Temp. gauge / sensor location / hot at high speed.

[davida1_hiwaay_net]

Hello, I've been daily-driving my 88 Olds Ciera with the second generation 2.8 MPFI engine, turbocharged. Driving around town (stop and go) or at low speeds (55 or less) on the highway, the temperature gauge reads about 180. The ECM reports around 180 also.

When I get on the highway at high speeds (75 to 80), the temp gauge creeps up past 220. The ECM is only seeing 190-ish.

I think I read somewhere there was a known issue with this which can be solved by re-locating the sensor for the dash gauge. But I can't find it!

Currently, the temp sensor for the gauge is in the corner of the rear head, and the ECM's sensor is in the water neck where the thermostat is located.

This is the engine in question:


Should I change to the 3-wire sensor (for both the gauge and ECM) and mount it in the thermostat housing?

Other than this issue, the car has been wonderful with turbo. It is a blast to drive and has made several successful road trips out of state. Win for a car bought from junkyard!

Sincerely,
David

[robertisaar]

it could be a couple of things causing this.... guage itself could be the issue, in which case the 3 wire sensor will report roughly the same temp.

[davida1_hiwaay_net]

it could be a couple of things causing this.... guage itself could be the issue, in which case the 3 wire sensor will report roughly the same temp.

Thanks. I may try another cluster since I have a few extras.

[85_Olds_Ciera]

temp gauge creeps up past 220. The ECM is only seeing 190-ish.

Via photo, get a new radiator. Tried a new temp sender? I use Temperature Gun Infrared Thermometer and poke around to various locations also, as a double check.

On another vehicle I own, temp gauge goes from cold to where its suppose to be...but issue is where wire-terminal hooks to temp sender.

On GM, I can't recall if a ground or open circuit pegs the meter.

[85_Olds_Ciera]

The ECM is only seeing 190-ish.

If ECM's temp sensor is an old one, I'd sure plunk down 20 bucks or so, and get a new one. As a mechanic told me, as they age, they give a lower reading.