hi, just got my octy back on the road after an accident, has been stood for 6 months or so. when i drive it on the motorway the temperature is all over the place (never colder than 90 though) have had to wire the fan on permanently til i figure it out. the heater blows cold when the gauge is high, and the gauge goes really high (110-120) if i go over 70 mph, could it be a blockage? would it be fairly simple to flush out myself? thanks in advance for any help, cheers

Is it actually overheating? If its really at 110 you'd be boiling the coolant.

If its not overheating then the problem is your coolant temp sensor

My experience is that a cold heater is almost always due to an airlock in the cooling system. That could explain the general lack of circulation too. Has the coolant been replaced during accident repairs?

Might be worth draining the coolant and putting in fresh with a new temp sensor.

When it "over heats" have you tried putting the fans on and seeing if that drops it?

Is it actually overheating? If its really at 110 you'd be boiling the coolant.

Not necessarily. Remember it's under pressure, not atmospheric pressure in which case 110 would be boiling. Release the cap on the expansion tank and she'd soon boil though. (No really, DON'T do that!)

The wife's beemer runs at over 115 under normal conditions, and whilst I haven't looked into it, I suspect it is a rather different grade of coolant, and probably higher pressure than the normal 7-9 PSI.

110 does indicate a problem on the Skoda though, for certain, and I agree that an airlock is the most likely candidate. These can be a pig to bleed at times (the AUM engined Audi A4 I did a coolant change on was a b@stard!)

its doing my head in, i dont really know a lot about engines (but am more than willing to learn) one pipe that enters the radiator at the bottom corner closest to passenger wheel is hot, yet the pipe from the other side is cold and sometimes feels like it has no coolant inside, could there be an airlock/ blockage in the radiator? going up hill on the m60 seems to make the temp shoot up too. and also heaters are blowing hot now. in response to pikpilot, the damage hasnt been repaired yet, but accident was to the rear. not sure about what coolant is in the engine, only had it for three weeks before the accident, has been in a yard until a week ago when i decided to go get it back on the road. would it be best to try to flush the whole system out first?

Id flush it out yeah. and make sure to bleed fully. If its still all over the place, get yer temp sensor swapped.

Water pump ??

Maybe ...... Dunno !!

didnt get around to doing the flush yet, but today i topped up water, put a splash of oil in, and squished the **** out of the hoses to the radiator, hot one, and cold one, kept squeezing for about 15 mins as the cold one started to warm up near the engine block, drove home (20 miles on m60) and the temp stayed under 90, even when putting my foot down a little (80 mph, uphill). could it be that the squeezing dislodged some gunk or air? could it be that simple? even switched the radiator fan off and it still stayed just below 90. is it still worthwhile doing the flush out anyway? cheers

If the temp is showing under 90 throughout you have a problem. The dash should display 90 once the cars warmed up and stay there whilst moving. It shouldn't go under at all

stayed under 90 with the rad fan permanantly on. flushed the system, seemed to do the job-ish, temp is now wavering between 90-100 (still usually uphill)

am thinking now though, that the thermostat has gone, as the heater fans are constantly cold now, going to replace it at weekend and see if that sorts it. could it be possible that during the flush out, some gunk has gotten trapped on the thermostat? its just that the heaters stopped working right after the flush. am i right in thinking that the coolant in the radiator (is that where the heater fan heat comes from?) doesnt start circulating until the thermostat opens (at a certain temp?) would that explain why the temp is erratic and the heaters not working?

Edited 3 April, 201214 yr by joe84

? its just that the heaters stopped working right after the flush

I've always kept an eye on heater temp, especially if the gauge starts getting a bit high,then drops. First indication ( I've found) of overheating is a drop in temperature in heater output. More so if heater has been working properly up to that point . But as said, it could be an airlock .Did you try a reverse flush on the rad .Might also be worth flushing the engine in the opposite direction to that previous .

reverse flush? i put the flushing agent in, did what it said on the bottle, then drained full system. i then put a hosepipe onto the plastic tube that looks like it goes right inside the block, left it for about 20 mins then filled with coolant and got my gf's pops to bleed it. the heater had been working up until the flush and it worked REALLY well for about 20 mins after flush (blowing taxi warm air) then stopped completely

have done over 1000 miles in a week though and the temp hasnt gone over (what i estimate off the guage) 97-98

Mine sits pretty constantly around 90, although I don't treat it hard. To be honest, initially it sounds just like an airlock was your problem anyway.

Squeezing the hoses with the cap off and releasing them quickly will help, as it will force the air up as the coolant drops back down heavily.

The gauge should constantly read 90 once warmed up not above or below. Might be worth checking with vcds what the temp actually is and if both the gauge and the ecu are getting the same readings

just let it idle with the cap off and let fan cut in a few times then top up.

take it for a short drive with some water with you (for topping up) and repeat

the fan doesnt cut in, i have it wired in a switch in the car, have replaced the fan switch, but as it was still getting hot i decided not to reconnect until problem is solved. have also done the pipe squeezing thing/idling with cap off, it helps for a very short period (20 mins or so if i'm on a long motorway drive) could a faulty thermostat be the cause of this? gonna take it out today(if the weather bucks up a bit that is) to see if it keeps the temp stable, if it does, would that mean just replacing thermo?

also on a side note, would a set of golf r32 wheels fit my skoda? have a customer who says i can have his old ones for a ton, sounds like a bargain

Give it a whirl, the thermostat isn't really an expensive part. Not sure where it is on the TDI's but it's a bit of a pig to change on the 1.8T's.

And if it's a Mk4 R32 then yes the wheels will fit (your brakes will look a bit puny underneath though!)

Give it a whirl, the thermostat isn't really an expensive part. Not sure where it is on the TDI's but it's a bit of a pig to change on the 1.8T's.

And if it's a Mk4 R32 then yes the wheels will fit (your brakes will look a bit puny underneath though!)

didnt think about that, cheers for highlighting it, can i put bigger brakes on, a set of vrs brakes maybe??

thermostat on the tdi is possibly the most accessable part on the engine, just attempted to do 20 miles on mway, aborted 3 mile in, temp shot up so am defo gonna try the thermostat today, just gonna wait til my neighbour come in so i can do it in his garage, its reet blowy in manchester today!! cant beleive it was 70+degrees last week!!

It's possible to change to 312mm VRS front discs and calipers but how easy it will be depends on what you have on at the moment. If you have FN3 calipers then it's a straightforward change of the caliper carriers but I think FN3s only came on the VRS, 1.8T and 4x4 and possibly the 130bhp TDIs.

More likely you'll have the FSIII calipers (it should be engraved on them) with 256mm discs in which case you'd need to change the whole hub for one that will fit FN3 calipers, then fit the VRS calipers, carriers and discs.

sounds a bit complicated, but will see what it looks like with standard brakes first, cheers man.

just tried taking thermostat out (should it be in the little plastic housing on the passenger side of the block?) but there was nothing there, would no thermostat at all cause the overheating and cold heaters? just ordered a thermostat anyway, 7 quid! was thinking it would be a fair bit more than that, happy days!

Edited 4 April, 201214 yr by joe84

SORTED!!!

problem solved!! it WAS the water pump, feel pretty proud with myself too, did it pretty much on my own, under guidance of a mechanic. temp stays at 90 always now. dropped the engine out, which was pretty scary when using a jack! didnt have the tool to lock the cams, but found that a 6mm drill bit slotted into a hole in the frontmost cam and locked it(mechanic friend was rather impressed at that too) kept belt on until it was all marked up with tippex. when i took the pump off, the impeller stayed inside (MASSIVE RELIEF!! not the head gasket, phew!) took me 6 hours all in all, and that included going to get more power steering fluid, cost me 35 quid for the part (with metal impeller) and 4 quid for the fluid, so less than 40 quid. lesson learned and money saved-happy days!!

cheers to all for your advice, now i can focus on getting some bigger brakes fitted as the 18" r32 wheels make the original brakes look miniscule, not even bothered putting them all on just to see what it sits like because they look sooooooo tiny! cheers again

joe