Coolant Temperature Sensor for 73 Centurion 455

**Buicklady** · 08-18-2011, 07:09 AM

Can you please tell me where to find the coolant temperature sensor on the engine?To me it looks like a spark plug. My husband passed and I am now the know nothing mechanic!!! My original water temperature gauge stuck in the middle when the engine overheated. I was told by a mechanic that he would have to take the dash out to replace it and I don't want to do that. I decided to have that sensor attatched under the dash with mounting panels instead but I was told I should still replace theTempsensor.Heres hoping one of you can give me some advice,love my car and it is missing the car shows because of this problem!!! Thanks in advance.

**bobc455** · 08-22-2011, 07:03 AM

Hi, Buicklady!

As far as I know, the coolant temperature sensor is located in the intake manifold. If you remove the air cleaner housing, it will be visible (maybe even visible with the air cleaner in place).

I'm not quite sure I understand what you are trying to do. Do you want to add an aftermarket temperature gauge? Or do you want to relocate your factory gauge to underneath the dash (not quite sure how that would work)?

-Bob C.

**Buicklady** · 08-22-2011, 03:37 PM

Thanks so much for your advice!! I am trying to add the after market water temperature gauge under the dash. My temp gauge on the dash is not working ( at least that is what it appears because the needle is stuck right in the middle )I want to replace the coolant temp. sensor also just to make sure it is working right.I do not want my dash taken out!
I hope you can understand what I am trying to do and say because this is a first for me!I had a new air cond. unit installed but the first time I drove it 17 miles using the air the car came to a boil!!I don't believe the air had anything to do with it though. I believe if I get these two gauges replaced that the problem may be solved. Thanks again for your help and if you think of anything else please pass it along!!! I love my Buick and want to show it before summer is gone!

**bobc455** · 08-22-2011, 04:31 PM

Buicklady-

First of all, the gauge isn't necessary for a show. As long as you aren't leaking coolant, the temperature gauge is really just a diagnostic tool and not necessary to drive.

However, if you have overheating problems, then you have some other issue. Typically it is a clogged radiator, but it's possible that you have a different issue as well. Most frequent causes for overheating:
- Clogged radiator
- Worn-out antifreeze (should typically be changed out every 3 years or so)
- Fan not working correctly - especially a clutch fan
- Worn-out thermostat

For those of us who do our own work, those are pretty easy fixes. However if you are having a real mechanic charge you for the work, these can get pretty expensive. Do you have a friend who can help you work on the car?

-Bob C.

**Buicklady** · 08-22-2011, 07:49 PM

I am hoping that my son in law or son understand what needs to be looked at from what you are saying. Mechanics around here work mostly on farm tractors ( no offense) as I live in a rural town in Indiana. I will call the man that installed the air cond. and ask if he flushed the radiator though. We did put in a new thermostat so I guess that isn't the problem. The last time I drove the car I was 22 miles from home and it was boiling,the thermostat said hot in red letters!!We got it cooled down but when I got back home it showed the needle at the half way mark. I lifted the hood and it was boiling again. The needle hasn't moved since then. Strange that this happened the first and second time I drove it after having the air conditioning unit installed.
Once again, thank you so much for your input and things I can check out. I will also drain the anti-freeze and replace it with new as I know it hasn't been done since before my husband got sick, he passed 18 months ago and I know that nothing had been done to the car for about a year or 2 before that.
I love my car, it is triple black, 50,100 actual miles and a love to drive! I am anxious to drive it before the snow flies again!!! Have a great evening!

**corey wilkins** · 08-22-2011, 08:56 PM

take it to a radiator shop

**bobc455** · 08-23-2011, 04:49 AM

Well if the thermostat was changed, then at least some of the coolant was changed. Some mechanics would drain & fill the entire cooling system when they change a thermostat - some coolant has to be drained, but if your mechanic drained some of the coolant then he might have drained all of it (that would not be an uncommon thing to do).

My head is spinning round and round to try to think of recommendations. Radiator cap, coolant test, lower radiator hose, etc. But I guess above all, you need to find a "car buddy" - someone who is a 1/2 decent backyard mechanic, but who isn't going to charge you $95/hr and triple the cost of your parts. Your car is fairly basic, but it will take some time to go through and check stuff. I'd hate to see you throwing hundreds of dollars at a problem which you could have fixed for very cheap.

For example, after I've been thinking about this, I'd bet that your real problem is that your lower radiator hose is collapsing while you drive. A new hose is about $15 or so, but by the time a "real" mechanic diagnosed the problem, fixed the hose, etc., you'd probably be into $125 or $150 for time and materials. A "car buddy", however, would do the job in exchange for much cheaper (maybe a total cost of $40 including the hose, some antifreeze, and a 6-pack and a sandwich).

Maybe you will need a radiator, or a fan clutch, or who knows - very hard to tell just from your description ("boiling"). But I'd hate to see you throw several hundred dollars at a problem which might be fixable for very cheap.

I don't mean any disrespect for "real" mechanics, but they can be fairly expensive.

So with regards to your original question about the gauge, I don't think I've ever seen the actual gauge fail. Most frequently I've seen a wiring problem, and sometimes the sending unit, but I've never seen the gauge fail. I'm not saying it is impossible, but I'd check the "easy" stuff first. (The dash is quite a chore to remove and repair).

-Bob C.

-Bob C.

**Buicklady** · 08-23-2011, 08:07 AM

When I referred to "boiling" I was talking about the small plastic container that says "engine coolant only". I think one of my friends called it an over flow? I do know that it is supposed to be full which it was but by the time I got to my meeting place it was almost empty.It had "boiled out" and was to hot to touch. One of the guys I was meeting to go on to the show with filled it with water but I brought it back home. I will check with my son in law about the engine coolant being put back in or if there is water in it!! I hadn't thought of that.
Thanks a million for all you have explained and being paient with me,lol. Heck of a time in my life to try and become a mechanic!!!!

Someone referred to that container as an overflow??
Theo

**bobc455** · 08-23-2011, 01:09 PM

Theo-

As you probably noticed, that container (overflow) is connected to the radiator. By the way, it's only supposed to be about 1/2 or 2/3 full, not all the way to the top. There should be some air in there too. Otherwise it will spill out.

First thing to check is your radiator cap. In fact, I would just replace it - they are cheap and available at any auto parts store. If this part is faulty, it will be releasing coolant into the overflow too early. This is quick and easy to change (do it while the engine is cold).

While you have the radiator cap off, visually check the coolant level in the radiator. It should be about 2 - 3 inches from the top, and be a light green color. If it is brown, muddy, dirty, etc., then the radiator & engine should be flushed (or minimally, drained and refilled). If it is low, then you can fill it up to the top (any extra will eventually work its way into the overflow container and it will eventually settle out to 2-3 inches from the top).

If you replace the cap and the coolant looks good, then we can figure out the next steps.

-Bob C.