I have a 2001 XJ with a radiator full of the most ungodly thick and dirty coolant you have ever seen. I plan to flush it by removing the lower radiator hose. My question is, can I run the engine with the lower radiator hose out and a hose pushing water through the rad filler cap? I do not want to have to connect the hose, run it, disconnect it, drain it, and then do all that again about 4 times.

Also, is it ill advised to disconnect and reconnect a radiator hose so many times. I have a screw style hose clamp.

 

The coolant flows in the top hose from the engine, and out the bottom hose. running the engine with the bottom hose off would just dump everything out of the engine into your rad and back out the bottom once it reached temp and the tstat opens fully. Unless I have overlooked something really dumb, why are you running the engine to flush your rad only?

 

To add on...I suggest you flush the whole system because if the rad is full of gunk, everything else is too. You need to figure out why the coolant is brown first, is it oil? do a search on how to flush the system properly as to not just flush crud from one area to the next. I believe flushing the heater core, rad, and block separate is a good idea.

 

I had simulat issue will rusty watery looking coolant when I first bought my XJ. Flushed everything, radiator, block and heater core. The stuff that came out of the heater core was the WORST. So YES, flush the whole system to get it all out. I flushed mine three times to get it normally looking.

 

can you flush the engine block by removing the upper and lower radiator hoses on the engine side and running water through the top one?

 

Not really. Cause there is a thermostat.

 

what about if you removed the thermostat? I am trying to flush the engine block too I just do not want to **** around with that drain plug. Or maybe I will just leave the thermostat in and run clean water through at a slow rate so as to remove anything just laying in there.

 

Only way to be sure to get all the crap out is to pull the plug on the side of the block. It's a lot less work that pulling the thermo.

 

I used to have a backflush "T" in one of my heater hoses that worked decent. I was able to flush my heater core with it by removing the heater hose from the pump. I could then hook that all back up and flush the engine with it off. I didn't have to flush the rad since I replace it, which may be a good idea for you assuming the passages are all blocked up with gunk.

I hooked everything up and ran it up to temp and drained out the water the best i could at the lower hose. I did that twice, but I had a fairly clean system. They sell flush kits and cleaners that work quite well I hear.

 

Sure u can.....remove the heater hose from the nipple on the t-stat cover and remove the bottom rad hose from the pump. Place a garden hose at the stat nipple and flush crud out at the pump. This way, u flush both the head and the block.