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Thread: Yamaha 300hp HPDI blown piston
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11-30-2020, 02:52 AM #1
Yamaha 300hp HPDI blown piston
Hi Folks
Looking for a bit of advice.
My 300HPDI has just blown the #4 piston, not #2 or #3 like most go.
Its a bit frustrating as its been playing up a bit so I have replaced all the filters including micro filters, had the injectors cleaned and tested.
My initial issue was the low pressure lift pumps which have since been replaced.
However I think this issue is an oiling issue, It still has an old oil pump which I have since found out had a recall.
I know its difficult but I have attached a picture of the piston and bore i'd appreciate your thoughts on if you think its an oil or lean burn issue.
All the other cylinders are fine and have comp between 110 - 115psi.
I'm sourcing a good 6D004 oil pump and will go back through everything again after the rebuild.
Cheers
Jason
Last edited by 225XCL; 11-30-2020 at 02:56 AM.
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.
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12-02-2020, 05:09 AM #2
Finished ripping the engine down, there is plenty of oil through out the motor actually a lot more than I would have expected.
All of the remaining oil is dirty, there are small metal flakes throughout the bottom end.
Also found some larger contaminants at the base of the bore, feels like sand.
I originally put this motor together from 2 engines I had picked up, all the parts were cleaned and inspected so this comes as a surprise.
I must have missed something somewhere.
Anyway I will get the block machined and cleaned, go through everything and clean or replace it.
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.
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12-02-2020, 05:31 AM #3
That sucks. Sorry for your pain. Any chance you can premix like we do on the mercs?
1990 Shadow bass boat w/ 2.4 200 Merc. Totally resto'd boat and love it!
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12-02-2020, 06:55 AM #4
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12-02-2020, 11:28 AM #5
Sucked something up through the intake maybe?
www.InjectorService.com
Call/Text - 204-326-0390
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12-02-2020, 12:36 PM #6
Looks like that cylinder has had some rust in it at one time, you can see where it has sat in two locations by the annular dark pitted rings. The dfi motors recirculate debris...no fuel mixture in the bottom end to wash unwanted material thru. I have seen it in etecs.
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225XCL thanked for this post
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12-02-2020, 04:02 PM #7
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12-02-2020, 04:05 PM #8
Good spot, the history of this build. I picked up 1 complete outboard that had been submerged and it came with a 2nd powerhead but it had a blown piston. I was able to hone the submerged motor and used that block. It had stains but was not catching, a couple of the other bores have the same staining.
I've sent the block out that had the blown piston to have that bore oversized .010 for my next attempt.Last edited by 225XCL; 12-02-2020 at 04:13 PM.
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.
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12-02-2020, 04:10 PM #9
Regarding the oil in the bottom of the crankcase I'd estimate about a 100ml, another weird thing I noticed, I would get oil coming back out the intake while it was sitting and tilted up and just off the trim rams (not running). Is this normal for HPDI's?
The only thing I can think off is the oil lines where not sealing well and the oil would drain out of them and run back out, this would all collect in the silencer and get drawn back in when it was next started.
Sold the old Formula 233.
Now have a 22ft Whittley Sea Legend powered by 225 Excel with Pro-V 200 covers.
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12-02-2020, 04:46 PM #10Screaming And Flying!
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What year is the motor and is it a Vmax HPDI 300 or a 25" ?
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12-02-2020, 04:57 PM #11
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12-02-2020, 07:27 PM #12
Factory pistons are outrageous for those things, I don't know why they made .25mm is a pia.
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12-03-2020, 08:46 AM #135000 RPM
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I once, while working at a Yamaha dealership, replaced 5 powerheads over a 2 year period on a 250 HPDI under warranty. None of them made it over 70 hrs. I have other Hpdi horror stories as well. Yamaha finally took the motor back and gave the guy a slamming deal on a fourstroke. The operating system is set up super lean. The 300's are a little better than the 250's. The 2.6 hpdi's fared much better maybe because they are closed loop with a O2 sensor. I personally believe the 3.3's are so close to the edge, old fuel, over propping, carboned rings, ect. will make them pop. I would reach out to Hydro Tech and look into getting a re-program on the ecu. They seem to know what it takes to make them live. I do think the motors have potential if you can figure out how to richen it up make it live. Good Luck
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12-03-2020, 11:26 AM #14
IMO Optis, Etecs, HPDI are all living on the lean side. It doesn't take much of a hiccup to burn any of them up.
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Call/Text - 204-326-0390
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12-03-2020, 01:02 PM #155000 RPM
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I have performed failure analysis on gearboxes that run dry until failure, seized bearings, lightning strikes, turbine exhaust exposure. Melted aluminum has a very distinct appearance but I cant quite see well enough in your photos. If the piston melted on the surface (especially near the exhaust port where it has the most heat exposure and least cooling transfer to cylinder wall) and its not melted around where the piston ring sits, you can be certain that a lean burn was the reason for failure on this single piston. Extremely unlikely this is a lubrication failure as I would expect to see more discoloration in the cylinder bore, but if you did have lube failure you would see that as you source of heat and therefore the aluminum would be more melted where the ring sits in the piston. I can also tell H20Perf has a very good eye and experience but I don't think those are resting lines. I've reviewed many pitting lines from when bearings sit for periods of time and condensation can form between two steel surfaces and start forming pits. It looks like at least one ring sat where I marked with a red line and there is smeared aluminum above and below where that ring came to a rest after the melt incident.
Edit picture i drew didn't post correctly just look closely.Last edited by Fishinmymission; 12-03-2020 at 01:05 PM.
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