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Relocated knock sensor?


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Has anyone relocated their knock sensor on the vg33e model engines?

 

It’s located under the lower intake and many relocate due to the amount of work required to remove the upper plenum and then the lower intake. With the risks of the lower plenum screws and bolts being seized and then stripping the threads when trying to remove.

 

But would it serve its purpose sitting on top the plenum after relocation?

 

I’m going to pull the upper plenum to replace injectors, IACV, FPR, some coolant hoses, the plenum gasket of course, and seals for the injector rail to lower plenum.

 

But currently skeptical about lower intake removal.

 

Any thoughts?

 

 

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I did the relocation on my 96 probably 5+ years ago. Although I don't have it anymore, I sold it to a guy just down the road from me. It's still going strong and he hasn't had any mechanical issues, aside from popping a code for a bad o2 sensor. As for the true functionality of the relocated sensor, I'm sure it's not as effective as it's original location, other than an easy fix to an otherwise involved (and sometimes very difficult) repair.

All that aside, if your doing all that other work, it shouldn't add too much time and effort to the job. In my (almost 30 years of) wrenching experience, I've found that a majority of stubborn fasteners, mangled threads and such are far more common on the more "external" engine components. Not saying I've never snapped a manifold or head bolt, but it is more easily prevented with patience, finesse and appropriate application of heat. Even an inexpensive handheld map gas plumbers torch can do the job in many cases. In fact, I rarely break out the oxy-acetelene torch anymore, unless I'm doing some "heavy" work or crude cutting. My little $40 map gas job is much less hassle.

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I did the relocation on my 96 probably 5+ years ago. Although I don't have it anymore, I sold it to a guy just down the road from me. It's still going strong and he hasn't had any mechanical issues, aside from popping a code for a bad o2 sensor. As for the true functionality of the relocated sensor, I'm sure it's not as effective as it's original location, other than an easy fix to an otherwise involved (and sometimes very difficult) repair.

All that aside, if your doing all that other work, it shouldn't add too much time and effort to the job. In my (almost 30 years of) wrenching experience, I've found that a majority of stubborn fasteners, mangled threads and such are far more common on the more "external" engine components. Not saying I've never snapped a manifold or head bolt, but it is more easily prevented with patience, finesse and appropriate application of heat. Even an inexpensive handheld map gas plumbers torch can do the job in many cases. In fact, I rarely break out the oxy-acetelene torch anymore, unless I'm doing some "heavy" work or crude cutting. My little $40 map gas job is much less hassle.

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Yeah, I was thinking might as well go all the way if I’m already over half way into it.

Wouldn’t heat be a bit of an issue there since the manifold is aluminum? And then applying a lot of torque to get the bolt out. Assuming it would be stuck. I was thinking of spraying them down with PB Blaster.

Not doubting you at with your help but heat is what worked best for you with those lower intake bolts?


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Yeah, I was thinking might as well go all the way if I’m already over half way into it.

Wouldn’t heat be a bit of an issue there since the manifold is aluminum? And then applying a lot of torque to get the bolt out. Assuming it would be stuck. I was thinking of spraying them down with PB Blaster.

Not doubting you at with your help but heat is what worked best for you with those lower intake bolts?


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PB is good stuff and works better than anything else, in my opinion. I typically will give ugly stuff a good soak a few days before (when possible), but if/when that doesn't work I always grab the heat wrench. Typically, with steel fasteners into aluminium, you get corrosion from the 2 metals not really liking each other, so patience and appropriate heat work great. Go slow, if it doesn't feel right, it's probably not. In these situations I pinpoint the heat to the area directly around the bolt. With aluminium you usually don't need much, just enough to "wake things up", which breaks down the corrosion. After I get it to free up, I'll back the bolt out little by little, until it feels like it's starting to bind, stop, give it a squirt of PB, change direction and thread it back in, then repeat until it's out. Most of my broken bolts or stripped/mangled threads are the result of forcing things. Granted there have been some that happened just because it was fate , but I can't stress enough how important patience is.
Once things are apart, clean out the hole as best you can (compressed air or even the keyboard duster "air in a can" works), determine the correct thread size/pitch and chase the threads with a tap. When you have to reuse an ugly old bolt, I also chase the threads on that as well. Makes things much easier to put back together.

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PB is good stuff and works better than anything else, in my opinion. I typically will give ugly stuff a good soak a few days before (when possible), but if/when that doesn't work I always grab the heat wrench. Typically, with steel fasteners into aluminium, you get corrosion from the 2 metals not really liking each other, so patience and appropriate heat work great. Go slow, if it doesn't feel right, it's probably not. In these situations I pinpoint the heat to the area directly around the bolt. With aluminium you usually don't need much, just enough to "wake things up", which breaks down the corrosion. After I get it to free up, I'll back the bolt out little by little, until it feels like it's starting to bind, stop, give it a squirt of PB, change direction and thread it back in, then repeat until it's out. Most of my broken bolts or stripped/mangled threads are the result of forcing things. Granted there have been some that happened just because it was fate , but I can't stress enough how important patience is.
Once things are apart, clean out the hole as best you can (compressed air or even the keyboard duster "air in a can" works), determine the correct thread size/pitch and chase the threads with a tap. When you have to reuse an ugly old bolt, I also chase the threads on that as well. Makes things much easier to put back together.

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Thanks a lot 01Pathmaker, that will help out a lot.

Hopefully when I do it I don’t run into any issues with that lower intake.

Btw, the block has to be drained for that lower intake removal? Or is radiator drain sufficient? I read in the manual to drain the block directly, but I was checking out some YouTube videos on this job and some mentioned draining the block while quite a few did not.


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Thanks a lot 01Pathmaker, that will help out a lot.

Hopefully when I do it I don’t run into any issues with that lower intake.

Btw, the block has to be drained for that lower intake removal? Or is radiator drain sufficient? I read in the manual to drain the block directly, but I was checking out some YouTube videos on this job and some mentioned draining the block while quite a few did not.


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Only time I've drained the block on these is when doing a full coolant flush. I will add that when the block gets drained, it can sometimes be a real chore to purge all the air out when refilling.

Take your time, take a break if you start getting frustrated, because that's when stuff gets broken and knuckles get busted!

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When I had my VG30E apart, I relocated the knock sensor to the back of the driver's side head. There was a drilled/tapped hole right there ready to go, and the harness reached. It hasn't caused any issues, though I doubt it would be as sensitive if there was a knock to sense.

 

+1 for chasing holes, just make sure you get the tap started straight. I salvaged an oxygen sensor bung in an exhaust the other day that I was sure was wrecked.

 

The lower rad hose hooks up lower than the lower intake, so I imagine you'd be alright just draining the rad. I remember pulling the drain plugs on mine for some reason, but I don't think it was before I had the manifold out. One of them didn't even drip until I jammed something up into the hole and broke through the sediment at the bottom of the water passage.

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They're similar enough that I wouldn't expect any difference that would matter here. Make sure you get the intake manifold gaskets for the 33, the 30 gaskets are thicker. I accidentally got 33 gaskets for mine and nothing lined up. Not sure if they've got the same tapped hole on the back of the head that I used for the knock sensor.

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They're similar enough that I wouldn't expect any difference that would matter here. Make sure you get the intake manifold gaskets for the 33, the 30 gaskets are thicker. I accidentally got 33 gaskets for mine and nothing lined up. Not sure if they've got the same tapped hole on the back of the head that I used for the knock sensor.

Yeah I got the OEM Nissan gaskets for the 33. The gaskets are a dry install for the upper and lower intakes correct? No sealant needs to be additionally applied to these gaskets?

And I’ll be putting the knock sensor back in the original spot.


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The service manual shows the gaskets going in dry. If the coolant ports on the heads/manifold are pitted, though, I'd be tempted to give those surfaces a skim of silicone before doing them up.

Any specific type of silicone you recommend in that case?

Would applying a skim of the sealant on both ends of the intake with the gasket in between cause a coolant or air leak at the lower intake/block mating ports?


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That's a good thought. Ultra black is the only silicone I've used on any engine applications for many years. It's very stable, stays pliable and is "sensor safe". Used sparingly and appropriately, it'll save a potential headache down the road.

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That's a good thought. Ultra black is the only silicone I've used on any engine applications for many years. It's very stable, stays pliable and is "sensor safe". Used sparingly and appropriately, it'll save a potential headache down the road.

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Should I apply it to the lower intake manifold and block ends? A light coat and then put the gasket on?

Do you think it could lead to a coolant or air leak there?

I guess I’ll have to see the surface first if there is much imperfections.


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3 hours ago, AR97Pathfinder said:


Any specific type of silicone you recommend in that case?

Would applying a skim of the sealant on both ends of the intake with the gasket in between cause a coolant or air leak at the lower intake/block mating ports?
 

 

I would just use a regular RTV silicone gasket product from your local auto store.

 

The skim would only need to be be very light only a few thou thick, you could do it two ways: skim and let dry then assemble, or skim and assemble wet. Either way should work fine.

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Ultra black is good stuff. Again I would only use it around the coolant ports if the surfaces are pitted, and just enough to fill the pits. I would assemble wet. Cured silicone above the surface might prevent the gaskets from sitting flat, causing other leaks. The VG33 gaskets I had were stamped steel, which I would not expect to conform to an uneven surface.

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Well this entire post has scared the crap out of me doing My damn knock sensor. Lol

A broken lower intake manifold bolt wasn't even a thought. Now I'm questioning whether to just let that hiccup ride...

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Well this entire post has scared the crap out of me doing My damn knock sensor. Lol
A broken lower intake manifold bolt wasn't even a thought. Now I'm questioning whether to just let that hiccup ride...

I actually got the upper plenum and lower intake off this evening. Took about 3 hours taking my time getting everything off including clean up after. I also took off the hood so I can climb in and move around freely when needed.

I have to finish changing the parts tomorrow ( injectors, FPR, IACV, coolant hoses) then put everything back together. I’ll also have to adjust back the idle and new coolant.

I installed the new knock sensor before calling it quits for the evening. The old one was completely destroyed. It was cracked in half and completely brittle. From the time I grabbed a hold of the harness the head of the knock sensor just broke off.

The bolts came out of everything with absolutely no problems at all. And I was worrying about this leading up to the project.

What I did do for several days prior was soak down all the bolts with PB blaster. I made sure to get all parts beforehand including extra screws, bolts, clamps, etc.


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