Hi all, as I said in my other post, i'm having some overheating issues with my octavia. She's a Mk1 1.9td1 (110) and here's the symptoms and what i've already done:

Get's up to temperature (90) within a very short time around 1 mile.

Does not leak, but uses water depending on how you drive it.

If i take it steady the temp will usually stay around 90, but if i give it some stick, or climb a steep hill the temp shoots up to 3/4.

Bottom hose cold and top hose hot both full of pressure.

When I have had the heaters on full it blows hot air, then cold.

What I have already done is:

Changed thermostat.

Checked water pump.

removed rad (Pig of a job!!) and laid on a flat surface then filled with boiling water to check for cold spots. I found the bottom quarter (around the bottom hose pipe) was cold, rest was very hot.

Since buying the car I've discovered that the headgasket has been changed along with the waterpump so somebody has tried to fix but have obviously not rectified the fault. Also the cooling system was full of bars leak headgasket sealer which would explain the blocked rad :(

Worst case scenario i'm thinking is a cracked head. Is this common on this engine?

Would a blocked rad be enough to cause this problem?

Any help is very welcome!

Thanks in advance

Trys

The rad is obviously knackered, so replace that, flush everything, and see how it goes.

Cheers, i've got a rad on order so fingers crossed it is the cause of it. Managed to get one off ebay for 35 squid posted, all I can afford right now plus if it turns out to be a crack in the head i'll need all the dosh I can get.

I agree it must be the rad... if the one hose doesnt get hot then the water isnt circulating.

I would have said thermostat and water pump are both most obvious, but you have ruled both of them out, so rad is only option.

Even if something else was making it run hot both rad hoses would still get hot.

Bit of an update - changed the rad but it's still pressurising and the lower hose is still cold. Not overheated as I haven't given it a good run yet, but i'm pretty sure it will.

Looks like it is the headgasket or worse a cracked head! As said the headgasket has'nt long been done but obviously did'nt cure the fault. If it does turn out to be a cracked head, how come the bottom hose is still cold - surely the water would still recirculate? Could it be that the bars leak headgasket sealer has clogged up the waterways?

Any help welcome!

Cheers

Trys

Microcracking in the cylinder head is a common problem - often seen with tuning boxes and chipped engines. Symptoms are incurable overheating and mysterious water loss. Water exiting via exhaust.

However your lack of heater output suggests either an airlock or more likely a duff water pump, often the impellor becomes detached from the shaft.

My neighbour was having a problem with his car over heating this week, with similar symptons as you, hot top hose, cold bottom hose. Turned out that when he tried flushing the colling system, there was a blockage in one of the pipes(some gunk of some kind), the one from the header tank down so no cool water getting to the engine. All he had to do was clean out the pipe and all is ok again. good luck, hope its not the head.

Howdy, I fixed a problem like this for a friend of mine before, If the wrong type of coolant was used ( blue generic type) it can react with the Vag red coolant and cause gunking a good flush will help and also take out the thermostat even if it has been replaced and clean it as the gunk can cause it to jam. read the manual and make sure you refill with the proper Vag coolant and bleed out all air. Hopefully this will help.

Yes, forgot about that. G11 (green blue) reacts with other coolants, notably the original G12 (Red) (not the G12+ - thats OK), to form a thick Gel thats very hard to flush out of the engine/ radiator