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Stumped/Given up. 4.7 Overheating problems

2K views 22 replies 7 participants last post by  skain8 
#1 ·
Hey guys, lost on this one and about ready to take it to a shop. So about two weeks ago my wj over heated on the way to work. Got her towed back home because I know a towing co pretty well and didn't feel like chancing it. So i took it home drained old antifreeze out, ran prestone radiator cleaner through it. Drained it out after the recommended 3-6 hours. With no over heating in the time span. They say to put 2 bottles in and the rest water. Replaced the thermostat. Filled back up with antifreeze and its been downhill from there. I drove it for about 5 mins and it ran up to 260 degrees. Got out, cracked the bleeder. Started back up, drove it home from 5 mins no problem. Started it up next morning drove it whole way to girlfriends house (15mins) no issues. Parked it there overnight. Got back in the a.m., drove it probably 6-8 mins over heated again. Got out, cracked bleeder yet again. Drove it back home no issue. So since I work so much its hard to even get around to my jeep. But tonight, drove it around for a while till it got up to temp and just kept driving and it overheated about 7 mins of driving, pretty cold night out. Took it home, took rad cap off. Cracked bleeder. Put bleeder back in, left rad cap off. Started engine for about 15 mins, let it spit bubbles and antifreeze out for 8 mins. Finally stopped shooting out. Filled back up, let it get steady, put cap back on drove it around 10 mins never over heated. Although now, its idle is so bad it sounds like it wants to shut off, I smell what I believe is a rubberish smell? And when i give it gas i hear what sounds to be a chain rattling. SO now I'm thinking I am screwed. Sorry for long *** post but I'm lost. BTW, water pump is not leaking. Exhaust is not blowing white smoke out, over flow is still full. What the hell is going on :dunno:
 
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#2 ·
Rattle could be your timing chains and guides getting worn out. Pretty common with the 4.7. As for the overheating, I would guess maybe your water pump might be going out. The impeller could be cracked and not spinning the same speed as the shaft it is pressed onto.
 
#3 ·
Just all of a sudden after the whole overheating issue for the timing chain i mean. And how can I tell if it is not spinning at the same speed as the shaft?
 
#7 ·
Where does it sound like the rattling is coming from? If it's coming from the front of the engine, it could be the timing guides/tensioners. If it sounds like its coming from under the valve covers or just one side of the engine, it could be a valve seat that's getting ready to let loose. Typically dropped valve seats are a result of an overheat event, as the seats themselves are a hardened steel pressed into softer aluminum heads. When the engine overheats, the two metals expand at different rates and the valve seat loses its press fit.

Usually a dropped valve seat will cause a misfire CEL to pop up, along with a lot of engine noise. In your case it may not be fully dropped, which means you really haven't caused any internal engine damage. I would suggest finding someone with a scope/camera that you can use to inspect the valves with via the spark plug tube. You can also buy a relatively inexpensive one from the local parts or Harbor Freight (right around $100). If you're lucky you can get by with just having the head rebuilt.
 
#8 ·
its hard to tell where it is coming from as I can only hear it if im driving. Ill have to double check tonight and see it if does it at idle as well. But if i were to guess i think its coming from the front of the engine. Can timing guides/tensioners cause bad idle? I never received an CEL while driving.
 
#10 ·
oh i havent been driving it hardly at all. I only drive it once in a while to try and diagnose the overheating issue. But then i noticed that last night. But of course it was night and didnt even think about timing guides and stuff. Guess i'll look today and hopefully be able to see. I didnt drive that long last night because it wasnt overheating but i thought i shouldnt drive it with whatever that noise was. I can say that if it would have been any other day it would have overheated on the drive i took for sure. How hard is timing guide/tensioners to replace? Me and my buddies are pretty good with a wrench and i already am taking it to a garage to do a heater core replacement so maybe i'll just have them do that too if thats what it turns on being. Im always thinking negative in these situations. I dont want to put all kinds of money back into her to make it run again.
 
#11 ·
started it up last night for just a few mins to see if it was making the same noise, Its not idle is smooth and sounds fine. I didn't drive it anywhere though.
 
#12 ·
When it overheats, run your heater on the highest setting and see if that slows the temp crawl down at all. If not, bad water pump. If so, radiator is still clogged & should be replaced.

I do fear for that engine with a visit to 260 though... Hows the oil look?

I would also have a combustion gas test done on the coolant. It checks to see if there's disolved combustion byproduct in the coolant with a simple dip test of the coolant.
 
#13 ·
technically speaking i have no heat since i have my heater core bypassed. The oil looks fine. That was what i have been checking oil and oil cap repetitively.
 
#14 ·
drove it around for a while yesterday it never went to 260 but it was around 220-240ish. But fluctuating quite a bit. Eventually it'd go back down to 210-215. Guess i'll try a thermostat again and do water pump just for fun..
 
#15 ·
What brand of thermostat did you use?

I know the top three preferred brands on here are Mopar, Stant and Motorad/Auto Zone Stainless. Use of other or no-name brands can cause coolant flow issues, as they inconsistently open or have incorrectly sized openings that don't flow enough coolant. Personally I use Mopar or the actual Motorad branded stats (available at O'Reilly). A quality stat will include a bleed valve built into it which allows air bubbles to bypass the stat to aid in initial bleeding after replacement. You will need to make sure (in the case of the 4.7) that the bleeder valve is installed at the 12 O'Clock position to ensure proper function.
 
#16 ·
I should kick myself for this but i believe it was a duralast one. Ha. And thats my plan to my mopar one. Can i only get one at a dealership? Sorry for my lack of education in advance but i am not sure what a bleeder valve is. Could you show me a picture?
 
#17 ·
No problem. Auto Zone IIRC, has two lines of t-stats, Duralast and Duralast Gold (someone correct me if I'm wrong). The Duralast Gold is a repackaged Motorad, which are a pretty good stat as they're 100% stainless steel and have the bleeder valve as well.

As for the Mopar stat, you can either order from one of the whosalers online/Amazon, Kolak here on the forum or locally at the Dealer.

The bleeder valve is also sometime referred to as a jiggle pin, and is the little brass pin pictured below:

 
#21 ·
jeep overheating

2003 jeep grand cherokee 4.0
My jeep was overheating. The point where the overflow hose goes to the overflow tank on mine was blocked. Apparently from the factory. There was no hole for the overflow to get back in the tank so check yours. Also, the connection to the electric fan on mine went bad and it started to overheat. I cut the connection off and wire nutted it back together. So check to see if your fan is coming on.
That is all I've got.
 
#22 ·
just in case anyone is trolling this thread later on i replaced my water pump whenever i replaced my heater core and everything is in tip top shape. Water pump was toast!!!
 
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