How much coolant needs to be drained when changing thermostat?

[cfiiman]

Got all my parts from Tator and would like to do it this weekend. Just wanted to know about how much fluid should be drained so I can take off the hoses and thermo without coolant spilling everywhere. The car is a 94.

Thanks!

 

[jdeft1]

A word of advise:
Do not try to drain it buy pulling the plug on the bottom of the radiator! Just pull the bottom hose and let it go into your catch pan.... The drain plugs are known to rip out of the bottom of the radiator!

Can't remember exactly how much will come out. I'd have 3-4 gallons ready to go back in tho.

Good luck! That's a PIA job.

 

[cfiiman]

Thanks, I used the drain the first time and didn't have a problem, it would be much more controlled if I used that again. My thought was to only remove just enough coolant to do the job, not all the coolant in the system which is what would happen if I pulled the lower hose. I just changed the whole system about 6 months ago with long life coolant, I was going to just reuse wouldn't that be ok?

 

[Steve-Indy]

Hi, "cfiiman". As I have not tried your plan as outlined, I will GUESS that you might get away with draining only a quart or so...especially if you loosened the t-stat's hoses first so a little air could enter there as the fluid flowed out. Again, just a guess. Be sure to avoid damaging the temp sensors back in that tight space!! Also, take care to put the new t-stat vent hole on top. Good luck.

 

[cfiiman]

Steve, thanks for the tip. Maybe I should just drain it all if that is what everyone else does, I just thought it made sense to only drain enough to work

 

[cfiiman]

Steve, I just checked my thermo from Chuck, it is a NAPA 180 but I don't see a vent hole?

 

[Steve-Indy]

Please consult page7-9 of your 1994 viper Service Manual...paying special attention to the last line of #1 under "Installation". Obviously, the OEM T-stats must have said bleed hole...and NAPA does not by your description. Doubt that you should sweat it. Check out page 14-20, figure 9 for temp sensor location. Look at page 8W-19 Fig.12 @ lower lefthand side of page as well. Have fun!!

 

[cfiiman]

Figured it was the OEM one but wanted to ask, thanks for the clarification. What was the vent hole for on the OEM one, sorry if that is obvious, but I'm thinking if it was on the thermo iteself there would be no way to access it so it couldn't be for bleeding the system or anything could it?

 

[Chuck 98 RT/10]

Seems to me it would be a good time to flush the system. It should get fresh fluid every year anyway.

 

[cfiiman]

Every Year it is long life coolant.

 

[Chuck 98 RT/10]

Your definition of "long life" and Prestone's definition is probably not the same. Between a couple gallons of coolant and a couple gallon of distilled you're looking at $25. Change it.

 

[cfiiman]

That is true, just thought 1 year was pretty soon to change, especially with only a few thousand miles, but hell if I have to drain it anyway your right just put new in, thanks.

 

[drlee50]

you can just drill a hole in it. and you should drill a hole in it.

 

[cfiiman]

you can just drill a hole in it. and you should drill a hole in it.

Thanks, I'm starting a new thread since I can not find a thread on the best way to do it.