heater and overheating problems

[polonuts]

Hi all and new year best wishes

I have got a slight problem with my MK3 1.0 squareback. The fan doesn't seem to cut in at all and the engine overheats badly. The other problem is that my car heaters will not blow hot air into the cabin. Are these related problems or is the heater matrix dead along with the thermal switch for the fan??? Please help if you know the answer as I do not want to change items unescessarily.

Oh by the way my accelerator pedal is sticking quite badly as well, the revs will shoot up to red line when I put my foot in on the clutch and I have to physically pull the pedal back up with my foot to reduce the revs. Any ideas for this problem as well

[Tahrey1043]

check your thermostat immediately, it may need replacing if its not sending anything to the radiator (also why the fan wont trigger - it's temp sensor is on the rad) and your engine will cook!

or, it could be a blockage just in the system near the 'stat, which i think may also be where the heater takes a feed off --- so the whole lot doesnt work. no hot "water" to the radiator, none to the heater, but plenty round the engine!

(or the heater may simply be a busted temp regulator..)

hoping here that cooling system bits are "easy" as i'm having to tackle them myself soon. trying to steel myself that it shoudlnt be any harder than an oil change, just requiring mole grips and an allen key rather than a 14mm spanner and something to twist the filter off with....


as for your throttle cable, a cubic megaton of WD40 should be your first port of call.. on the ... axle or whatever you call it that the pedal levers on, on the cable, inside surface of anything the cable runs through, and the external and internal bits which the cable ultimately acts on (you'll have to take off the whole filter housing to get a good shot at this stuff)

best of luck!

[bstardchild]

I have got a slight problem with my MK3 1.0 squareback. The fan doesn't seem to cut in at all and the engine overheats badly.

Checked the fuse? Assumes you've done that

OK first check the fan works - trace the power lead - disconnect and then with a couple of lengths of wire (crocodile clips on each end) ground one to the chassis and connect to one terminal. Connect the other to the remaining terminal and touch on the battery Positve terminal (if negative ground)

OK at this point the fan should spin or its FUBAR

FUBAR means replacement required

If it spins then something it telling it not too or not telling it too

Next step find the temp sensor - sorry don't know where it is but a MKIII owner will

Once you find the sensor and with the fan you know works un plug the lead to the sensor and connect the two terminals in the plug the goes to the sensor - with ignition on the fan should again spin

If it does - replace the sensor it's FUBAR

If it doesn't then life gets fun!!!!!! Cos you will probably have a wiring fault somewhere so you are looking at running a new feed or finding the fault

The other problem is that my car heaters will not blow hot air into the cabin.

The heater fan doesn't run at any speed or the heater fan runs but only get cold air?

Are these related problems or is the heater matrix dead along with the thermal switch for the fan??? Please help if you know the answer as I do not want to change items unescessarily.

Unrelated IMHO but looking forward to a bit more detail

Oh by the way my accelerator pedal is sticking quite badly as well, the revs will shoot up to red line when I put my foot in on the clutch and I have to physically pull the pedal back up with my foot to reduce the revs. Any ideas for this problem as well

This ones tricky

Sounds like a spring missing or seized cable

Disconnect throttle cable on carb or throttle body in engine

Does pedal still stay down and is it free and easy to move cos if it does stay down it's normal but if it's stiff to move it's not and thats why the spring on the other end of the cable is struggling to return the pedal

This may be Cable frayed inside or as previously suggested a missing or broken return spring on the throttle body or carb

Bout it for me

[bstardchild]

check your thermostat immediately, it may need replacing if its not sending anything to the radiator (also why the fan wont trigger - it's temp sensor is on the rad) and your engine will cook!

or, it could be a blockage just in the system near the 'stat, which i think may also be where the heater takes a feed off --- so the whole lot doesnt work. no hot "water" to the radiator, none to the heater, but plenty round the engine!

(or the heater may simply be a busted temp regulator..)

<snip> (as always)

as for your throttle cable, a cubic megaton of WD40 should be your first port of call.. on the ... axle or whatever you call it that the pedal levers on, on the cable, inside surface of anything the cable runs through, and the external and internal bits which the cable ultimately acts on (you'll have to take off the whole filter housing to get a good shot at this stuff)

best of luck!

Tahrey - you are just plain bonkers and your replies scare the bejzus out of me

[Tahrey1043]

didnt consider the fuse / spring angle

guess i'll bow out to the more knowledgable ones!

however i will say that i'd be concerned over the thermostat as i very, very rarely have the cooling fan come on - like blue moon kind of thing. I know that my thermostat is stuck on fully open, but even sitting still with the throttle propped to 2000rpm it takes forever to work up the necessary heat to turn the fan on - the radiator, if it's plugged into the circuit, just does that good a job of cooling it (and certainly when the car runs at over 15mph) that i have to stick in low gear and race the engine to get much over 70 degrees... so it shouldnt overheat in normal use, just stick at whatever temperature an almost-fully-open thermo represents (about 90 degrees?)

may do in traffic of course, but the answer here is ... engine overheating cuz you're not going anywhere? switch it off and save some fumes!

all theoretiballs of course

[bstardchild]

however i will say that i'd be concerned over the thermostat as i very, very rarely have the cooling fan come on

local knowledge - very handy - I'm in agreement on that basis that the stat would be first port of call -never had a MKIII so all knowledge of suggestions offered are general application

[polonuts]

thanks for the input guys, I'm going to try and sort out the accellerator first as it scared the crap out of me this morning on the way to work I'll let you know what I find later in the week.

[ste mk1lx]

the rad fan is easy checked get a short piece of wire bare both ends and bridge the 2 terminals on the temp sensor on the rad the fan should run(watch you're fingers though as fan works without ignition) if the fan run's you will need to replace the sensor.

[LogIK]

Your thermostat is stuck shut, I'm pretty sure.

When the engine gets hot, feel if the radiator is hot. If it's stone cold, there's your answer.