My starboard (Volvo Penta D1-30) engine has developed an oil leak that I need to track down.

My plan of attack is to thoroughly clean the bilge then degrease everything before trying to track down the leak working top down, i.e., identifying the highest part on the engine that is oily. I figure if it's leaking at the top it will incriminate the crankcase ventilation valve, whereas if it leaking lower down it something else, such as the oil pressure sender, and if it leaking at the bottom it's probably the oil pan gaskets or the oil pan itself.

Does anyone have any other tips for tracking down oil leaks?

Degrease the engine don't worry about the bilge just yet
Start at the top and work your way down
Tappet cover , head gaskets any high oil or vent hoses ,oil presser sender
Front pulley seal and the rear also have a look at your drive system

After you find it and stop the leak clean the engine and bilge
That's what I'd do

All depends on the engine trans design
Also Google
Title common oil leaks on a Volvo penta d1-30
Which I'm about to do

could not find much also check around the fuel pump

check where the throttle come outs seems to be a few goggles out the about that . The motor seems to have so many bits bolted to it with crevasses every . Looks like a hard one to check for oil leaks in such a tight area.good luck . A good light and one of those tiny cameras to look around might be worth it.

http://www.ebay.com/itm/5M-Waterproof-Inspection-Boroscope-Borescope-6-LED-Endoscope-7mm-HD-Camera-/231285818520?hash=item35d9b58498&item=231285818520&pt=Motors_Automotive_Tools&vxp=mtr

I'm not suggesting you have a big head OK

www.ebay.com/itm/Mobile-PC-to-watch-by-WiFi-Automotive-inspection-camera-Electronic-Endoscope-/171600243914?hash=item27f42becca&item=171600243914&pt=Motors_Automotive_Tools&vxp=mtr

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HG02 said..
check where the throttle come outs seems to be a few goggles out the about that . The motor seems to have so many bits bolted to it with crevasses every . Looks like a hard one to check for oil leaks in such a tight area.good luck . A good light and one of those tiny cameras to look around might be worth it.

http://www.ebay.com/itm/5M-Waterproof-Inspection-Boroscope-Borescope-6-LED-Endoscope-7mm-HD-Camera-/231285818520?hash=item35d9b58498&item=231285818520&pt=Motors_Automotive_Tools&vxp=mtr

I'm not suggesting you have a big head OK

www.ebay.com/itm/Mobile-PC-to-watch-by-WiFi-Automotive-inspection-camera-Electronic-Endoscope-/171600243914?hash=item27f42becca&item=171600243914&pt=Motors_Automotive_Tools&vxp=mtr

Thanks for the excellent tips. I must try and get one those WiFi inspection cameras

a water proof one could be put over the side make a interesting alternative as your cruising checking out a possible anchorage is one that comes to mind also
Special in a Cat as you guys tend to get close the the waters edge

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HG02 said..
a water proof one could be put over the side make a interesting alternative as your cruising checking out a possible anchorage is one that comes to mind also
Special in a Cat as you guys tend to get close the the waters edge

I like your thinking. And it's not too late for a Christmas present request either

Has anyone used a product like Nulon "Engine Stop Leak" in their marine diesel engine's lubrication system?

www.nulon.com.au/products/engine-treatments/engine-stop-leak

Presumably it only works for very small leaks, such as those due to worn seals/gaskets. Seems almost too good to be true...

Snake oils like the Nulon work. They just soften of the gaskets.

As ramona said those additives just soften the seals chemically may be a temp fix but it will come back and haunt you
So it once and do it properly
Your motor will love u for it
Plus you might find some thing else to fix while at it [:)

Find the leak first and then decide how to fix it. I found a hint of oil in my bilge one day that I tracked back to a hairline crack (caused from vibration) on the oil line that feeds the overhead rockers. If I hadn't of noticed and repaired it straight away it may have resulted in a big $$$ job. The excess vibration on the oil line was due to a previous owner/mechanic removing (or not putting back on) a support bracket. I had already made up and installed brackets for the fuel lines that were missing, but hadn't notice there was also a missing bracket on the oil line.

Moral of the story. Always do the job properly.

One mistake that occurs regularly over the years is spin off filters leaving there oil seal on the housing when removing the filter . The unsuspecting person spins on the new filter with two oils seals the old one stuck to the filter housing ,plus the new one on the filter presto you have a major oil leak if not straight away very shortly after.
first check Id do is around the filter and the oil sender unit then the tappet cover . all depending if you can see which side the oil is leaking from.
Like most marine engines theres is always some hard to see places that why I suggested the camera and you always have it on hand for other applications.

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HG02 said..
Degrease the engine don't worry about the bilge just yet
Start at the top and work your way down
Tappet cover , head gaskets any high oil or vent hoses ,oil presser sender
Front pulley seal and the rear also have a look at your drive system

After you find it and stop the leak clean the engine and bilge
That's what I'd do

All depends on the engine trans design
Also Google
Title common oil leaks on a Volvo penta d1-30
Which I'm about to do

could not find much also check around the fuel pump

So while I'm waiting for my endoscope to come from HK, I tried taking some pictures. Unfortunately I didn't capture the exact source of the leak but it appears to be leaking somewhere below and to the left of the crankshaft pulley (top half of photo). That would also place it below and to the left of the oil pump. I also noticed for the first time that it is leaking even when the engine is NOT running.

The fact it it leaks even when not running makes me suspect the sump drain plug, except there is oil higher than the plug. Is the oil pump likely to leak even when it is not running? Any other thoughts?

I would put some money on the leak being your crankshaft seal. It is in behind the pulley. Easy enough to replace but a bit time consuming to pull the pulley off etc.
Oil on a car engine can go anywhere with the air flow. On a boat it goes down not up, unless it is coming out under pressure which in your case it isn't.

I would check number 7 see if its running down the block, there would be a couple of copper washers there which could leak as you stated the oil appears to be leaking ever when the engine is stopped . This makes me think its either what Morning Bird has already stated or perhaps a oil pipe has a crack or the copper washers or some thing around the ( number 7) oil delivery to the valves rocker gear.
It makes it a bit hard when there only this photo to get perspective.
Also when you look next time . question.
Is the engine sitting level , thinking at the same time where would the oil run from could it run from the oil pressure sender forward . Id spray some degrease around where its oil wet and wash it off run the engine and seen what you can find even using a mirror and torch around the front seal.

I also question number 6 to me it appears to be a idler gear and the oil pump below inside that cylindrical unit beside the crank that outer plate could leak oil and run down also I don't think the arrow is pointing to the right number 6 could be wrong with out looking at it makes it harder
Also I'm not sure of the direction of rotation of the engine which might help also finding with the oil leak near the crank pulley
Morning Bird could be right but Id wash it down and run it when its clean and dyed with a rag before starting
CRC Brake clean is a good pressure pack to use as far as less mess and evaporates for washing away oil quickly

Thanks MorningBird and HG02. I'll clean it up again and take another look tomorrow - and hopefully pinpoint it, or at least narrow it down.

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scruzin said..
Thanks MorningBird and HG02. I'll clean it up again and take another look tomorrow - and hopefully pinpoint it, or at least narrow it down.

if you can buy a can of CRC brake clean its good stuff for what your doing

Well, it took some time and a bit of technology, but I tracked down the source of the leaking using fluorescent dye, which as you can see is readily visible under UV light (photo attached). There are 4 bolts securing a plate attached to side of the oil pan (diagram) and located under the oil pump. The bottom ones are leaking like a sieve, even when the engine is not running.

The vertical plate through which the bolts pass then curves up and horizontal and supports one of the suspension points.

It's hard to the believe that the bolts penetrate all the way into the oil pan, so perhaps the leak is somewhere nearby and just surfacing at that point.

Anyone got any thoughts before I drain my oil and start to take things apart. Thanks!