Air Trapped in Head - after fluid change?

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   How do you get the air trapped in the head out when refilling the coolant?
Never had a problem with this in the past 40 years - but last night it was a struggle.

Details:  I replaced the water pump in our 1946 CJ2A with a L134 pretty much bone stock engine. 

I filled the radiator and squeezed the upper radiator hose as the engine idled.  It took about 6 minutes to get the last of the air out of the system and I did see the temp gauge go over 220 degrees before the thermostat finally opened.  This engine temp runs about 185 degrees most of the time.  It will hit 205 normally when starting up.  I read posts about 170 degrees thermostats but every time I change one they run 180 degrees and will hit 205 -210 to open on my uncalibrated dash gauge.

I have heard of people drilling a hole in the thermostat - never done that but it is on my list of things to try going forward.

Thanks,

Adding:  Yes- I am concerned with that flash temp but will just have to see if it did any damage.

Edited by Stev - 17 May 2021 at 9:44am

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Stev Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 27 July 2016 Location: Cincinnati Status: Offline Points: 2389	Post Options Post Reply Quote Stev Report Post Thanks(0) Quote Reply Topic: Air Trapped in Head - after fluid change? Posted: 17 May 2021 at 9:40am
	How do you get the air trapped in the head out when refilling the coolant? Never had a problem with this in the past 40 years - but last night it was a struggle. Details: I replaced the water pump in our 1946 CJ2A with a L134 pretty much bone stock engine. I filled the radiator and squeezed the upper radiator hose as the engine idled. It took about 6 minutes to get the last of the air out of the system and I did see the temp gauge go over 220 degrees before the thermostat finally opened. This engine temp runs about 185 degrees most of the time. It will hit 205 normally when starting up. I read posts about 170 degrees thermostats but every time I change one they run 180 degrees and will hit 205 -210 to open on my uncalibrated dash gauge. I have heard of people drilling a hole in the thermostat - never done that but it is on my list of things to try going forward. Thanks, Adding: Yes- I am concerned with that flash temp but will just have to see if it did any damage. Edited by Stev - 17 May 2021 at 9:44am
	Stev 1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored

Lee MN Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 13 Aug. 2008 Location: Harris, MN Status: Offline Points: 4950	Post Options Post Reply Quote Lee MN Report Post Thanks(0) Quote Reply Posted: 17 May 2021 at 10:16am
	Drill a hole in the thermostat 👍🏿 2 Doesent hurt 😂. If you buy a better quality stat the come with a bleeder hole in them that in most cases has a loose rivet in it...... Lee
	LEE 44 GPW-The Perfected Willys 49 2A “If you wait, you only get older” 67 M715 American Made Rolling History

JonJ Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 18 Apr. 2020 Location: Essex, UK Status: Offline Points: 322	Post Options Post Reply Quote JonJ Report Post Thanks(0) Quote Reply Posted: 17 May 2021 at 2:49pm
	Ah the thermostat hole again I drilled one my new thermostat, fitted it and worked a treat first time. There’s a big long post about it around here somewhere

Bruce W Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9651	Post Options Post Reply Quote Bruce W Report Post Thanks(0) Quote Reply Posted: 17 May 2021 at 3:02pm
	Don’t take it out to drill a hole in it. The holes purpose is to release air as you fill the system. If the thermostat has opened once the air has been dumped. If you have air after that you have a problem somewhere. Everything I own goes to 200 or more on first warm-up of the day, and they’re all fine after that. They all have a hole. It’s the thermostat, not air (or at least it had better not be air), that causes that. As long as it settles down after that, no problem. BW
	It is NOT a Jeep Willys! It is a Willys jeep. Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep.

Stev Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 27 July 2016 Location: Cincinnati Status: Offline Points: 2389	Post Options Post Reply Quote Stev Report Post Thanks(0) Quote Reply Posted: 17 May 2021 at 5:07pm
	Sound like drilling holes in the thermostat is going to happed from know on! Thanks
	Stev 1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored

mbullism Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member x 4 Joined: 29 May 2015 Location: MA Status: Offline Points: 4783	Post Options Post Reply Quote mbullism Report Post Thanks(0) Quote Reply Posted: 18 May 2021 at 5:55am
	I have the drilled hole, never known anything different and works great... but I'm curious about these higher "warm up" temps. My normal op temp is 180ish, which will climb if pulling a hill, or towing the bantam on a hot day with the chaff screen, etc. When I start it from cold it climbs to 180ish and stops, no matter if sitting idling or just normal cruising.
	Those who do not learn from history are doomed to repeat it... Welcome to 1930's Germany