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burning oil


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Okay, just got back from Havasue for a 5 day vacation. I changed the oil before I left and used 5.5 quarts to fill it back up. We took two boats and used mine all day on Thursday, Friday, and Sunday. If anyone knows about Lake Havasue, to get to the back beach, you have to haul A$$ in the beginning because there are spots that get about 1.8 feet in depth and you want to keep the boat as high out of the water as you can get it. So, after those 3 days of wakeboarding in the morning and then going almost wide open throttle for about 12 minutes to the back beach in the shallow area (each way), I started to notice a very loud sound from the engine after the last trip out on Sunday. I opened up the cover and it sounded like ALL of the lifters were hitting. I'm no motor head, but I know a little bit. Either way, it didn't sound good. Turned it off and checked the oil to only find nothing registering. I added two quarts and then all of the noise stopped instantly. Not sure why I didn't check the oil that morning or the day before, but I didn't think about it.

at WOT speed, my RPM's register about 5400. My Oil PSI guage always pegs when i'm pulling people or definately over 3400 RPM (weighted down or not). Malibu told me that's common sometimes with our boats. When I'm done each day after using the boat, the back has an obvious film on it. When we ride behind my boat, you can smell a slight oil smell, but we don't see any smoke. We also don't see any unburned oil coming out while putting around slowly or at idle. I'm obviously burning a little oil if I smell it while riding. It's not a heavy burning smell by no means, but you can tell compared to riding behind other friend's boats.

Any ideas? I'm gonna do a compression check on it tomorrow or the next day. I have about 610 hours on it. I have had a cracked head and my dealer fixed it up very nicely about 3 years ago. No problems since

To think about all this, I had taken my boat out before and after the 3rd time last time, I was out of oil too. If it doesn't register on the dip stick, do I still have a few quarts in the engine still?? I had an earlier post on something similar, but also it was about using synthetic oil. I had changed to synthetic and after the 3rd time on the water, the oil was gone. I believe most on here said it was probably okay to switch back really quick to regular oil and I did. I had the problem before I switched and am not worried that that is the issue. I have been smelling this while riding for about 4 months now. I know these are performance engine and will burn a little, but some people I know don't burn anything at all....????

Keith

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I think your compression test will tell you what you most likely already know. ( B.O.A.T.) How do your plugs look?

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If it's not just a simple oil leak which is unlikely since you would have most likely discovered an oil leak by now, it sounds to me like an internal problem that is probably going to get worse over time. my prediction> it's going to be expensive :(

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Yah, I'm thinking it's internal too. It runs GREAT, but with the exception of the oil consumption and residue that I have to deal with (oh and smell). I will be pulling the boat back out after work today and do a compression check as well as taking pics of the each spark plug labeled by cylinder.

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do I just screw the compression checker into the chamber and then take the kill switch off to turn it over (without starting it)??? Or take the distributor cap off while turning the engine over to check it?

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Warm up the motor, remove all spark plugs, open throttle plate, check away.

I've always grounded the coil wire, but the kill switch will do the same thing. No need to take the cap off.

-Chris

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Let's air into the motor....I was told to always have the throttle wide open by two top mechanics.

-Chris

Your very right, you can't baby these motors and if you load them up and never take the boat over 30 MPH you will create more problems for yourself (like oil consumption) Especially if you have a hammerhead, with all the aluminum parts and low friction rings to help free up some horsepower in the 383, carbon build up is a big problem if you baby the motor, open it up and have some fun with that 400HP!

Some tips

1. Always make a WOT pass at the end of the to blow out carbon build up, since our engines run at 160 (thanks to the coast guard) and not 240 like cars do we get a lot more impurities and carbon build up on the cylinders and oil. The WOT pass (3-5 minutes) will help clean the motor out and stop oil consumption. If you do have bad oil burn off you can run a piston ring cleaner from GM

2. OE platinum plugs only last a year or two, GM ships the motors with platinum plugs in them and rather than pull them out and throw them away they leave them in. Replace them with hotter plug like a NGK that brings a little better combustion.

3. Never run any type of fuel treatment, other than Sta-bil

4. Stabilize gas if the boat is going to sit more than 2 weeks, fuel needs to stay above the 87 octane rating, 89 is preferred since you drop a octane rating a week (so i was told)

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thanks for the info. I have the monsoon and always run it at WOT after i'm done for at least several minutes. I have always made a habit to never just run it at one speed all the time (wakeboard speed).

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okay, compression check done:

~Back of the boat~

1- 180 psi 2- 180 psi

3- 170 psi 4- 175 psi

5- 175 psi 6- 175 psi

7- 180 psi 8- 175 psi

~Front of the boat~

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okay, compression check done:

~Back of the boat~

1- 180 psi 2- 180 psi

3- 170 psi 4- 175 psi

5- 175 psi 6- 175 psi

7- 180 psi 8- 175 psi

~Front of the boat~

compression looks great

refresh my memory how many hours does it take to get 2 or 2 1/2 qts low?

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Well usually in 3 trips it seems to be gone. Which could be somewhere around 4 hours each time (total of 12-15 hours on the engine in 3 days)

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Compression looks great. Yes it does. Still don't no about oil rings or valve guide or seals? This is telling you the compression rings are working and the valves are sealing. And only at TDC the bore could have damage further down the stroke. Is there someone around that can run a blow by test. Good speed shop. Just a thought.

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sixball, you hit it on the spot. That's exactly what the dealer said (rings, seals, valve guide). They are going to run a blow by test on the 14th

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sixball, you hit it on the spot. That's exactly what the dealer said (rings, seals, valve guide). They are going to run a blow by test on the 14th

Hope you find something simple like seals. Good luck keep us posted.

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  • 3 weeks later...

after testing looks like it's either rings or valves. However, would have to tear the engine down to figure out exactly. Engine still runs great! You can still smell oil/gas while riding. To do rings or valves, i would assume this is at least a $2,000 job.

i'm just wondering if it's best to get a new block at this point if i'm going to keep the boat. Or ride it until it locks up and deal with an oil consumption.

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