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MOnsoon 350 High Oil Use


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Hoping the crew can give me some tips.

Boat is 3 hours away down at the river.

Monsoon 350 with CAT's & 540 hours

Started last season using a bit of oil, this season it is using more.

After about 20 hours the oil moves from full to the bottom of the hashed area on the dip stick

Last weekend while packing up I noticed some scum across the rear of the transom at the water line, river is clean so I know it is not river scum plus the rest of the boat is clean.

The old wet finger rub did not remove the scum & as we were packing up didnt have time to dig out some solvent to try.

It has been bugging me ever since so I am looking for ideas to try when I am down there next.

I did notice last weekend the engine did not idle as smoothly as I recall, stil ran fine while underway & stared fine after shutting it down for maybe 10 minutes while talking crap after a ski.

Having FAE, without starting it with a hose connected on the trailer I can't check for smoke out the exhaust.

Thought process

1. check the plugs to see if I can identfy one or two slightly fowled plugs, may identify a cylinder or set of valve seals?

2. maybe change the PVC valve as I have a new spare

from there not familliar with compression tests or the wet dry compression tests

Looking for ideas or a logical process to eliminate causes. Being a Center mount, access is great

 

Thanks in advance

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@Andrew63:  1 quart in 20 hours is excessive oil consumption so you certainly have something going on.  I would pull plugs and check for contamination as a starter.  Also look over the breather system to ascertain whether excessive oil is going through the hoses to the intake, you should see some oiling evidence if that is the case.  A very small amount of oil will actually make a big mess in the bilge so from you comment, it appears most of the oil consumption is going through the engine and out the exhaust while the engine is running, hence the rough idle.  Compression and leak down test would also provide clues.

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21 hours ago, electricjohn said:

Check drain hose and around filter area for leakage.

Should have mentioned the Bilge is clean. Would have liked this to have oil as this would have been an easy fix

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8 hours ago, Woodski said:

@Andrew63:  1 quart in 20 hours is excessive oil consumption so you certainly have something going on.  I would pull plugs and check for contamination as a starter.  Also look over the breather system to ascertain whether excessive oil is going through the hoses to the intake, you should see some oiling evidence if that is the case.  A very small amount of oil will actually make a big mess in the bilge so from you comment, it appears most of the oil consumption is going through the engine and out the exhaust while the engine is running, hence the rough idle.  Compression and leak down test would also provide clues.

First instinct is look at the plugs for any noticable fowled

Check the breather system? Do you mean the PCV valve or just check the breather hose for evidence of oil within? I would expect there would be some oil in the breather hose, as in a film, not any more to cause a drip. Would this be correct?

Yes, Bilge is clean so it is going out the back. May have to get a local mechanit to check the compression & leak down particuarly if I have one or more oily plugs

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2 hours ago, minnmarker said:

Rings or head gasket leaking?  If you have friend that's a good auto mechanic...

Head gasket is relatively easy and in-expensive to DIY.

Doubt the head gasket would be the issue as the engine runs very cool 130-140 deg F

Rings, hoping not the case but trying to rule out Valve stem seals before going to rings. Guess start at the top.

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@Andrew63:  Yes to your question on PCV, basically all the components to see if there is excess oil or a stuck valve (assuming you have one per your note as many do not and simply have open breather hoses that dump in the intake so as not to let fumes go in to the bilge).

Your water temp will not be affected much by a bad head gasket, you are constantly drawing fresh water from a very large source.  Head gasket issues will result in rough running but that won't be a reason for excess oil consumption. 

To check your rings v valve stem seals, a leak down test would pinpoint that as long as the person doing the test listens carefully.

Has there been an 'event' (overheating being the probably culprit) prior to the symptoms developing?  Have you had the ECM checked for codes?

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1 hour ago, Woodski said:

Has there been an 'event' (overheating being the probably culprit) prior to the symptoms developing?  Have you had the ECM checked for codes?

Early on in my ownership 4 yesrs back the temp did rise to an uncomfortable level, but not enough for the alarm to sound.

Applied the cooling system upgrade & it has run nice & cool even when we give surfing a go.

The oil consumption only started this season.

have not checked the ECM for any codes. I thas the Malivue dash, I recall there is a screen in diagnostics which will display any codes.

Failing this, may have to have the local Mechanic which has a good reputaion to hook it up to his diagnostic gear.

May even have him check the leak down test as I am comfortable with the usual maintanence stuff but little experience with electronics or delving into the core engine components.

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12 hours ago, Andrew63 said:

Early on in my ownership 4 yesrs back the temp did rise to an uncomfortable level, but not enough for the alarm to sound.

Applied the cooling system upgrade & it has run nice & cool even when we give surfing a go.

The oil consumption only started this season.

have not checked the ECM for any codes. I thas the Malivue dash, I recall there is a screen in diagnostics which will display any codes.

Failing this, may have to have the local Mechanic which has a good reputaion to hook it up to his diagnostic gear.

May even have him check the leak down test as I am comfortable with the usual maintanence stuff but little experience with electronics or delving into the core engine components.

What consists of that upgrade?

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FWIW, I had a monsoon 350 in a 2008 LSV that would burn through just as much oil. I would add a quart every other weekend. I had a couple mechanics look at it and was told by the dealership that this motor just burns a lot of oil. No one could find anything wrong with it. The more hours I put on the motor, the more oil it would burn. Not sure that helps, but figured I would chime in. 

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9 hours ago, formulaben said:

What consists of that upgrade?

A bit of reading but start with this post as I have severl links in a reply I posted including info from lary @ Indmar about the upgrade

My last post in this link highlights a trap for the hose length on a CM Vs RM V drive as the manifolds are reversed.

Hope this helps.  Fould after the mod when we have a play at a surfing I can put my hand on the CAT manifold, about a hot as a cup of hot coffee

 

Edited by Andrew63
typo
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8 hours ago, M235Ozark said:

FWIW, I had a monsoon 350 in a 2008 LSV that would burn through just as much oil. I would add a quart every other weekend. I had a couple mechanics look at it and was told by the dealership that this motor just burns a lot of oil. No one could find anything wrong with it. The more hours I put on the motor, the more oil it would burn. Not sure that helps, but figured I would chime in. 

Since the consumption has increased this season where in the past seasons I could get to the 50 hour oil changes without adding, I am not buying this is to be expected.

Found an interesting article on another mechanics forum where after a rebuild he was using oil. Heads were refirbished & the inlet manifold changed for an aftermarket manifold for claimed improved performance.

After a lot of checking he found the angles between the base of the valley inlet manifold & heads has a taper close to 0.30". gaskets would not seal & oil straight out the exhaust

Valley inlet manifold skim machined to suit & his oil consumption issue stopped. As a bunus, performance picked up a little as well.

As this is a new problem for myself, I know I wouldn't have this issue, but it may have been the issue all along on your 2008 LSV without attention to detail, the dealer would not have picked or maybe even checked this. We all assume these components have been machined correctly.

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21 hours ago, Andrew63 said:

Since the consumption has increased this season where in the past seasons I could get to the 50 hour oil changes without adding, I am not buying this is to be expected.

Found an interesting article on another mechanics forum where after a rebuild he was using oil. Heads were refirbished & the inlet manifold changed for an aftermarket manifold for claimed improved performance.

After a lot of checking he found the angles between the base of the valley inlet manifold & heads has a taper close to 0.30". gaskets would not seal & oil straight out the exhaust

Valley inlet manifold skim machined to suit & his oil consumption issue stopped. As a bunus, performance picked up a little as well.

As this is a new problem for myself, I know I wouldn't have this issue, but it may have been the issue all along on your 2008 LSV without attention to detail, the dealer would not have picked or maybe even checked this. We all assume these components have been machined correctly.

Very true, i just assumed the dealership was correct. Good news is that the boat is no longer mine, therefore its no longer my problem to worry about. Keep us updated on your issue!

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