2002 Grand Cherokee 4.0 Overheating

[tylermatt]

I was driving home the other day and out of no where my jeep starts to overheat. Started spraying coolant out of the over flow. Smoking and carrying on. I instantly pulled over and shut it off. Got it home and it over heats while driving and idleing. Replaced the thermostat. Fan kicks on and works fine. My next guess would be water pump. Any other suggestions?

[arks]

Yup, the water pump is suspect -but before taking it off, make sure the radiator isn't blocked internally. Simply pull off both hoses and run a hose into the top. If it flows freely out the bottom you're OK. If not, try backflushing from the bottom.
Good luck.

[fredjacksonsan]

Agree with arcs.

First off, how many miles on, and when's the last time you changed the coolant?

You've already replaced the thermostat. Check the radiator for flow, and keep in mind that with a 10 year old vehicle you may have some restrictions to flow that aren't apparent testing it with the hose. Water pump is next.

But...since you said it's all of a sudden and it overheats quickly -- if the above does not cure the problem I would suspect a head gasket. Do you have any oil in your coolant, coolant in your oil, or white smoke coming from the tailpipe?

[tylermatt]

Keep in mind it sat for about 2 1/2 weeks just under a half tank in be 30 degree weather. With that being said I replaced the water pump. No leaks from the t-stat or water pump. It is still over heating not as bad but i still don't have heat. The radiator fan is kicking on, thought they may have been a problem. Now it runs like shit and doesn't want to stay started. Keeps studdering as if not getting gas. I suspected moisture in the gas/gas lines. So i used ISO-HEAT fuel treatment still no luck. Any suggestions there?

[fredjacksonsan]

I'll ask again how many miles and how long since coolant was changed. Reason I ask is that if it has never been changed you likely have some restriction in the radiator which is reducing cooling capacity. No heat is an indication that the heater core could also be restricted.

To solve these issues, you'll need a new radiator. You can try to flush the heater core with a hose (making it flow both ways) and that might clean it out so you can get some heat.

Leaving a 10 year old vehicle sitting for that amount of time with bad coolant will cause corrosion.

[tylermatt]

Sorry it has 143,000 on it. I flush the syster now I have a heat and it doesn't overheat anymore. That problem seems to be solved. Still runs like crap and doesn't want to stay started. ISO HEET didn't seem to help. Im debating on a mass air flow sensor or spark plugs. The only problem is i can't find a parts store that carries the mass air flow sensor. is it called something else?

[fredjacksonsan]

Running like crap: replace the plugs first. Either Champion or NGK have worked well for me, in both my 2000 and 2004 with the 4.0. I tried other plugs but they didn't last or missed, or both. If you have more than 30k miles on the plugs it's time to replace them.

You might also have some bad gas from it sitting so long, so a can of gas treatment of some kind that also removes water won't hurt. Fill up when you put it in.

[msdz]

https://www.moparliquidators.com/ http://www.trademotion.com/partlocat...?siteid=214996 http://www.moparpartsamerica.com/spl...?siteid=214583
A couple of sites to find the OEM parts for your jeep. Also these places are usually cheaper than buying the aftermarket parts from your local parts stores. Only down side to ordering from these places are the wait time on shipping, even with overnight shipping some parts are still cheaper than the local aftermarket parts stores.

MAP sensor, jeeps do not have a Mass Air Flow sensor. It is a MAP sensor. As for the sitting for just two & a half weeks, haha. If a vehicle ends up with bad gas that fast stop getting the gas where you are getting it from. Two & a half months maybe. Gas should not go bad in 2 1/2 weeks. You should be able to tell instantly by the smell of the exhaust if the gas is bad. If anything it may be a clogged injector but still doubtful. Mine had sat for 4 months with no bad gas and no treatments of any sort & it ran fine when I fired it up.

I would at least pull and inspect the spark plugs before changing. I can't say for sure on the 4.0L but on the 4.7L a misfiring plug will send a trouble code that tells you exactly what plug is misfiring.
Fuel filter, fuel pump, or TPS are just some thoughts that come to my mind.