Engine Temperature Sensor Woes

[TomoHawk]

Would you believe the connection pin for the coolant sensor (for the gauge) pulled out!?    

I had to replace the bullet connector and thus the whole wire, and while I was pulling out the slack, the thing suddenly got loose, so I kept pulling and there was the end!  FYI, the pin has a wire that goes through the sensor body, to the base of the sensor, where there's a little washer-like thing that probably generates the resistance for he gauge.  The sensor is hollow.   It's not leaking coolant.

BTW-  can you get the connector for the other (EFI) coolant sensor?  It looks like a fuel injector connector, but the groove is offset, probably so you don't plug it onto the wrong thing.  The wires broke off inside the old factory connector.

[Captain Obvious]

On ‎4‎/‎30‎/‎2018 at 5:46 PM, TomoHawk said:

Would you believe the connection pin for the coolant sensor (for the gauge) pulled out!?

Would I believe it? Absolutely.  Haha!

The sensor shell is what they call a "thermal well". It's essentially a dry cavity that is inserted into whatever fluid you are trying to measure. The well keeps the sensor segregated from the fluid. That sensor actually makes it's seal at an angled face on the body about halfway down the shank. The threads are on the dry side.

As for the EFI temp sensor, I'm messing with one right now. I had bought a new sensor a while ago and I'm just now putting it in. The new sensor has an offset tab on the body, but my original one has the tab centered. And the groove in the mating connector on my car is in the center as well (matches the old sensor).

Does your car have an offset groove on both the connector and the sensor?

[TomoHawk]

Yes, both the sensor and the old, factory connector has  the offset tab.

I think I could just use a Dremel with a small grinding stone or bit to make a groove on the new connector I wired on.  I can get the connector on as it is, but it's not easy.

What I have is an engine harness from a BMW which I got from a recycler in AL.  Vines Auto)  I saved all the injector-style connectors and some others that would fit my engine, but none of the m have the offset groove.

[Captain Obvious]

Well that's interesting. My car has no offset on either the sensor or the connector. They both have the tab centered. The connector is a new one I put on when I rebuilt the entire harness, but I'm assuming the sensor is original.

Now... Adding to the confusion, is that my new sensor (which I haven't installed yet) has the offset tab. That means I'll have to make some change as well. I'll either have to change the connector over to one that has the offset slot or modify something like you mentioned. However, I think it would be a lot easier to grind the male tab off the sensor body instead of trying to grind a second slot into the connector housing.

Even easier might be to pull the connectors out the back of the connector shell and get a replacement from a junkyard. Most of that style of connector that Bosch used is interchangeable between bodies. Been a while since I looked at the details of those connectors, but maybe cut a connector off any car that has the slot where you want it, take the old pins out, and snap your existing pins into the body?

 

 

[TomoHawk]

I just presumed the offset tab was so you don't connect the things wrongly.  The one is a resistance to the ECU, an I think the other is for the thermotime switch. 

That suggestion to go to the JY is reasonable.  Besides, you can take your notepad, tape measure, camera, snipper, (sandwich?) etc., and maybe make a few notes on something you might want to get later.  I could walk several miles browsing the pull-a-part in my area- and all that entertainment for just $1.

But it would help to know which types or makes of cars have the needed connector.

Edited May 3, 2018 by TomoHawk

[Captain Obvious]

Yeah, I also presume the tab location was to try to prevent improper connection. Which makes it odd that my car has the centered tab on both the temp sender and the thermotime. It makes much more sense to have those two devices keyed such that it would be difficult to connect them wrong.  Maybe a PO switched mine around somehow.

In any event, the reason I'm messing with mine right now is that I removed my cold start injector years ago, and (since it's now useless) I'm removing the thermotime as well to simplify things. In fact, I'm replacing the whole thermostat housing with one from a 260 because it's simpler and has fewer holes.

[TomoHawk]

You were correct.

I just took a photo of mine.  It has the groove centered on the old connector, as you see here. So I will try to make  an off-center groove on the connector I just wired on, and if not successful, I  will file off (what's left of) the old off-center tab.  But in the long run, I think I will see if I can get the correct sensor & connector, just for a little piece-of-mid.  Maybe someone can identify a source for the correct sensor & connector.)

It's no wonder the thing was a PITA to get off, and the other slipped off easily, after pressing the retaining clip.

The second photo is of the sensor itself.  I'm not sure it it's the original sensor, because I replaced several including the thermotime switch  many years ago.

Edited May 5, 2018 by TomoHawk

[TomoHawk]

Hey,

Are you sure you have the correct sensor?  I'm wondering if I got the wrong one (because some computer says it's "equivalent") so it might be making my engine run, but not like it should.    looked at  some of those things on eBay, and every one had the tab in the center.

I know I replaced the thermotime switch with one from BlackDragon, but I think the others are "original" but you never know for a 30-year-old car.

[Captain Obvious]

Am I sure? Not really, I guess. I bought one off rockauto a couple years ago because it was cheap and it came from the same location as something else I was buying so the shipping was free.

If you look at rockauto, they have about ten different offerings for this sensor and some of them have the center tab, some have the offset tab, but most of them have no tab at all.

The temperature curve would matter more to me than where the tab is. I'd just file the tab off and be happy. But if the temperature response is wrong... That would be an issue.

[TomoHawk]

This is what happened to the gauge sensor:

 

[TomoHawk]

I think there is information on the atlanticZ website(resistance versus temperature data) to tell you which sensor should be the right one, but you'd have to buy a few then check  the calibration to find the correct sensor. I think that's unless you can get one via the Nissan factory part number, which should be the correct part for your engine.

Edited May 5, 2018 by TomoHawk

[Captain Obvious]

Well I tested my original EFI temp sensor and my new replacement (with the offset tab) in a pot of water on the stove yesterday. The results are that I believe the replacement is close enough to the original to be considered a suitable replacement.

I've got graphs and charts and numbers and stuff that I will post when I get more time, but unfortunately I'm headed out of town now and won't be able to get to it for a couple days.

In the meantime, I can tell you that the sensor I bought was AIRTEX / WELLS5S1523 (SU4115). Interesting that the pics on rockauto don't have any tab, but the part I have definitely has the offset tab.