Hey guys, I've been having issues with replacing my coolant temp sensor and was hoping for some advice.

I have a 1999 EFI/OHC (fairly certain it's an SL1) that was having some issues with overheating. Upon taking out the old coolant temp sensor I found it was cracked, and clearly needed to be replaced.

I bought replacement part number SU1131VC from AutoZone, which claims it will fit my car (any S model from the same year, according to the website), and the one review for the part even backs this up. But when I go to thread it into place, it just wiggles around, almost like it doesn't actually fit. AutoZone swears it should fit, but it's simply not threading. The old part is easily threaded back into place by hand.

Anything I might be missing here? In the past I've found some really useful discussions here for working on my car, so I'd appreciate any input. Thanks!

 

Looks like Autozone, Rock Auto and Napa all show that same sensor. It is the same and used both as a air temp and a coolant temp sensor for all S series cars 91-02. From the picture it looks like 1/8" national pipe thread. If your sensor was cracked through the threaded area the hole may be stripped.

 

Hey, thanks for the quick reply. The crack was on the plastic/resin tip of the sensor, not really near the threading at all.

I'll double check the threading on the old part tomorrow, but that looked to be fine. Not really sure I'll be able to check the threading on the car itself.

One thing I've noticed is that most people recommend using thread sealing tape, but as far as I know it should screw in even without this, right?

 

Yes, national pipe thread sizes are a tapered thread not a straight thread like a bolt. The thread tape is to help seal since you do not want to over tighten and break something.

 

If and the operative word is in deed IF! The sensor is a direct replacement it should indeed thread in with out a problem.
And I do not believe that sealing tape is needed nor desired. Nor do I know from memory what the threads are for the sensor, SAE or American or Metric pipe threads.
That sensor though has long been a part that has been problematical as a replacement part as to it's proper function.
It has been a number of years since I have purchased that sensor however those supplied by national auto parts stores historically had the wrong operational function and purchasing one and installing it caused additional problems.
So the only place to safely purchase one of them is to go to a GM dealer and their parts department and order one for the Saturn engine.
Here locally a Chevy Dealer makes it known that they are Saturn Friendly.
I would with out much effort try to find a GM dealer you can order that sensor from.
Something that threads in and wiggles around indicating it is not threaded correctly is also obviously he wrong part, it really makes no difference how many places carry the same part, wrong is wrong. Get the right one.

 

Do you have a thread pitch gauge? If so, check the threads on both sensors. If not, take it to NAPA or somewhere with a machine shop and have them compare the thread count. Sounds to me like you've got one not cut correctly. Why the hell doesn't Autozone just swap you another one and let you try it? I'd sure be asking for a swap, if it were me.

 

Return the Autozone part for store credit, and use the store credit for a shock collar that is triggered whenever you try to enter an Autozone building.

If it don't fit, it's ****. Actually it was **** before it got anywhere near you and is a generic sensor with the wrong temp vs resistance curve for an s car. Sorry, it just is.

Wrong.

Obtain thru GM dealer as noted above. Was this a brass or resin tipped sensor? I thought they started using the brass in production in 99. Must have been 2000.

After knowing for a good 7 years that several million with a design flaw were out there causing overheating, seized engines those who ignored the oil idiot light, the temp gauge, and temperature idiot light-- the idiot lights design especially for them, difficult or no starting, blah blah blah.

Just like the ignition coverup fiasco, except people had to die. What do they do? Duck responsibility when they bankrupt old GM and leave its liabilities laying on a desk in an abandoned Bulgarian office building with the window open.

Profit more important than customers' lives. Sets a great example for every kid of an upper management GM employee: Duck and run. Don't stand behind your product -- those who have not yet died may back over you repeatedly.

Yeah, get an ECTS from a GM dealer. Check the connector for corrosion--if green or other corroded color get the matching pigtail and solder/shrinkwrap it in.

 

Love that rant Derf!

Seriously though, my first thought is maybe the dude at the parts counter grabbed the wrong part off the shelf.

It's not like they would know the difference. Most people that work in big name autoparts stores have very little automotive understanding or experience at all. Truly I dread buying parts because it's so rare the person at the counter has any idea what I'm talking about. Many of them don't even have basic search skills. Sometimes I ask them to just let me look it up on their computer myself because I can find it faster. Then, when you do have the right part number they'll still grab the wrong part and want to argue that it doesn't matter because it's the same part.

sorry, didn't really mean to rant.

Best policy if it's at all possible is to bring your old part with you so they can match it up.

 

What really pisses me off is the fact that most chain store employees are too frigging lazy to look in the parts catalogs under the counter for you. They see "part not available" on the computer and that's as far as they go. I wasn't like that when I worked for Autozone or Advance. I always made every effort I could to see if we had the part for our customers. Customer service was something I've always provided and yet another reason I quit working for both places. Upper management told me I was wasting too much time on busy days. When I told them I had loyal customers because I always made the effort, they shut up.

 

Hey guys, thanks again for the advice.

I went to AutoZone and swapped for a new replacement. I was feeling pretty good when I looked at it in the parking lot, because the threads looked more well-formed than on the first one. Sure enough, this one fits nicely. So it looks like the first one had bad threads.

During a test drive things are definitely running better than before, and the temperature gauge is responding in a reasonable manner. I'll look into getting a GM part to replace the generic one, like a few of you have suggested.

As for AutoZone, I can't really complain about the service. They offered to replace the part as soon as I let them know I thought it was defective, and they gave me a box with the right part number the first time, so I don't think they gave me the wrong part.