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Oil Leak Where are you?


hawaiianstyln

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finding oily residue all over my floor bilge.  I'm sure the tiny bit of water that does get in there sloshes (wherever the leak is) oil around consistently in the bilge.  This is making it hard to find out where it is coming from.  I started investigating and I due see fresh dirty oil when I feel directly underneath the engine where the engine meets the transmission (bell housing area?)  there is some decent amount of residue on the brass plate/strut where the shaft goes thru the hull.  I did see some oil residue on the bottom of my throttle body which I thought was odd.

Checked the dip stick and it was half down, so I was missing about 1.5 - 2 quarts to get it back to the max fill line.  I topped off some oil about 20 hours ago (about 1 quart was missing since the beginning of the summer).  At that time, I did see some oily residue that I cleaned up in the bilge.  However, I had found at the time that my PCV valve came out and it looked like some oil was able to get out.  I thought that may have been the culprit.  Now i'm starting to think it isn't.

I cleaned everything up just now and about to take it out tonight for a cruise.  Hopefully I can find out where this oil leak is coming from and limp around the remainder of the season.

 (2008 - 340 Monsoon 720 hours runs AWESOME)

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25 minutes ago, hawaiianstyln said:

finding oily residue all over my floor bilge.  I'm sure the tiny bit of water that does get in there sloshes (wherever the leak is) oil around consistently in the bilge.  This is making it hard to find out where it is coming from.  I started investigating and I due see fresh dirty oil when I feel directly underneath the engine where the engine meets the transmission (bell housing area?)  there is some decent amount of residue on the brass plate/strut where the shaft goes thru the hull.  I did see some oil residue on the bottom of my throttle body which I thought was odd.

Checked the dip stick and it was half down, so I was missing about 1.5 - 2 quarts to get it back to the max fill line.  I topped off some oil about 20 hours ago (about 1 quart was missing since the beginning of the summer).  At that time, I did see some oily residue that I cleaned up in the bilge.  However, I had found at the time that my PCV valve came out and it looked like some oil was able to get out.  I thought that may have been the culprit.  Now i'm starting to think it isn't.

I cleaned everything up just now and about to take it out tonight for a cruise.  Hopefully I can find out where this oil leak is coming from and limp around the remainder of the season.

 (2008 - 340 Monsoon 720 hours runs AWESOME)

Given the location, rear main seal would be my guess if it is bellhousing area.

Your TB having oil suggests that your pcv system is puking oil.  The fact that it had previously popped out suggests that you might have a lot of blowby

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32 minutes ago, UWSkier said:

Check oil pressure switch. Mine failed and would drip very slowly. 

I will check this

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39 minutes ago, oldjeep said:

Given the location, rear main seal would be my guess if it is bellhousing area.

Your TB having oil suggests that your pcv system is puking oil.  The fact that it had previously popped out suggests that you might have a lot of blowby

or cold it be leaking out of the PCV valve tube which is nearly sitting right above where the leak seems?  Not super familiar about blowby issues.  Does that have to do with the rings.  If the PCV system is the culprit, what is the fix?

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Just now, hawaiianstyln said:

or cold it be leaking out of the PCV valve tube which is nearly sitting right above where the leak seems?  Not super familiar about blowby issues.  Does that have to do with the rings.  If the PCV system is the culprit, what is the fix?

Could be - that should be obvious.  If that is the case then maybe you just need a new valve cover grommet.  Although that would not explain there being much oil in the TB.

The test is a leakdown test, and yes it would be bad rings

 

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ran the boat on the trailer up to temp and no leaks could be found.  Now I understand that this leak could be only happening at/near WOT or under more RPM.

Just before I ran the boat and after I cleaned the bilge (spotless), I checked everything underneath the throttle body that had residue.  I ran my finger underneath this connector (nearly sits underneath the throttlebody) and it had some fresh dirty oil on the bottom of the connector.   Hmmmmm

IMG_5440.thumb.jpg.07478084a906c97e05a6b9287ef31a17.jpgIMG_5441.thumb.jpg.24669fa0028f42785c53a4ee7ad935d7.jpg

 

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add:  I did just get that plenum powder coated in the spring, first summer with it on and running.  I had to obviously remove the TB.  Wondering if I doinked anything up in that regards and didn't tighten down good and blowby is leaking from there

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13 minutes ago, JasonK said:

I have about the same thing. I'm sure mines coming from the PVC breather hose that ends at the air filter. I'm at 1,560 hours on the barefooter.

do you consume oil as well?  how much is yours leaking, so bad you have to clean your bilge a lot?

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:) I had to walk down and check b4 I answered. It's right on the full mark. That's where it's been all summer. I haven't added any. 50 hours so far.

My filter will have a couple drops at the bottom edge at the end of the summer. My 1st filter change 3 years ago, when I first bought it, had a very oily filter. I suspect the dealer servicing it skipped the filter. It was a beast to remove. It had me cursing. Had to use heat. I was afraid of cracking the throttle body. yada yada yada lol

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well, after cleaning bilge and areas where I found oil, sure enough after about an hour of driving at mid to high RPM I found build up on my throttle body again.  I will show before and after pics (clean, then residue again after tonight's cruise)

After I cleaned TB off

IMG_5441.thumb.jpg.5074013d0dbfc854127ef18874a92f1c.jpg

After Cruise tonight (you can see build up bottom right)

IMG_5442.thumb.jpg.5dcaf270822e7d0266e5c21315b25376.jpg

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Update:

took off plenum and hello oil build-up and pooling right near where the throttle body is.  The entire intake is wet with oil and the two vent ports are soaked, vent port on the right appears clogged?  It shouldn't be full of oil right?  PCV valve rattles nicely, doesn't appear to be failed.  I don't list my boat or surf much at all so how am I getting so much oil up here.  I have however, (willingly admit) that I occasionally do some power turns when nobody is around as the kids think it is fun.  Maybe i'm turning to tight and the oil is getting pushed up and thru the PCV valve and vent holes?

I'm assuming by the looks of the gasket, oil is either getting past the gasket and leaking into bilge OR oil is travelling down to my throttle body mount and somehow leaking out from there.  If you look at the K&N filter, it looks like dirty stained oil at the bottom.

 

IMG_5445.thumb.jpg.8277b7041c0ca35eb1bc37346c51c80b.jpgIMG_5446.thumb.jpg.34a52ca7c07568a833ee1b7888a52d95.jpgIMG_5447.thumb.jpg.ff4d7687ec1cff3bf4101f275a5b8872.jpgIMG_5448.thumb.jpg.05579f07eb3ca3b757013132d66760bf.jpg

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When I had my plenum off earlier this year I noticed a small amount of oil in the same location but didn't think much about it. However, I have not noticed any oil in the bilge area.

My K&N filter looked similar to yours.

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Well i see where and how the oil was coming out into bilge from throttle body mount. Shouldnt this have a gasket?  It didnt have one and look at all that oil residue.  Still doesnt explain why oil is getting there.  At this point i switched out PCV valve and cleaned everything up and hoping to see where i am at after next few days of running it

66B80A32-5D40-425F-B597-F000737AD376.thumb.jpeg.122241fc1b2101a18dbeb256348f7331.jpeg

 

Edited by hawaiianstyln
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If oil can leak out, air can leak in. 

I would run a very tiny bead of aviation shellac around the outside edge before assembly.  The idea is get just enough to seal, but not in a way that lets it spooge into the throat when you tighten it.  It shouldn't take much. 

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This stuff

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid/?locale=en_us

Just take it easy, it makes a huge mess and is a pain to remove from everything. 

The fact that oil can leak there says that there is an air leak.  I would have expected a gasket to be there.

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37 minutes ago, oldjeep said:

This stuff

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid/?locale=en_us

Just take it easy, it makes a huge mess and is a pain to remove from everything. 

The fact that oil can leak there says that there is an air leak.  I would have expected a gasket to be there.

Yes, exactly that stuff.  It is my go-to for most sealing issues in addition to most anti sieze applications.  It's a sealant/thread locker/anti sieze in one! 

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5 minutes ago, justgary said:

Yes, exactly that stuff.  It is my go-to for most sealing issues in addition to most anti sieze applications.  It's a sealant/thread locker/anti sieze in one! 

I use it as a gasket dressing for pretty much everything except head gaskets.

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funny, I had some permatex and used that last night putting it back together.  however, I did find that a gasket should be there and ordered one last night from MichiganMotorz.  I should be good with the permatex for the weekend.  Wondering if that had an air leak would that cause a vacuum and possibly a reason why oil was getting in that area to begin with??

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Yes, it has a vacuum in there, but in general the flow of air is away from the intake and toward the pistons.  A high speed pass should help move it through. 

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