1997 528 Cooling

Mum's car. Possessed. Evil. Horrid little thing.

Started overheating a couple of years ago. Had the head gasket
replaced. Runs good. No oil in the water, no water in the oil, plugs
look great.
Overheating again. I bled the crap out of it. Ran great for about a
week and then over heated on the interstate. Then overheated in
parking lot. Then overheated under normal driving. I checked and found
the push fan not working. Mum had to drive it (on the interstate) and
went about her merry way. It overheated. Broke the top right radiator
neck off. Upon further inspection I have found the fan clutch to
appear new but is quite "loose" in it's cold operation.

This week I am replacing:
Thermostat
Water pump (metal impeller)
Radiator
Push fan
Fan clutch

Am I missing something? Any other recommendations or suggestions? I
already have the clutch fan and radiator out - will get the water
pump, thermostat and dead fan out over the coming days. I only get so
much time a day to work on it!

"ReddDawg" > wrote
> Started overheating a couple of years ago. Had the head gasket
> replaced. Runs good. No oil in the water, no water in the oil, plugs
> look great.
> ...
> This week I am replacing:
> Thermostat
> Water pump (metal impeller)
> Radiator
> Push fan
> Fan clutch
>
> Am I missing something? Any other recommendations or suggestions? I
> already have the clutch fan and radiator out - will get the water
> pump, thermostat and dead fan out over the coming days. I only get so
> much time a day to work on it!

Expansion tank. All hoses (since you'll have them off anyway.).

FloydR

ReddDawg > wrote:
>Mum's car. Possessed. Evil. Horrid little thing.
>
> Started overheating a couple of years ago. Had the head gasket
>replaced. Runs good. No oil in the water, no water in the oil, plugs
>look great.

Why didn't you do the water pump and thermostat at the same time, just
pre-emptively? Wouldn't have hurt to do an acid flush on the radiator
either.

> Overheating again. I bled the crap out of it. Ran great for about a
>week and then over heated on the interstate. Then overheated in
>parking lot. Then overheated under normal driving. I checked and found
>the push fan not working. Mum had to drive it (on the interstate) and
>went about her merry way. It overheated. Broke the top right radiator
>neck off. Upon further inspection I have found the fan clutch to
>appear new but is quite "loose" in it's cold operation.

Has anyone done ANY diagnosis on this? Like checking the flow rate on
the radiator? Or even pouring water into the top of the radiator and
seeing how long it takes to come out the bottom?

> This week I am replacing:
> Thermostat
> Water pump (metal impeller)
> Radiator
> Push fan
> Fan clutch
>
> Am I missing something? Any other recommendations or suggestions? I
>already have the clutch fan and radiator out - will get the water
>pump, thermostat and dead fan out over the coming days. I only get so
>much time a day to work on it!

It seems kind of silly to just shotgun everything out... but at this
point you might as well now that you've damaged the radiator anyway.
BUT, after doing all this... you might want to measure the flow rate.
You might also want to do an acid flush beforehand anyway, just to clean
whatever junk is in the block.

While you're shotgunning all this stuff out anyway you might as well
replace the hoses too if you haven't done that before.

Have you been changing the fluid and flushing the system annually like
the manual tells you to do?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

> Have you been changing the fluid and flushing the system annually like
> the manual tells you to do?
> --scott

Read my first line. Mum's car. I am intervening and yes, I probably
should have before this but "she was handling it."
Clutch - a bit loose.
Push fan - dead.
Radiator - tried running water through it. More water came out the end
with the hose. Not the case with the new radiator. I believe this is
the culprit.
Thermostat - looks good but replacing all the same and going with the
metal housing.
Water pump - plastic. Going metal.

Water flows through engine well. Flushed it in case of debris from
radiator neck breaking. So out of the 5 items I am "shot gunning" I
have found issues with 3 and a potential problem with the 4th. I would
say those are pretty good odds.

And...

Had not thought about the expansion tank. I did not mention the hoses
because they are more routine than what I am doing. I feel much better
finding a restricted radiator and think I am on the right path to get
her back safely on the road.

Thanks for the feedback, folks!

In article
>,
ReddDawg > wrote:
> Had not thought about the expansion tank. I did not mention the hoses
> because they are more routine than what I am doing. I feel much better
> finding a restricted radiator and think I am on the right path to get
> her back safely on the road.

Has the car always had the correct coolant changes? If so wonder how the
rad got blocked?

--
*You're just jealous because the voices only talk to me *

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

"ReddDawg" > wrote in message
...
> Mum's car. Possessed. Evil. Horrid little thing.
>
> Started overheating a couple of years ago. Had the head gasket
> replaced. Runs good. No oil in the water, no water in the oil, plugs
> look great.
> Overheating again. I bled the crap out of it. Ran great for about a
> week and then over heated on the interstate. Then overheated in
> parking lot. Then overheated under normal driving. I checked and found
> the push fan not working. Mum had to drive it (on the interstate) and
> went about her merry way. It overheated. Broke the top right radiator
> neck off. Upon further inspection I have found the fan clutch to
> appear new but is quite "loose" in it's cold operation.
>
> This week I am replacing:
> Thermostat
> Water pump (metal impeller)
> Radiator
> Push fan
> Fan clutch
>
> Am I missing something? Any other recommendations or suggestions? I
> already have the clutch fan and radiator out - will get the water
> pump, thermostat and dead fan out over the coming days. I only get so
> much time a day to work on it!


Your motor, Mum's motor really, is the M52, which is very similar to the M50
used until production of the '96 model year cars -- one of the differences
is the Smog Control stuff that was changed from OBD I to OBD II.

A known issue with the M50 head is that it can develop a small crack in the
wall of the water jacket to the adjacent #3 Cylinder Exhaust Port. When this
happens, coolant seeps into the exhaust stream and gets blown out the tail
pipe. You will never know this is happening by simply looking at the exhaust
coming out the back of the car, but you willo notice that the coolant level
is difficult to keep up.

It is possible that an exhaust sniffer can detect the trace amount of
coolant, but your eye will never see it, especially in the early stages of
the crack. I found my crack because the engine happened to be parked in just
the right position where the #3 exhaust valve was open, and coolant dribbled
into the cylinder, then on the subsequent restart the engine locked because
as the piston came up and the valve closed, the liquid could not compress
and the crank stopped turning.

Sorry, I can't devise any test for you other than the sniffer in the tail
pipe. Since your car is OBD II, perhaps the O2 Sensors will report an out of
range condition as a result of the coolant content in the exhaust stream. My
car is OBD I, and the sensor was silent on the coolant content -- I had no
idea there was a problem except that I had to top off the radiator once in a
while. I suppose that's an indication. But the only way to know is to pull
the head and look.

In article >,
Jeff Strickland > wrote:
> Sorry, I can't devise any test for you other than the sniffer in the
> tail pipe. Since your car is OBD II, perhaps the O2 Sensors will report
> an out of range condition as a result of the coolant content in the
> exhaust stream. My car is OBD I, and the sensor was silent on the
> coolant content -- I had no idea there was a problem except that I had
> to top off the radiator once in a while. I suppose that's an
> indication. But the only way to know is to pull the head and look.

If appreciable amounts of water gets into a cylinder, the plug will show
it by looking particularly clean.

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

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

"Dave Plowman (News)" > wrote in message
...
> In article >,
> Jeff Strickland > wrote:
>> Sorry, I can't devise any test for you other than the sniffer in the
>> tail pipe. Since your car is OBD II, perhaps the O2 Sensors will report
>> an out of range condition as a result of the coolant content in the
>> exhaust stream. My car is OBD I, and the sensor was silent on the
>> coolant content -- I had no idea there was a problem except that I had
>> to top off the radiator once in a while. I suppose that's an
>> indication. But the only way to know is to pull the head and look.
>
> If appreciable amounts of water gets into a cylinder, the plug will show
> it by looking particularly clean.
>
> --

That would require the crack to be on the Intake Port.

The crack that afflicted me, and the M50 head in general, is between the
water jacket and the #3 Exhaust Port, and if the engine stops with the valve
closed, then no water leaks in to give a hydrolock on a subsequent restart,
and water never gets to the plug while the engine is running because the
airflow is moving away from the combustion chamber not towards it.

I keep repeating the #3 Exhaust Port because the wall of the water jacket is
very thin in that specific location, and is thicker at all of the other
points where the jacket and the valve seats are nearby. This particular
point is probably 2mm thinner than the other locations where the valve seat
and the water galley come together.

When I had my issue (it's been about 6 years now), I went looking for a head
and discovered the problem I'm describing now. When I told my mechanic of
the problem, he was able to see the crack with a magnifying glass, but did
not see it without specifically looking in the precise location. He pulled
the head expecting to find a failed head gasket, but the gasket was not
compromised, which is to be expected if there is no oil and water being
mixed. His only clue, and mine, was that the engine was locked from coolant
pooling in the cylinder.

I found the coolant because I pulled the plugs and turned the engine with a
socket wrench, and it squirted out. I had the car towed to the shop, but it
occured to me later that I could have put the plugs back in and driven it
down. I haven't the tools to pull a head and put it back on properly, so I
had to pay for service. When the head gasket was found in good condition, I
researched other problems and found out about the cracked wall in the water
jacket.

In article >,
ReddDawg > wrote:
>
>> Have you been changing the fluid and flushing the system annually like
>> the manual tells you to do?
>
> Read my first line. Mum's car. I am intervening and yes, I probably
>should have before this but "she was handling it."
>Clutch - a bit loose.
>Push fan - dead.
>Radiator - tried running water through it. More water came out the end
>with the hose. Not the case with the new radiator. I believe this is
>the culprit.
>Thermostat - looks good but replacing all the same and going with the
>metal housing.
>Water pump - plastic. Going metal.
>
> Water flows through engine well. Flushed it in case of debris from
>radiator neck breaking. So out of the 5 items I am "shot gunning" I
>have found issues with 3 and a potential problem with the 4th. I would
>say those are pretty good odds.

So, it sounds like the basic issue is that lack of regular coolant changes
caused the radiator to gunk up.

You could try the acid flush to clean the block out as well, since that is
probably not much cleaner than the radiator. Problem is, it's apt to cause
anything marginal that is sealed by corrosion to start leaking all of a
sudden. Water flows through fine because the water jacket doesn't have a
lot of little fiddly bits like the radiator does, so the lime can build up
pretty heavily without affecting flow. It's still reducing cooling, though.

The plastic and metal water pumps both have premature failure problems, they
are just different problems. Won't hurt to replace it while you have the
thing apart, though.
--scott

While you're at it, too... I'd change the brake fluid, power steering
fluid, transmission and differential fluids too... odds are they have not
been getting changed on schedule either.
--
"C'est un Nagra. C'est suisse, et tres, tres precis."