Low coolant level -- what potential damage to engine?

All,

I bought a very nice used 2000 BMW 328i a few days back and have been
very happy so far. After a few days I was driving in city conditions
(stop/go/idle a lot) and noticed some steam coming from under the hood
while driving and a slight antifreeze smell. Then the
low-coolant-level light came on.

The service guy at the station tried to unscrew the coolant cap and
water/coolant came out -- he said it look overall full. I drove on a
bit more, parked, let the car cool while doing some other things.
When I came back and unscrewed the cap there was no visible coolant --
filling with maybe 3/4 a liter of water (8.9 liter capacity total)
brought the level to max. On the way home (about 40 miles) I did this
again twice -- about 1/2 liter each time.

So a few comments/questions:

- the engine temp gauge never indicated overheating (it was
suspiciously
constant at half-way on the gauge, but I did confirm that it works
because on cold start the same gauge registers a cold temperature,
and gradually rises till it maxes out at "1/2" level on gauge

- does this temp gauge reflect the true engine temperature, or
does it measure temperature of some proxy, e.g., temperature
of the coolant? If the gauge didn't exceed halfway point
then can I be assured that the engine itself didn't overheat?

- with the coolant lid completely sealed should the cooling system
be under pressure? Should the hoses that transport water around
the engine be firm to touch? In my case they showed no real
pressure.

- I'd rather not tow my car to a shop, I'd rather drive there,
perhaps close to work (30 miles), and maybe do some errands
in the mean time. Am I safe as long as I make sure the water
is replenished often, that the check-coolant light doesn't
come on for too long, and that the engine temperature gauge
never exceeds what looks to be its "optimal" engineering
halfway-on-gauge value?

Thanks for reading this far, I look forward to your answers.

Nathan

"Tqz" > wrote in message
om...
> All,
>
> I bought a very nice used 2000 BMW 328i a few days back and have been
> very happy so far. After a few days I was driving in city conditions
> (stop/go/idle a lot) and noticed some steam coming from under the hood
> while driving and a slight antifreeze smell. Then the
> low-coolant-level light came on.
>
> The service guy at the station tried to unscrew the coolant cap and
> water/coolant came out -- he said it look overall full. I drove on a
> bit more, parked, let the car cool while doing some other things.
> When I came back and unscrewed the cap there was no visible coolant --
> filling with maybe 3/4 a liter of water (8.9 liter capacity total)
> brought the level to max. On the way home (about 40 miles) I did this
> again twice -- about 1/2 liter each time.
>
> So a few comments/questions:
>
> - the engine temp gauge never indicated overheating (it was
> suspiciously
> constant at half-way on the gauge, but I did confirm that it works
> because on cold start the same gauge registers a cold temperature,
> and gradually rises till it maxes out at "1/2" level on gauge
>
> - does this temp gauge reflect the true engine temperature, or
> does it measure temperature of some proxy, e.g., temperature
> of the coolant? If the gauge didn't exceed halfway point
> then can I be assured that the engine itself didn't overheat?

The temp gauge is designed to indicate "normal" for a wide (too wide) level
of operating conditions. Evidently this was done a number of years ago to
eliminate owners complaints/concerns when they noticed engine temps varying
somewhat (as they do depending upon driving conditions). Bottom line, you
won't show an overheat condition until the damage is done.

> - with the coolant lid completely sealed should the cooling system
> be under pressure? Should the hoses that transport water around
> the engine be firm to touch? In my case they showed no real
> pressure.

Yes.

> - I'd rather not tow my car to a shop, I'd rather drive there,
> perhaps close to work (30 miles), and maybe do some errands
> in the mean time. Am I safe as long as I make sure the water
> is replenished often, that the check-coolant light doesn't
> come on for too long, and that the engine temperature gauge
> never exceeds what looks to be its "optimal" engineering
> halfway-on-gauge value?

Risky, but doable as long as you don't have a catastrophic failure along the
way. BMW's cooling system has several plastic parts: thermostat housing,
overflow tank, and radiator. These tend to be far less robust than the
engine they are designed to cool. Cracking and leakage (sounds like your
problem) is a frequent symptom and its been known to happen fairly early in
the life-cycle of the cars. (Far more common on V-8's than Sixes) If your
car is somewhat north of 70,000 miles, a full cooling system inspection is
certainly in order. If cooling system components need replacement, you
might go the preventative route and replace everything while the mechanic is
in the Thermostat and housing (aluminum housing if available for M52
engine), radiator (Nissen aluminum vice OEM) and overflow tank.

R / John

My independent BMW mechanic told me that the cooling systems are the weak
link in the engines. He said this is the number one cause for complete
engine failure.

I would spend the $$$ to have it towed unless you have thousands of $$$
tucked away to put in a new engine.

Greg

"Tqz" > wrote in message
om...
> All,
>
> I bought a very nice used 2000 BMW 328i a few days back and have been
> very happy so far. After a few days I was driving in city conditions
> (stop/go/idle a lot) and noticed some steam coming from under the hood
> while driving and a slight antifreeze smell. Then the
> low-coolant-level light came on.
>
> The service guy at the station tried to unscrew the coolant cap and
> water/coolant came out -- he said it look overall full. I drove on a
> bit more, parked, let the car cool while doing some other things.
> When I came back and unscrewed the cap there was no visible coolant --
> filling with maybe 3/4 a liter of water (8.9 liter capacity total)
> brought the level to max. On the way home (about 40 miles) I did this
> again twice -- about 1/2 liter each time.
>
> So a few comments/questions:
>
> - the engine temp gauge never indicated overheating (it was
> suspiciously
> constant at half-way on the gauge, but I did confirm that it works
> because on cold start the same gauge registers a cold temperature,
> and gradually rises till it maxes out at "1/2" level on gauge
>
> - does this temp gauge reflect the true engine temperature, or
> does it measure temperature of some proxy, e.g., temperature
> of the coolant? If the gauge didn't exceed halfway point
> then can I be assured that the engine itself didn't overheat?
>
> - with the coolant lid completely sealed should the cooling system
> be under pressure? Should the hoses that transport water around
> the engine be firm to touch? In my case they showed no real
> pressure.
>
> - I'd rather not tow my car to a shop, I'd rather drive there,
> perhaps close to work (30 miles), and maybe do some errands
> in the mean time. Am I safe as long as I make sure the water
> is replenished often, that the check-coolant light doesn't
> come on for too long, and that the engine temperature gauge
> never exceeds what looks to be its "optimal" engineering
> halfway-on-gauge value?
>
> Thanks for reading this far, I look forward to your answers.
>
> Nathan

"John Carrier" > wrote in message
...
>
> "Tqz" > wrote in message
> om...
>> All,
>>
>> I bought a very nice used 2000 BMW 328i a few days back and have been
>> very happy so far. After a few days I was driving in city conditions
>> (stop/go/idle a lot) and noticed some steam coming from under the hood
>> while driving and a slight antifreeze smell. Then the
>> low-coolant-level light came on.
>>
>> The service guy at the station tried to unscrew the coolant cap and
>> water/coolant came out -- he said it look overall full. I drove on a
>> bit more, parked, let the car cool while doing some other things.
>> When I came back and unscrewed the cap there was no visible coolant --
>> filling with maybe 3/4 a liter of water (8.9 liter capacity total)
>> brought the level to max. On the way home (about 40 miles) I did this
>> again twice -- about 1/2 liter each time.
>>
>> So a few comments/questions:
>>
>> - the engine temp gauge never indicated overheating (it was
>> suspiciously
>> constant at half-way on the gauge, but I did confirm that it works
>> because on cold start the same gauge registers a cold temperature,
>> and gradually rises till it maxes out at "1/2" level on gauge
>>
>> - does this temp gauge reflect the true engine temperature, or
>> does it measure temperature of some proxy, e.g., temperature
>> of the coolant? If the gauge didn't exceed halfway point
>> then can I be assured that the engine itself didn't overheat?
>
> The temp gauge is designed to indicate "normal" for a wide (too wide)
> level of operating conditions. Evidently this was done a number of years
> ago to eliminate owners complaints/concerns when they noticed engine temps
> varying somewhat (as they do depending upon driving conditions). Bottom
> line, you won't show an overheat condition until the damage is done.
>
>> - with the coolant lid completely sealed should the cooling system
>> be under pressure? Should the hoses that transport water around
>> the engine be firm to touch? In my case they showed no real
>> pressure.
>
> Yes.
>
>> - I'd rather not tow my car to a shop, I'd rather drive there,
>> perhaps close to work (30 miles), and maybe do some errands
>> in the mean time. Am I safe as long as I make sure the water
>> is replenished often, that the check-coolant light doesn't
>> come on for too long, and that the engine temperature gauge
>> never exceeds what looks to be its "optimal" engineering
>> halfway-on-gauge value?
>
> Risky, but doable as long as you don't have a catastrophic failure along
> the way. BMW's cooling system has several plastic parts: thermostat
> housing, overflow tank, and radiator. These tend to be far less robust
> than the engine they are designed to cool. Cracking and leakage (sounds
> like your problem) is a frequent symptom and its been known to happen
> fairly early in the life-cycle of the cars. (Far more common on V-8's
> than Sixes) If your car is somewhat north of 70,000 miles, a full cooling
> system inspection is certainly in order. If cooling system components
> need replacement, you might go the preventative route and replace
> everything while the mechanic is in the Thermostat and housing
> (aluminum housing if available for M52 engine), radiator (Nissen aluminum
> vice OEM) and overflow tank.
>
The first thing you should do is *bleed* your cooling system and check for
leaks. If things check out, I too would recommend replacing your water pump
with its plastic impeller, plastic thermostat housing (BMP and others have
metal ones), and radiator. These should all be part of your 60K miles
service.

In article >,
John Carrier > wrote:
> The temp gauge is designed to indicate "normal" for a wide (too wide)
> level of operating conditions.

Not really much point in having a gauge, then?

> Evidently this was done a number of years ago to eliminate owners
> complaints/concerns when they noticed engine temps varying somewhat (as
> they do depending upon driving conditions).

Wonder which owners these were?

> Bottom line, you won't show an overheat condition until the damage is
> done.

Strange. My E39 did just this - the gauge went to high and the light came
on. I stopped and let it cool down. Then checked the coolant which was
low. Filled with water and drove home - luckily not a great distance.

Found a weep at the thermostat housing. Replaced this plastic part and
changed the coolant. No more problems.

What can cause problems is ignoring the gauge. If it goes over normal
stop, let the engine cool, and check the level. If the level is ok, try
again. Even if something like the waterpump is shot the engine won't come
to any harm while there is still water in it.

Ignore things because you're in a rush and be prepared to pay.

--
*OK, who stopped payment on my reality check?

Dave Plowman London SW
To e-mail, change noise into sound.

In article .net>,
Greg > wrote:
> My independent BMW mechanic told me that the cooling systems are the
> weak link in the engines. He said this is the number one cause for
> complete engine failure.

Running out of water for whatever reason is probably the number one cause
of failure on any modern engine. The days of cast iron lumps that could
tolerate this to a degree are long since gone - thankfully.

--
*Santa's helpers are subordinate clauses.*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" > wrote in message
...
> In article >,
> John Carrier > wrote:
>> The temp gauge is designed to indicate "normal" for a wide (too wide)
>> level of operating conditions.
>
> Not really much point in having a gauge, then?

How true. There are aftermarket kits that retrofit 3 REAL gauges to the
E36/46. Wish there was a nice system that would go into the 5er seamlessly.
Real water temp, oil pressure, oil temp, volts would be nice. MPG guage (is
it US only, or universal) could go.

>> Evidently this was done a number of years ago to eliminate owners
>> complaints/concerns when they noticed engine temps varying somewhat (as
>> they do depending upon driving conditions).
>
> Wonder which owners these were?

Much more likely to be US than European.

>> Bottom line, you won't show an overheat condition until the damage is
>> done.
>
> Strange. My E39 did just this - the gauge went to high and the light came
> on. I stopped and let it cool down. Then checked the coolant which was
> low. Filled with water and drove home - luckily not a great distance.
>
> Found a weep at the thermostat housing. Replaced this plastic part and
> changed the coolant. No more problems.
>
> What can cause problems is ignoring the gauge. If it goes over normal
> stop, let the engine cool, and check the level. If the level is ok, try
> again. Even if something like the waterpump is shot the engine won't come
> to any harm while there is still water in it.
>
> Ignore things because you're in a rush and be prepared to pay.

There have been a number of posts on the roadfly E39 board where the car
showed the overtemp, the driver immediately rolled to a stop, and still had
significant damage. Usually the 4.4 liter V-8, but the amount of warning
was quite short ... usually a rapid loss of fluid caused by a major radiator
failure.

Your earlier comment is right on. Modern engines have less tolerance for
high temps than the old lumps of the past. The OEM BMW cooling system parts
don't seem to be made from the most durable materials, but rather the least
expensive ones. Would the cost of the vehicles be that much higher if they
spec'd all-aluminum radiators, aluminum thermostat housings, and metal water
pump impellers?

Newest 6 has electric water pump for cooling. Theoretically, this offers
several advantages. But I wonder how the system involved (motor, wiring,
etc) will perform over the long haul. The BMW engine, properly maintained,
can go several hundred thousand miles without major work (overhaul). Yet a
major failure in a subsystem (cooling, oil pump bolts) can bring all that
engineering excellence to an abrupt end.

R / John

Be sure the engine is running or already cold before adding coolant or
water.

"Tqz" > wrote in message
om...
> All,
>
> I bought a very nice used 2000 BMW 328i a few days back and have been
> very happy so far. After a few days I was driving in city conditions
> (stop/go/idle a lot) and noticed some steam coming from under the hood
> while driving and a slight antifreeze smell. Then the
> low-coolant-level light came on.
>
> The service guy at the station tried to unscrew the coolant cap and
> water/coolant came out -- he said it look overall full. I drove on a
> bit more, parked, let the car cool while doing some other things.
> When I came back and unscrewed the cap there was no visible coolant --
> filling with maybe 3/4 a liter of water (8.9 liter capacity total)
> brought the level to max. On the way home (about 40 miles) I did this
> again twice -- about 1/2 liter each time.
>
> So a few comments/questions:
>
> - the engine temp gauge never indicated overheating (it was
> suspiciously
> constant at half-way on the gauge, but I did confirm that it works
> because on cold start the same gauge registers a cold temperature,
> and gradually rises till it maxes out at "1/2" level on gauge
>
> - does this temp gauge reflect the true engine temperature, or
> does it measure temperature of some proxy, e.g., temperature
> of the coolant? If the gauge didn't exceed halfway point
> then can I be assured that the engine itself didn't overheat?
>
> - with the coolant lid completely sealed should the cooling system
> be under pressure? Should the hoses that transport water around
> the engine be firm to touch? In my case they showed no real
> pressure.
>
> - I'd rather not tow my car to a shop, I'd rather drive there,
> perhaps close to work (30 miles), and maybe do some errands
> in the mean time. Am I safe as long as I make sure the water
> is replenished often, that the check-coolant light doesn't
> come on for too long, and that the engine temperature gauge
> never exceeds what looks to be its "optimal" engineering
> halfway-on-gauge value?
>
> Thanks for reading this far, I look forward to your answers.
>
> Nathan

(Tqz) wrote in message . com>...
>>

> - does this temp gauge reflect the true engine temperature, or
> does it measure temperature of some proxy, e.g., temperature
> of the coolant? If the gauge didn't exceed halfway point
> then can I be assured that the engine itself didn't overheat?
>

Sometimes even with real themp sensors if there's no water near the
sensor it'll give a lower temp reading.



> - with the coolant lid completely sealed should the cooling system
> be under pressure? Should the hoses that transport water around
> the engine be firm to touch? In my case they showed no real
> pressure.

When the engine is a little bit warm when you release the rad cap you
should get a whoosh of air under pressure. If not then probably the
rad cap is defective & you're losing water (steam) out of it.



>
> - I'd rather not tow my car to a shop, I'd rather drive there,
> perhaps close to work (30 miles), and maybe do some errands
> in the mean time. Am I safe as long as I make sure the water
> is replenished often, that the check-coolant light doesn't
> come on for too long, and that the engine temperature gauge
> never exceeds what looks to be its "optimal" engineering
> halfway-on-gauge value?
>

The cause could be all sorts of things. For instance if the fan ins';t
working then the car will onyl overheat at low car speeds but will be
fine on the highway. If the thermostat is stuck (why??) then you'll
be ok for a few miles while the car heats up. Whatever you do don't
put cold water into a hot engine!

If you want to akwe the risk of ruining your engine then that's up to
you. I guess you bought the car privately? Otherwise you should have
some comeback on the trader.

In article >,
John Carrier > wrote:
> The OEM BMW cooling system parts don't seem to be made from the most
> durable materials, but rather the least expensive ones. Would the cost
> of the vehicles be that much higher if they spec'd all-aluminum
> radiators, aluminum thermostat housings, and metal water pump impellers?

Dunno. However, failure of rads and water pumps isn't unique to BMW. And
all cars have hoses which can and do fail eventually.

Also, some model BMWs seem far more prone to rad failure than others.

--
*Very funny Scotty, now beam down my clothes.

Dave Plowman London SW
To e-mail, change noise into sound.