Cooling system questions

899 Views 5 Replies 4 Participants Last post by gregert12, Oct 13, 2010

xor1

Discussion Starter · Oct 5, 2010

Anyone know:

- What the capacity of the TJ Rubicon 4.0L cooling system is? My Factory Service manual says 9.9L (10.5 qts), my owners manual says 13.7L (14.5 qts). I need to know how much coolant I need to add to get a 50/50 mix after flushing wih water.

- What size is the square drive drain plug on the engine block??? I just assumed it was a 3/8 drive, but that doesn't fit. WTF :-x What size is it and where can I get a tool to take it out? I can't seem to drain off enough water to add in even 4 qts of coolant using only the Rad. drain.

- Are there usually any problems getting air trapped (vapor lock) in the system when you drain and refill? If so, what do you need to do to prevent or purge the vapor lock?

Thanks!

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JimmyB

· #2 · Oct 7, 2010

how close is the 3/8 drive from fitting? if the square is in between 3/8 and 1/2 then it's probably a custom one that they don't intend for you to remove. try pulling the lower hose off the motor that'll let some more fluid out....you could pull the upper off the radiator and then start the motor for a second and that'll pump some out. just don't run it very long.

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gregert12

· #3 · Oct 7, 2010

xor1 said:
Anyone know:

- Are there usually any problems getting air trapped (vapor lock) in the system when you drain and refill? If so, what do you need to do to prevent or purge the vapor lock?

Thanks!

No. After filling, keep the radiator cap off for a few seconds with the engine running. Keep filling until the fluid level does not drop, secure cap and check the reservoir.

You can also drain the rad by turning the drain plug (plastic)

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xor1

Discussion Starter · #4 · Oct 12, 2010

Well, I never did end up taking the block drain plug out. Apparently it is a 5/16" square drive - I'm still not sure where I would get this tool although I'm sure my Snap On tool dealer would love to sell me one for a ridiculous amount of money. I've read a lot of people just grind down a 3/8" extension.

I just ended up flushing the cooling system over and over until it all came our clean, then drained off enough water to add in around 7 quarts of coolant. If you keep the external tank up to the full line, the system purges any air if you just idle it for 10 mnutes unit its warm and then let it cool off completely. You may have to top off the external tank while it is cooling down. Check the level again after the next couple hot / cool cycles.

Anyone know if a standard cheap specific gravity coolant tester (to determine the % coolant in the mix) will work accurately with the G05 HOAT coolant?

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f9k9

· #5 · Oct 12, 2010

xor1 said:
.............Anyone know if a standard cheap specific gravity coolant tester (to determine the % coolant in the mix) will work accurately with the G05 HOAT coolant?

I don't see why not. I went through the process this past weekend and the FSM does include pulling the block's drain plug
to do a coolant change.

I parked my heep with it's arse end uphill to drain and turned around to fill it up but, didn't pull that block plug. One thing that you are probably aware of is if, the HOAT isn't premixed, is to get distilled water to add. I paid under $2 for 2 gallons of it at the grocery.

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gregert12

· #6 · Oct 13, 2010

xor1 said:
Anyone know if a standard cheap specific gravity coolant tester (to determine the % coolant in the mix) will work accurately with the G05 HOAT coolant?

This only measures the glycol level and will work with the HOAT coolant, you need a hydrometer for the coolant concentration(do you mean this by your question?). If you are running the low/no-tox addictive (propylene glycol), you will need a different gravity tester, such as this http://www.247autoparts.com/store/antifreezetester.html.

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