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Overheating 300tdi


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Hey

Im having a slight issue with my engine overheating when doing around 70 on the dual carriage way. The strange thing is that when driving around town or idleing the temperature is fine. I dont really have much time at the moment to mess around with it so thought id get some suggestions from your good selves?

Like the title says its a 300tdi with 96 000 miles on it and a full width allisport intercooler and a tweaked fuel pump. Intercooler has been fitted for a while now with no problems up until recently.

Any ideas would be great

Cheers Jason

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Hey

Im having a slight issue with my engine overheating when doing around 70 on the dual carriage way. The strange thing is that when driving around town or idleing the temperature is fine. I dont really have much time at the moment to mess around with it so thought id get some suggestions from your good selves?

Like the title says its a 300tdi with 96 000 miles on it and a full width allisport intercooler and a tweaked fuel pump. Intercooler has been fitted for a while now with no problems up until recently.

Any ideas would be great

Cheers Jason

RAdiator radiator or even the radiator

Keith

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Also check the viscous unit. I found that is was not working properly (engine running hot on long slopes on the motorway in Switserland, but all fine at low speed) and after fixing the viscous unit to the nut that screws onto the pulley the engine temp was fine going up the Gotthard pass. Temp was slightly left of the centre on the meter.

I fixed it with a piece of rope, pulled tight between the viscous unit and the nut and tightened the end of the rope around two oposite fan blades.

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Presumably you have checked coolant level etc. Assuming all OK, if it starts to overheat, turn the heater and fan on full, and ease off the throttle (OK you probably won't do 70!) as the cylinder head can be easily damaged by overheating. Might be worth out a flush out of the radiator etc if it hasn't been done for a while, and you have some fins remaining. I'd suggest that as it happens at high speed, it's probably not a fan problem - it suggests there is more heat going to water than can escape, but there should be plenty of airflow - hence radiator has to be the prime suspect as western said

Nigel

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interesting mine had a new rad around a year ago and now has developed this after a good dunking, and despite washing the rad fully it get's a wee bit warm on long drags at 70mph, mine is also tweaked a bit but I have an EGT gauge to keep an eye on it and she rarely crosses 600degrees.

Before it was perfect and never got hotter than halfway up the gauge.

I did wonder if the eletrical connection on the sender had got dirty and was causing dodgy readings?

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interesting mine had a new rad around a year ago and now has developed this after a good dunking, and despite washing the rad fully it get's a wee bit warm on long drags at 70mph, mine is also tweaked a bit but I have an EGT gauge to keep an eye on it and she rarely crosses 600degrees.

Before it was perfect and never got hotter than halfway up the gauge.

I did wonder if the eletrical connection on the sender had got dirty and was causing dodgy readings?

I think that could be a possibilty - as could the thermostat- and both very easy to check/change.As a matter of interest, have you advanced the timing any on yours?

Nigel

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Thanks for the suggestions. All coolant levels are tip top but the radiator is a bit worse for wear in fact I reckon that could be the problem. As for turning the heater and fan on full, thats a negative as the only heater that is available is an extra jumper on the passenger seat :) I didnt think that it could be a faulty thermostat as it does not overheat when idleing which if it did would mean that it was stuck closed? But I will check it anyways. Will keep you informed on the sit rep

Jason

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mine has been running with the timing 2degrees advanced on the injector pump for a around 2 years now and only recently developed this fault. It does help the performance a bit IMO.

I'm going to try changing the thermostat as it's getting progressively worse, on the 3mile run to the chippie it got the gauge above halfway!!

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The temperature gauge earths through the sender unit. The hotter the engine, the lower the resistance of the sender and the higher the reading. A bad or dirty contact would increase the resistance and lower the gauge reading, not increase it. The sender could be faulty, but it's unlikely.

Timing and breathing faults (valve clearances and blocked exhaust) can cause similar temperature problems, but a failing thermostat which doesn't open fully at the correct temperature is the most likely cause if the rad appear to be in moderate condition (not blocked and has lost less than 10% of its fins). If the rad is missing more than that or is blocked by mud or the entangles damaged fins, then the rad is the likely cause. It certainly isn't the fan or viscous unit.

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..mine has been running with the timing 2degrees advanced on the injector pump for a around 2 years now and only recently developed this fault.

It sounds like the fault(I'd guess thermstat as that's cheapest to try!) is unrelated to the advance. I have tried a little advance and it does feel a little better with less smoke, as I think the setings are oriented towards tolerance of poor fuel and lower emissions, but wondered what the long term effects would be (like would the head gasket handle increased cylinder pressure) Interesting you have some history of that with no problem.

Regards

Nigel

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It sounds like the fault(I'd guess thermstat as that's cheapest to try!) is unrelated to the advance. I have tried a little advance and it does feel a little better with less smoke, as I think the setings are oriented towards tolerance of poor fuel and lower emissions, but wondered what the long term effects would be (like would the head gasket handle increased cylinder pressure) Interesting you have some history of that with no problem.

Regards

Nigel

In those 2years I have put nearly 50k on this engine.... I have also run it with a VGT (1.2bar max pressure) and upp'ed fuel settings. It's always been reliable.

I have changed the thermostat and low and behold it's fixed, run just under halfway again and the hoses feel cool after doing a couple of highspeed A roads.

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In those 2years I have put nearly 50k on this engine.... I have also run it with a VGT (1.2bar max pressure) and upp'ed fuel settings. It's always been reliable.

I have changed the thermostat and low and behold it's fixed, run just under halfway again and the hoses feel cool after doing a couple of highspeed A roads.

That's good to hear.

Nigel

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