Coolant level going down very slowly
 

A4 2.8 1996 - 46,000Km

Coolant is slowly decreasing. About 1 month from max to min.
No leaks, smokes or smells.
Temperature - oil & coolant - Ok.

Curiously, when I topped the coolant to Max I noticed a few hours
later some coolant in the floor. (engine cold - not turned on in any
moment)

Can it be just a minimum fracture in the higher part of the reservoir
or should I be looking at somethng else?
I imagine that the coolant works under pressure - cannot understand
leaking with the engine cold and no pressure at all.
BTW: after the mentioned leak - no more than 12 hours later - no leaks
at all. (and reservoir at MAX level)
Thanks in advance for your help.
Jorge

>From: (Jorge Fonyat)
>
>A4 2.8 1996 - 46,000Km
>
>Coolant is slowly decreasing. About 1 month from max to min.
>No leaks, smokes or smells.
>Temperature - oil & coolant - Ok.
>
>Curiously, when I topped the coolant to Max I noticed a few hours
>later some coolant in the floor. (engine cold - not turned on in any
>moment)
>
>Can it be just a minimum fracture in the higher part of the reservoir
>or should I be looking at somethng else?
>I imagine that the coolant works under pressure - cannot understand
>leaking with the engine cold and no pressure at all.
>BTW: after the mentioned leak - no more than 12 hours later - no leaks
>at all. (and reservoir at MAX level)
>Thanks in advance for your help.
>Jorge
>


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

> A4 2.8 1996 - 46,000Km
>
> Coolant is slowly decreasing. About 1 month from max to min.
> No leaks, smokes or smells.
> Temperature - oil & coolant - Ok.
>
> Curiously, when I topped the coolant to Max I noticed a few hours
> later some coolant in the floor. (engine cold - not turned on in any
> moment)
>
> Can it be just a minimum fracture in the higher part of the reservoir
> or should I be looking at somethng else?
> I imagine that the coolant works under pressure - cannot understand
> leaking with the engine cold and no pressure at all.
> BTW: after the mentioned leak - no more than 12 hours later - no leaks
> at all. (and reservoir at MAX level)
> Thanks in advance for your help.
> Jorge

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

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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

NTISPAM (dave) wrote in message >...
> >From: (Jorge Fonyat)
> >
> >A4 2.8 1996 - 46,000Km
> >
> >Coolant is slowly decreasing. About 1 month from max to min.
> >No leaks, smokes or smells.
> >Temperature - oil & coolant - Ok.
> >
> >Curiously, when I topped the coolant to Max I noticed a few hours
> >later some coolant in the floor. (engine cold - not turned on in any
> >moment)
> >
> >Can it be just a minimum fracture in the higher part of the reservoir
> >or should I be looking at somethng else?
> >I imagine that the coolant works under pressure - cannot understand
> >leaking with the engine cold and no pressure at all.
> >BTW: after the mentioned leak - no more than 12 hours later - no leaks
> >at all. (and reservoir at MAX level)
> >Thanks in advance for your help.
> >Jorge
> >
>
>
> 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

>From: (Jorge Fonyat)
>
>
>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

Christoph Bollig > wrote in message >. ..
> > A4 2.8 1996 - 46,000Km
> >
> > Coolant is slowly decreasing. About 1 month from max to min.
> > No leaks, smokes or smells.
> > Temperature - oil & coolant - Ok.
> >
> > Curiously, when I topped the coolant to Max I noticed a few hours
> > later some coolant in the floor. (engine cold - not turned on in any
> > moment)
> >
> > Can it be just a minimum fracture in the higher part of the reservoir
> > or should I be looking at somethng else?
> > I imagine that the coolant works under pressure - cannot understand
> > leaking with the engine cold and no pressure at all.
> > BTW: after the mentioned leak - no more than 12 hours later - no leaks
> > at all. (and reservoir at MAX level)
> > Thanks in advance for your help.
> > Jorge
>
> 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

Hi Jorge,

> I think it would be difficult to get an UV light here. (have to check)

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,
http://www.rs-components.com/index.html )

> As for the cap + valve I am not sure I can produce this small tools.

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

--
Important: Emails sent to me which contain my full name
in the "to:" or "cc:" field will bypass my spam filter.
With most programs "Reply" should do the job.

"Jorge Fonyat" > wrote in message
m...
> A4 2.8 1996 - 46,000Km
>
> Coolant is slowly decreasing. About 1 month from max to min.
> No leaks, smokes or smells.
> Temperature - oil & coolant - Ok.
>
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


"RoBe!" > wrote in message >...
> "Jorge Fonyat" > wrote in message
> m...
> > A4 2.8 1996 - 46,000Km
> >
> > Coolant is slowly decreasing. About 1 month from max to min.
> > No leaks, smokes or smells.
> > Temperature - oil & coolant - Ok.
> >
> 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