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Fman

Quick drain block modification

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Fman

I did this mod on my 2008 Supra with the Indmar 340 when I installed the hotwater shower, it worked great to quickdrain the block. My son is going to be getting a dry suit soon so we might be riding a little more in the winter months, it would be great to add this to my VLX to drain the block out after we are done riding. I never had any issues with this, some mentioned the knock sensor needs to be directly off the block, but I never noticed any issues with 230 hours on my last boat. My brother in law also runs this on his MC X-15 without any issues.

Assuming the Monsoon 350 would not be any different from the Indmar 340.

Does anyone see a problem?

quickdrain1.jpg

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Molarbu

I think the main concern would be scale. When I winterize I pull the plugs then poke a screwdriver into the block because it sometimes doesn't drain completely. Remember, it's not clean water inside the block so scale builds up and I think it could potentially clog something like that device.

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Murphy8166

So here is what knock sensor does: Knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. A knock sensor is comprised of Piezoelectric materials; Crystals that when impacted, generate a voltage (same idea as a BBQ ignitor). This voltage is monitored by the computer, and when an irregularity is detected, the computer corrects timing in VVT

I would think that moving the knock sensor off the block by more than an inch and putting a piece of metal with a valve that narrows the chamber would not be benficial for the acurate measruing of imacted crystals. I wouldn't personally do it on my boat, but then again - it's your boat!

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shawndoggy

It's a great idea for an LCR motor (no knock sensors), but I'm with Murphy -- I wouldn't do it on my knock-sensor-equipped boat.

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Bobby Light

I'm going to go with the Indmar Certified Technician on this one and say NO, it's a bad idea.

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martinarcher

Agreed. A knock sensor is a microphone that listens for engine pinging and retards timing to prevent detonation under load. Moving the sensor off the block would not be a good idea IMO.

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Fman

Appreciate the feedback, I am going to do a little more research on this. I ran this for two seasons on my last boat without any issues, the motor always ran perfect. My brother in law has been running this setup for 5 years on his '07 MC X-15 with zero problems. It really makes draining the block a simple twist of the valve.

Again, thanks for the feedback.

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tvano

Appreciate the feedback, I am going to do a little more research on this. I ran this for two seasons on my last boat without any issues, the motor always ran perfect. My brother in law has been running this setup for 5 years on his '07 MC X-15 with zero problems. It really makes draining the block a simple twist of the valve.

Again, thanks for the feedback.

i've heard the same warnings that are posted above.

iirc you may not know if you have a knock problem until you have a hole punched in your piston or head.

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Fman

Just for kicks, does anyone have an idea that would allow a quick drain with the knock sensor mounted closer to the block?

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BillFooter

If the drain keeps the knock sensor from picking up detonation, it will not make your engine run bad. It will run fine until one of the pistons has a hole burnt in it. That is what a proper functioning knock sensor prevents.

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Molarbu

I'm going to go with the Indmar Certified Technician on this one and say NO, it's a bad idea.

Bobby, I'm not an Indmar Certified Technician.:Tease3:

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Lance B. Johnson

Appreciate the feedback, I am going to do a little more research on this. I ran this for two seasons on my last boat without any issues, the motor always ran perfect. My brother in law has been running this setup for 5 years on his '07 MC X-15 with zero problems. It really makes draining the block a simple twist of the valve.

Again, thanks for the feedback.

thats just it fman unless your ear is really good you may not hear the engine detonating. Do you trust your ear or your drivers ear? Very few people are going to notice the detonation over the sound of the engine/ stereo etc......better safe then sorry. How hard is it to pull a knock sensor to drain the block anyway?

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a92harley92

i've heard the same warnings that are posted above.

iirc you may not know if you have a knock problem until you have a hole punched in your piston or head.

No need to get violent. :Tease3:

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Fman

If the drain keeps the knock sensor from picking up detonation, it will not make your engine run bad. It will run fine until one of the pistons has a hole burnt in it. That is what a proper functioning knock sensor prevents.

Cool, so if I dont mind a hole in the piston it should not be a problem?

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Fman

thats just it fman unless your ear is really good you may not hear the engine detonating. Do you trust your ear or your drivers ear? Very few people are going to notice the detonation over the sound of the engine/ stereo etc......better safe then sorry. How hard is it to pull a knock sensor to drain the block anyway?

I agree, better safe than sorry.... pulling a knock sensor is not a big deal annually, but doing it twice a week might become a little bit of PIA... this was just a remedy my brother in law came up with. He did talk to a certified marine mechanic before doing this and the mechanic said as long as the knock sensor is in line with the threaded hole, it would not be a problem. If you mounted the knock sensor off to the side it would be a problem.

My brother in law is probably one of the smartest guys I know and very mechanically gifted. He has been running it for five years, but like you said, maybe he is doing damage to his pistons every time the boat is being run? Im going to follow up with him on this and also contact Indmar to see what they say about it.

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martinarcher

I agree, better safe than sorry.... pulling a knock sensor is not a big deal annually, but doing it twice a week might become a little bit of PIA... this was just a remedy my brother in law came up with. He did talk to a certified marine mechanic before doing this and the mechanic said as long as the knock sensor is in line with the threaded hole, it would not be a problem. If you mounted the knock sensor off to the side it would be a problem.

My brother in law is probably one of the smartest guys I know and very mechanically gifted. He has been running it for five years, but like you said, maybe he is doing damage to his pistons every time the boat is being run? Im going to follow up with him on this and also contact Indmar to see what they say about it.

No damage done at all unless the engine has detonation while running. Normally this isn't the case, but bad gas with low octane, extra load, hotter engine, hotter plugs, etc could cause deto. The knock sensor will pull time to protect the engine for you and you never know anything was wrong. Thumbup.gif

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Bobby Light

Bobby, I'm not an Indmar Certified Technician.:Tease3:

:lol:

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Bozboat

Nothing more dangerous than a brother in law, other than mother in law

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gorilla

pulling a knock sensor is not a big deal annually, but doing it twice a week might become a little bit of PIA...

I pull mine every time I have run in freezing temps. It literally takes 2 minutes to pull them both and the same to put them back in. I'd rather spend the extra few minutes to make sure the knock sensors see knock properly. Directly attached to the block is the ONLY way those sensors will work properly as any amount of extension will "dampen" the shock wave from the knock and the sensor will not see it correctly. Just my view, but not worth the risk.

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Ndawg12

So could he put his KS back and tap another hole to either side of the KS and run a valve straight out of the block?

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Hammertime

So could he put his KS back and tap another hole to either side of the KS and run a valve straight out of the block?

That's what I was just thinking, hum...

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Murphy8166

Ah - the know it all borther in law. From mechanical to financial advice - they got it all covered.

Best thing I did was to go and get a 1" stubby open box end wrench from Sears to remove the knock sensors.

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Brett B

As everybody has already said, that setup will limit the effectiveness of the knock sensor. The knock sensor does not need to be in a water passage. If you could relocate the knock sensor to another area while still keeping it directly threaded into to the block it will still work as intended, allowing you to use your quick drain valve.

Fuel octane rating is essentially a measurement of its propensity to detonation and/or pre-ignition, which are different things but are both commonly referred to as "knock". Higher octane=less likely to knock. You could also lessen the risk of encountering knock by running only premium fuel from a trusted source that is always fresh, since a fuel's properties degrade with time and exposure to air.

Most naturally aspirated engines can endure a whole lot of detonation without any serious damage if they aren’t aggressively tuned. But no gasoline engine can endure pre-ignition for more than a couple cycles before catastrophic damage results. A knock sensor can help prevent both conditions, especially since intense detonation can often quickly transition to pre-ignition.

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Bake's Marine

uote name='Fman' timestamp='1323889591' post='501300']

I did this mod on my 2008 Supra with the Indmar 340 when I installed the hotwater shower, it worked great to quickdrain the block. My son is going to be getting a dry suit soon so we might be riding a little more in the winter months, it would be great to add this to my VLX to drain the block out after we are done riding. I never had any issues with this, some mentioned the knock sensor needs to be directly off the block, but I never noticed any issues with 230 hours on my last boat. My brother in law also runs this on his MC X-15 without any issues.

Assuming the Monsoon 350 would not be any different from the Indmar 340.

Does anyone see a problem?

I see a very big problem, The knock sensors are sensitive enough that they do not even want us using Teflon tape on the threads (its pipe thread so its not necessary to begin with)

I had a customer that bought the quick drain kit and installed it on his 2008 Response LXI with a Hammerhead motor and he almost destroyed the motor. The knock sensors control the ignition timing advance and in his case the motor was running so bad mechanically we thought something was broken in the top end of the motor. Turned out It cooked and carbon fowled everything on the top end of the motor.

Here is a picture that I took, I forgot to get a picture of his valves but there was so much carbon build up the exhaust side could not close so he had super low compression on half of his cylinders.

post-4023-095861900 1324074824_thumb.jpg

If I were you, I would be removing that T fitting, remove all the Teflon tape and re-install that knock sensor the way it was from the factory to avoid the head ache.

-Paul

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Fman

Hi Paul, this mod has not been done on my 2011 VLX... I am still using the stock knock sensor with no drain kit. I was considering do it, but after reviewing all the information and data going to pass on it. Thanks for the confirmation and pictures.

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