Chasin' oil leak on Volvo Penta 4.3L

[KTglastron]

We're befuddled with a nagging oil leak on our 205 Glastron S/F. Can't determine exact location and am ready to pull the engine. All good knowledge from history with this engine and troubleshooting advice is most welcomed. OK, specifics and background:

- The engine is a 1998-99 4.3GI PWTR.
- Maybe 500 hours on it. It goes out ~20times/year, freshwater.
- oil is dripping from the back/transom end of the engine only
- it developed ~2 years ago (after over-filling with oil by 1/2 qt...coincidence?)
- the leak into the bilge is evident ONLY after running it for the day and back on trailer
- for ~1yr, it was maybe 2-4 tablespoons leaking after each trip
- 5 months ago it went to ~10tablespoons/trip
- a year ago, we cleaned the engine and added UV dye to oil
- ran it several times, climbed into the compartment with black light(s), mirrors and such, and never found a pinpointed glow....but oil was there. Added more dye, still the same thing.
- leak is always at the rear of the engine, above oil pan, and it seems about half way up

Gotta fix it.
While we hope it is NOT the rear main seal (..and doesn't that leak typically during operation), we can't find experienced intel on other possibilities, like: oil sender, PCV clog, distributor housing gasket, oil pan gasket, etc.

Before we pull the engine, I'd like to get your feedback. After we pull it, we will put it on a stand, clean it, run it, find it, and fix it. Any procedural items we should know with this engine? and 205 Glastron S/F? I downloaded the shop manuals (thanx iboats.com!) and have a GoodWrench friend to help.

Thanks much for your time and considerations

 

[Bondo]

Re: Chasin' oil leak on Volvo Penta 4.3L

Ayuh,... You're Sure it's engine oil,..?? Right,..??

Rear main would be my 1st guess if so...

 

[Don S]

Re: Chasin' oil leak on Volvo Penta 4.3L

Pull the outdrive and see if there is oil in the bellows. Could be the input shaft seal on the outdrive leaking. Have you been checking the gear lube on the outdrive?

 

[KTglastron]

Re: Chasin' oil leak on Volvo Penta 4.3L

Bond-O and Don.....thanks for the feedback.
- Definitely engine oil. Burns about 1/2 qt. for ~4 trips (running ~1.5hrs/trip).
- Have checked outdrive, no 90W in bilge, we drain/replace each spring as part of PM
- I feel/wipe oil from back of engine up to ~1/2 way up
- eliminated the coupling between dipstick housing to engine
- with cardboard under engine, oil drips come from behind the pan
- have replaced Mobil1 synthentic w/dino oil for old engines...no change

Procedure-wise, my next step is to clean engine, add more dye, run it with muffs, then UV/blacklight for leaks again...and use small digital USB camera to see in back. The benefit would be to pinpoint the leak before pulling the engine.
- A huge help would be to have a diagram and/or pictures of 4.3Gi engine which shows the back side with anotated arrows/names of locations which are suspect. The workshop manual does not have explicit enough diagrams. Any thoughts were to download such diagram or pictures?
- Another question: don't rear main seal leaks manifest during operation when there is crank rotation and a bit of pressure? is it typical for main rear seals to leak when the engine is cooling down?
**24hr test: just pulled cardboard I placed under engine yesterday. Pattern leaks onto 4 spots at rear of cardboard. 3 locations had a single(?) drip and were ~1.5" apart in a row. 1 location had ~4 drips and 4" away and 2" closer to front (from run-down to and drip from oil pan?) **

- OK, thanks for proposing actions to pinpoint most likely culprint, and procedure for pulling/pinpointing/fixing. Colllective knowledge is often better than a shade-tree mechanic hacking around.

 

[Bondo]

Re: Chasin' oil leak on Volvo Penta 4.3L

A huge help would be to have a diagram and/or pictures

Ayuh,... I guess you're Dreaming on that 1... There's the Rear Main Seal...
I doubt it's leaking from the welchplugs in the cam galley...

Another question: don't rear main seal leaks manifest during operation when there is crank rotation and a bit of pressure?

There's Never pressure on the seal, only splash or static oil...