I am going for a record for radiator replacements for a 99 540i.... since Nov 05, I am installing number 5. It is a '5' series, after all. I replaced the one that was in the car when I bought it because the side tank burst. That was an OE BMW radiator. The first replacement was a Behr, leaked, second, another Behr, leaked again, third and fourth, Nissens, fifth going back to Behr. Sixth will be a Zionsville. All of the leaks were side tank joints where they were crimped to the core. The last two also leaked at the drain plug. The rest of the cooling system has been replaced including heater hoses. Checked the engine mounts also, no problem there. I will probably replace the valley pan gasket this coming summer. All of the radiators have been covered under warranty by the place I bought the first one from. Unfortunately, I have to provide the labor (but I am getting fast at it) and the car is usually down for a week when it starts to go.
Incredible run of bad radiators. Anyone else have that kind of experience?

When it's working, it's wonderful.

Cheers
Wayne

With that many replacements having been done I'd want to know what the peak cooling system pressure is. You might have a small head gasket leak that is overpressurizing the cooling system.

How can you tell it was leaking from the radiator? Which side of the radiator is it leaking, driver or passenger side? Have you had a leak down test?

Like the above replys, I think something else is wrong. Could be the mounting is stressing the unit and causing the same type of failures.

I've got 165K miles and my one replacement has been because the water pump broke and pushed the fan into the radiator. If that hadn't happened I would still be on my original radiator. It was my 2nd water pump so I'm on my 3rd water pump.

After replacing my rad then later replacing the tank I discovered the problem was the aux cooling fan all along. It was allowing the system to run too hot and build too much pressure. The crazy thing about the temp gauge is it doesn't tell you the thing is hot until it is REALLY HOT. Does the fan make a growling noise when it kicks on? After replacing the fan I was pleased to learn the fan can't be heard at all from inside the car. If you can hear yours kick on from inside with the windows rolled up I would seriously consider having it checked out.

So far, all I have completed is a compression check. All eight cylinders were in the 170-175 psi range. The engine was warm to the touch, but not to operating temperature. I am waiting for the differential pressure gauge to arrive so I can do a leak-down test. I will also be installing a pressure gauge to test the cooling system pressure.

There are no signs of antifreeze on the oil fill cap, dipstick or in the drain oil.

It does not appear that the pressure cap has bled pressure or spewed antifreeze from the overflow port. All of the leaks have started after the temperature outside has dropped below 10 deg F and have spanned a year with no leaks over the summer (of course...it would be too nice to work on the car then). The aux fan works fine.

So, if it does turn out to be the head gasket(s), how tough is it to get the exhaust manifolds off with the engine in the car ?


Cheers
Wayne

I've got 165K miles and my one replacement has been because the water pump broke and pushed the fan into the radiator. If that hadn't happened I would still be on my original radiator. It was my 2nd water pump so I'm on my 3rd water pump.


Frank were there any signs of water pump failure on yours (leaking etc.?) I am on the second water pump and radiator at 130K. Both were replaced about 30K-40K ago. Just wanted to know if I should be looking for anything.

Frank were there any signs of water pump failure on yours (leaking etc.?) I am on the second water pump and radiator at 130K. Both were replaced about 30K-40K ago. Just wanted to know if I should be looking for anything.

No warning. The impeller broke and jambed which then cracked out the housing and the whole mess went into the radiator. I imagine the belt pulled it and pivoted it into the radiator. I've never heard or saw anything like that before. You could see the shaft and impeller and what was left of the water pump casting still bolted to the block.

So far, all I have completed is a compression check. All eight cylinders were in the 170-175 psi range. The engine was warm to the touch, but not to operating temperature. I am waiting for the differential pressure gauge to arrive so I can do a leak-down test. I will also be installing a pressure gauge to test the cooling system pressure.

There are no signs of antifreeze on the oil fill cap, dipstick or in the drain oil.

It does not appear that the pressure cap has bled pressure or spewed antifreeze from the overflow port. All of the leaks have started after the temperature outside has dropped below 10 deg F and have spanned a year with no leaks over the summer (of course...it would be too nice to work on the car then). The aux fan works fine.

So, if it does turn out to be the head gasket(s), how tough is it to get the exhaust manifolds off with the engine in the car ?


Cheers
Wayne

I guess it is Minnesota thing, I did replace 2 radiators on my 540 too, before I went with Zionsville's one. Exact the same symptoms too - very slow leak at the seams started when the temperature dropped below 10F

I'm on my 3rd Nissens radiator in a month. Leaking from the seam on the passenger side but only sometimes. It is a very small leak and all three have leaked from the same spot. I'm beginning to think this is a Nissens quality issue.

^^^Same thing happened to me with a small leak in the passenger side tank. I replaced my radiator with 2 Nissens and they both leaked within a month. I finally bought the zionsville super duty cooling kit and it will be installed thursday. Check it out at www.zionsville.com (http://www.zionsville.com).

There are no signs of antifreeze on the oil fill cap, dipstick or in the drain oil.


Did you also check for traces of hydrocarbons? How's the exhaust - any white smoke or smell of burnt coolant?

Quick update: All summer, no leaks, pressure test on rad when running indicated max of 20psi & rad cap released at 30psi after I pressurized system. No probs w/leakdown test on engine. Outside temp drops below 20, now, leaks from both sides of radiator at the drain plug and at the hose on right side at hose fitting/radiator connection. All hoses, exp tank, pump, thermostat, cap and (multiple) radiators had been replaced last winter. Maybe I'll get a Zionsville for Christmas !

Wayne

I am at 55k and replaced radiator at 50k. Next replacement will be a Zion so there will be no fing around at that point. The amount of radiators you have replaced do suggest that something else is going on.

98k and still on the original (knock on wood) but had to replace my E32 radiator three times. The Nissen rads have been known to be problematic so go with Behr or (and I'm sure most here would agree) drop the bucks on a Zionsville and NEVER deal with the rad again! Changing it out so many times should be unacceptable IMO...

Weak fan clutch causing chronic high temps?
Water pump?
Sensors?
Head gasket?

Five radiators? Something else is clearly wrong.

whoo-hoo - it was a lot - but i do love the zionsville...replaced my original radiator at 68k with the zionsville. do it once...do it right...it's cheaper in the long run.

Weak fan clutch causing chronic high temps?
108 deg C after warmup.... Hot/cold outside temps & engine temp never varies more than +/- 2 deg. It only leaks when sitting, cooling off or running from cold to warm.
Water pump? New Hepu last winter.
Sensors? All indications agree with analog test equipment plumbed into system both pressure/temp
Head gasket? Leak down test showed negative, pressure test on rad showed negative, new lower pressure cap, no change.

Five radiators? Something else is clearly wrong.

Drain plug leaks during the transition from operating temp to ambient temp. While it sits (two days now at 20-10 deg F) no leaks. Lower hose leaks (new last winter also) at radiator under same conditions. All summer, no leaks anytime.

Again, this thing <ONLY> leaks when the outside temp drops below 20 deg and then, only when the car sits and cools down after running and again only when it warms from ambient to running temperature. While it is hot, no leaks, when it is cold, no leaks. Current radiator is a Nissens. All hoses have been replaced and using BMW antifreeze. New water pump, thermostat, expansion tank and cap.

I'll be trying a different lower hose and drain plug this weekend or early next week. $40 is a lot cheaper than a Zionsville if it works. I am doggedly trying to make the thing work as designed.