Oil Pressure Dropping

[sailingchance]

Hey all, thanks for all your help with my starter/solenoid. Now I got a new one for you.

This has been a consistent theme since I have owned the engine. I have an early model A4 that is pretty basic. I have new oil pressure sending unit and a new gauge.

When I start engine and "cruise" at roughly 2000 RPMs I get good oil pressure, about 40PSI. My engine temp holds steady at 130F. Over the course of an hour cruising, my oil pressure will drop to abot 20PSI and hold there. I use 40 weight (its all i can find in the bahamas). I have tried tightening the oil pressure needle a turn, and then another, and still no change. It does HOLD at 20 PSI though.

I check for a leak at the gauge, the pipe, nothing. I get that the oil thins out as it heats up, but a loss of 20PSI?? Any other thoughts or suggestions?

Also, I change my oil very regularly. about once every 30 hours. I know that sounds like overkill, but what the heck. IF After about an hour of motoring, when I let the oil cool, the oil will be black. Don mentioned possible gas in the oil, but I dont smell gas.

ANy thoughts on either would be great. Thanks!

[Mo]

suggestion

Next oil change go to 15w40 diesel and see what happens. 20 psi is OK if that's the actual pressure...sounds like it is.
-Is your engine freshwater cooled or raw water cooled?
-Is your temp gauge functioning properly...if someone has a infra red thermometer around you there you could get a pretty good idea of what it's doing.
-If you rev the engine does your oil pressure jump upwards, downwards, or stay put. With engine warmed up....If it rises with rpm, that's a good thing; falling means bearings on the way out; staying put pretty much means may be wear but maintaining oil pressure.

[edwardc]

Ths is pretty typical behavior. I don't think you have anything to worry about.

Don's guidlines are at least 10 psi for every 1000 rpm, so you look to be fine.

The switch to 15w40 oil may help some, and carries a couple of other benefits:

• Valve lifter noise at low RPMs will be quieter
• It's known as "diesel oil", and is available just about anywhere (unlike 30W)

I've been running it for the last year.

[marthur]

Ths is pretty typical behavior. I don't think you have anything to worry about.

+1 to this.

[sailingchance]

Good thoughts

Next oil change go to 15w40 diesel and see what happens. 20 psi is OK if that's the actual pressure...sounds like it is.
-Is your engine freshwater cooled or raw water cooled?
-Is your temp gauge functioning properly...if someone has a infra red thermometer around you there you could get a pretty good idea of what it's doing.
-If you rev the engine does your oil pressure jump upwards, downwards, or stay put. With engine warmed up....If it rises with rpm, that's a good thing; falling means bearings on the way out; staying put pretty much means may be wear but maintaining oil pressure.

Deisel? Will the engine run on diesel oil? I thought it was different, combustion vs. compression. My engine is raw water cooled. I have two temp gauges and two oil pressure guages, both reading the same things. I just revved the engine for 10 minutes, oil pressure stays the same.

[Mo]

It will run like a dream on 15w40. Been using it since 2007 without a hitch. Like you I change my oil frequently as well ...typically between 20-25 hrs. After a few oil changes the oil will look pretty clean come change time as well. If you had the rpm up for a bit and it holds at 20 that seems to be pretty much where it is set. 40 at start up is good. Mine has 40 at start up and about 30 psi when running for a while...either way, you have lots of oils pressure there.

You can see next oil change if there's a difference in 15w40. Right now I wouldn't be worrying too much about it unless it somehow changed from something you are used to looking at.

[sailingchance]

Deisel? Will the engine run on diesel oil? I thought it was different, combustion vs. compression. My engine is raw water cooled. I have two temp gauges and two oil pressure guages, both reading the same things. I just revved the engine for 10 minutes, oil pressure stays the same.

Mo... just to be ABSOLUTELY certain I understand what you are saying. Are you saying switch to 15W40 motor oil for gas engines or 15W40 for diesel engines (i.e. clearly marked "diesel")?

It may be my mistake, but I thought gas engines couldn't run on "diesel oil". In know you said it, and kinda said it again, I just want to make EXTRA sure I understood. I am hitting the only NAPA on Eleuthera in about an hour (Rock Sound) and will be buying, amongst other thing, more motor oil.

Thanks again, and sorry I am such a ninny

[edwardc]

Although it's known as "Diesel Oil" because of it's wide use in diesel engines, if you read the certs on the bottle, it's certified for both gas and diesel engines.

[sailingchance]

Thanks!

Although it's known as "Diesel Oil" because of it's wide use in diesel engines, if you read the certs on the bottle, it's certified for both gas and diesel engines.

Thanks Ed/Mo!!! I will give it a shot when I hit the NAPA.

[Mo]

Mo... just to be ABSOLUTELY certain I understand what you are saying. Are you saying switch to 15W40 motor oil for gas engines or 15W40 for diesel engines (i.e. clearly marked "diesel")?

It may be my mistake, but I thought gas engines couldn't run on "diesel oil". In know you said it, and kinda said it again, I just want to make EXTRA sure I understood. I am hitting the only NAPA on Eleuthera in about an hour (Rock Sound) and will be buying, amongst other thing, more motor oil.

Thanks again, and sorry I am such a ninny

Absolutely certain it is just fine, it actually has some better qualities that our engines like not added in the normal gas engine stuff...and is even better again if you have to run that baby up and make her work

You will become a believer....

[67c&ccorv]

I think the guys are referring to Shell Rotella oil - 15/40...designed to withstand the rigors of diesel engine use but works well in the Atomic 4.

[Mo]

I think the guys are referring to Shell Rotella oil - 15/40...designed to withstand the rigors of diesel engine use but works well in the Atomic 4.

We sure are 15w40. I'll take anything (although not a Castrol or QuakerState fan). Mobile, Shell, Havoline, etc.

[Marian Claire]

SC. With your early model you also should have the cone shaped oil pressure adjustment. Have you removed and dressed the the oil pressure adjustment. I have gone thru this, what you describe, several times with my early. Seems to hit immediately after an oil change. Why???.
Have you tried adjusting the oil pressure. If it does not change then you need to dress. A slight turn, 1/4 turn, on the adjustment will, if working properly, make a noticeable change in oil pressure. Say 3 to 4 PSI.
Dressing can be as simple as GENTLY inserting and turning a Phillips head screwdriver of the right size. MMI has a tool for this.
Dan S/V Marian Claire

[sailingchance]

Now an even bigger oil problem

I dont know if this should be it's own post - probably, but I will start here since I have your attention.

I was writing and commenting on this post while motoring for about 6 hours. Now, two days ago, after motoring for 6 hours, I checked the oil and the dipstick was dry. I mean bone dry - and my bilge was filled with oil. Don mentioned the only leak that could cause that is tha the oil pressure gauge, which had never leaked begore but sure enough I found a crack in the 1/8NPT pipe sticking out. It broke off when I removed it, but I did replace it successfully. New pipe, sender reinstalled, new oil added, problem solved right?

Well, while asking about oil, after about 5 hours of motoring I happened to look down and my oil pressure was ZERO!!!!! I immediately shut off the engine. It hadn't been running funny. Sounded okay. BUT... I checked the bilge, found more oil. Dip stick was dry again. I opened the reversing gear cover and there was still SOME oil in there, but not much. I added 2 quarts to get me to a place I could anchor, started the engine and had 20 PSI. I anchored and killed the engine.

I am searching like crazy for an oil leak that could do this. I have one leak I know about - the reversing gear cover weeps oil, but it wouldnt weep 4 quarts in 5 hours. The oil pressure pipe seemed fine.

Where else could this be leaking this much oil from??? I've had nothing but issues with this engine. Mostly minor, mostly easy fixes, but this is not minor. and I am really concerned (especially since I am in the Bahamas).

Thanks

[Mo]

I dont know if this should be it's own post - probably, but I will start here since I have your attention.

I was writing and commenting on this post while motoring for about 6 hours. Now, two days ago, after motoring for 6 hours, I checked the oil and the dipstick was dry. I mean bone dry - and my bilge was filled with oil. Don mentioned the only leak that could cause that is tha the oil pressure gauge, which had never leaked begore but sure enough I found a crack in the 1/8NPT pipe sticking out. It broke off when I removed it, but I did replace it successfully. New pipe, sender reinstalled, new oil added, problem solved right?

Well, while asking about oil, after about 5 hours of motoring I happened to look down and my oil pressure was ZERO!!!!! I immediately shut off the engine. It hadn't been running funny. Sounded okay. BUT... I checked the bilge, found more oil. Dip stick was dry again. I opened the reversing gear cover and there was still SOME oil in there, but not much. I added 2 quarts to get me to a place I could anchor, started the engine and had 20 PSI. I anchored and killed the engine.

I am searching like crazy for an oil leak that could do this. I have one leak I know about - the reversing gear cover weeps oil, but it wouldnt weep 4 quarts in 5 hours. The oil pressure pipe seemed fine.

Where else could this be leaking this much oil from??? I've had nothing but issues with this engine. Mostly minor, mostly easy fixes, but this is not minor. and I am really concerned (especially since I am in the Bahamas).

Thanks

Allot of oil is splashed at the reversing gear cover when the engine in working...if it is leaking you should fix it. These engines burn oil as well, you will find they burn less with the 15w 40. No problem for an atomic 4 to use a quart of oil in 6 hrs of hard use. I'm talking a well running engine burning oil...these are old design etc...they use it.

So, I think you can safely count one quart used and perhaps another beat out around the reversing gear cover. A silicone seal around that cover will seal it until you get a gasket. Clean it up, put the silicone (grey, blue,or orange) on it and leave it for about 15 minutes. Then place top on and hand tighten all screws. A few hours later you can snug the bolts down and then it should be OK.

I would be thinking maybe 2 sources of loss for the oil. Oil is like blood...a little goes a long way and often looks worse than it is.

BTW...what was your cruising oil pressure (engine warm) before this happened. That would be 2 episodes of running low on oil...no telling what was starved for a time. Rings could wear a bit, bearings, top end....put the heavier oil in and see how it works. It's possible the bearing took a bit of a wearing and rings as well. Bearing wear would drop your pressure and ring wear would make the boat use more than usual.

With this in mind, I think you should move up to 15w40, try and adjustment on the adjuster, fix the cover Religiously keep an eye on the oil level. I'd be shutting down and checking every hour until you know where you sit with it. Main thing is not to get too excited over it 1. There was some oil and 2. the engine didn't seize. These are tough little beasts.