SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 79tunnell429 on October 11, 2011, 12:06:29 AM
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So here we go, just had my 429 built, had about 11 hours on the motor when I heard a little tick, took it to the shop ends up being a bad roller lifter that scored the cam a little.. Upon bottom end inspection, the builder calls me and says we've got bigger problems, 3 Out of the 8 pistons were literally blue and scored to shit right through the rings as well, and the rest were mildly scored.. The tops of the pistons were covered in carbon, just the sides looked they got hot, I've had the motor for about 60 days at this point and a total of 11 hours on it. The motor builder is trying to tell me that I ran it to lean that's why this happened. Keep in mind that I changed nothing on this motor just pulled it out with a broken crank, had it rebuilt, and put it back in. The pistons that were pulled out of this motor were near perfect after 8 years of solid abuse.any input on this would be very helpful!!
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Were there any other signs of a lean condition? Detination?
When rebuilt did you give the builder any specs or did he do what he thought was right? Did he offer you a spec card for the build?
Did he understand that it was going to a boat with an open cooling system?
I'm guessing here, but it sounds like he didn't give enough clearance between the pistons and the cylinder walls for the application.
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Block full of sand? Manifold leak?
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ok you said they reused the same pistons??? sounds like they did not put the pistons back in the same holes!!!!
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No they did not re use the same pistons, everything was new, no! There's no sand in the block! I'm thinking the guy didn't give enough clearance or tolerance for the cylinder/piston expansion! When you say signs of detonation what do you mean? I k ow the headers are black on the inside, same with the exhaust ports on the heads, and the plugs were nice and dark also, there's no way this was running lean.
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No they did not re use the same pistons, everything was new, no! There's no sand in the block! I'm thinking the guy didn't give enough clearance or tolerance for the cylinder/piston expansion! When you say signs of detonation what do you mean? I k ow the headers are black on the inside, same with the exhaust ports on the heads, and the plugs were nice and dark also, there's no way this was running lean.
May be just the opposite,, too much fuel running down the cylinder walls washes off the oil. Tops of the pistons and inside of the headers being "black" indicate that it's running rich,, was it smoking too?
Even if he had regular "street" type clearance, I have never seen pistons turn blue, there had to be lots of friction and heat to do that. If you were closer I would be happy to look at the parts for you, but even photos may help.
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The three damaged pistons near each other?
Hyperautectic pistons?
Moly rings?
In all honesty, it sounds like you have/had an oil problem, you say a roller failed, that is not what I would call normal. Would love to see what the ring gaps were too.....I'm reaching though. :screwy:
GT
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The three damaged pistons near each other?
Hyperautectic pistons?
Moly rings?
In all honesty, it sounds like you have/had an oil problem, you say a roller failed, that is not what I would call normal. Would love to see what the ring gaps were too.....I'm reaching though. :screwy:
GT
I'm kinda on this same thought path. Obviously, something went VERY wrong, and I can't say I've ever seen a BLUE piston. Seen many blued rods and cranks, and know what caused THAT, but a piston? New one on me.
As GT said, inadequate gaps in rings, slugs way too tight to bores (I would be looking SERIOUSLY there). Not going to contradict Barry, but would seem to me "lean" is pretty much out of the question given what you said, and I can't see where overly rich "wash" would have caused THAT so quickly. To be THAT rich it wouldn''t even have run, I would think. Post pics and maybe THAT part can be ruled out.
The failed roller lifter raises my eyebrows a little, and did you see it? did it "spit" out and cause total oil pressure loss? It all sounds to me that MAYBE, total failure of the oil system due to a spit or destroyed lifter MIGHT have caused this. But without pics and seeing it all, as GT said, just a SWAG.
Ray
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Well whatever the case, it didnt work . I'd tell the dude to get it handled, pronto. Get specs as the engine goes together this time.
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May be just the opposite,, too much fuel running down the cylinder walls washes off the oil. Tops of the pistons and inside of the headers being "black" indicate that it's running rich,, was it smoking too?
Even if he had regular "street" type clearance, I have never seen pistons turn blue, there had to be lots of friction and heat to do that. If you were closer I would be happy to look at the parts for you, but even photos may help.
To expand upon what I wrote, it's critical that you don't have a bunch of raw fuel in the cylinders if you want the rings to seal on a new engine. On top of that, if the rings don't seal and you continue to pour raw fuel into the cylinders, it's going to be forced past the rings and into the oil.
Anything I run, from my turbo charged Schiada that I used to race, down to any of my street vehicles, one of my normal maintenance checks is to smell and feel the oil from the dipstick.
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Ray brotha :) "Fuel wash" will destroy an engine in no time, bearings , rings, cyl. cross hatch etc. Really THAT QUICK! jus my 2 cents :beer:
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So here we go, just had my 429 built, had about 11 hours on the motor when I heard a little tick, took it to the shop ends up being a bad roller lifter that scored the cam a little.. Upon bottom end inspection, the builder calls me and says we've got bigger problems, 3 Out of the 8 pistons were literally blue and scored to shit right through the rings as well, and the rest were mildly scored.. The tops of the pistons were covered in carbon, just the sides looked they got hot, I've had the motor for about 60 days at this point and a total of 11 hours on it. The motor builder is trying to tell me that I ran it to lean that's why this happened. Keep in mind that I changed nothing on this motor just pulled it out with a broken crank, had it rebuilt, and put it back in. The pistons that were pulled out of this motor were near perfect after 8 years of solid abuse.any input on this would be very helpful!!
This would be very difficult to diagnose over the internet based on your description and without a lot of detailed pictures, but go ahead and post them up as we all may see something very telling.
Not to dismiss your claims but to bring a few things into perspective: black carbon on the pistons and exhaust ports does not in-and-of-itself prove that the engine was not running lean while under load at WOT. Pistons will usually score heavily and seize before turning "blue." And, any single change in your engine combination can dramaticallly affect tune-up.
I've noticed on this forum that you have had a lot of trouble with your jet boat engine(s) and although I cannot be certain, reading about all the problems you are having gives me pause and makes me wonder how knowledgeable and well versed you are in maintaining these temperamental, high-maintenance vessels. Not trying to be condescending; I am stating my perspective based on what I have read thus far.
In fact, I would be happy to help. If the engine is in your posession, I will be in the greater Sacramento area over two days next week and would be happy to have a look at the engine and do my best to make an independent diagnosis. I can even make suggestions for your next build.
PM or call directly if interested,
LO
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Shit!! Sorry guys I lost my ways of Internet for awhile! :banghead: I am going to the machine shop where my engine is located on Friday to take some pictures. Are you in Sacramento this week Lakesonly?
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Are you in Sacramento this week Lakesonly?
Tentatively, I'll be in your area next Tues/Weds/Thurs (25-26-27), around Yuba City, Sac, Antelope, Citrus Heights. Somewhere inside of those three days I need to make a one-day hop over the mountain to Bill Miller's (Carson City) for a few sets of aluminum rods and then right back to where you are.
You can reach me via the number in the clickable link in my signature line below.
LO
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Any news on how this is turning out? Definately a curious case.
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Any news on how this is turning out? Definately a curious case.
I tried contacting while I was in town; no reply.
LO