Problem refilling coolant--could this damage something?
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Tuned
Joined: Apr 2021
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Problem refilling coolant--could this damage something?
'77 F150 with the 300 six. Just had a weird coolant issue and wanted to check in. I've had my cooling system apart (on this truck and others) a few times and never had any trouble refilling it. Always the same process--refill coolant, start engine with rad cap off, top off once the thermostat opens. Easy. Today I replaced the heater core and refilled it again. This time when the thermostat opened there's a big blast of steam out of the radiator and the coolant vanishes. I had to put over a half gallon in to bring it back up to the visible level in the radiator. Now it seems to be fine and everything's working correctly.
I'm assuming there was a giant air bubble in the block and it boiled what coolant was in there. Any chance I damaged the head? Never had this happen before. Ambient temperature was around freezing. Going ahead if I have to do this again, should I try to bleed the block by popping the heater hose off the thermostat housing?
I'm assuming there was a giant air bubble in the block and it boiled what coolant was in there. Any chance I damaged the head? Never had this happen before. Ambient temperature was around freezing. Going ahead if I have to do this again, should I try to bleed the block by popping the heater hose off the thermostat housing?
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
I doubt that you damaged the head. Hopefully, it will be quite a while before the heater core will need to be changed again, but you could try the bleeding process next time to make it a bit more gentle.
Laughing Gas
Joined: Jun 2016
Posts: 855
Likes: 56
From: Des Moines, Washington
Some thermostats have a bleed hole to vent the air trapped behind them. If you installed a new one, it may not have had a vent or you may have put it down instead of up. I bought a vacuum filler a couple of years ago, it pulls a vacuum on the system then uses that to pull coolant from a 5 gallon bucket. No more wondering if there is trapped air and no more coolant burped into the fan and being sprayed all over the engine.
Michael
Michael
Cargo Master
Joined: Sep 2005
Posts: 2,954
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I've never had much trouble with the old stuff, when we started going to transverse engine with electric fans a lot of cars had issues filling so we got in the habit of poking a hole in the thermostat with an ice pick on the t-stats that didn't have there own vent. If your's wants to be stubborn poking a bleed hole won't hurt a thing. As for your head, I can honestly say I have never had a 240 or 300 with a warped head in my entire life so they must be pretty strong. I owned a radiator shop for 20 years.
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