Sporadic coolant temps

[DOCS1]

Has anyone experienced coolant temps that jump up 20-30F then back down in a 1-2min span?

Recently the coolant temp readings on my scan gauge have been jumping around like crazy. But, only on the freeway. It'll be cruising around 200F, then start climbing rapidly to as high as 230F, and then start coming right back down. It goes up then back down in under 2 min and happens every 15 min or so while staying at 65-70mph on the freeway.

-New head gasket
-New clutch fan
-Expansion tank full

 

[Flyfish]

Potentially air in the system and coolant is only hitting the sensor at higher water pump rpm’s.

 

[jymmiejamz]

Given that it is highway driving, I’d put in a new thermostat (I consider that a maintenance item) and radiator.

 

[DOCS1]

Feels so good to finally have a steady temperature reading. The problem was either air trapped in the system or a slightly clogged heater core or both.

I added a bleeder valve to the heater hose and while I was there I also reverse flushed the core. I got some small pieces of rust out and I was finally able to bleed out all the air. No more wooshing water sounds from inside of the cabin and coolant temps are steady.

 

[robertf]

I put a wix 24770 and 24070 coolant filter on 2 of mine that were loaded up with block sealer and trash when I bought them. Im happy with the results

 

[Greg_M]

I put a wix 24770 and 24070 coolant filter on 2 of mine...

Looks a tidy way to eliminate the stepped heater hose as well.

 

[robertf]

Files attached. It looks goofy at the bottom as at attempt to clear the heatshield, which has a lot of variability as it fits fine on 1 and not on the other. Also to clear the oil lines which are all over the place when comparing disco to disco.

take the 2 rear ac bolts out, put the bracket on, reinstall.

 

[DOCS1]

Files attached. It looks goofy at the bottom as at attempt to clear the heatshield, which has a lot of variability as it fits fine on 1 and not on the other. Also to clear the oil lines which are all over the place when comparing disco to disco.

take the 2 rear ac bolts out, put the bracket on, reinstall.

View attachment 64390

Nice bracket. Thanks for sharing. I also have an Epsom green discovery with a slightly tilted PS reservoir.