Oil pressure very low; Pull the engine?

[Nauti Buoy]

Yep. Gasoline will certainly affect the viscosity. And it's an electronic Facet fuel pump.
Gary

[hanleyclifford]

That gasoline smell in the oil should be investigated. Also, have you tried the 15w - 40 Rotella oil to increase pressure?

[Administrator]

From Don in a separate communication:

We have no cases on record that I know of where an electrical fuel pump can cause fuel to enter the crankcase.

In any case, gasoline in the oil can absolutely greatly decrease oil pressure. In cases where enough gasoline has entered the crankcase, we have reports of oil pressure as low as 5 psi. In these cases, enough gasoline has entered the crankcase to noticeably raise the level on the dip stick. His comment that the oil seemed to get dirty quickly is also consistent with gasoline getting into the oil. The gasoline dissolves the carbon in the oily sludge in the bottom of the oil pan and turns the oil black very quickly (within hours).

The only other cause of enough fuel to enter the crankcase (other than fuel pump) to create a smell of gasoline in the crankcase is one or two cylinders missing. This allows unburned gasoline to work past the pistons and into the crankcase. The distinction between this scenario and gas leaking past a leaky diaphragm is the amount of fuel in the crankcase. However, unless the level is rising on the dip stick, I wouldn’t normally suspect gasoline being the cause of the low oil pressure, despite the strong odor of gasoline. The engine would have to be missing badly for quite a long time. Fuel coming through a leaky fuel pump diaphragm, on the other hand, can build up to oil thinning consequences within minutes.

He needs to find out why his plugs are so black and oily. A quick compression check, even using the thumb method should rule out a basic engine issue. As long the compression blows past his thumb no matter how hard he presses, the compression is at least functionally OK and not part of his problem.

Don

[Nauti Buoy]

I haven't tried the Rotella 15 w 40. Didnt see it on the shelf anywhere I went and traight 40 weight is a thing of the past I guess.

The Lucas Oil was a huge improvement but not a cure. I can at least run the engine for the 30 minute trip to harbor. Tool has been ordered.

Trying to mentally calculate cost of overhauling engine myself, vs cost of hiring it done with the local reliability factor built in vs buying a long block or short block. Only a couple of trustworthy mechanics in this area and they have only a passing acquaintance with A4's.

Replaced the fuel/water separator yesterday and removed the plastic see througn filter for the obvious safety reasons. The seal was rough on the filter seat. Cleaned it up. No difference. Looks like a new fuel pump in the near future. Then discovered engine compartment blower was bad.
I love my boat.

[hanleyclifford]

I haven't tried the Rotella 15 w 40. Didnt see it on the shelf anywhere I went and traight 40 weight is a thing of the past I guess.

The Lucas Oil was a huge improvement but not a cure. I can at least run the engine for the 30 minute trip to harbor. Tool has been ordered.

Trying to mentally calculate cost of overhauling engine myself, vs cost of hiring it done with the local reliability factor built in vs buying a long block or short block. Only a couple of trustworthy mechanics in this area and they have only a passing acquaintance with A4's.

Replaced the fuel/water separator yesterday and removed the plastic see througn filter for the obvious safety reasons. The seal was rough on the filter seat. Cleaned it up. No difference. Looks like a new fuel pump in the near future. Then discovered engine compartment blower was bad.
I love my boat.

Whether you elect to fix the engine yourself or hire it done is a personal choice. All I can say is that this forum stands ready to assist with solid advice and support not to mention the first class treatment you can expect from Moyer Marine. I have personally been thru the exact low oil scenario you are in now. I did several things while rebuilding the engine and cured the problem completely. If you have access to a machine shop where you can deliver the block you can do the job yourself. Meanwhile I suggest you buy a jug of Rotella 15w-40 at your local WalMart and give that engine one more chance before tearing it down. Make sure you are reading from a reliable direct reading oil pressure gauge.

[Mo]

Post a few pictures of the engine...especially the fuel pump and behind the carb...where the old one should have been removed. Just to make sure. Here the gas in oil that I saw last year.

http://www.moyermarine.com/forums/showthread.php?t=8498&highlight=pressure

[toddster]

Hmm... Since about February, my oil pressure gauge has read zero. The needle twitches a bit on startup, but never climbs. Since I installed the engine warning system, with an independent OPG, and the buzzer does not sound after start-up, I have been assuming that it's just the old oil pressure sender has worn out. It has been kind of far down on my list of things to worry about.

Seem reasonable?

[ndutton]

Toddster, NO - not reasonable!!

I don't know from your post if you have the basic Cole-Hersee warning system or the MMI EWDS but in either case they are not intended as substitutes for functioning gauges. They are both warning systems intended to get your attention as things are going South.

Both systems use the same oil pressure switch with a trip point of 2~6 PSI so alarm silence only means you have at least 2 PSI oil pressure. Please, let's get your gauge functioning properly. It's important.

[toddster]

Well crepe. I'll try to get an alternate gauge on it tonight or tomorrow. Had hoped to go sailing.

Also scheduled for an oil change this week, but maybe I'll deal with this first.

[Nauti Buoy]

From Don in a separate communication:

Again, the most puzzling thing about the low oil pressure symptom is that it starts out normal to high, then dwindled down to near nothing. The only thing I can come up with is the oil pressure reg seat. I also suspected worn bearings but have been told if the bearings are worn pressure will be low immediately. Opinions?

The addition of the Lucas Oil additive keeps the pressure up to around 15 to 18 psi after idling at around 1500 to 2000 rpm with short excursions to 2400 over a 40 minute period. Long enough to reach open water but.....

Since my last day of troubleshooting I have discovered low compression in 2 of the 4 cylinders (63 & 65 psi) and 85 psi in another. Only 1 was at 97 psi.

From the previous bore scope observation which caused concerns about possible water contamination inside the block I have to wonder if some of the rings are "frozen" to the piston(s) causing unburned fuel to enter the crank case and dirtying up my pretty new oil. The oil level isn't rising on the dipstick and the gas odor from the oil isn't overwhelming.

A friend has agreed to help remove the engine from it's confines and assist in diagnosing possible ring and oil pump failure. He's confident he can gauge the ring to cylinder wall fit without removing the pistons. I'm a fairly proficient mechanic but have no idea how he'll accurately gauge that.

We'll also be able to get a better read on the condition of the oil pressure regulator seat.

Waiting to hear back from Ken for complete pricing, just in case.

[toddster]

Toddster, NO - not reasonable!!

I don't know from your post if you have the basic Cole-Hersee warning system or the MMI EWDS but in either case they are not intended as substitutes for functioning gauges. They are both warning systems intended to get your attention as things are going South.

Both systems use the same oil pressure switch with a trip point of 2~6 PSI so alarm silence only means you have at least 2 PSI oil pressure. Please, let's get your gauge functioning properly. It's important.

Well it appears to have been a bad gauge. Mechanical gauge went right up to 35-40. Hard to tell exactly on this 0-100 range. (The only one available locally) but it seems OK.

[Nauti Buoy]

Progress

After much wailing and gnashing of teeth we are replacing our engine. The following was copied and pasted from the Moyer Marine online catalog. It is an excerpt from the description for new oil pump gears.

"When the output from an oil pump drops off below a certain point, oil pressure will decay over several hours of operation even though all bearing clearances are normal. When this condition occurs, the problem is seldom excessive wear on the oil pump gears themselves, but wear within the housing of the rear main bearing cap in which the gears rotate (including the four holes in the housing which serve as bearings for the rotating shafts of the gears)."

So, even if we replaced the pump ($400+) we still are unsure of the rings, crank, bearings, etc. We cannot determine why the oil gets dirty so quickly (Head gasket, stuck valve(s), rings), the oil still has a slight gas odor to it, the fuel pump is way too noisy, low compression in 2 cylinders and engine runs hot. Heat exchanger was removed and visually inspected. Clear. Too many unknowns and variables.

The biggest challenge will be removing and replacing the engine at the slip. I would love to see a video of somebody pulling an A4 from a Pearson 323.