cooling system capacity

DDCxj

NAXJA Forum User
Location
Natick, MA
I got my new radiator today and will be putting it in on saturday but I got a couple of questions:
First of all, what is the cooling system capacity for a '91 w/ a 4.0? I will also be flushing the entire system, so is it necesary to take the plug out of the block or can someone tell me how much water will be left in there so I know how much straight coolant to put in?

Dean
 
If your flushing the entire system it would almost mandate removing the block drain plug wouldn't it. :doh: As for capacity it holds 12 quarts so you'll want 1.5 gallons water and 1.5 gallons coolant.
 
If you get all the cleaner out with a prestone back flush kit you will have 100% water in there. Dump in a gallon of PURE 100% Mopar coolant, that should be pretty close to 50/50 as a start. Then split the other gallon of mopar coolant into the just emptied gallon and refill one with distilled water. You now have a 50/50 mix in one of the gallon jugs. Dump that in and use one of those prestone coolant testers to check the mix/protection level. If it's still low protection wise add more pure coolant till you get where you want it to be... Put the prestone flush kit on the old heater hose. When replaceing the heater hoses remember not to pull them off, slice them lengthwise with a razor knife, less chance of breaking the heater core bungs.
Remember to remove the overlfow tank and clean it out good then reinstall and fill it up to the hot mark, once you get it pretty much burped the system will pull the excess in as it finishes it's self burping. If you are putting a new rad in I would do the hoses also as well as the fan clutch seeing as how you have it all apart anyway...
1. Install backflush kit on old hoses. Flush system, add cleaner, follow directions and back flush. Remember to turn your heater on hot so that gets flushed too. The 7 hour flush works the best.
2. Remove old hoses, fan clutch and old rad. Remove and clean overflow tank.
3. Install new hoses, fan clutch, rad, tstat and new pressure cap.
4. Add gallon of pure coolant. Start topping off with 50/50 mix.
5. Test protection level with prestone tester [about $3, looks like a baster with squeeze bulb] If low protection level add more pure coolant.
6. Burp system. Done
I use the OEM Jeep hoses, they come with clamps, covers, spring and they fit. I bought them a couple weeks ago, it was either $60 or $80 for the complete set.
 
The tip on the heater core is a good one. I've had to change many heater cores after someone else had just installed hoses.

Another tip on the heater core is to go to a hardware store and purchase garden hose female repair connections. Place them on the heater hose ends at the engine side of the hoses. Attach one to your garden hose and power flush the heater core. The other hose end should be directed into a bucket to catch the discharge. It will be filthy. Then swith the garden hose attachment and flush in the opposite direction.

I did this to my 89 after reading a post from Martin, what a difference in heat in the cab & low cooling temps after completing this "heater core only" flush.

Last thoughts; The flush may break loose metal that was sealing a leak you didn't know about, so if there is any concern that the raditor is a goner, than just replace it. Got a price for a 3-row GDI from 1-800-Radiator this week for $129.
-and-
Dispose of the old coolant properly, it is poisionous to the environment.
 
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