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Coolant temp sensor fixed my smelly car

vwblue1967

Member
Joined
Apr 3, 2010
Location
NC
This is more of a post for information hopefully to help someone with a nasty exhaust smell.

I have owned my 85 245 n/a for several years and the exhaust has always been smelly. I wasn't sure if it was a bad cat (so I gutted it.. shouldn't have) or bad fuel mixture. I have always got decent mileage usually around 26 mpg so wasn't really sure it was running rich. I searched for rust holes in the rear of the car, extended the exhaust pipe thinking maybe it didn't stick out far enough, checked the rear hatch seals...it stunk. I couldn't roll down the windows without it sucking in a bad smell enough to make your clothes stink.

Last night I swapped in a new coolant temp sensor and it fixed it. I didn't have to remove anything probably took a good 20 mins to figure out the best way to squeeze my hands and tools in there but it was a easy cheap fix. Ive read so many articles about a sulfur smell, rust holes pulling in exhaust, bad gaskets... So just a heads up this may make your car not stink like mine.
 
When I bought it, it had thick nasty green looking coolant. I flushed with distilled water and replaced with zerex g05 I believe...it's been a while. It was something I found here that seemed to be a good alternative to Volvo coolant.
 
Coolant should not affect temp sensor readings unless you are thinking of oxidation isolation, in which case the radiator would also be affected and the car would have cooling issues.

100% coolant or coolant that the PH has gone bad is no good for your motor. Distilled water is good, I believe RO water may not be well balanced.

When good water is not available, I have resorted to buying the 50 50 coolant (even though it costs more) it has properly conditioned water in it.

PH test your coolant if it has been in the car a long time. PH test strips are available at NAPA or other fleet type distributors (truck shop).

If the PH goes bad it will increase galvanic corrosion and eat away at the softest metal parts.
 
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I would think that the replacement coolant temperature sensor allowed your car to go into closed loop operation (as opposed to open loop). As a result, your car is running much less rich all of the time.

Just a case of your car doing what it was told all along.

On the plus side, your fuel economy should go up. On the down side, it'll likely be a smidge less peppy.

I would also replace my O2 sensor if I were you.
 
I would think that the replacement coolant temperature sensor allowed your car to go into closed loop operation (as opposed to open loop). As a result, your car is running much less rich all of the time.

Just a case of your car doing what it was told all along.

On the plus side, your fuel economy should go up. On the down side, it'll likely be a smidge less peppy.

I would also replace my O2 sensor if I were you.




Yep...working like it should. I honestly didn't know the function of the coolant temp sensor but it all makes sense now. I drive 60+ miles a day just to and from work so I'm cool with better mileage over a little power.

I meant to mention that earlier, I replaced the o2 sensor hoping that was the original problem a little while ago.
 
It'll do the same thing if you have no/too low temp of a thermostat. Keeps the car locked in open loop 'warmup' mode.
 
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