Coolant leak

[Alexlib]

Hi
Been using the van for two 100 mile trips a week, each week it loses 700 ml of coolant from the header tank, the exspansion tank level is good, new blue cap and no over heating, no obvious drips, about 3ml per minute of driving
Any suggestions?
1987 1.9 dg

[Rik]

Seems like you've got two different problems. You're losing coolant and your expansion tank isn't topping up the header tank.

What does your oil look like? Are you sure there are no wet spots around the cooling system? Does your exhaust smoke?

Maybe its worth to pressure check the coolant system. Are you filling the header tank up to the brim? 3 mil per min is not too much of course, but you would think it will leave some drips on the floor after parking up.

[Alexlib]

Thanks for the comment, oil looks good , not burning any, no smoke, driving really well.
I do fill to the brim, cannot see any leaks, I will look at the exspansion tank when the van is hot to see if it has expanded into the header

[TONYT25T25]

Ive had a leak problem with mine for ages but thats between the plastic pipe and rubber pipe to the rad yet to repair. Are there any visible leaks in the engine bay which may be evaporating due to heat. Some leaks are not easily visible due to the heat in the engine bay evaporating them, although a stain is normally visible in the area of the leak, could be a loose hose clip.

[Alexlib]

I have been ill for a few days but had a chance to look again, I topped of the header tank, took it for a drive, got it warm, couldn’t see any leaks for there is a faint coolant smell in the engine bay.
Interesting that the expansion tank fluid was cold, I had expected that the header tank would have push some hot coolant in.
I am unsure how the blue cap works, it quacks when I blow in it and I cannot suck back, so how does the system work?

[multisi]

I have been ill for a few days but had a chance to look again, I topped of the header tank, took it for a drive, got it warm, couldn’t see any leaks for there is a faint coolant smell in the engine bay.
Interesting that the expansion tank fluid was cold, I had expected that the header tank would have push some hot coolant in.
I am unsure how the blue cap works, it quacks when I blow in it and I cannot suck back, so how does the system work?

Having a small leak may prevent the header tank from pushing out the coolant into the expansion tank, i have this same problem but cant see a leak but i know i have a dodgy join between a plastic and rubber pipe.
 

[SurfT25]

I too have a small leak and often top up the reserve and check the tank.
When topping up the main tank there are always bubbles in it. To remove the air I use a straw with a strong copper wire shape like the letter J in it. Cover the top end of straw with thumb (not to let air escape) insert in bottle ,position other end in bubble , release thumb and most of air will be pushed out. Do the same to other bubbles.
Once done top up to rim, when replacing expansion tank tube I lower tube till coolant appears seal with my thumb then quickly put it on Dalek cap.
This doesn't solve leak but I now know that little or no air was in the system at start of journey.
Best of luck

[MarkHughes]

I have something a bit like this. 

https://www.amazon.co.uk/Orion-Motor-Te ... r=8-5&th=1

Not only good for finding leaks but great for bleeding the system, Fill it, pressurise it and bleed the radiator until the air is gone, Makes it a doddle. If you plan on long term ownership it might be worth the investment.

 

[Alexlib]

Interesting thanks , do you know what pressure the blue cap is set to ?

[MarkHughes]

Interesting thanks , do you know what pressure the blue cap is set to ?

You can just pump to whatever pressure you like using the gauge on the pump. The caps themselves just have a connector on to let the air in.

[Rik]

Interesting thanks , do you know what pressure the blue cap is set to ?

I think the coolant system operates at about 1 bar (please correct me if im wrong), so it should let fluid out when that pressure is exceeded. It doesnt require any specific pressure for letting fluid enter the header tank again. Just lower than ambiant so it will actually be pushed into the header tank.

[Alexlib]

Found a small leak on the back of the Weber carb, my fault as I fitted it , hopefully that is it sorted now