Coolant temp fluctuating up and down

[El Tigre]

I use AN-10 fitting/hose so adding things into a particular circuit is made far easier

 

[GoToGuy]

One item many don't realise or aren't aware of. You do a flush and get alot of crude and old degraded coolant out. In with the new and all done! One thing when doing the flush. Pull the hoses off the heater core in and out. Use your flushing hose on those in and out fittings. Flush both ways if you desire. The heater core can become a " settling pond " for any dirt, rust bits, or other debris. Preventing adequate flow of water and insulating core from heat transfer. Good luck!

 

[GoToGuy]

You've completed your flush and now you filled the radiator. Start and run to operating temp getting thermostat to open, topping the radiator. With the cap still off i would run the rpm up getting a high flow rate. To try ensure no air pockets; as fluid level in radiator dropped, topped it off and installed cap. Released throttle rpm to idle. That worked for me. I haven't used any of the new Vacuum fill device's yet. Good luck!

 

[Courchained]

Sorry guys forgot to post what my fix was. Silly me never inspected the condition of the temp sensor. Lots of build-up. Put in a new Delphi and now she warms up to about 195ish and stays steady.

 

[Courchained]

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[Supercharged111]

I'm less concerned with that sensor and more concerned for the rest of your cooling system.

 

[Courchained]

Yea I'm due for a good block flush. Everything but the heater core lines are new.

 

[Papablunt]

What's the best way to do a block flush if the T-stat is still in place? Remove heater hose from manifold?

 

[kennythewelder]

What's the best way to do a block flush if the T-stat is still in place? Remove heater hose from manifold?

I cut the supply heater hose, and I stalled a Preston flush kit. It's a "T" that fits in the heater hose. It allows you to back flush the cooling system with a garden water hose, by removing the radiator cap. The end of the garden hose to the "T". The yellow hard plastic pipe, fits into the radiator, where the radiator cap fits, once you remove it. If been using them for years. They work grate. Once your done with the flush. There is a hard plastic cap that screws onto the end of the "T".

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