BS: car overheating

Subject: BS: car overheating
From: GUEST,befuddled
Date: 28 May 03 - 12:35 PM

ok the other night my car was overheating on the way home from work. I checked the oil and the coolant...it had plenty but to be safe i added more.

it is a 1997 dodge neon sport.

the next day me and my dad went to where I left the car and determined it to be the thermostat...so i took the old one out...and since it is a holiday weekend could not get to a auto parts shop in time. So I got the new thermostat yesterday and installed it.

Everything was fine, the car ran great...even this morning...until I was almost to work when it started getting warm again...

there is still oil and coolant...the belt looks fine. Did not check the thermostat cause it was too warm to open...plus am at work...

besides I would hate to think that the brand new thermostat has already gone bad....

what else could it be???

Subject: RE: BS: car overheating
From: greg stephens
Date: 28 May 03 - 12:40 PM

Summer?

Subject: RE: BS: car overheating
From: Rapparee
Date: 28 May 03 - 12:44 PM

Could be something is gunking up the radiator and not enough coolant is circulating. Also, there might be a fan that's gone bad, or a thermostat on a fan is faulty. If the car is air conditioned there might be problems with the compressor.

Sorry, best I can do.

Subject: RE: BS: car overheating
From: curmudgeon
Date: 28 May 03 - 12:44 PM

Check the fan.

Subject: RE: BS: car overheating
From: Bee-dubya-ell
Date: 28 May 03 - 01:25 PM

Agreed. Check the fan. Modern cars have an electrically-driven fan instead of the belt-driven ones of the old days. They only come on when a temperature sensor reaches a certain point. Usually, the fan will only come on when the car is idling or in stop-and-go traffic. Open-road driving usually provides adequate airflow to keep the coolant temperature in the normal range. So, if the car is overheating in traffic but not on the highway it's probably a fan problem. If it's overheating on the highway too, get a can of radiator flush, flush the radiator and replace the coolant. If that doesn't do it, check the radiator hoses. Sometimes an old hose will delaminate and form an internal bubble that will constrict coolant flow. If that's not the problem you may have to have the radiator physically cleaned at a radiator repair shop.

Bruce

Subject: RE: BS: car overheating
From: Leadfingers
Date: 28 May 03 - 01:33 PM

Temperature sensitive switch will turn the fan on after the engine has reached optimum temperature.Faulty switch,no fan on so overheating.Just another thought for you.

Subject: RE: BS: car overheating
From: John MacKenzie
Date: 28 May 03 - 02:52 PM

Airlock or blocked heater matrix, take the heater hoses off, and connect a hose to the outlet, turn it on full pressure, the flow going the opposite way to normal, will flush the crud out. If the overheating only occurs when you're in traffic, or going slow, then it's the thermal switch as said before......Giok

Subject: RE: BS: car overheating
From: curmudgeon
Date: 28 May 03 - 03:27 PM

Also check out the water(coolant) pump.

Subject: RE: BS: car overheating
From: GUEST,Egal
Date: 28 May 03 - 03:32 PM

Check if there is a film of oil on the water in the radiator or any creamy deposit on the oil filler cap - if there is it is a blown head gasket.

Subject: RE: BS: car overheating
From: open mike
Date: 28 May 03 - 03:39 PM

sometimes if you are really desperate,
you can drive with the heater on to
dissapte heat from the engine...yikes!
this only happens when it is hot outside
usually, the time when you would least
want to turn on the heat.
but it can keep the engine from boiling
over .
Also the water pump might be siezed up.
most anti-freeze contains water pump
lubricant to help things to keep flowing
smooth. hope you find out how to fix this
as it is getting hotter every day.
(in the northern hemisphere)

Subject: RE: BS: car overheating
From: katlaughing
Date: 28 May 03 - 04:16 PM

might also check to see if there is a blown fuse for the fan

Subject: RE: BS: car overheating
From: Bobert
Date: 28 May 03 - 05:15 PM

Thermostats generally aren't the problem, though many are sold to customers who are then sold other stuff, the the supposedly "needed". A bad radiator cap will also cause overheating especially if the electric fan is working.

If you end up having the system flushed, be mindfull that flushing sometimes kills off the last of what was holding yer radiator together so be prepared for the guiy to come to you and tell you that you need a new radiator.

Good luck,

Bobert

Subject: RE: BS: car overheating
From: Gareth
Date: 28 May 03 - 07:56 PM

Flush, check fuses, and connections to fan. Put can of "Radweld" or equivelent in header tank.

I asumne that if she starts and runs without difficulty the timing is no problem.

Has the choke jammed ?

Is there a build up of carbon on the exhaust tail pipe ?

Did you inadvertantly put leaded petrol in rather than unleaded, or vice verce.

Failing all else join the AA or AAA and "brake down on the road", at least they will diagnose the problem !!!

If not take her to a (UK) "Fred in a shed" mechanic and point out this is not an insurance job.

BTW I lost my break servo last week at Bedlinog, South Wales, gradient 1 in 5, ran her into a grass bank thank God. And thank God I was in bottom gear. £60 for new servo (reconditioned) and a new pair of trousers.

For a minute or so I thought we were ging to have a re-run of the "Ballad of John Axon" with me in the starring role.

Gareth

Subject: RE: BS: car overheating
From: Rt Revd Sir jOhn from Hull
Date: 28 May 03 - 09:16 PM

head gasket gone? look at the oil filler cap , see if there is mayonaise on it.

Subject: RE: BS: car overheating
From: GUEST
Date: 28 May 03 - 09:19 PM

no like i said the oil and the coolant are fine....

I have had blown head gaskets before...and I know what to look for...

thank you everyone for your suggestions.

Subject: RE: BS: car overheating
From: JohnInKansas
Date: 29 May 03 - 01:38 AM

The thermostat suggestion was probably a reasonable suggestion, since it's one of the cheapest things you can try to fix; but thermostats almost always "fail open" (they're supposedly designed that way) so they almost never cause an overheat problem.

I don't have "the book" on your model, but suspect it does have an electric fan, so that needs to be checked.

You've indicated there are no symptoms of failed head gaskets. If you haven't looked already, you should be able to see water moving with the radiator cap off, which will give some indication of whether the water pump is working. (don't open while the engine is hot, but warm it up some with the cap off if there's any question about whether there's motion there) Sometimes you can feel the "movement" by squeezing one of the larger hoses, so you might try that before opening the system.

A fairly common cause of overheat in "newer" cars (yours qualifies) is one of those many vacuum hoses that ties into the emission control systems. If one of these comes off, or leaks in a "major way" it can cause a lean mixture that can cause overheating. Since you indicate that the overheat occurs at "cruising speed" when the mixture would normally be fairly lean, this is a good possibility.

Vacuum from the carburetor base is also sometimes used to operate brake boost, heat and vent actuators, and such; and a break in the diaphragm of any of these can cause a lean-out that can cause overheating.

Unlikely possibilities:

a dragging brake, possibly due to a sticky parking brake cable or linkage.

If you have an automatic transmission, a slipping clutch or malfunctioning "governor" can put rather high loads on the engine, which could cause an overheat. (The power "wasted" in the transmission forces the engine to produce higher than normal power output at a given speed - the max torque isn't really much higher.) Extreme clutch slippage with a manual transmission would cause the same thing, but usually you smell the smoke before the engine gets too hot.

Have faith - there is a reason, and you will find it.

John

Subject: RE: BS: car overheating
From: kendall
Date: 29 May 03 - 01:53 AM

All good suggestions. Two more; check the radiator pressure, and, another thing could be the culprit, the catalyic converter.

Subject: RE: BS: car overheating
From: John MacKenzie
Date: 29 May 03 - 05:09 AM

Gareth I can send you the words of The wreck of the FFV, a forerunner of said John Axxon.
"Up the road she darted, against the rock she smashed
upside down the engine turned, poor Georgie's chest was crushed
His head lay in the fire-box door, the flames were rising high
I'm glad I was born for an engineer, on the C&O road to die"

All good gruesome stuff, and we're glad it didn't happen to you.

Failte.....Giok

Subject: RE: BS: car overheating
From: JohnInKansas
Date: 29 May 03 - 05:13 AM

In addition to things already mentioned, there are two components that could be the culprits in your problem, and they're both part of the emissions system.

You probably have an "oxygen sensor" in the exhaust manifold that tells the engine control (call it the computer if you must) when the mixture is too rich. At cruise, the controller tries to run as lean as possible without causing excessive combustion temperatures. If the sensor fails, it screws up the mixture control and it may go lean and cause overheating. If you get to the point of having a "professional" work on your car, DON'T LET HIM TOUCH THE CARBURETOR until he has TESTED the oxy sensor - or proved that you don't have one. Scream and holler and make threats, if necessary.

Many autos from your vintage and later also have one or more "knock sensors." Their function is to signal the "computer" to retard the spark and slightly enrich the mixture if it goes lean enough to knock. It should work at "subaudible" levels of knock, so you won't hear it, but if the knock sensor(s) go bad your mixture goes haywire.

(The knock sensors are the most frequent cause of the "check engine" idiot light that lights up at cruise speed. If the knock exceeds a certain threshold, the light comes on. It goes out if you shut the engine off and restart. And for some reason, the computer "memory" doesn't retain why the light came on. Us a higher octane fuel and the problem goes away. Most common in "larger" vehicles than the one in question.)

EITHER of these components, when present, can be totally destroyed by even small amounts of leaded or otherwise contaminated fuel, although it's usually the oxy sensor that goes. Much is said about leaded fuel poisoning your catalytic converter, and it will, but a malfunctioning converter usually doesn't have much effect on engine performance; but loss of the oxy sensor and/or knock sensors will prevent you from ever getting things otherwise "right."

John

Subject: RE: BS: car overheating
From: A Wandering Minstrel
Date: 29 May 03 - 08:23 AM

Almost certainly the fan. Most run through a relay or a fuse which turns on when the radiator thermostat reaches a trigger temperature. To check Open the bonnet, switch on the engine when it starts to heat up see if the fan starts. If not clean all the contacts and replace the fuse for the fan circuit. If still no luck get someone with a circuit tester to check out the connections in the fan circuit.

Subject: RE: BS: car overheating
From: kendall
Date: 29 May 03 - 10:14 AM

I've seen cases where the cat stopped the engine completely.

Subject: RE: BS: car overheating
From: GUEST,Mr Red (and no hotter)
Date: 29 May 03 - 10:23 AM

I have had both thermostat and head gasket go over the years. If the oil is frothy it might be gasket. The two symptoms are similar unless you look for water in the oil (froth/emulsifying) or bubbles in the radiator (run without the radiator cap on tickover till warm) bubbles can be very small. I have never had a fan fail on me but the fan should be cutting in and out on tickover and especially if you reach the overheating point.

Modern engines don't always have radiator caps as we know it. Didn't Spaw say he had worked a lot in repair shops over the years? He MUST have an opinion here.

Subject: RE: BS: car overheating
From: GUEST
Date: 29 May 03 - 12:43 PM

Is water circulating round the whole system? The thermostat should be closed when the engine is cold but open when it warms up. If you do think the thermostat is stuck closed, it may be possible to run without one to try and see if it cures the fault.

If the water appears to be circlating round the whole system and you have an electric fan check that it comes on when the engine is getting hot.

Subject: RE: BS: car overheating
From: GUEST
Date: 29 May 03 - 12:53 PM

When my car over eats I stop feeding it - :-)

Subject: RE: BS: car overheating
From: GUEST,original guest
Date: 29 May 03 - 01:07 PM

well, I found out the problem the hard way this morning...it overheated to the red again...after I just put coolant in it...and well the coolant tank was empty and nothing in the cap...and there is a leak...the gasket for the thermostat for some reason is not sealing....now neither is the old gasket....

this morning i watched the water leak out as i was pouring it in...am frustrated here...but at least I know what's wrong...

Subject: RE: BS: car overheating
From: GUEST
Date: 29 May 03 - 01:17 PM

You probably damaged the thermostat housing.