EWP By-Pass Tube

[sprint95m]

I understand what you are getting at Steve
but what of the start up procedure where the cap is removed from the header tank?


Thanks

Ian

Leaving the rad cap off the header alone wouldn't make any difference. I always leave the cap off any car (not just Dolomites) that I have drained and refilled until the engine has run long enough for the stat to open and the coolant level to stabilise, then I top it up and fit the cap. I'm also still inclined to remove the original filler plug from the stat housing when filling to improve self bleeding of the system. But that doesn't get round the pump housing airlock possibility either. Only a running pump with enough power to push the trapped air into the block and thence upwards through the stat housing and into the header via the thin pipe will do that. On my controlled EWP system the pump doesn't run at all on startup and only gives 10-30 second pulses during warmup, so it's doubtful if the pump would run enough until the motor is pretty hot. Which sounds a bit risky to me!

Maybe i'm being overcautious, I call it outwitting Murphy's Law! 50 years in this business has given me a sensitivity to airlocks on refilling, I can tell from the way the water level in the header behaves on warmup, when to suspect one. But I am very aware that not everyone has my wealth of experience and could make an expensive mistake through no real fault of their own. So when I design or mod something, I try to make it as foolproof (or even squaddie proof, a much higher standard) as possible! Someone MUST agree with me, or the modified bypass pipe wouldn't exist!

Steve

Being vey inclined that way, I appreciate you cautious approach Steve,

but your set up is different to mine
given that I am using a Stewart pump which runs continually (at 200 litres/minute).

With such, the flowing coolant will pull any air to the vent,
it is the same idea as bleeding the hot water on a kitchen mixer tap.


Out of curiousity
I have actually bought one of they handheld thermometers following a post that Tony MacKillop put up
showing a photograph of his engine's temperature.



thanks

Ian

[sprint95m]

can you explain to me how a header tank with a screw top cap,releases water went they over heat

They caps are built to withstand a certain pressure (something like 18 or 20psi I think),
if the overheating causes the pressure to reach this then the cap will allow the coolant to spew out.
After sorting the cause, you then need a new cap.


Ian.

[new to this]

can you explain to me how a header tank with a screw top cap,releases water went they over heat

They caps are built to withstand a certain pressure (something like 18 or 20psi I think),
if the overheating causes the pressure to reach this then the cap will allow the coolant to spew out.
After sorting the cause, you then need a new cap.


Ian.

Ian

You said if the water comes out the cap,your need a new cap does it melt something then ?

The main reason im asking is i bought off Ebay, a cheap alloy header tank it came with a screw cap,but the thread size was odd, and i could find another cap to fit the thread,so opened up a Vauxhall one, inside the cap there were cut outs,i had my alloy cap machined for the same cut outs and fitted the inside of the Vauxhall cap to mine

Thanks Dave