Hello all.

 

It seems that my engine has developed an irritating propensity to overheat, it seems. What troubleshooting steps should I undertake?

 

Initially the car lost some coolant every so often. This has graduated to the coolant boiling over with irritating regularity. Lately it seems to have gotten worse - after my 10 mile commute to one of my clients today I was getting steam coming from under the bonnet, which hasn't happened to me before.

 

What I've done so far:

 

- Replaced thermostat

- Replaced expansion tank

- Replaced expansion tank cap

 

Symptoms:

 

- Dashboard temperature reading not functional

- Heater is intermittent, often not working; aircon works fine. 

- Top radiator hose is painfully warm.

- Bottom radiator hose is stone cold, although warmer where it goes into the engine.

 

Given that there's a huge difference in the temperatures of the radiator hoses, I suspect that my radiator might be blocked. Being a berk I put some radweld into the system when I was loosing coolant initially, a while before reading that doing so was a dumb idea. Is there anything else that I should do / check for?

The water pump on this engine has a plastic impeller as standard, and it seems to be quite prone to stripping the splines or even breaking up, with a likely Mean Time Between Failures of about 80k miles.

 

So, when was the timing belt last changed? It's actually quite common to change the water pump with the belt because that's normally done about every 60k, and it takes 10 minutes to change the pump when the belt's out, or 2 or 3 hours if you have to do the full strip.

 

BTW, you're right about not using Radweld (or similar) until you positively know that there is an actual leak.

The water pump on this engine has a plastic impeller as standard, and it seems to be quite prone to stripping the splines or even breaking up, with a likely Mean Time Between Failures of about 80k miles.

 

So, when was the timing belt last changed? It's actually quite common to change the water pump with the belt because that's normally done about every 60k, and it takes 10 minutes to change the pump when the belt's out, or 2 or 3 hours if you have to do the full strip.

 

BTW, you're right about not using Radweld (or similar) until you positively know that there is an actual leak.

 

I'll check on the service history when the timing belt was changed last. The car's done around 128k, 5k of that is myself.

I'll check on the service history when the timing belt was changed last. The car's done around 128k, 5k of that is myself.

It will be down as "toothed belt" in the service log.

It will be down as "toothed belt" in the service log.

 

Was changed at 88k according to the service logbook.

Was changed at 88k according to the service logbook.

Check the matching bill, if available, or contact the dealer if there's a readable stamp and no bill. Water pump isn't an official VAG service item, but most independants will automatically quote cam belt change including a new pump for reasoning stated.

 

Experience says it's probably the water pump, but if it's not then it's about £300 spent unnecessarily, and your speculation about a blocked radiator was correct, so I'm trying to get you as much evidence as possible about the 2 possibilities.

Indeed. I'll have a look to see if there are any receipts and stuff. I keep all of mine, but this was years before I owned the car.

 

Should I just replace the radiator anyway? Are there any other methods to ascertain which issue it is?

sounds to me like the pump failed, had a sdi octy that done this and it was the water pump, but your last belt was done at 40k ago, so it's due a belt really, waterpump might not have been changed from last belt change, highly doubt your pipes are blocked, but being said I recent suffered overheating on my missus Alhambra and that was down to a reducer vale at the expansion bottle being blocked which was only found once waterpump was ruled out after being replaced, but belt was due on that so done it anyways.

 

So I'd get the belt and pump done, as your not going to get full circulation without it

More info: Just drove home, expansion tank had much more fluid in it than at rest, and steaming. I had topped it up to the recommended level before I set off. Level then fell.

More info: Just drove home, expansion tank had much more fluid in it than at rest, and steaming. I had topped it up to the recommended level before I set off. Level then fell.

That's pretty normal, and further suggestion that it is the water pump that's failed.

Righteo. Waterpump replacement it is!

A good indication the water pump has failed is sod all coming through the overflow hose.

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Just in case check for a head gasket blow; the symptoms can be similar.

Any emulsion under the oil filler cap?

Regards, Mike

Oil looks clean, no emulsion of any sort that I can see on the underside of the oil filler cap. Oil level is a little low, at the bottom of the acceptable range.

Oil looks clean, no emulsion of any sort that I can see on the underside of the oil filler cap. Oil level is a little low, at the bottom of the acceptable range.

Buy 1l of oil, but don't actually top up. Just have it ready and run for a bit to see if the oil level warning works.

 

Also, I'm about as sure as I can be that the problem is the water pump, and the cambelt is due in year or so anyway, so you'd not lose that much changing it.

I'm about as sure as I can be that the problem is the water pump, and the cambelt is due in year or so anyway, so you'd not lose that much changing it.

^ what he said.

Hello all! Back with status report:

 

Just today changed the cambelt and waterpump. The old waterpump was intact, and seemed fine, and the old belt looked to be in fair condition. Also found out why my temperature reading wasn't working - I'd forgotten to plug it in after replacing it a while ago.

 

Drove home and the car is still overheating. Temperature reading dropped off a couple of times on the journey and when it returned it was hovering between 90 and 110, with steam coming from the bonnet.

 

As an added bonus, it has also gained a really fierce boost leak. One of the gaskets on the turbo -> intercooler pipe was buggered. Not having the replacement handy we shoved it back on to test if it overheated still.

 

My accomplice that I did the job with is thinking that it's the head gasket.

Ballcocks!!!

 

Plan B - An exhaust gas coolant analysis will confirm or deny the HGF.

How do I go about doing that? Can't see any smoke from the exhaust, although when I got the MOT done it needed a fair amount of running to pass the emissions. I'd had it sat for about 10 days after realizing my MOT had expired. The tester suggested that was likely from it being sat for so long, but now I'm not so sure.

How do I go about doing that? Can't see any smoke from the exhaust, although when I got the MOT done it needed a fair amount of running to pass the emissions. I'd had it sat for about 10 days after realizing my MOT had expired. The tester suggested that was likely from it being sat for so long, but now I'm not so sure.

If you have to ask, get a garage to do it (included in price suggested).

I've not gotten a quote yet, but the garage chap person guy said that it would be wise to get the head skimmed, especially the number of times that the thing has overheated.

I've not gotten a quote yet, but the garage chap person guy said that it would be wise to get the head skimmed, especially the number of times that the thing has overheated.

Mibbae aye, mibbie nay. It would be wise to have the head checked for trueness if it's coming off, but until it fails a trueness test don't agree to a skim.