Coolant Temperature Dropping After Hard Acceleration

[Jimbo052]

As the title suggests, my coolant temperature drops after hard acceleration. I believe normal operating temperature is 190°F and my engine will get there...but when I get on the throttle and let off, the temperature drops as low as the upper 170°F's. At that point, the temperature will rise back up to 190°F rather quickly.

The two parts that I wanted to blame at first were the thermostat and the coolant temperature sensor but after thinking about it, I'm thinking it may be the fan clutch. I'd appreciate any input I can get and I have a scan tool if anyone would like some more specific information.

 

[The_Roadie]

I'd blame the thermostat for being sluggish and not closing down quickly enough when it sees a slug of cold coolant from the radiator. At 210 degrees on the gauge the fan clutch shouldn't be engaged hard anyway and you should be able to stop it with a cloth around the edge.

You can confirm that by unplugging front fuse #20.

190, if that's really where your gauge is at, is too low anyway. Should be locked on at 210 straight up.

Will your scan tool tell you the raw temp data coming out of the sensor?

 

[Jimbo052]

Will your scan tool tell you the raw temp data coming out of the sensor?

Yes, 190°F is the true temperature reading from the scan tool. The gauge shows 210°F. I'll try pulling fuse #20, but just to confirm...what exactly will that do?

 

[The_Roadie]

It will kill the fan clutch so there's no chance (unless it's locked up) that it can overcool the radiator. A radiator can't be really overcooled anyway, since it also gets frosty in the wintertime.

Edit - if it's the scan tool temp and the gauge stays at 210, that seems to be OK and it's why the designers put the data filtering in the gauge display. Coolant temp also goes down when you coast down a long hill. That shouldn't bother you either. The system may be operating as intended. I thought you meant your GAUGE drooped from 190 to 170.

 

[Jimbo052]

UPDATE - I pulled fuse #20 under the hood and the fan was still engaged when i started the engine. The fan stayed engaged for my entire ride. I have pictures and videos to upload once I get them on my laptop.

EDIT - Adding Photos

 

[The_Roadie]

Engaged hard, or just spinning from residual friction?

 

[Jimbo052]

It looked to be spinning quite fast. Can I test this?

 

[The_Roadie]

Grab its edge carefully with a rag to slow it down. Careful if there's high friction in the clutch it will resist this process.

 

[Jimbo052]

Grab its edge carefully with a rag to slow it down. Careful if there's high friction in the clutch it will resist this process.

After initially wearing through my rag I was able to stop the fan. This was on a cold start with fuse #20 in. It looks like it has been residual friction that I've been observing.

Would a new thermostat and temperature sensor be recommended? Thanks.