HGF, radcaps and Kseal dissent.

[Des]

Modern cooling systems run under pressure, usually something like, roundabout, give or take, 1 bar -ish. Advantages of this are raising the boiling point of the coolant and sealing the system so we don't all have to top up 8 or 9 times a week. Over the years I've had 3 of my own cars do the hgf thing, first was a Saab, usual early symptoms of misfire on start up and using coolant, I left the pressure cap loose and carried on driving as normal and replaced the gasket when it suited me, next fail was a Sprite, same story again, loosened the cap and motored on before changing the gasket at my leisure. Had a Range Rover act the maggot and ignored it for over a year, topping up once a month, the pressure cap flopping around on its first couple of threads. What all these cars have in common is an airspace in the cooling system, you can brim them all you like but as sure as night follows day when warmed up expansion will see half the header tank displaced, on cooling the 'right' quantity of air is drawn in. So I've found in the past that leaving the radcap askew prevents hgf boiling the engine dry along with all which that entails, warping the head, cooking the thermostat, generally exacerbating the problem, at least for a while. My theory, this allows the combustion gasses which find their way into the cooling system to calmly exit rather than build up before violently chuffing out the coolant. Now what happens when the nazis design a system without this airspace and the pressure cap itself has an outlet feeding a vented to atmosphere overflow tank? Unwind the cap and the bloody things going to piss out and permanently lose an amount of coolant with each heating / cooling cycle, the loose cap trick isn't going to work here. This is what perplexed me a bit before Xmas. Buzzed down to the arse end of Cornwall in an aging VW so the missus can visit her mother. Halfways and the temp gauge climbed higher than normal, stopped to check and the old fascist wagon had blown out enough coolant to get a bit hot, assumed the worst so filled it back up adding a bottle of Kseal, carried on stopping and topping frequently. Clocked up a lot of miles while in Cornwall, every journey was a long series of diversions around landslides and downed trees from the prior rainy spell, but I had to visit Trago Mills whatever the cost, amazing place, owned by an outright nutter and way cheaper for oil, paints, tools and stuff than even wholesalers here in the smoke, the van now behaving itself, let's chalk up another Kseal win!!!

Or maybe not.

The return from Cornwall saw a tedious repeat of the stop up and top up routine, before setting off I figured the Kseal I'd added had been fairly well diluted so threw in another, (£7 from Trago Mills BTW), and that was where it all went wrong again, which did seem strange. So I parked up the van 5 months ago, then last Thursday took a look at it. Popped a pressure tester on, fired it up and saw no untoward readings, next day found it had held pressure overnight, I've yet to give it a sniff test but I don't now think it's head gasket.

Gave the cooling system a good flush, which I did when I first got the van 3 years ago as it was rust coloured and a little sludgy looking, this time some crap came out, but 3/4 of it was the Kseal copper filings which are intended to reinforce the sploodge that does the sealing.

Drove around a fair bit today and it's now behaving itself.

 

My Kseal conspiracy theory!!! Not OMG! New World Order Blakes 7 David Icke ate my lizard!

 

I think my overheating problem was the result of a bit of crap in the Panzer looking caps valve allowing loss of pressure on a squarehead designed cooling system that cannot tolerate such a state, the copper bits from the Kseal later caused the same problem as the bit of crap, the stuff gets everywhere and I think it's unlikely not to bugger up the tiny valve in a plastic screw on cap. Now if we look at the cooling systems with an airspace this buggeration will have the same outcome as leaving the cap loose, as I have done in the past to good effect. When the VW first overheated I didn't even consider the loose cap trick as it's the wrong side of the header tank, and dived straight in with the Kseal.

I don't know if I'm happy or not now, was waiting for good weather to drop the engine and do the gaskets, (not head gaskets as we know them, funny rubbers and sealing rings that are about as expensive as printer cartridges, HP ones). Maybe now I don't have to, but would have been a good opportunity to check over the valves, the clutch, all those little important bits that remain unseen.