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  #21  
Old 10-26-2013, 12:23 AM
Skyskiguy Skyskiguy is offline
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Pretty sure I was TDC on each one. Performed the tests just as the dealer instructed. I found TDC by holding my thumb over the air hose threaded into the sparkplug hole and bumped the starter until I felt pressure. When I connected the gauge to apply air pressure from the compressor it was pretty obvious whether it was at the top of the stroke with valves closed. If it was short of TDC, the compressed air would actually push the piston back down. Or, if I was past TDC, the pressure would complete the stroke. If it was in any other position the compressed air would just flow right out either the intake or the exhaust. It usually took some fine tuning with several small bumps of the starter to get it just right.
When I say "low" range, I am assuming that because I could clearly hear air moving through the intake (cylinders 3 & 5) or exhaust (cylinders 4 & 6) that the leakage into the crankcase in those cylinders is probably similar to the good cylinders - which was 15-25%.
Also, with the good cylinders (1, 2, 7 & 8), if I plugged the PCV ports in the valve covers and had the dipstick in place then held my palm over the oil filler hole while pressurizing the cylinder, pressure would slowly build in the valve cover/crankcase, confirming the "low" (15-25%) ring leakage in those cylinders. With the other cylinders (3, 4, 5 & 6) the pressure that built in the crankcase, under the same conditions, seemed about the same - thus my assumption of ring leakage percentage being similar to the others. I don't know of a way to determine what percentage of the leakage is past the rings vs. thru the valve in a particular cylinder.
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  #22  
Old 10-26-2013, 01:14 PM
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CantRepeat CantRepeat is offline
 
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Um, maybe leaving in the other spark plugs would give more back pressure and keep the pistons from moving. (after thought)

At TDC there shouldn't be a 60% leak through any valves unless they are bent or burnt.

Here's a rather long video that might help.

http://www.youtube.com/watch?v=WgrfT0LFMhc

"Maybe" your issues are valve train. The oil consumption could be guide seals but normally that is seen by blue smoke at start up after sitting for a while.
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  #23  
Old 10-26-2013, 09:44 PM
Skyskiguy Skyskiguy is offline
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Originally Posted by CantRepeat View Post
Um, maybe leaving in the other spark plugs would give more back pressure and keep the pistons from moving. (after thought)
Yeah, it would - I considered that but this way worked.
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  #24  
Old 10-28-2013, 02:46 PM
Skyskiguy Skyskiguy is offline
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The more I learn the more confused I get.
This is a 2006 X30 MCX. I bought it in the spring of 2012 with 93 hours on it. I did test drive it before the purchase - it ran great - but didn't do any other investigative work on it. I have been a bit surprised at the amount of fuel It consumes - especially compared to my neighbor's 24' 2007 Tige' (same 5.7 GM block but not Indmar).
As I said, it runs great. It now has 212 hours on it - 60 last year and 60 this year. The only thing that started me down this path was that I only got 3.5 quarts of oil out of it when I winterized it last week.
So after thinking that my leak down and compression numbers weren't making a lot of sense, I retested the leak down on several of the cylinders this morning - same results. I tried to remove the raw water pump so that I could crank the engine manually but that proved to be more work than it was worth - that thing was't wanting to come off. So I once again used the remote start to bump the engine until I could feel pressure in the tester hose. I am confident I was indeed testing @ TDC on each cylinder. I'm confident in the results I reported earlier in this thread. The cylinders that I said were leaking into the intake (3 & 5) I re-confirmed by holding my hand over the throttle intake (where the K&N filter attaches) and pressure was definitely building in the intake. The cylinders I said were leaking into the exhaust (4 & 6) were definitely creating a lot of noise in the muffler and exhaust hoses.
But shouldn't leakage thru the valves make it not run well? There is no question that cylinder 5 is burning oil and some in 3 as well.
Again, I'm no professional mechanic, but things just aren't adding up. I know I have never abused this engine. Could the original owner have not broken it in properly and caused these kinds of issues? Could the fact that the original owner only put 93 hours on it in the first 6 years (which means it sat a lot! - I don't know when it was last used prior to my purchasing it) have caused things to gum up to where I am having these kinds of leakage issues. Or am I just totally off base with my tests? I'm going to check with the dealer for service records - I think the previous owner had them do all the service.
I have a neighbor who is the local distributor for BG Products. He wants to run a couple of BG products through the oil and fuel systems to clean things up and claims that I will be amazed at the results. He thinks my problems are from the fact that it sat so much during the first 6 years. Could the answer be that simple? Have any of you had any experience with BG products? What do I stand to lose by letting him try it?

Another thought - what could I learn by running an analysis on the oil I drained last week?

Again, thanks for all of the valuable input.

Last edited by Skyskiguy; 10-28-2013 at 02:57 PM.
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  #25  
Old 10-28-2013, 03:14 PM
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blackhawk blackhawk is offline
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I am not a professional mechanic either. I could see how sitting so much could have left some deposits in the engine. Maybe the previous owner did not change the oil every year and let that old oil set in there through the winter. Maybe there are some deposits on the valve seats and that is what is holding the valves slightly open causing the leak by. Are cylinders 3 and 5 on the same side? If so, I would pull off that head before taking out the entire engine.

I have never heard of BG products before. I have always been nervous about oil additives. Fuel additives scare me less. But, at this point it could be worth a try before going to all the trouble of pulling off the head. Maybe the BG will clean off some crud somewhere that is not allowing the valves to close fully.

The bearded mechanic on Gas Monkey Garage had a good quote one time. He said "an engine wants to run".
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  #26  
Old 10-28-2013, 03:50 PM
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CruisinGA CruisinGA is offline
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I don't see how sitting could lead to deposits other than rust.

Until you borescope the engine, it is all speculation. If you were closer I would borrow one from the service dept at work and bring it by for you. However, you should be able to rent one locally.

If we suspect an issue, we don't do anything to our multi-million dollar 1-5000+ hp engines until we borescope them.
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  #27  
Old 10-29-2013, 08:44 AM
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http://www.harborfreight.com/digital...era-67979.html
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  #28  
Old 10-29-2013, 11:33 AM
Skyskiguy Skyskiguy is offline
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Originally Posted by CantRepeat View Post
Great. Thanks.
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  #29  
Old 10-29-2013, 07:04 PM
Skyskiguy Skyskiguy is offline
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Dealer records indicate "Engine overheated and started to smoke" back in July of 2009.
They replaced a toasted impeller and dug/flushed out the pieces of rubber, cleared the codes, and it ran fine.
Check service records PRIOR to buying a used boat!
Dealer says hard to believe that an overheat could cause valve and/or ring damage because the boat would have gone into limp mode at 200 degrees.
Thoughts?
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  #30  
Old 11-07-2013, 07:33 PM
Skyskiguy Skyskiguy is offline
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So I let my neighbor run the BG products through it.
We started by putting 44k in the fuel tank, then dumped 109 Compression Restoration into the crankcase. Next, we put the Injection System Cleaner into the BG injection apparatus, hooked it to the fuel rail, hooked in the shop air at 53 PSI and started her up! When that was done we dumped the Air Intake System Cleaner into the apparatus, attached the sprayer attachment, stuck that into the throttle body and ran it some more. Next was an oil and filter change. I have to admit that I was alarmed at how black the oil was! This was fresh oil - I had just done an oil change two weeks prior - couldn't have been more than one hour of driveway run time on it. As part of the oil change we put BG MOA in the crankcase with the new oil.
The results? Compression in cylinder 5 came up from 145 to 155. Cylinder 3 up from 150 to 153. Cylinder 2 was previously the highest at 172 - it came down a little to 168. The remaining cylinders were relatively consistent with the original numbers. The highest cylinder is now 170 PSI. The compression numbers are now right at 10% from high to low. I did not do any leak down re-testing. All of the spark plugs now looked pretty nasty so I also took the opportunity to install new ones. Then I winterized and put her to bed for a long winter's nap.
Snake oil? As they say, the proof is in the pudding. I'll post pictures of the oil and plugs when I get a chance. Unfortunately, now we get to wait until spring to see how the story ends.
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