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There's a hole in my Polo
(MK2 Coolant pipe)
On a joyous and bright Sunday I drove my car down to visit Siôn Hudson of Morsels and Motors YouTube channel. He kindly filmed a detailed review of the car. I was pleased that on returning the car Siôn also returned the verdict that it was much more refined than he expected. However he also noted it smelt like the car had a leak (oh and that the speedometer wasn’t working - more on that another time!). Lifting the bonnet, it initially smelt more like an oil leak, but what we found visually were traces of leaking coolant.
On the drive home I got a whiff of an oil-like smell again and a small puff of steam from the bonnet when idling. Keeping a close eye on the temperature gauge I pressed on and made it home without calamity. The coolant level had definitely dropped and on lifting the bonnet again the sweet unmistakable smell of coolant wafted out of the engine bay. Fortunately (in one sense) it was quite a bad leak - much of the expansion tank’s contents had disappeared - but usefully it was now quite clear to me where the coolant was leaking from: I could see patches of coolant on the pipe behind the engine.
You may just about be able to make out the offending leaky pipe in the terrible photo below.
There were fresh bubbles emerging from a couple of locations along this steel pipe indicating pinholes where the coolant was coming from. I surmised that gradual corrosion had meant its time on this car was up and swiftly sourced a replacement.
The process of replacing this pipe was a challenge and I wasn’t confident it could be done without removing the entire intake manifold. Indeed one Polo expert I consulted indicated it is a job much better performed with the whole engine removed.
Being an obstinate individual, with some experience of extracting and replacing engine ancillaries from confined spaces, I decided to attempt the job without removing anything more than the air filter housing.
In truth the job was not technically too complicated - on the 1043cc HZ engine it involves:
Removing all 4 hose connections (inlet manifold, heater, expansion tank and rad if I recall)
Removing 2 nuts from the studs on the flange where it connects to the block at the water pump end
Removing 1 bolt which attaches it to the gearbox casing
Replacing the pipe with renewed gasket and reattaching all hoses & fixings
However it isn’t easy to do for two reasons - reaching the hoses is difficult and cleaning the mating surfaces near impossible. The first I tackled by obtaining a proper ‘remote’ spring clamp tool. The latter with application of sinful RTV gasket maker / sealant.
As you can see the old pipe was very rusty. In the case of one connection I had to carefully clean the corroded metal from inside the hose that connected to it.
At the same time I used the opportunity to replace the old expansion tank which had a cracked mounting with a new Polo 2F style spherical tank. So far it’s connected up with some pretty makeshift bracketry, but it does the job for now and I can perfect that later.
It took me a good few hours spread over several days to get the pipe replaced. I then put in a mix of nice new coolant and de-ionised water and fired the car up. I topped up the coolant, kept an eye on the temperature and used the heater bleed tap to reduce the chance of air in the system. After an initial inspection with no leaks I took it for a drive and everything seemed to be working fine.
So there you have it one less holey Polo. Doubtless there could be more coolant or oil leaks that appear over time but that’s one significant source of leaks dealt with and not a moment too soon.