3XAZOWNER

There are four sensors in the front of the housing thermo area. My gauge shows the temp is maxed out but the car is NOT overheating and is running fine. I figured it must be a sensor. That is where it gets crazy. Which sensor does what? This is what I have gathered from searches:

One sensor has a wire coming out of it, i have been told that it is the aux. fan sensor.

One sensor has a yellow wire with a bullet shaped plug clip going to it, i have been told that it is the water temperature sensor for the gauge.

One sensor has a injector type plug that goes to it, i have been told that is the thermo time sensor that controls the cold start valve.


Then there is one sensor that has a plastic cap with three hoses running to it. I have no idea what it does. Any ideas?

Can anyone verify these sensors or correct me where I am wrong?
I went to the Nissan dealer yesterday and a buddy of mine looked it up and it only showed two sensors and both were injector type plug ends.
I am trying to get my gauge to work correctly, before i put it on a 7 hour trip to ZDAYZ in N.C.
I swapped a rebuilt motor from my parts car to my driver that I bought in Jan 06 for $650.00.
The analog temp gauge in the parts car worked correctly before i removed the engine.
The digital temp gauge in the driver worked correctly before i removed the engine.
But when I put the engine from the analog gauge car into the digital gauge car it doesn't work right. I think all is wired correctly. Any suggestions?
and what is the sensor with the black plastic cap with three small hoses going to it?

Skully

are these what you are talking aboot?

jfairladyz

3XAZ, you are correct in your identification of all those sensors. The remaining sensor you are foggy on, the one with the hoses, is not a sensor. Its a thermal vacuum valve and it's responsible for controlling the vacuum advance on the distributor. It keeps the advance from engaging while the engine is cold.

And just to verify you, yes, the one with the Yellow wire is for the guage.

3XAZOWNER

The one from the dealer looked similar to that, but mine only has one that has a injector type clip and the dealer says that it is the thermo time sensor that controls the cold start valve i am attaching some pics of the one from my engine if i can figure out how. They show attached at the bottom so we will see what happens. The dealer went back to the old microfish this morning and found the one he says I need.
the first thumbnail shows three of the sensors.
1. what they say is the thermo time sensor for cold start valve (has injector type clip).
2. the sensor with the wire coming out of it, which they say is the auxiliary fan (injector fan i suppose?)
3. a sensor with a black cap don't know what it does, but it has broke off of the sensor on the now installed engine. it has one medium and two small (vaccum hoses going into it.

the second thumbnail shows:
4. the stem like sensor (to the right and up from the black capped sensor), that i have been told is the water temp sensor that signals the gauge. it has a yellow wire with bullet shaped female clip. My gauge is not working. but was working with previous digital engine and the engine i put in had a working gauge in its previous car.

My next problem is that the black cap has broken off the sensor, the dealer said this would cause my car to idle rough, but it runs great except that i either show no temp as it did tonight or maxed out temp. gauge.

jfairladyz

In your pics:

First pic:
Top right is the thermotime switch
middle left is the water temp sensor for the A/C.
On the very bottom is the TVV I mentioned

Second pic:
The sensor above the TVV in the second pic is the coolant temperature sender for the temperature gauge. You want a sender, not a sensor. Do NOT get the injector style sensor if you're trying to fix you're gauge. It's the sensor with the yellow wire that you want. It's around $20.00 from the dealer without the sleeve nut.

jfairladyz

And just so you know, the first time I went to the dealer to get a coolant temperature sensor I recieved a cylinder head temperature sensor (known as a water temp sensor). It also uses an injector type connector but it's normally located on the passenger side of the cylinder head. That is what is pictured in Skully's post. Not the thermotime switch. Though they do look similar.

3XAZOWNER

Yes, the one like skully showed me was what the guy tried to sell me. his computer showed two in thermostat housing with a injector type sensor, but i told him i only have one with an injector type plug. I will also need the thermal vacuum valve,my son broke it off and tried to glue it back on. That TVV comes as one unit right? If you break that black valve cap off you see a stem like sensor inside it. Thanks for the help, the dealer told me what he thought i needed and has it ordered. I also need to get a TVV ordered too.
thanks for your help and skully's on this. If it weren't for this forum i would have tossed a lot of money paying someone else. thanks again, will let you know how it turns out.

jfairladyz

Yes, the TVV comes as one unit. And yes, they break easy, so be careful when reinstalling it and the rest of the sensors. Install the TVV last or you risk breaking off one of the vacuum line fittings.

RodMoyes

I can vouch for that

Rod.

81 Black L28E

One thing i found in helping figure out what everything is and where it all goes and how much it should cost is a victoria birtish catlog ..i dont buy from them...
well only one or two small things , however they list all the parts and have break aways to show you where it all goes ...its worth the 5 bucks to order one or mabe it was motor sports that made me pay ...ether way both are of good value to any zcar owner......dealers are a bunch of wack *** fools if your trying to get a part for anything thing that wasnt made in the last five years ....

Bob79280zx

Didnt want to start a whole thread about this, but have you guys ever watched your Temp gauge bob up and down. Mind did this last night, it doesnt move a whole lot, but it was moving back and forth, not a drastic movement, but i could watch it go back and forth.

Any ideas?

Bob

NismoPick

It should do that. As driving conditions change, so will the temp a lil. If you're going full throttle up a hill, the engine will obviously get hotter than coasting down a hill.

When I rebuilt my L28ET, I used the 190 degree thermostat, but when I was hard on the throttle, the temp gauge would go over 3/4 the way. I put in a 160 & I can throttle that biotch all day now.

PooFlinginMonke

Weak battery or bad connection from body to engine or body to negative cable......or a bad alternator can cause that.

NismoPick

There would be many other signs if that were the case.......

Bob79280zx

I just threw in new alternator about two months ago. i just thought it was kind of weird, i understand it will move under diffrent driving conditions. my 87 integra, yes, i was once a honda owner, would move if i looked at it funny at a stop light. i just had never seen the bob effect on the gauge before, just thought it strange. But it never overheated or anything, so, no biggie.

Bob79280zx

BTW...Ok, i was looking at the illustration at the top of the thread. I understnad that the smaller, shorter sensor is the water temp, but did anyone explain what the bigger one is to the left of it is. I know the sensor, with just the one wire that attaches to it is the one for the gauge. i unplugged it once, and wow, not temp reading. So, what does that sensor do? I just call it the bigger one when referring to it.

jfairladyz

^ Thermotime Switch. It controls the Cold Start Valve.

Bob79280zx

Thanx j.

PooFlinginMonke

Now just don't start checking whether that green/white wire that goes to pin 4 of the ecu does anything because it doesn't.

Not sure why they ran the wire to an ecu that doesn't populate the pin.

RodMoyes

Maybe it's just an optical illusion caused by the maniacle way you "bob" your head while listening to all that shitty Misfits music...

Rod.

NismoPick

Mm. It's actually an optical illusion. It's the pattern on the pants. It's not flattering in the crotchal region. I'm actually taking them back right now.

Bob79280zx

Don't act like your not impressed!

I dont know if you know this, but i am kind of a big deal. People know me. I have many leather bound books, and my apartment smells of rich...Mohagany.