2013 Volvo Penta 4.3GL Oil Pressure Drop & Valve Tapping / Rattle

[paoutdoorsman]

Hello all!

My question is on a 2013 Hurricane SunDeck Sport 188 with a Volvo Penta 4.3GL IO (190hp 2bbl carb) - with 190 original hours. It has an intermittent valve train tap/rattle on the left side of the engine towards the front that generally exhibits/correlates with a drop in oil pressure, and a fluttering of the oil pressure gauge needle.

On first startup and easy running, oil pressure is strong and the gauged is rock steady (40 psi +). The issue generally presents after a 10-15 minute near full throttle run, or when towing a skier/tuber for a time. The first indication can be noticed in a drop of oil pressure on the gauge - down to around 20 psi accompanied with a fluttering gauge needle. When this occurs, if you bring the engine down to an idle the valve chatter is strong, oil pressure remains about 20 psi and the gauge continues to flutter rather than hold steady like it does when the noise is not present.

This problem presented itself several years ago, but mostly went away with a switch from dino 10w40 to synthetic 10w40 engine oil. It still would happen on rare occasion, but very infrequently. Now it is doing it even after a fresh 10w40 synthetic oil change.

When it happens, if we shut down the engine for 15-20 minutes, and then fire it back up the noise is usually gone.

I suspect this could be a collapsing lifter. Does anyone have any other thoughts given the symptoms it is having? Is this a common issue with this motor?

Had the boat since new and put about 20 hrs a summer on it. Always stored indoors, always serviced by the marina spring and fall with annual oil changes.

 

[alldodge]

If your loosing oil pressure it's not normal and 10w40 should be plenty to keep it up. Put a mechanical gauge on the motor to verify pressure is dropping and if it is then there is a problem.

 

[dubs283]

Not a common issue with a 4.3, they are sound, proven marine engines with a solid track record of reliability

Issues sounds like oil starvation to the top end with the valve train chatter along with lower pressure guage readings.

WAG at this point is oil overfull and frothing under a load or a piece of debris intermittently/partially blocking the oil pickup in the pan/crankcase

As mentioned a mechanical guage will prove oil pressure readings are accurate during the issue

 

[Lou C]

Also get a hold of a mechanics stethoscope so you can better locate the sound & compare it to either camshaft or crankshaft frequencies. A crankshaft/rotating assembly noise will be a very fast repeated sound whereas a camshaft/lifter noise will be a slower repeated sound because the cam turns at 1/2 crank speed.
If it were me if I localized it to the valve train I’d pull the ex manifolds & valve covers & take a look. The older 4.3s had adjustable valve trains the newer ones do not so if it’s valve train related you may be able to see which lifter/pushrod has noticeably more play than the others….

 

[paoutdoorsman]

Thanks for the thoughts guys. I had decided against a starvation issue since the valve tapping is always isolated to the front left cylinder. Wouldn't a starvation issue make all valves chatter?

I'll find a mechanical oil pressure gauge to test with and compare to the dash.

From a mechanical theory standpoint, If a hydraulic lifter fails (collapses), would oil bypass and cause a pressure drop?

 

[alldodge]

Lifters will not cause pressure to drop

 

[Lou C]

That would be either a bearing issue or oil pump issue.
All the time I have had my old 4.3; I haven’t had dropping oil pressure and engine noises, normal idle is 40 psi, it may drop to 20 after coming off plane as the oil gets hot but no change in noise. With more time idling as the oil cools off it comes back to 40. Max on the gauge is 55-60 psi at speed on plane. This has been the case with the Merc 25/40 conventional oil I used to use & the Merc 25/50 syn blend I’m using now.

So I think your seeing 20 psi with a hot idle is not unusually low.

Get a mechanics stethoscope and check
Doing an oil analysis is a good idea as well to rule wear…
If high Fe (iron) that’s steel & cast iron parts
If Cu (copper) and Pb (lead) that’s bearings
Oil analysis can also tell you if water is getting in the motor oil (head gaskets, intake gaskets & exhaust), and if the oil is holding up under use.

 

[paoutdoorsman]

@Lou C what's your reasoning for running the 25/40 & 25/50 weight oils?

 

[Lou C]

Lower viscosity automotive oils thin out in marine use especially in engines that don’t have an oil cooler. Mercruiser has recommended the 25/40 for years. You could also use a 20/50.
I’ve done 4 oil analyses on this same engine and the Merc/Quicksilver oils I have used maintain their viscosity over time.

 

[paoutdoorsman]

Interesting. I've only ever used Volvo 10w40 (in both dino & synthetic) in this engine as that is what they recommend. I wonder why Merc recommends a heavier weight than Volvo in essentially the same engine.

 

[stresspoint]

if i had to take a couple of guesses , i would say the oil filter you are using is a dud.
second guess is the check valve in the oil pump sticking.

 

[Lou C]

Interesting. I've only ever used Volvo 10w40 (in both dino & synthetic) in this engine as that is what they recommend. I wonder why Merc recommends a heavier weight than Volvo in essentially the same engine.

This has been discussed for years with no real conclusion. Merc wants to sell their special oil, but Volvo, has recommended (first) straight 30 syn, then they changed it to 10/40 syn. So the oil they recommend is "special" too.
Merc allows the 25/40 in conventional and 25/40 syn blend. They also have a 25/50 syn blend for high performance use (towing sports etc)
To my knowledge, in recent years Volvo has always recommended full syn. I would not use a conventional 10/40 in a marine inboard. 20/50, or the Merc oils, or even 15/40 is a popular choice. I say do an oil analysis, see if it holds viscosity in your use for a full season. Then you know one way or the other. Another option is the Valvoline VR-1 20/50, this is an HD racing oil for old school muscle cars, with engines similar to the GM marine engines both Merc and Volvo used.

 

[paoutdoorsman]

Just wanted to give you all an update on this. I believe I have this issue resolved. I put a mechanical oil pressure gauge on and took the boat out for a full throttle run 3-4 miles up the lake. Watched oil pressure steadily fall into the low 30's. Pulled it back to an idle and had the valve tap as expected.

Decided to change the oil to Merc 25w40. I was shocked when I sucked 7 quarts and 4 ounces of oil out of the engine. Oil capacity according to the engine decal is 4 quarts! The overfill was never noticed. Refilled to the correct oil level with the Merc 25w40 and did a 5 mile full throttle run. Oil pressure on the mechanical gauge started at 70 psi at idle, and never dropped below 57 psi on the entire run. Pulled back to idle and it ran smooth and quiet. I suspect the oil was getting aerated and causing the low/fluctuating oil pressure, and ultimately the valve tick.

You'd like to think you can trust your professional marina mechanic... but sometimes it's just better to do your own maintenance!

 

[paoutdoorsman]

@dubs283 - Your WAG was apparently spot on. I was surprised when my 5 quart container did not hold all the drain oil, but you coulda bought me for nickel when I sucked another 2 quarts and 4 ounces out of the motor.

 

[Lou C]

Wow so your problem was actually excess oil causing the crankshaft to run in the oil kicking up a froth that lowered the oil pressure. Easy solution, do your own oil changes!
There is a quirk to checking oil on some of these engines that I've observed over time....it is due to the use of the oil dipstick tube that connects to the bottom of the oil pan with a banjo bolt. V/P in some years used the same exact set up as OMC used, but I know some newer ones are different.
In any case what I have found with this design is that the oil must rise to the same height in the tube, as it is in the pan, to get a valid reading. What can happen is pressure or vacuum in the tube will throw the readings off:
When the engine cools, the air in the tube contracts, and that pulls some oil out of pan and then it reads overfull, but it isn't really. What you do, is pull the tube out and leave it out for a few minutes, this gives it time to equalize the oil level in the tube vs the pan.
When the engine is hot, the opposite can happen, hot air in the tube may prevent the oil from climbing up to the correct level in the tube, and it reads low. You do the same thing, pull the dipstick out for a few min and check again.
There is a hole in the tube near the top to allow pressure to equalize, but these false readings still occur.
This oddity I have observed consistently with this design oil dipstick tube over the 20 years I have owned this boat.
Checking the oil on an inboard boat with the oil withdrawal style dipstick is a bit more complex than on vehicles.

 

[paoutdoorsman]

That is exactly what it looks like was happening.

This is a buddies boat, and it is stored in high & dry indoor racks, so he just pays the marina to do all the maintenance. They boast that all of their mechanics have 20-30 years experience, so you'd think they could handle a simple oil change. I suspect they simply are not taking the time to make sure that all of the oil is extracted before re-filling. Or that possibly there is an issue with the oil withdrawal dipstick if using the hose connection? I used SeaDog pump with the small plastic tube style sump that inserts to the bottom of the oil pan. I may have to start servicing it for him.

 

[Lou C]

I use a Topsider vacuum pump with a garden hose connector, it gets most of the oil out but you still have to be mindful of not overfilling and just keep the stick out for a few min to allow the level to equalize in the tube if you have that design.
I wouldn’t be surprised if they give oil changes to the least experienced guys. They’re usually too much in a hurry to do a good job like you can do yourself. So teach you friend at least how to check it correctly even if he doesn’t want to change the oil himself.