This photo shows a plug, but on my 91 B18A, there is a threaded hole in the plug and a sensor that goes into it. Any idea what it is or what it does? I want to install the Endyn breather setup, but it requires removing this sensor. Endyn claims it makes no difference, but I can't believe Honda put it there for no reason. Thanks for any help.

If it makes any difference, in the next few months I will be converting to OBD-I and using a p75 ecu.

 

does it have two prongs sticking out of it, if so its the fan switch

 

I don't have it in front of me unfortunately. However, the passage that the sensor is plugged into is a crankcase passage, not a coolant passage, so I am not sure why the fan would be triggered from there.

 

Anyone else have an opinion?

 

to be honest that doesnt look like a sensor. arent those things look called freeze plugs. when they machine the block. im not sure. y dont u just remove it and see whats in it.
are u talking about the thing in the red box or the thing next to it ?

 

nope guys it ain't from machining the block but is a plug though

since I got one of those also

and put something in there be sides my finger to see where it goes

LoL

but seriously that is the knock sensor input

need it if using obd0 ecu

yuck I hate thoses but without it u won't know when u detonating

 

or also where is ur breather box at???

that is funny maybe this is where it was suppose to be???

 

that is just a ''freeze plug'', breather box is not there, he prolly took it out and b18a block dont have knock sensor nor a place to screw it in.

 

Sorry if there was any confusion - the photo is not my block, just one I found (the red box is my addition though). The pic shows a plug, but on my block the plug has a sensor that threads into it. It's got a 2-prong electrical connector on it, so it may be some sort of temperature sensor as mentioned above. Any more info is appreciated.

 

Ideas welcome. Thanks.

 

I believe that it's where the knock sensor goes.

It sure seems strange that Endyn says you don't need it, but didn't say what it was!!!!!

Wes

 

*thinking*

oil temp sensor


found on all B18A's

not on B18B's, your B18B P75 ecu doesnt look for it

come one guys!! that was an easy one

 

Oil temperature sensor makes sense, judging by the location in the crankcase passage. I just did a search on some part numbers, and learned some strange things:

1991 B18A: sensor located in the block, PN 37760-PM3-003
1992 B18A: sensor in same location, PN changes to 37760-P00-003 OR 37760-P00-003 (both are listed)

Skip to 1994: the B18B has the same part numbers listed as the 1992 B18A sensors, but the sensor is located in the thermostat housing! In all cases, the sensor is described as 'switch assy.' or 'switch assy., thermostat'.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by im_poor &raquo;</TD></TR><TR><TD CLASS="quote">does it have two prongs sticking out of it, if so its the fan switch</TD></TR></TABLE>

Is this it? The same sensor used in 2 different places - is it used for the same purpose? Or is it doing something different on the B18B?

There is also another temp sensor on the back of the B18A blocks which threads into the water jacket and doesn't seem to appear on the B18B blocks. The sensors in the head seem to be the same (although PN changes for one of them in 1994).

If anyone can make sense of this, I'd be very grateful.

 

definately not a knock sensor or a fan switch. not sure what its called. The part he's talking about is about 4-5 inches long and threads into crank case passage,where the red box is.

 

It is a spot for an oil temp sender for the ECU. I remember asking myself this same question a long time ago and from what i remember it also ties into the fan circuit and can allow the fan(s) to run if the oil temp is above a certain temp. I could be wrong though... BTW, they also came on B17's.

 

Oil temp it is. After looking through my Helm manual, it appears that it is used to run the A/C fan for 15 minutes if the engine is off and the oil temp exceeds a certain limit. No sign of it on the 1994 circuit. I think I can safely remove this until the OBD conversion. Thanks for all the help guys.

 

yah tehy are on preludes also along with a few other obd0 cars

but yes u can ditch the sensor

and no honda didnt move it to the water neck on the b18b, you are thinking of the thermo fan switch

Glad we could help