knock sensor removal

[rsmigel]

Just a late response to this topic... it took me 5 hr to replace the EGR system on my '94 850 turbo doing it the first time in my garage as a 'shade tree' mechanic. I've got all the tools but I still wouldn't want to do it again. Given that I may need to replace my knock sensors, this is a wonderful tip for me.

Given that you have to 'follow the wires' to the knock sensor, I assume you can disconnect the wiring too. That may be my entire problem... a slightly corroded connection.

[rsmigel]

One more quick question... where is the knock sensor harness connection located? Is it difficult to separate with the intake left on and all the other stuff in the way?

[erikv11]

On your 94, the factory harness connects right at each knock sensor.
Here is a good pic: viewtopic.php?t=57786

Alternatively it may have the updated version, like this: https://www.volvopartswebstore.com/prod ... 70492.html?

[abscate]

Don’t overtoghten those sensors, you rush the piezo sensor

It’s a pet peeve of mine when people say you can do this or that without removing this or that as recommended.

You don’t save time when you round off fasteners because of poor tool fitment.

Of course there are time savers, but the pain of those mistakes is seldom posted

[rsmigel]

On your 94, the factory harness connects right at each knock sensor.
Here is a good pic: viewtopic.php?t=57786

Alternatively it may have the updated version, like this: https://www.volvopartswebstore.com/prod ... 70492.html?

That's the problem... I'm trying to figure out what part(s) to buy before tearing things down: individual sensors or two pre-attached on a harness.

I called the dealer with my VIN #. That didn't seem to help as they show both discrete sensors and sensors mounted on a harness.

[erikv11]

On your 94, the factory harness connects right at each knock sensor.
Here is a good pic: viewtopic.php?t=57786

Alternatively it may have the updated version, like this: https://www.volvopartswebstore.com/prod ... 70492.html?

That's the problem... I'm trying to figure out what part(s) to buy before tearing things down: individual sensors or two pre-attached on a harness.

I called the dealer with my VIN #. That didn't seem to help as they show both discrete sensors and sensors mounted on a harness.

Are you replacing them?? Knock sensors basically never go bad. E.g. junkyard parts should work just fine.

As far as getting parts in advance, just choose which setup you want to go with, either setup will work for sure:

- For old style setup (two separate sensors, no harness), be ready to go by just getting the knock sensors. If you get in there and find out your car was converted to the new style then you can just remove the conversion adapter/harness and go back to old style. That's probably the cheapest route.

- For new style knock sensors (two pre-attached on one harness), you can be sure to have the right parts on hand by getting (1) the conversion adapter/harness and (2) the pigtailed knock sensors. That allows you to convert old to new. If you get in there and already have the new style then you can simply return the conversion adapter/harness at the end of the job.

A 94 is most likely still old style, but I agree you can't know without looking.

[rsmigel]

OK, so I took the advice above to remove the radiator fan to gain a little more access to see the knock sensors. And remember, there are two of them, one on the passenger's side of the block behind an EGR hose and one on the driver's side. Using a mirror I can see the driver's side knock sensor (I have the discrete sensor style, not the style with two sensors integrated into one harness) but it is impossible to see, let alone reach, the knock sensor on the passenger side. My check engine light does not differentiate between the two sensors so I plan to replace both. So, in the end, I burned two hours learning how to remove my radiator fan but I'll need to remove the intake to replace the two sensors. I may only need to remove, clean and reconnect the sensor connectors but while I'm in there I might as well replace the sensors and check the EGR system I replaced 10K miles ago.

I don't expect the intake removal to take more than 2-3 hours with steady work given that I've already removed the intake once and I don't need to replace the EGR plumbing. Here is an excellent video showing what to do to replace the ERG system, which entails removing the intake manifold:

I picked up a few items to do the job: (2) Bosch Knock Sensors (P/N 0261231046 or 0261231006), (1) Intake gasket Victor Reinz 9146266, 10 Fuel Injector O-Ring Kit - 30731375KT and (1) Oil Pick Up Tube O-Ring - Reinz 30637867.

[erikv11]

That 30637867 is for inside the oil pan. I wouldn't buy Reinz on it either, FWIW.

[rsmigel]

That 30637867 is for inside the oil pan. I wouldn't buy Reinz on it either, FWIW.

Darn, bought a throttle body gasket I don't need either.

I purchased a Reinz intake gasket. Isn't that OEM quality?

[erikv11]

I actually don't know on the IM gasket. Some of the Reinz gaskets are not great, for example would not go with their head gaskets, their cam seals are junky. Anything rubber I always advise be super careful on the source, I buy from Volvo unless I am certain about Volvo's manufacturer. But I wouldn't sweat it for the IM gasket.

Maybe pull off the throttle bottle at this time and clean it super well, since you have the gasket? If you do, be careful to not douse the TPS with solvent.