2.7 crd overheating on inclines

[Seriusrod]

Hello guys. I have a 2002 Grand Cherokee 2.7 crd that I got from a friend a year ago. My intention was build it as an overlander, so I did a complete inspection and some fixes, the injectors seals, changed three of them, fuel pump rebuild, and a coolant system flush and refill.

I only used the car around town and nearby, but today we did a small 100kms highway travel to a nearby city, the car still being stock.
The coolant temperature was steady at the center mark (100C). I've always seen it there, so I think it's normal. Then on inclines, the temperature raised fast to the red line.
I pulled and checked that the fan was running (and it sounded like a jet plane).
The coolant in the bottle raised to the cap.
After a while idling it cooled down, so I continued. In every incline it was the same and if I could make it to the descent the temperature would lower to normal.

Apparently there's nothing wrong with the engine. It sound so good. No leaks and nice idle.
Auto box is another thing. It seems to me very flacky with low power at launches. Auto low level I think it's high, and I tried to get it to level but seems it's too complicated for me. Always too high or too low.

Could that be the auto box overheating the coolant?
What do you guys think It could be?

[Classic Boy]

It will need further testing it could be a number of issues anything from a simple bleed to a plugged rad or a combustion leak into the coolant. I would try a new rad as they are fairly cheap then buy a block tester if the rad replacement doesn’t help.

[layback40]

It does sound like a coolant blockage of some sort. Could be a blocked radiator, could be a problem with the thermostat not fully opening. How does the coolant look? Has it had the wrong coolant put in & all gelled up?
When its hot, how cool is the radiator return hose? If its a lot cooler than the hose from the thermostat to the radiator, definitely a blockage of some sort.
A decent radiator place can do a flow check with the radiator in place. If you have access to a high flow water hose, you could do it yourself.

[Deezelweazel]

Since the Diesel needs to have a specific coolant anyway I would flush the radiator, exchange the thermostat.

One of the best tips I got here on this website is using Caterpillar ELC.
That stuff has exceptional capabilities to keep your system operational- it's not cheap, but it's worth every penny!

Typical Characteristics:
Color Strawberry Red

Boiling protection with 15 psi (1 bar) radiator cap
50% Cat ELC/50% water 129°C (265°F)
60% Cat ELC/40% water (ELC concentrate added) 132°C (270°F)


Radiator cheap? Then you get a crappy radiator- stay away from them. You want a radiator with built-in turbolator fins. The cheap ones do not have them. Heat transfer is a total different world with a quality radiator.

[Seriusrod]

Thank you guys for you suggestions. I confess I'm devastated. There was a lot of work made on this car and it ended like new. Last week it went to the shop for an ac refill and the chief told me that the engine sounded and looked great. It had the black death in it.
Then I used it for a year, but no inclines there.

@layback40 I hope you're right and nothing to do with the engine. I'm broke for this. When I got the truck I did a reverse flush on the engine. I removed the radiator and cleaned it the same. But using a garden hose.
Then I bought a pink coolant. I remember the guys from the shop telling me something about aluminium-steel diesel blocks and how the fluid should be specific one for corrosion and "emulsion?". I remember something about being organic. Nonetheless is not a factory one.
I'll try what you asked me.

@Deezelweazel It is the factory radiator. I'll order a new thermostat and perhaps a pump. I can easily take out the radiator and bring it to a decent radiator shop I worked with before.
I hope I can get the coloolant your mention. If not, would be right to go to Mercedes and buy it there?

So you guys seem to discard a problem with the auto box and sending tons of heat to the radiator through the water exchanger. Couldn't that be?

EDIT: The empty coolant can says: 50% / Organic / And in the specifications MB 325.3 along with some others. It doesn't say anything more, but per teh warnings, it seems ethanol based.

[Deezelweazel]

The specifications for the required coolant from Jeep are very strict.
But I don't see the need as Caterpillar stuff (which is usually sold by Cat dealers) meets or even exceeds the standard requirements.

Problem with the flush is the second coolant bottle in the bottom of the bumper. Yes, you read correct. You can not flush that bottle with a hose, you needto disassemble the bumper to get access to that one. Make sure the coolant is not mixed with old stuff!!!

fior the tranny you need an extra dipstick, cost you about 7 to 9 € depending where you at.
It must be mesured while the engine is running and the coolant at operating temperature- that AT fluid expands hugely. Check the colour- here you need the original fluid ATF +4 - which is not cheap. If the colour is different from red you need to flush- if it's pink or foamy, thats an alarm, you need to drain that asap otherwise the friction rings will swell and you need a new tranny. And by the way, flushing the tranny uses around 20L of that stuff...

[Deezelweazel]

Taking out the radiator easily??? Don't be to confident.
I can tell you it's a pain in the a**, to get it out. You need to remove the entire front to do that.
Be careful with those A/C hoses and with the power steering reservoir. It likes to snap. Replacement ain't cheap...