What is this part/sensor?

[gman90706]

Volvo Penta 5.0gi pefs ... don't remember unhooking anything from this when I took the engine out - but then again??? Wanna make sure I'm not missing something here b4 preparing to put 'er back in....

Happy Thanksgiving All

 

[captmello]

Re: What is this part/sensor?

looks like the drain for your block

 

[kwoolard]

Re: What is this part/sensor?

It is a tee connection that has a block drain on one port and a knock sensor on the other port. The rusted looking part with the black connection is the knock sensor.

 

[captmello]

Re: What is this part/sensor?

The rusted looking part with the black connection is the knock sensor.

Would you mind explaining how the knock sensor works.

Thanks

 

[kwoolard]

Re: What is this part/sensor?

The Knock Sensor is a Piezo Electric device, meaning, when you stress it a voltage is produced. If the engine is knocking or pinging the sensor will produce an AC voltage spike. If your engine is equipped with a Knock Module, the knock module will monitor this AC voltage from the knock sensor and if spark knock is present, it will send a signal to the Ignition Control Module and will retard the spark timing.

 

[gman90706]

Re: What is this part/sensor?

It is a tee connection that has a block drain on one port and a knock sensor on the other port. The rusted looking part with the black connection is the knock sensor.

Thanks kwoolard - I guess I need to recheck all the wiring, as mentioned I don't remember disconnecting it when removing the engine. If it was already discon'd should it have been kicking out any check engine codes? Or does it only throw voltage when it senses a prob...? I'll try reading up more on it, first thing's first find the wire....

 

[kwoolard]

Re: What is this part/sensor?

I think it could have easily been pulled off without noticing what you were disconnecting. If you do indeed have a knock module then you should have the wire. With the wire disconnected, it will not harm the engine...the ICM will just not be able to adjust the timing if the engine starts to knock.

 

[JUSTINTIME]

Re: What is this part/sensor?

you can test it by using a timing light, then using a dead blow hammer by it
you will see the timing jump around

 

[JustJason]

Re: What is this part/sensor?

What you have there is a block drain. What should be in that hole is a simple brass plug. The T fitting, and whatever else that is doesn't need to be there, and should not be there. Just pitch it and put the correct size plug in it.

 

[gman90706]

Re: What is this part/sensor?

Actually kwoolard's right, it's definitely a knock sensor (T-d into the drain plug). Either I was drunk when disconnecting it or the mechanic that replaced the starter last time never hooked it back up.... funny how sometimes things are right in front of your eyes and u don't see 'em: checked it out a bit ago & in the lower right corner of the pic, that's the starter harness, and that black plug is the wire that hooks into the sensor....

Finally found it in the manual, but can't find the volvo penta part#, from the looks of the corrosion on it I'd assume it's not anything marine-specific & a standard GM replacment would do if I decide to replace?

 

[Dunaruna]

Re: What is this part/sensor?

In this era of suspect fuels, the knock sensor is invaluable. Worthwhile testing it.

iboats store has them, part# 3850357.

 

[TilliamWe]

Re: What is this part/sensor?

checked it out a bit ago & in the lower right corner of the pic, that's the starter harness, and that black plug is the wire that hooks into the sensor....

If I could draw a circle on your picture, that is what I was going to circle. Is the end of that plug cracked?

 

[gman90706]

Re: What is this part/sensor?

If I could draw a circle on your picture, that is what I was going to circle. Is the end of that plug cracked?

nah, plug is fine that's just the flash reflection in the pic. I think I'll go ahead and replace the sensor, if anything just to get rid of the ugly corrosion since I'm cleaning everything else down there.

Not being cheap, but I can pick an automotive one up for $30 tomorrow vs. ordering a $50+ 'marine' one online & waiting for it ... it's just a GM 305 v8, think it makes a diff? also, think a coat of paint on a new one would hurt it any?

 

[newport dave]

Re: What is this part/sensor?

Not being cheap, but I can pick an automotive one up for $30 tomorrow vs. ordering a $50+ 'marine' one online & waiting for it ... it's just a GM 305 v8, think it makes a diff? also, think a coat of paint on a new one would hurt it any?

The knock sensor is pretty critical, I don't think I would try to save $20 at the risk of my engine. Also, if the automotive part is different it may set a "no knock" or "continuous knock" fault code which would cause the ECM to run in full knock retard all the time.

 

[dan t.]

Re: What is this part/sensor?

just to get in and stir the sh-t a little, I cant see the automotive one being any different. if the original was marine specific you would think it would have a stainless steel or plastic housing. this one looks identical to an automotive knock sensor

 

[TilliamWe]

Re: What is this part/sensor?

It's the same part, automotive to marine. Exactly the same.

 

[gman90706]

Re: What is this part/sensor?

It's the same part, automotive to marine. Exactly the same.

That's what I was thinking... at least I can pick it up tomorrow vs. waiting for ups delivery - I think the bigger problem will be getting that rusted pos off, had enough hassles with those mounts, oil pan bolts, starter & a bunch of other fun rusted up stuff...

Thanks much for the replies fellas, appreciate it!