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Houston

Who's had an Indmar Monsoon blow up?

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Houston

My 2005 23 LSV came with an Indmar 340 Monsoon (5.7 GM block). It ran great - until it blew at 300 hours. Rods and pistons came loose, breaking through the lower block and punching holes in the oil pan. This engine had been perfectly maintained, never abused, and ran great until then. $5,800 later, I have a new 5.7L engine installed.

It appears the oil pickup tube (oil screen) that sucks oil from the pan simply fell out of the block and starved the engine of oil. The tube is pressed into the block and had worked loose. It was laying in the pan unscathed.

Please post if you have had a similar issue. I am thinking this is not an isolated incident and would like to hear if others have had same issue. Indmar is saying, "sorry, out of warranty."

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happypappy

sorry to hear that....of all the engines out there, the monsoon is the most bullet proof, problem free marine engine on the market.

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Malibuss

Boy if that happened to any engine it would crater. I guess thats why most speed guys braze the tube to the pump !

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Falko

If you lost oil that long, did it not show on the gauge or set the alarm off? I think the pick up might have come off during the engine flail. What actually broke in the engine, crank shaft, rod, cap, pin??

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malibu2004

If you lost oil that long, did it not show on the gauge or set the alarm off? I think the pick up might have come off during the engine flail. What actually broke in the engine, crank shaft, rod, cap, pin??

yep

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SkiZilla

This is a common 350 Chev failure. I have a nice little 383 that I built up for an older Trans Am. If sufficient oil is in the pan the pump will draw oil without the pick up, when mine worked itself loose on the 383 it held oil pressure right up until it mangled part of the screen and sent it through the oil pump. At that point the snap/ping sound was clearly audible as the oil pump drive shaft broke. Fortunately as I heard the sound I also was flooded with memories of my fathers voice reminding me to always watch the oil pressure gauge. My beautiful little engine ran for less than 30 seconds without oil pressure. I took the opportunity to make a winter project out of it, disassemble the whole thing to make sure it was clean, freshened up the rings and bearings and was sure to use a good quality bolt on oil pick up.

While it is a common failure I am sure a gauge, warning light, or audible alarm must have indicated the problem at some point before it became catastrophic. Sorry to hear of the damage but to quote my father "ALWAYS KEEP AN EYE ON YOUR OIL PRESSURE GAUGE"

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Sixball

Hard to say without looking at old parts but Falko is thinking along a good line. Our boats have a sensor that looks at no oil pressure and should put it into Limp mode or shut down fuel. Witch will shut down. I have known of smiler events but not common. I don't know if they were on the 340 Monsoon. Did a rod brake?

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RTS

I am thinking this is not an isolated incident and would like to hear if others have had same issue. Indmar is saying, "sorry, out of warranty."

I would disagree and say that this would, indeed, be an isolated incident. If it was common, it would be all over this board, as the Monsoon is a very common engine in the boats on this site.

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Bill_AirJunky

I was told the Monsoon was Indmar's most reliable engine ever.

I do know a guy who had this same problem (oil pickup tube fell off) on a big block that was in an RV.

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Falko

There's no doubt, the oil pick up can come off, I'm not sure it is common though. I'd be more suspect of a bad crank, rod, improperly torqued rod or main cap, etc. The Monsoon series had a cast crank with a 2 bolt main, if I remember correctly. While they are reliable, they are not the most robust lower end.

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chadwick02

A very common engine, not a common problem at all. A bummer, the monsoon is pretty bulletproof, but stuff happens sometimes, it is almost 10 years old... At least you are up and running now!

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Houston

The boat would show low pressure on the gauge on holeshot, but quickly recover. Was advised by either Indmar or Malibu cust service (can't remember which I talked to) to change sensing unit. Did that and changed oil. Seemed to help, but still reduced OP on holeshot. Light/beep did not occur until failure. I believe the oil tube had loosened and finally fell out.

Moral of story: low OP on takeoff may equal loose oil pickup tube. Especially if your model uses one that is pressed into the block (not screwed or welded).

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Sixball

I have a hard time believing you could maintain oil pressure without the pick up tube. You would be running the crank in an oil bath. The crank is not touching the oil!

This is why you should not over fill oil.

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