I have an E36, 1998, 328i. Sometime after 108,000 miles I noticed a
slight coolant loss. Amount of loss seems dependant on mileage driven
between checks, not ambient temperatures.

I have recently replaced the coolant cap. And I have checked the
hoses. There does not appear to be a visible leak; no puddles on the
floor.

Earlier in 2006 the thermostat and related gaskets were replaced. The
engine warms up as it should and never overheats.

I noticed micro stress cracks in the coolant overflow reservoir. Seem
like they have been there a while, but maybe not forever.

There was a mention in this NG recently about the reservoir cracking
and leaking.

Any help? TIA!

"Opossum" <splat@o.possum.net> wrote

its not a BMW but I have just sources a similar problem with my sons car.

about 2 months ago I replaced the cylinder head gasket.

not immediately after but say 2 weeks it started loosing water but only on
long runs.

my son would top it up and he would report back saying system is OK and
holding water. I did not appreciate he was only doing short, under 2 mile
runs, at that time. He would then drive a 10+ miles and find a lose in water
but could not see any signs of a leak under the engine.

This past weekend I managed to get my hands on the car to give it a check
over. I ran the engine up to very hot and hey presto...........top hose slow
dripping. I must not have given it a good tightening. He could not see this
because it was dripping onto a hot engine and evaporating. And it was only
evident with the engine above thermostat opening temperature. The water
system pressure would have contributed to forcing water out.

so my sug is while you don't see any leaks they just might be there.

A pressurized leak test is best to pinpoint where the leak is. You may
also check after the car has run for a while and without shutting off
the engine. This keeps the pressure.

Another thing that may go slowly and leak is the waterpump, if you
haven't replaced it already.




Lez Pawl wrote:

In article <87ubp2d6ttki7bvhkdicoqe04tbqkmr6t4 (AT) 4ax (DOT) com>,
Opossum <splat@o.possum.net> wrote:
On my 528 it turned out to be the waterpump - although nothing showed. It
probably only leaked when hot and the coolant evaporated off leaving no
trace. Found by adding dye to the coolant and pressurizing it. Be careful
of anyone who says 'it's the head gasket' without doing this check first.

--
*What happens when none of your bees wax? *

Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.

"Opossum" <splat@o.possum.net> wrote

Run the engine up to temperature, ideally take it for a fast run then pull
up and leave it running, and watch for water or steam coming from anywhere
in the engine bay. Rev it up on the throttle to pressurise it. As Dave
said, it's tempting in these cases to assume an internal leak (head gasket
or crack) but actually that's very unlikely. It's incredible how much water
can be lost through a leak you can hardly see. There might even be more
than one leak.

"Dan Buchan" <danbuchan (AT) email (DOT) com> wrote:

Wasn't able to see anything. About May 1st, FINALLY saw some dripping
on the driveway. Radiator was leaking on the driver's side, somewhere
above the drain plug and below the hose. Had the radiator replaced,
and while at it, the coolant recovery bottle & level sensor.
Now that I think back on it, I noticed some "crud" where the metal and
plastic meet on the driver's side, top of the radiator, last year.
Think it was after the thermostat was replaced, and I assume the
system was pressure-tested. There was about 6 months lapse between
the thermostat work and the impossible to locate micro leak.
That should have cured it. I wish I could have gotten the parts
myself & did it, but..... Oh well.

On Sat, 30 Dec 2006 05:35:43 GMT, Opossum <splat@o.possum.net> waffled
on about something:

I had a slow leak on my E36, it turned out to be a small hole in the
front of the radiator caused by a stone.

The hole was small enough that it only leaked when under pressure, and
was evaporating off the hot radiator core leaving no puddle under the
car.

Have a look through the kidney grill with a torch, assuming you had
antifreeze in the car, the staining will be easy to see if it's the
radiator leaking.

Dodgy.
--
MUSHROOMS ARE THE OPIATE OF THE MOOSES

In article <3gq543ththgp998qjv5cpi34pedhp81nr4 (AT) 4ax (DOT) com>,
Dodgy <Dodgy (AT) earth (DOT) planet.universe> wrote:
I had similar on my E39 - loss of water and pressure. Stop the hot engine
and the top hose soon 'felt' soft indicating pressure loss. But no sign of
coolant ever. Eventually had dye put in the system which immediately
showed a weep from the waterpump seal. I'd been told by my main dealer it
was a head gasket problem...

--
*Change is inevitable ... except from vending machines *

Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.