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Tee Fitting for Knock Sensor?


Addictedto6

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I was wondering if anyone has added a tee fitting between the knock sensor and the manifold for more convenient draining of the block. I am adding a tee and drain valve to the shower side so I don't have to pull the shower plug out.

Officially, the knock sensor is supposed to go directly into the engine with no tape, etc. But I am curious if anyone has added a tee and drain valve without any adverse effects....

Edited by Addictedto6
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I don't see what's so hard about putting a 7/8" ratcheting box wrench on the knock sensor to get it in and out. I have just this one ratcheting box wrench in my boat tool box just to do this one job.

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I don't see what's so hard about putting a 7/8" ratcheting box wrench on the knock sensor to get it in and out. I have just this one ratcheting box wrench in my boat tool box just to do this one job.

I seem to take the wrong car out to the lake and forget my tools just when I need them. I am thinking I will be doing more frequent draining this year. I don't like leaving alll the tools out there due to theft issues, but you are right I am probably better off just leaving an extra wrench in the boat. But I am still curious to know if there are any adverse effects of adding a drain before the sensor

Edited by Addictedto6
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I seem to take the wrong car out to the lake and forget my tools just when I need them. I am thinking I will be doing more frequent draining this year. I don't like leaving alll the tools out there due to theft issues, but you are right I am probably better off just leaving an extra wrench in the boat. But I am still curious to know if there are any adverse effects of adding a drain before the sensor

Mine has a Y fitting from the factory, I run 93+ octane so having a knock problem is very unlikely which means I really don't know if it is adversley affected. Seems fine though, just your standard piston skirts slapping into the cylinder wall sound that you can hear clear across the lake. other than it is fine. oh yeah and the blueish white smoke coming out of the exhaust. but its all good.

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...just your standard piston skirts slapping into the cylinder wall sound that you can hear clear across the lake.

Just the thought of that sound gives me the heebee jeebee's (sp?).

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I pulled the knock sensor on mine from a tee fitting that I beleive is factory and it was full of sand and grit to the point that it was up in the engine. I looks to be a great way of collecting junk and since it is out of the normal water flow of the cooling system it is a perfect pocket to fill with crud. I will probably screw the sensor into the block next spring and forget the tee.

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I seem to take the wrong car out to the lake and forget my tools just when I need them. I am thinking I will be doing more frequent draining this year. I don't like leaving alll the tools out there due to theft issues, but you are right I am probably better off just leaving an extra wrench in the boat. But I am still curious to know if there are any adverse effects of adding a drain before the sensor

Sorry,

Want to add that it's an offset ratcheting box wrench.

Actual wrench

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Mine has a Y fitting from the factory, I run 93+ octane so having a knock problem is very unlikely which means I really don't know if it is adversley affected. Seems fine though, just your standard piston skirts slapping into the cylinder wall sound that you can hear clear across the lake. other than it is fine. oh yeah and the blueish white smoke coming out of the exhaust. but its all good.

So ignoring the sarcasm, you are saying engine came from the factory without the sensor directly in the engine. If so, I wonder why is Indmar so adamant on having the knock sensor directly in the block with nothing on the threads Dontknow.gif What engine & what year is your boat?

Edited by Addictedto6
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I was poking around some more. In my manual, Indmar says you must NOT use thread sealant when installing the knock sensor. In the 2003 owners manual, it says you MUST use thread sealant.... :unsure:

Edited by Addictedto6
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So ignoring the sarcasm, you are saying engine came from the factory without the sensor directly in the engine. If so, I wonder why is Indmar so adamant on having the knock sensor directly in the block with nothing on the threads Dontknow.gif What engine & what year is your boat?

it's a 95 mercruiser 350 mag ski mpi. but merc doesn't want tt on the threads, infact they put the y sensor on in the factory ad say removing it will void the warranty

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it's a 95 mercruiser 350 mag ski mpi. but merc doesn't want tt on the threads, infact they put the y sensor on in the factory ad say removing it will void the warranty

Thanks for the followup. Interesting to see the mfgs approaches changing/being different. Maybe different sensors? In any case, After digging around and seeing the different configs, I am going to spend my money on that wrench instead of additional fittings for the knock sensor side.

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I can tell you that the cooling system is not under much pressure and there is little need for teflon tape or thread sealant on the knock sensor. Even if it did leak it would not be an appreciable amount. The only thing I might be tempted to use would be a little anti-seize compound.

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If you add metal between the sensor and the block you will make the sensor less able to pick up the frequencies of block vibration when knocking occurs.

I would strongly suggest NOT doing this mod to your boat.

-Chris

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I wouldn't do the mod and adding sealant is a bad idea. Most knock sensors have one wire and use the threads to block as the ground, hence the MFG not wanting sealant on the threads. Also by putting a tee in line it may make add or remove vibrations depending on the frequency.

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