is poor, IMHO).
c) klacking noise???? See a)
This might all work out fine, but I don't see a path through the thunder clouds yet.

I did make a big mistake and didn‘t run the engine long and under much power as I bought it.
I will check the oil pressure (mechanical gauge) tomorrow and report.

The things I read so far about this problem would lead to a bad bearing. The bad thing to say is that I probably won‘t remove the engine (is there any possibility I could remove and change the bearing with the engine in place?). I know I should not have done this but I bought this boat to sail from Florida to Columbia in a few months and sell it there. Right now, I guess, I will try to sell it in Florida and fly on to Columbia. I haven‘t given up hope but I nearly am at this point. The engine seemed to run hard at 1200rpms as it was full throttle, so I thought 190 degrees were okay. I don‘t have a Infrarot Thermometer and I was reading the electric gauge installed to my controls (rpms, water temp, oil pressure). The oil pressure sensor is located at the opposite site of the prop shaft. I will read the pressure at this point tomorrow with a mechanical oil pressure tester.

The boat goes forward with nearly 5knots at 1200rpm. Reverse speed is as expected. Moving water in f and r. I get a lot more than 1600rpm in reverse (because of the relation 1:1.7?).

Some of the things that can result in low oil pressure:

1. Worn rod, cam and main bearings.
2. Oil pressure regulating valve, poor seat condition.
3. Worn or failed oil pump.
4. Clogged pickup screen (not indicated because of good oil pressure at cold start up).

All of these can be solved for under $1000.00 in parts and a few days work. I suggest as long as you're gong that deep into the engine, you may as well re-ring it too and still remain under the $1K budget.

The low max RPM in forward suggests a couple of possibilities. The first and easiest to check is the timing advance mechanism under the electronic ignition plate. Make sure the flyweights are lubricated and move freely. Beyond that, check the prop size. Assuming it is not overgrown with barnacles, a 12x7 prop on a direct drive engine should allow you to max out at around 2000 RPM. I am currently running a 10x8 and my max RPM in forward is 2600 RPM.

Knowing you have electronic ignition you should also do a system current calculation to be sure you are under 4 amps. Measure the coil input voltage at 1000 RPM (neutral is Okay for this measurement), measure the coil resistance (engine off) between the two small posts (at least one post with all wires removed), divide the latter into the former.

We are also assuming the tach is accurate and it may not be.

Folks, I think we're spinning our wheels here. Owner wants to take the boat to Columbia to sell it (likely for a profit). People have been sailing to Columbia long before they put engines in sailboats. At this point, I'd say 'Bon Voyage'.