Coolant level going down very slowly

could it be your coolant bottle cap?

you notice coolant on the ground or garage floor? or what do you mean "in the floor"? later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

I think you could use a UV lamp to detect small traces of coolant. On alt.lasers, they had a discussion some time ago about using UV LEDs for that purpose. Apperently, it works quite well and the UV LED shouldn't be expensive. You might have to clean your engine first, since they said those thing detect extremely small quantities.

I also saw somewhere mentioned that you could fit a tyre valve (e.g. from a bycicle tube) to the cap of the reservoir (best get a spare cap for this) and then pump it up to some pressure to detect leaks.

Good luck,

Christoph

Dave, I should have said "on the floor" - the garage floor. (english is not my native language...) No chance of the bottle cap being the culprit. Topping was a clean operation. Thanks, Jorge

I was thinking that the cap should hold a minimum pressure and sometimes they fail to do that. When that happens the cap can allow some pressure and fluid out of the bottle. Ah it was just a though! :-) later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Christoph, Thanks for your points. I think it would be difficult to get an UV light here. (have to check) As for the cap + valve I am not sure I can produce this small tools. (BTW - Audi uses exactly the same technique) Best Regards, Jorge

Hi Jorge,

Shouldn't be too difficult. They suggested LEDs because you should be able to get them much easier than normal UV lamps.

I don't know where you life, but RS Electronics is in a lot of countries. Their no 454-4403 is a UV LED which is most likely suitable (Cannot guarantee, but it looks like what I would try. I just did a search for "uv led" on their web page,

That shouldn't be difficult either. A normal valve has a diameter of 5 to 6 mm (just guessing), so all you need is a drill of that size plus maybe an o-ring.

Christoph

Had this on a 90 a few years ago , it was a microscopically small crack in the rad matrix , so I suggest a bottle of "bars leaks" in the rad as this will gum up minor holes for a while , should prove the theory , and costs less than £2.00

First of all thanks to all for the support. Now an update:

- I tried to replicate the topping/bleeding mistery. Mistery ended: no bleeding at all.

- On the other hand I was finally able to spot tiny drops coming from the rad matrix (probably). Saw them in two places. The origin may be the same.

I am leaving for a trip and will follow this after my return. In the meantime: what are the typical brands of the "bar leaks" products? Are they effective in an oily environment such as the coolant? And can't they create problems with the overall efficiency of the system ? Thanks again, Jorge