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Old 18-05-2010, 17:51   #1
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Oil, Oil Everywhere...Make it Stop (Long Post) ;-)

I did my first rebuild in January with a friend of mine on my westerbeke w27 -- everything went relatively smoothly, until we went to put on the water pump">raw water pump, it's attached to a steel plate that is bolted behind the timing gears underneath the timing cover, we must have had the wrong bolt and over tightened the raw water pump onto the steel plate and bent it back breaking the gasket seal there, so when we first ran the engine it gushed about 2 quarts of oil into the bilge.....we removed the timing cover, tightened down on the retaining bolts for the raw water pump mounting plate and reduced the gush to a leak......I was at the dock at the yard and getting charged per day to be there so we took off ASAP, I didn't glean the bilge very well (big mistake) and motored for 3 days down the ICW to Hilton Head where I had a free dock to use for a month or so to finish getting the rest of the boat together before we were going to take off cruising.

The boat is finally back into sailing condition (somewhat........always more to do....but we're breaking her in now) and now that I've cleaned all the oil out of the bilge I've realized that one oil leak is actually many, everytime we take the boat out and motor for more than a few hours there is a lot of oil in the bilge, I'm using oil absorbant rags underneath the engine, but they need to be changed every ~ 8 hours of motoring....eeek, today the engine hesitated and lost some oil pressure when I was running it higher rpms (~2000 - 2200) the pressure dropped to 25 - 30 lbs, I got out of the channel we were in and anchored to inspect, oil was leaking out of the side of the block from what looks like a relief valve type thing, but I couldn't find any mention of it at all in the manual

the oil pan gasket is solid black and leaking oil too, I used a thick cork gasket for it with no sealant --....

here's my guess as to what's going on:

1) I put in too much in oil -- the technical manual says the sump capacity is 5 quarts and the filter holds another half quart, I put in ~5.5 but may have erred on the high side, which caused the leak out of the pressure relief valve which was the hesitation I felt, can anyone confirm that 5.5 quarts is how much oil I should put in it or is that just maximum capacity?

2) the oil pan gasket is not properly sealing, we initially tightened it with a torque wrench to the appropriate torque, after a few of our recent trips I noticed the gasket was solid black and was leaking pretty much all the way around so I went around and tightened all the nuts alternating sides/back/front until they were snug and as equal as I could get them, I guess I just need to pull it and replace it? the gasket is thick cork -- should I go back with cork or I had a friend suggested just RTV? maybe a combination of RTV and cork? I think I can pump all the oil out and drop the pan without pulling the engine -- it looks like there's enough room that a strange move?

as for the leak behind the timing gears....I can live with that for the short term, but all these leaks make me nervous I need to be able to count on my engine (and I want to take care of it after all the work to rebuild it

thoughts, suggestions, questions much appreciated

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Old 18-05-2010, 18:20   #2
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Are you getting any blow by?

A Walker airsep may help.

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A cork gasket is designed to absorb oil and swell to produce the seal. Don't use a sealant with it. There are combined cork/rubber gaskets that may do a better job but if a new gasket is leaking it was probably installed wrong. Sometimes I had to soak them in order to restore flexibility to a new cork gasket that had dried out to much.

Can't help you with the capacity question. Westerbeke should be able to help you though.

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Old 19-05-2010, 09:34   #3
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I'm going to try the cork oil/combo and while I'm at it see if I can't fix that leak behind the timing cover -- I think there was too much oil in the engine -- my dipstick read very very very high, but I thought it was wrong because of the incline of the engine.......

the oil also has a bad almost burnt rubber smell after about 8 hours of use, a lot of blow by? not sure.....

I wish I wouldn't get so many conflicting oil amount reports the operators manual says 4.5, technical manual says 5.5, the brochure says 4....ugggh, guess I'm just going to stick with the dipstick, but I am getting low oil pressure <50 -- I thought that was ok, but the manual says it should be 50 - 70! wondering if the poorly sealed oil pan is causing that?

today is a great day to be a mechanic......

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Old 19-05-2010, 19:53   #4
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Wow - Unfortunately it sounds like you have a lot going on at the same time. Maybe it's best to go back to the basic design of the oil system - It sometimes helps to figure out what might be happening.

Oil System - Most small engines have a constant volume pump. A gear pump with a fixed volume that has a pick up in the sump submerged in the oil. With increasing RPM you get more flow. Pressure is created by the resistance in the oil galleys. It is not unusual for the oil pressure to be lower at idle and then increase to maximum as RPM increases. If there were no way to regulate the pressure it would increase continually with rpm. So there is a "pop off" valve that is set by removing a plug and adding or subtracting washers under a spring. Sometimes they will have a port with an adjust screw inside and no washers. The bypassed oil usually just flows back into the sump.

Oil Quantity - Within a range oil quantity is not too critical. However too low a quantity will result in the pickup being exposed and loss of pressure. Too high a quantity can result in the oil level reaching the spinning crankshaft - this acts like a blender and will foam the oil. Foamy oil may not get picked up by the pick up. Low oil pressure will result in high oil temperatures. Low oil quantity will also result in high oil temp as a lot of heat is drawn off by the oil.

Leaks - The thought the you have multiple leaks after an overhaul begs the question about blow by. Most of the galleys where there is pressure are internal. The exceptions being penetrations for pumps, pressure sensors etc. The oil pan and its gasket are very low pressure. Leaks here are usually a result of bad gasket install or blow by.

Blow by - Generally all the combustion pressure should stay in the combustion chamber. The chamber has 4 openings. Two valves, the head to block joint and the piston to cylinder. Each of these must be sealed. Blow by of the valves results in pressure/oil out the intake or exhaust and low compression. Blow by of the head usually results in oil in the water and low compression. Blow by of the rings/cylinder results in pressurizing the lower end and exposing the pan gasket to increased pressure. (Note - Blow By generally refers to pressure "blowing by" the rings - I am using it for multiple pressure leak types for brevity)

More on valves - The valve stems also pass through the intake and exhaust manifolds into the head. The valve stems themselves are a tight clearance and have valve seals. These can leak and you get oil in the intake and exhaust and may see blow by out the valve cover vent.

Checking for Blow By - The easiest check is to pull the dipstick and oil filler cap while the engine is hot and running. You can see the fumes blowing out. A little is normal. Put your hand (carefully it's hot) over the filler cap hole and feel for pressure. There shouldn't be "pressure" but a little smoke is normal.

Most logical guess - For me, after an overhaul, I would suspect cylinder blow by. A PITA cause is when the pistons were installed a set of rings inadvertently had the end gaps line up and you are pressurizing the sump. The pressure can be significant and could cause both leaks you describe.

Before simply changing the gaskets I would check for blow-by or you might just be throwing a good gasket on top of an underlying problem.
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