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Old     (1sikkvlx)      Join Date: Apr 2009       02-05-2018, 9:00 AM Reply   
I have a 2012 Malibu MXZ with about 150 hours on the Indmar 6.0. Last summer at the beginning of the season I switch to synthetic oil.I heard a light tapping coming from the engine. I quickly switched to a thicker synthetic oil. When it continued, I went back to conventional oil. The noise revs up with the engine and doesnít go away with higher rpmís. I know itís not a rod knock ( iíve felt that pit in my stomach before) But it seem to be coming from the valvetrain. I took the boat to boat masters in Livermore, a ď certified Malibu service shopĒ. They remove the valve cover and valvetrain from one side and said everything looked good and they had no idea what was wrong with it. I paid them $350 for the tear down and put it back together myself changing the needle bearing rocker arms to Bronz bushing trunnions. I took it out last night and I still have the noise. Has anyone had any experience with something like this? Iíve been reading that a bad lifter will sound like this, but my engine is so new. Oil has been changed at least once if not twice a year and is very clean. Iíve never seen any metallic flakes in my oil and itís been doing it since the beginning of last summer. Iíve been out every weekend last summer running it at 4500 rpm all day and it still runs great. Any advice, recommendations, or suggestions would be appreciated. Iíll try to upload a video..
Old     (1sikkvlx)      Join Date: Apr 2009       02-05-2018, 9:10 AM Reply   
Here’s a link to a video. Thanks again!
https://www.youtube.com/watch?v=vTQi-ws7RgI&sns=em
Old     (Stazi)      Join Date: Sep 2011       02-05-2018, 9:16 AM Reply   
Did you replace the lifters?
Old     (1sikkvlx)      Join Date: Apr 2009       02-05-2018, 9:37 AM Reply   
No.. you have to pull the intake and heads to check the lifters.
Old     (Stazi)      Join Date: Sep 2011       02-05-2018, 10:03 AM Reply   
Well there is your issue.
Old     (Froggy)      Join Date: Nov 2013       02-05-2018, 4:29 PM Reply   
You need a different shop with real mechanics. The fact that they removed a valve cover and only inspected then put it back together tells me they don't know what they are doing. The 350.00 charge without a clue of whats wrong is just short of criminal.
Old     (onetogofast)      Join Date: Jun 2012       02-05-2018, 5:45 PM Reply   
Sounds lifter to me as well...
Old     (cwb4me)      Join Date: Apr 2010       02-05-2018, 6:45 PM Reply   
You don't have to pull the heads to replace the lifters.
Old     (cwb4me)      Join Date: Apr 2010       02-05-2018, 6:52 PM Reply   
Also if you use too thick of an oil the lifter won't pump up. I would try a 5w30 and see if the noise goes away. Otherwise you may have a lifter leaking down.
Old     (CALIV210)      Join Date: Jun 2015       02-06-2018, 7:26 AM Reply   
Thats a LS based GM engine right ? If so even for as reliable as they are every now and then they have lifter failures . The problem is if you keep running it with out fixing it you might need a lot more then a lifter .
Old     (1sikkvlx)      Join Date: Apr 2009       02-06-2018, 8:17 AM Reply   
I checked the pushrods last night and they are perfect. When I torqued on the rocker arms the lifter is so stiff , it actually preloads the valve instead of pushing the plunger down on the lifter. I think it might be the ls “piston slap”.. I think that if it was a lifter something would’ve happened by now. There is less than 150 hrs. On this boat. If the lifters weren’t under the heads, I would’ve checked in already.. I sent the video to indmar. Hopefully somebody there can point me in the right direction.
Old     (Fixable)      Join Date: Oct 2012       02-06-2018, 9:00 AM Reply   
Quote:
Originally Posted by cwb4me View Post
You don't have to pull the heads to replace the lifters.
Pretty sure you do on an LS......
Old     (Stazi)      Join Date: Sep 2011       02-06-2018, 12:52 PM Reply   
LS1 you donít have to pull heads, newer LS2 and up, you do
Old     (onetogofast)      Join Date: Jun 2012       02-09-2018, 5:45 AM Reply   
The 6.0 requires pulling the heads... Iíve seen plenty that act tight according to the push rod but the rotating motor puts a lot of load on them. Is the noise louder when first cold started and then get better 5 seconds in to oil pressure?
Old     (1sikkvlx)      Join Date: Apr 2009       02-09-2018, 11:31 AM Reply   
Not really. It’s the same consistent sound hot or cold. The noise revs up with the motor and doesn’t go away but becomes faster and eventually the engine noise drowns it out. Would there be any difference in speed to determine if it was Valvetrain or piston slap? I’ve pretty much decided I’m gonna just run it. Ive been reading those engines have a huge problem with the pistons being loose in the cylinders but it sounds way worse than it is. If I’m wrong and it WAS the cam, I had to pull the engine to swap out the cam/ lifters our anyway. I’ll just throw another short block in it in a weekend.. Thanks for all of your replies!
Old     (corerider)      Join Date: May 2008       02-09-2018, 12:04 PM Reply   
This is a far fetched idea, but worth a look... I've noticed newer engines have really loud injectors... GM seem to be some of the loudest. Now the video you posted sounds much more solid and louder than any injector I've personally heard, and I'm pretty sure I hear a quieter tick of the injectors, but maybe there is one that is much louder than the rest??? It would explain the valve train seeming to be okay, no metal in the oil, and the sound speeding up with the engine speed as well.
Old     (alexair)      Join Date: Oct 2008       02-09-2018, 1:01 PM Reply   
Did any one to check compression in cylinders?
Old     (Bam6961)      Join Date: Apr 2011       02-09-2018, 6:08 PM Reply   
Could be an exhaust leak! They sound pretty similar.

I'd replace the gaskets for the headers first.

Last edited by Bam6961; 02-09-2018 at 6:16 PM.
Old     (alexair)      Join Date: Oct 2008       02-10-2018, 2:26 AM Reply   
Piston skirt
Old     (DealsGapCobra)      Join Date: May 2010       02-10-2018, 5:51 AM Reply   
As crazy as it sounds, Bam might have a point. I chased a valve train noise for quite some time on an old Ford engine just to find out it was the header gasket.
Old     (Reddog78)      Join Date: Mar 2017       02-10-2018, 8:20 AM Reply   
Stethoscope. It will be very apparent if you have a exhaust leak.
Old     (1sikkvlx)      Join Date: Apr 2009       02-10-2018, 9:23 AM Reply   
I’ve had the header off a couple of times with no change. I’m using some reusable aluminum gaskets
Old     (bill)      Join Date: Feb 2001       02-10-2018, 9:41 AM Reply   
i know that Malibu states to use 15W40 and the Malibu Dealer heres Mechanic told me all they use is 20W50 in their service department for ALL Malibu's..

is there still a warranty on engine? you'd hope they would pay for this as it sounds like just a coincidence it happened after you switched oils..each time you switched oils after the knock you changed the filter again, correct?

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