chicocherokee

Hey Guys , need help , took my 99 jeep cherokee 4.0 to a small shop and they were trying to figure out why it was running at about 220 (temp gage) instead of about 200 where it normally ran . they were gunning the engine and testing for bad head gasket with pressure. well turns out the thermostat was bad and they overheated it when gunning the motor , finally burned out the anti freeze that was left in the motor , thermo wasnt letting any new coolent in . when i got in the jeep and started it, it went to about 250 and it sounded like it had an exhaust leak which it never had before ? i drove it to another shop and it was overheating when i got there ? What kind of Damage could these nitwits have cause gunning the Engine with the radiator cap off and hardly no fluid in the Engine ? seems to have an exhaust leak now like a sputter or a miss ?

RubenZ

not to beat you when your already down, but first rule of any coolant issues is to check/replace simple little parts that cost less than 10.00 like the T-STAT or do a simple Coolant Flush etc. I don't know what SHOP in their right mind would even think that "gunning" it is acceptable to figure out a COOLING Issue. Any number of things could have gotten screwed up.

Cane

it's hard to diagnose something like this over a forum post, especially with work you haven't done yourself. what I can tell you though is look into consumer protection where you live, sometimes they have protection against stuff like this. like rubenz said a proper mechanic wouldn't do what you just described. if they're registered and everything that is, if it's just some guy doing work out of his garage then that won't work.

drewactual

if you drove it at 250 for any measurable distance, you can almost guarantee the head gaskets are blown and a good possibility you cracked a head... the new 'exhaust leak' might not be a leak in the exhaust at all but a leak at the head...

Jeepin'_Aint_EZ

aroundincircles

cracked head, blown head gasket, rings could be damaged as well. Driving it that far at that temp starts to turn your engine into slag. That's the temp your temp sensors pick up, not the actual temp of the engine, which would be much higher.

Fred/N0AZZ

Sometimes those small cheap shops can end up costing you a lot of money, like cheap parts do.

You will be very lucky if you have not trashed the engine completely driving it with those temps. Hope you can get by for under a grand.

AceWhite

First advice I'd give you is buy a service manual for your Jeep and familiarize yourself with it. The better you are at pinpointing issues, the cheaper the repair will be from any mechanic. If you rely on a mechanic to diagnose for you, they're opinion is only as good as their skill. On top of that you PAY someone else to figure it out, which is never cheap and as you're finding out not always right.
In this case, get your jeep and spend some time troubleshooting issues first before taking it to a mechanic or posting looking for gold.
Gook luck

investinwaffles

Yikes, definately pass the bill along to those idiots. Obviously don't go to that shop again but also remimber if you have to pony up to have a mechanic work on your car, you might as well pay a bit more for quality work vs paying less for garbage work that ends up blowing your head gasket/warping the head.


Good luck - it sounds like you should find a reliable mechanic that specializes in Jeeps. Hard to diagnose over the internet (and with no real history) - the exhaust sound could be simply a cracked header or exhaust pipe, could also be a crack in the head by the exhaust manifold.

Edit:

Never ever overheat a motor. Even if you are going to be subject to some embarrassment while waiting for it to cool down in the middle of the road.

Kill the motor as soon as you realize temps have spiked above 230*F (I commonly think of this as "death range" as you can warp the head and/or blow out the gasket FAST at anything above these temps). 240*F or above is "shame-on-you" range IMO, although mistakes and circumstances do happen and I'm not trying to rub your nose in it or anything.

Just live and learn - luckily the Jeep 4.0 is so common you could probably find a good condition motor for $200

NewbJeep

Ah man. Sorry to hear that. This is why when I have to have something done to the ol girl, I like to go reputable, even if I have to spend more. Something with a name and a corporate who will cave to customer complaints. Sounds like you had a shade tree mechanic without the shade tree.

My Jeep was owned by my brother a few years back. Blew the head by riding hot. His shade tree mech found a JY 4.0, replaced the head but never bothered to diagnose the overheating, until my brother almost lost another engine... Then the mechanic decided to find out that it was the water pump; the same water pump which he re-installed from the old engine... Maintenance and proper diagnosis will keep your Jeep creepin a long time.

chicocherokee

Hi , bottom line , i went to that small shop knowing 95% sure it was the Thermo , those idiots told me they were checking for blown head , i should of realized the thermo could have been stuck but didnt dawn that the engine might be dry . Anyway , i did drive the Jeep 8 to 10 miles pegged on 260.
After that ride down the hill it cracked the Radiator . The fluid in the overflow resevoir was Boiling LOL when it overheated steam was coming from the middle of the motor after i shut it off . long story short the Jeep seems to be running better than ever now that i replaced the Thermo and Radiator , 2 days after repairs and it rides under 200 where it should be . The 4.0 is Bullet Proof , my God

NewbJeep

Right on. Glad it's running better. They are bullet proof but heat is their kryptonite. Might take precautions and run some coolant and compression tests just to be safe. Make sure that head gasket is still tight. You might have lucked out on this one.

Fred/N0AZZ

Glad to hear that, you were very lucky "THAT TIME" don't be surprised if it didn't do some long term damage to the engine running at those tempsfor 10 mi.

investinwaffles

Yeah, if the head gasket is blown I would replace it sooner rather than later.

At least you can pull the head with minimal effort - if you trash the crank bearings because there is coolant in the oil you will need a near-full rebuild.

Or buy a junkyard motor and build a stroker yourself, run the current motor until it bursts into flames and swap the stroker in

drewactual

I've got my flak jacket and helmet ready for the impending incoming firestorm this is about to cause- but:

if an engine is 250+ degrees, and it's NOT blowing steam and/oil screaming, sometimes it's better to let it run- to keep the water moving and to keep oil from coking on hard parts.......

a water hose spraying through the radiator on a cooling system that is maintaining pressure (not boiling or flash steaming) will knock thirty to fifty degrees off the engine in a heartbeat. oil can handle the heat- most quality oils can handle several cycles of 250 before they start to degrade- most won't flash (or burn minus required o2 which is 'coking' and which leaves that wicked hard 'cajun crust' on hard parts) until nearing 400*....

that engine will get MUCH hotter as soon as it stops running and circulating oil and water. the coolant/water WILL flash (poof) like a steam machine if the cooling system isn't close and under pressure... the oil becomes stagnant and thickens on surfaces 250+*....

IF IF IF the cooling system is intact, spray water on the radiator for a few and then ****** the cap off and stick it in... the threat of hydra-locking isn't massive until you try to start it again after such a failure... IF the engine doesn't have bearings screaming this is an option.... as soon as it is under control- control being 220ish, THEN shut her down......

watch a nascar race (requires heavy drinking) and watch a delay... they'll stop the cars on the track and roll a cart out to them... that cart has everything needed to keep both oil and water circulating while they sit... after you turn off that key, THIS is when warping happens and shifting of mated surfaces occurs while metal expands/contracts at a different rates, causing gaskets to blow (other than cylinder pressure and catastrophic failure, this is when most head gaskets and/or water pump gaskets are compromised- during the 'sitting- first super heating and then slowly cooling phase)