Thread: TDI COOLING SYSTEM

Originally Posted by Judo

A bit late to the party here, but I'm quite sure coolant doesn't change the boiling point. It has anti corrosion and anti boil properties. The pressure increases the boiling point, which is ones of the reasons it's such a bad idea to remove the cap on a hot system - the coolant instantly boils as the pressure drops.

Google boiling point of water at 15psi and the answer 121*C. No coolant in the equation.

Good luck Nick.

Originally Posted by gromit

So it has 'anti-boil' properties but doesn't raise the boiling point ??

The pressure raises the boiling point and the addition of ethylene glycol raises it further (the amount depending on the concentration).



Colin

Sorry, that's a terrible typo. What I meant to type was anti corrosion and anti FREEZE properties.

Anyway I just googled ethylene glycol and perhaps I was partly wrong. It seems ethylene glycol is used primarily as anti corrosion and anti freeze, although it does also increase the boiling point, it's only by a few degrees. It doesn't raise the boiling point enough to be safe. The pressure is used to raise it past the safe operating temp of the engine.

I thought i had all my cooling issues sussed, in the last few months i have replaced almost all the cooling components bar the radiator.
Did the head gasket 2 weeks ago and after 1 week was getting a few temp spikes and mild boil over, fitted a new viscous fan clutch and seemed fine til this morning.
Another mild temp spike which came down as quick as it went up with no coolant loss ( could also be air pocket ) , only thing left to do is a rodding/test/clean of radiator.
Stupid part is it ran fine over the weekend we were up at Jamieson with no issues at all and that was with a suspect head gasket .

Judo did raise a good point before that little tangent about glycol. Hows the pressure cap?

Before mine died i had assembled materials to make up a bleed screw to put into the heater hoses. Still have them........ somewhere. Worth a try?

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Originally Posted by SSmith

Judo did raise a good point before that little tangent about glycol. Hows the pressure cap?

Before mine died i had assembled materials to make up a bleed screw to put into the heater hoses. Still have them........ somewhere. Worth a try?

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New cap about 3 weeks old, going to check if the brass Y piece is possibly blocked.
Noticed the core plug on the LH side of the head had a tiny weep so gave it a tap with a socket and hammer and spread gasket goo around the lip.

Originally Posted by loanrangie

This was not about the co-efficiency of coolant V water, thinking that i'm still up for a head gasket since i'm getting coolant loss out of the cap but otherwise gauge temp and running wise its fine.
Never ran without coolant so not sure how well a good system will function on straight water or very weak coolant mix.

'Fred' has been sold ( shock - horror !!! ) and the Black Beauty 300TDi auto has taken it's place and was brought sight unseen from auction.
BB was doing as above and coolant was gushing out of the cap.
Stripped the head off and yes the gasket was blown.

I have a brand new head to go back on, but before I did, I decided to check the block face for true and ( Gloom !!! ) a high spot between one and two cylinders of over .003" .
Back to using the old head as I don't want to throw a thousand dollar job into the bin. The block will need planing, so for now using the old head bolts, the old head goes back on with the high spot draw filed, this is to get the worst of the high spot, the head bolts will be torqued down slightly past the recommended 40 Nm to say 50 Nm and then the sequence of 60 degrees plus 60 degrees for all the bolts and then 20 degrees for the last group of bolts. ( by the way, the flats on a six point bolt head are 60 degrees apart. )

I have seen too many cracked blocks from frost damage not to run a strong mix of coolant, then leaving the coolant in longer than a couple of years is also inviting disaster IMHO, as I believe it looses it's anti-corrosion properties and will end up attacking the laminated head gasket.
BB has no lip in the cylinders and the cross hatching is still as new, just that high point on the block face is the worry.

Had my radiator reco'd and i'm still getting some overheating and gurgling in the heater core.
Core is not leaking so is it possible to suck air in from leaking seals ? , clutching at straws and now the waterpump is the only item not recently replaced.
If i dont get this sorted soon there will be a bonfire at my place .

Unfortunately that gurgling sound + extra heat seems very like cracked head,

If a small amount of air is getting in and the Y piece bleed hose is blocked, then it's perhaps possible that's the issue. It's another small and cheap alternative before you pull the head again...