Thread: Temp guage gone whacky!

i might be getting confused but i thought because you have 2 different metals in contact with the coolant, each metal has a different electrical potential, hence creating an electric potential. or in simple words, you have created a galvanic cell or in simple words, a battery from your cooling system.

this creates acid which corrodes?
or maybe it causes oxidation?

Apparently if you have copper fittings upstream of a farm irrigation system with aluminium pipes and fittings the copper lets particles out which settle in the alloy pipes and destroy them. I suppose a similar mechanism is in play here. I'd always run proper 8mm heater hose the full length, Bursons at Mt Barker stock it. I won't work under the bonnet of a P38/D2 without chucking these horrible plastic pipes in the bin. Better safe than sorry.

thanks, ive been trying to google info but its not really much help LOL. those plastic pipes are horrible, i only bumped mine a couple weeks after i got the disco and it shattered. ill go visit bursons tomorrow. if the copper pipe is going to damage the cooling system it will go!

Originally Posted by Epic_Dragon

i only bumped mine a couple weeks after i got the disco and it shattered.

was that original hose?
if so, 10-15 years from rubber hose in a hot engine bay isnt bad.

it was probably really old, but even new they are a hard plastic prone to snapping. a hose that goes where that is needs to have some flexibility in it as there is strength in that.

Originally Posted by Epic_Dragon

thanks, ive been trying to google info but its not really much help LOL. those plastic pipes are horrible, i only bumped mine a couple weeks after i got the disco and it shattered. ill go visit bursons tomorrow. if the copper pipe is going to damage the cooling system it will go!

Hello Miss Dragon,

As pointed out, the original plastic pipe lasted over 10 years in the extremes of an engine bay... They too are a service item.

The reaction created is Galvanic (battery) and can be checked against the Anodic Index.
Attachment 69557

The difference between 2 metals - for storage in a non humidity controlled area should be less than 0.25v between values in right column.

In a cooling system the stray current should be less than 0.15v or engine damage will occur - with a lower reading being better!

This can be checked with a DMM.

yeah i dont know when the hose in mine if/wsa ever replaced. but if can improve on design then i will. knowing my luck id snap a brand new one of those just as easy lol!

thanks for that tombie, i think i understand. how does that work if metals are not touching though? or is it just stuff gets on the coolant and then it spreads/contaminates?

The coolant / water / moisture in the air work in much the same way as acid in a battery (electrolyte).
This also occurs to some extent between the block, head and radiator.

Interestingly, a new, factory hose is quite flexible. I have one here in the workshop and they are very flexible, certainly not brittle or likely to crack in any hurry.