I've had my XJ for about 4 years now and the cooling system has always worked well. It sat at 210 during several long weekends of driving around in the Mojave desert. The Jeep was driven maybe once a week until recently... It was driven probably 2000 miles in the past couple months with a couple of long 400+ mile trips. I opened up the hood to find red spray from a bad radiator cap (replaced that) but what happened to my coolant?!?

It was green and clear as recently as about 3 months ago and now looks like the worst maintained system I've ever seen!! What would cause this??
Still stay around 210 on the gauge, although it's hasn't gotten too hot outside recently.

 

Transmission fluid is red......hope it's not green now.....if it is, u need a new radiator and give the tranny several good flushes. Give the cooling system a good flush as well.

 

wow! that is exactly how the coolant looked like in the 2001 cherokee i bought over the summer. the factory tranny cooling system runs through the radiator and it failed and was letting transmission fluid into the cooling system.

i would recommend checking your tranny fluid level.

Install a flush-t after replacing the radiator..... i had to run over 100 gal through mine to clean up the coolant system.

Not in all cases will coolant get into the tranny though.....my tranny had no signs of coolant

 

I share the concerns for mixed ATF. It's very unlikely to be rust , if 3 months ago all was green and well even after a few long drives, that showed no overheating issues or similar.
Have a look (dipstick or better, drain) your trans fluid and let us know how this looks. BUt But I reckon it could still look pretty normal, if it spilled into the coolant and not the other way round.

 

If the rad mounted tranny cooler leaks, it's virtually guaranteed both coolant AND tranny fluid have co-mingled. The cooling system is pressurized and will push coolant into a leaky tranny cooler, especially when a hot motor is turned off.

Some tranny fluid in the cooling system....no big deal. Coolant in the tranny can be really bad depending on how much and for how long. If tranny fluid/coolant have been mixing, replace the rad and flush the tranny fluid several times. Keep very close tabs on the tranny fluid color/smell on the dipstick.

 

If coolant mixes with transmission fluid both the transmission and converter are toast.

 

.......and if the cooler leaked, u can bet they mixed.

 

..this is not the good news thread....

 

Not very good news for sure, but you have to start somewhere, like a new radiator, flush everything etc. Trans doesn't hold a whole lot of fluid, so draining it may show if it has coolant in the fluid..

Don't really know if coolant would go to the bottom of a glass jar, like water would, to make it visible, or stay mixed with the ATF, (?)

Never tried it...

 

well, a drain of the ATF will only take out about 4 Qrts. A dry refill is about 9. I would do a forward flus using the trans' own pump to do a near total refreshing of the sytem...and repeat that after a bit of driving. And then be done with it.

 

Pulled the transmission dipstick and level is good, fluid is cleaner than I thought it would be, and no sweet coolant smell. Probably going to go for a good flush (vinegar and then hose through the water outlet with t-stat removed) and see what happens. Local shop that does lots to Jeeps suggested they pull the water pump and all core plugs and hit it with a pressure washer through all openings... seems like overkill since it hasn't had any issues heating up, but they want to do it all for $350... any thoughts?

Edit: I'm wondering if the long periods of relatively little use and then the sudden couple of long hauls maybe broke a large layer of corrosion loose somewhere??

 

Well, it might have broken up some corosion....but not turn that coolant into orange blood...

 

One thing u must remember is, the tranny is vented to the atmosphere so when the tranny heats up, small amounts of coolant (but not all) will evaporate out the vent. However, even a small amount of coolant/water in the tranny is not good......so do several tranny fluid drains/re-fills once it's been positively determined that the tranny cooler is leaking and after the rad has been replaced.

If core plugs r the same as freeze plugs, a bunch of stuff must come off the motor to get to the freeze plugs. I believe the motor must be removed to access the rear freeze plugs. Again, a big job to remove/replace ALL core/freeze plugs.

To flush the entire cooling system is really simple........remove the heater hose and rad hose from the t-stat cover and the bottom rad hose from the water pump. In this order......1. stick a garden hose in the heater hose and flush. 2. stick the garden hose in the heater hose nipple on the stat cover and flush. 3. stick the garden hose in the top rad hose and flush.

 

It's probably obvious, but be sure to flush the heater core in both directions.

 

IF you determine that in fact the transmission cooler line * I use that term loosely* in the radiator is bad then what I would do after the obvious *new radiator, cooling system flush* is to take the transmission OUT line to the radiator, put that in a bucket then take the transmission IN line and put it in a bottle of new fluid.

Start the rig and idle it and shift through different gears *with help*. You will want to pump in however many quarts it takes from a dry fill. You'll have to look that up. Once you have pumped out / in that many quarts shut it off and button it all back up.

Better yet, once the new rad is installed completely bypass that b.s. radiator trans cooler and use a good external unit.

My method of fluid replacement still applies even with an external cooler.