OT--Jeep Grand Cherokee

I know that this is OT for tractors per se, but I have seen lots of knowledge on this forum about engine problems. Today I was driving my 2006 Jeep Grand Cherokee, 102K, about 50 miles from home when I was alerted to "check gauges." The coolant temperature gauge showed "hot." I slowed down, watching everything for possible problems, until I came upon a basic "service station." No one there knew anything, even less than I! I found the overflow coolant tank empty, so I bought a gallon of 50/50 and installed it. By that time it seemed back to normal so I drove on, only to observe the temp gauge climbing above normal again. When I got to my destination the message was "transmission over temp." I spent some time at the purpose for my trip, came back out and things seemed ok again. Then on the way back home, same thing. Stopped every 5 miles or so, checked under the hood, there didn't appear to be anything inordinately hot so kept on driving at comparatively low speed, still stopping frequently to check under the hood.
Finally made it home with no problems beside the temp gauge and the attendant warning messages. I had set the heater setting at maximum heat and found that going downhill with maximum engine braking effectively cooled the engine (at least according to the gauge!) I did observe that with the heater on "full max," it would emit hot air after making a right turn sufficient to generate a "slosh" of fluids. I now have an appoint Monday morning with my Jeep dealer, but I would like to be just a bit more knowledgeable when I talk to them. Any bits of wisdom concerning the problem before the Monday encounter?
TIA--Cool













G

Typical stuff, fan clutch (does it show any leakage?), thermostat, fan belts, plugged trans cooler etc.
Assume you checked trans fluid.

" Blows hot air on a hard right turn" new one to me, but sometimes you have to bleed/purge a cooling system when filling, sometimes it gets a air bubble in the system,might be a valve or just remove a heater hose to bleed the air out.

If you want to have a small bit of info to give the dealer (reduces diagnostic time) GET A COMBUSTION GASSES IN COOLANT TEST STRIP KIT (cheap) head gasket, or crack are possible if gasses are found. Also look for a leak to the ground from the hoses or other coolant containing areas. Pressure testing the cooling system is also cheaper than the hour they would charge for that diagnosis. you would hook a hand tire pump (only) to the radiator overflow hose and pump up the system (you can't ofer pressure it this way as the cap will bleed off pressure above its rated pressure. Do this when it is cold (ambient) and it should stay pressurized for several hours. Feel the hoses and get a feel for how hard they are when the pressure is up. Keep feeling them every 15 min or so if it bleeds off right away or within 15 minutes, I would pull the spark[plugs and have someone spin it over while watching for coolant coming from the plug holes. I hope you find a pinhole leak in a heater hose. Jim

Just a thought. A lot of newer units recommend adding coolant to the rad only. Adding to the overflow tank doesn't really fill the rad (when the rad is full - might take a couple of tries if it is really low - then top up the OF tank). Happened on my '08 Mazda PU and that was the fix. HTH

Had a Jeep that got hot when pulling cool down when not. Was a head gasket.

As Bob said check coolant level in the rad itself before doing anything else. Just filling the overflow doesn't help because it takes time to get it to suck in. I had a similar experience with a Dodge pickup when the coolant was low. Still have not figured out why the coolant was low but had not checked it for some time so figure that a bit evaporated over time. Pay more attention to coolant now.

You're low on antifreeze and have a air bubble in the system. Most engines have a small bleed screw on the thermostat housing or the line coming off the waterpump.

Just a thought, as I am 81 years old, I was really "into" the old flat head Ford V-8. I remember that they had two coolant pumps, one for each bank. I don't know exactly how the later V engines are configured, but what was going through my mind was possibly a coolant pump failure on the left bank. It is a 3.7 V-6. Maybe this could be the reason for the "right turn issue?"

The heater blowing hot when turning is an indication of low coolant.

Just adding coolant to the overflow tank (if it really is an overflow tank) will not get coolant into the radiator and engine.

If the plastic tank has a screw on type pressure cap, then it is not an overflow tank, but an integral part of the cooling system. That should have gotten coolant into the system unless it was so hot it steam pressured it back out. But it would have been very hot, churning and boiling, doesn't sound like that was happening.

Chances are it is loosing coolant somewhere, possibly a hose, water pump, radiator. etc. A pressure test will likely reveal the problem. Depending on how hot it got, the thermostat may have been damaged from overheating. Worst case, a head gasket or head problem.

Beware of the dealer! You may have a good one, but they have a reputation for price gouging. If it doesn't sound right, get a second opinion elsewhere.

Besides all the other good advice,I would make real sure the radiator is full before I drove it again.Running it hot does a lot of damage that may not be apparent for a while.Mark

Thanks Steve. How exactly does one do a radiator pressure test? Sounds like something I'd really to do before going to the dealer's shop.

You added a gal. of coolant :?: A hole gal.

Tells me it was low in coolant and still may be low. I have put a few radiators on early 2000 models they are a P.O.S. (the jeep in general)

I get 4 hr. to replace a rad on them and its worth ever penny. Its a jigsaw puzzle with no rhyme are reason. Its a fight to get the rad out even with the front end removed :evil:

I've got a Jeep Grand Cherokee Laredo. I replaced the rad/shroud/fan
assembly this summer. Around 10 screws or bolts and removed and
replaced in less than an hour.

Lot's of videos on location of screws and what needs to be removed.
The videos are on u-tube and made the work so much easier.


I too, had the same symptoms as the OP...pin hole in rad. Bought the
rad assembly off Amazon and had it at my door in 3 days.

You want to be very careful about running this engine hot. It is a cast iron block with aluminum heads. When the heads get hot, they have a tendency to drop out the valve seats. I've already had to have heads redone on a couple of them.
To correct one misstatement, there is only ONE coolant pump on this engine. As far as I know, the old Ford flathead V-8 was the last engine to use more than one pump - at least in automotive applications.
This does sound very much like you are having a major coolant loss. Head gaskets are a possible suspect. Pinholes in hoses are another possible culprit. As always, diagnosis is your best friend. You will be far ahead in the long run to have some tests done before spending any significant money.

Also, to janicholson : the "strip test" for combustion gases in the coolant is unreliable. It gives way too many false positives, and from other sources than head gaskets. It also only "tests" a part of the entire system.

Check under the engine after parked over night ,look for coolant dripping fluid. Or if you add antifreeze to the radiator before driving in the morning (because the coolant is low if it checks low) check under the water pump for dripping coolant. The water pump should be right behind the lowest belt pulley on the front of the engine. The water pump or water pump bearing seal could have failed and is leaking coolant out at that location. Those engines can have water pump failure at about your mileage. The cure is a new water pump installed and possibly a thermostat. All this is just if you see fluid drip or evidence under the front of the engine. BE SURE the radiator not the reserve tank is full before driving anywhere. You may be able to drive a long time with a slow leak by just adding antifreeze, but a fast leak needs attention right away. A new pump is not that expensive but be sitting down when they estimate your labor bill for the install if at a dealership.

It can not be done in a hour.

You can not pressure test find the leak drain the coolant refill pressure test again bring it up to operating temp,clean it up test drive confirm no leaks again and no leaks at the trans cooler lines in a hour and confirm a kill.

That does not include any time to remove and replace the radiator that is hidden, captured, sandwiched tween them with a ungodly mess of engineering by the condenser and radiator cooling fan.

If I got good at it I could shave a hour off my time only because I would get it in my head its not worth trying to remove it with out removing the bumper cover and every thing that's is tween the bumper cover and the condenser. That is the best way and the best way to get the air deflectors back in place were they should be.

If you somehow yanked it out and somehow got it back in you hacked it and defeated the factory engineered air defectors for the condenser.

Folks seam to think it should be a freebie its not at my shop you pay to confirm the issue and get paid to confirmed its repaired and ready to ship.

Sounds like you have many issues. The coolant is leaking somewhere and I am guessing from the radiator. Have you checked the level of the transmission oil? With both reading hot it sounds like the transmission cooler in the radiator and the coolant coils have both been damaged. With the Dodge 3.7 they have a habit of blowing head gasket even when everything is perfect - getting them hot at 100K about guarentees the head gaskets are now blown - so it would not surprise me if you have both a leaking radiator and blown head gaskets.

The 3.7 does have a bleeder valve to burp air from the block, but there's a lot of work to be done before you get to that point. You need to find the leaks, fix them and then service your transmission fluid. Heat kills transmission fluid, I would change the transmission fluid before driving regular. Dodge is known for POS transmissions - don't tempt fate by running the vehicle with heat damaged fluid.

Hobo,NC- I forgot to post it is a 2004 model. Anyway, I did see a
drop of antifreeze coming from the rad and that was how I decided the
rad needed replaced.

I removed the front grill, hood latch assembly and cross member
support. Drained the fluid while removing parts. Unbolted rad and
lifted up to remove. When re-installing had to be careful to work rad
behind the trans. cooler. Hooked everything back up and added
antifreeze. Started up and good to go.

I hour start to finish.

It takes a special tool-a radiator pressure tester.The tool has an adapter that screws on to the radiator in place of the cap and you pump it up to the cap specified pressure and look for leaks and drop in pressure.You can also test the cap to see if it holds pressure.Mark