'99 V70 XC: High underhood temperatures?

[Bob Sisson]

The first REALLY hot day my V70 was showing REALLY high underhood
temperatures, actually front bumper temperatures on in dash outside
temperature display. I was seeing 140's and I KNOW it wasn't 140. (F of
course)

My (water) temperature gauge never moved from its normal resting place dead
center in it range. I did overflow a bit, but the tank returned to normal
cold level after it cooled off that night...

It seems when it gets over about 90deg, the outside (bumper) readings go
nuts...

Is this telling me something? Is something else amiss.

 

[Mike F]

The first REALLY hot day my V70 was showing REALLY high underhood
temperatures, actually front bumper temperatures on in dash outside
temperature display. I was seeing 140's and I KNOW it wasn't 140. (F of
course)

My (water) temperature gauge never moved from its normal resting place dead
center in it range. I did overflow a bit, but the tank returned to normal
cold level after it cooled off that night...

It seems when it gets over about 90deg, the outside (bumper) readings go
nuts...

Is this telling me something? Is something else amiss.

Probably the sensor is not in the correct location. There are 2 sensors
below the front bumper, one's for the dash display the other is for the
fuel computer. One should be snapped in the left grille in the fog
light hole, the other is in the plastic shield/air guide on the big
central intake on the right side, visible through the right fog light
hole grille. These locations pick up road heat, so they're a little
hotter than ambient, and will pick up engine heat during stop and go
driving. They're very slow to react, so it takes them a while to cool
off.

--
Mike F.
Thornhill (near Toronto), Ont.

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