[eug]

Hi everyone, I've got yet another cooling-system-related question on my 2004 330Ci.

A month or so ago, the radiator light would go on and off occassionally, every now and then. I kept checking the coolant levels and it's full. The float goes all the way to max - maybe too full?

Anyway after some searching I figured it was the coolant level sensor. I haven't gotten around to replacing it yet. I kept a close eye on the temp gauge and it's always on the halfway point.

Today I was sitting in the car in a car park reading something. I suddenly noticed the temp gauge was at red! Horror. I switched the engine off immediately and popped the hood, but the temperature seemed normal. Will an overheating engine be ... very hot? There was no smoke or anything.

I switched it on again a minute or two later and the temp needle behaved a bit oddly. It went to normal, then slowly crept up to just under the red bar, but when I started moving slowly (stop/start traffic), it went back to the middle and stayed there for the rest of the 20 minute drive home.

I switched to the temp reading (test 7) on the dash display and the temp moved around between 90ish to 111ish. 111 was the highest I saw. It changes pretty quickly. One second it could be 93 and 4 seconds later it could be 101.

At home I waited till the engine cooled down and had a closer look. There's white residue on the thermostat connector. Coolant level is still full, engine oil level is correct. There's no milky residue, and I don't see any oil in the coolant. I'm not sure how to check for coolant in the oil though.

My question is, could it just be the thermostat (and coolant level sensor) that's the problem? Looking at how quickly the temp can change, could it be a faulty temperature sensor? I'm wondering if the brief red period really was the engine overheating.

http://img9.imageshack.us/img9/9466/20120428190649medium.jpg

Thanks

 

[jjrichar]

The fact that the temperature jumps around so much could be either the thermostat not operating correctly (could be the cause looking at the thermostat connector) or the coolant temp sensor. The only way to see if it is the thermostat is to change it. However there is an easy way to check if it's the temp sensor. The coolant temp sensor (way down the back of the head under the intake manifold) is the same sensor (part no.) as the oil temp sensor on the oil filter housing. There are two sensors on the OFH, temp and pressure. Temp is the top one that pokes out the side (not out the back) and is a probe type sensor. Swap the two temp sensors around and see if you have the same problem. Doesn't cost you anything, but is a bit of a pain to get to the coolant temp sensor.

However, looking at the theromostat plug, a betting man would point to that as the cause. The thermostat is electrically operated, and if not getting a good connection, the engine temp might fluctuate, and give the indications you have.

 

[eug]

Thanks for the reply!

It actually jumped around for a short period of time, then mostly stabilizes, fluctuating more slowly after that.

I've decided to just overhaul the cooling system if I can find the parts locally. Everyone keeps talking about broken water pumps and expansion tanks, so since I have to remove the clutch fan which I found a real pain to put back on, I might as well replace the other parts at the same time.

I envy you guys in the US where parts are a lot cheaper. Sigh!

Based on the bmw330ci.net cooling system DIY, I'll be ringing Imparts tomorrow to get a:
- water pump
- crush washer
- temperature sensor
- radiator cap (is this necessary?)
- upper and lower radiator hoses
- expansion tank
- thermostat

Anyone in Australia know roughly how much the above bits cost?

I've gotta drive around to pick up the parts and tools tomorrow, I sure hope the red light was a false alarm. What are the symptoms of an overheating engine?


Edit: Just got off the phone with Imparts, the prices (including tax) are:

Thermostat $110
SKF Water pump $88
Upper radiator hose $72
Lower radiator hose $77
Expansion tank $120
Radiator cap $16
Lower hose temp sensor $55
Coolant level sensor $45

 

[jjrichar]

Piece of advice buying all the parts in Oz. I found it much cheaper to just import them from the US. I did what you are doing a couple of years ago. Far cheaper to get them from AutohauzAZ or pelican parts.

 

[eug]

Piece of advice buying all the parts in Oz. I found it much cheaper to just import them from the US. I did what you are doing a couple of years ago. Far cheaper to get them from AutohauzAZ or pelican parts.

Too late for me now!
I always thought shipping would reduce the savings. Do you remember how much you paid and what you bought?

 

[jjrichar]

I can't remember exactly, but I can remember doing the sums. I worked out that if I spent $200 in Oz, that was the break even point. Anything beyond that, it was getting much cheaper to import. Some stuff was a quarter of the price. I was buying from HSY parts in Sydney, which was the cheapest I could find.

 

[Hey-G]

Hi everyone, I've got yet another cooling-system-related question on my 2004 330Ci.

A month or so ago, the radiator light would go on and off occassionally, every now and then. I kept checking the coolant levels and it's full. The float goes all the way to max - maybe too full?

Anyway after some searching I figured it was the coolant level sensor. I haven't gotten around to replacing it yet. I kept a close eye on the temp gauge and it's always on the halfway point.

Today I was sitting in the car in a car park reading something. I suddenly noticed the temp gauge was at red! Horror. I switched the engine off immediately and popped the hood, but the temperature seemed normal. Will an overheating engine be ... very hot? There was no smoke or anything.

I switched it on again a minute or two later and the temp needle behaved a bit oddly. It went to normal, then slowly crept up to just under the red bar, but when I started moving slowly (stop/start traffic), it went back to the middle and stayed there for the rest of the 20 minute drive home.

I switched to the temp reading (test 7) on the dash display and the temp moved around between 90ish to 111ish. 111 was the highest I saw. It changes pretty quickly. One second it could be 93 and 4 seconds later it could be 101.

At home I waited till the engine cooled down and had a closer look. There's white residue on the thermostat connector. Coolant level is still full, engine oil level is correct. There's no milky residue, and I don't see any oil in the coolant. I'm not sure how to check for coolant in the oil though.

My question is, could it just be the thermostat (and coolant level sensor) that's the problem? Looking at how quickly the temp can change, could it be a faulty temperature sensor? I'm wondering if the brief red period really was the engine overheating.

http://img9.imageshack.us/img9/9466/20120428190649medium.jpg

Thanks

I think I'm having the exact same issue on my M. I'm scared to drive it, but I'm trying to bring it over to the garage so we'll see if anything blows on the way there...

Like you stated, my engine temp will start off in the middle, then creep up slowly to almost the red. Then sometimes at stop signs/lights, it will slowly creep down, then sometimes creep all the way up to the red. That's when I pull over and turn off the engine. I then check the engine bay and nothing is too hot. My coolant level's fine, and after a few minutes, my engine temp gauge is back down to 1/4 or 1/2. Anyways, I hope it's not too dangerous, but like I said, I'm going to attempt driving it to the garage.

 

[eug]

I think I'm having the exact same issue on my M. I'm scared to drive it, but I'm trying to bring it over to the garage so we'll see if anything blows on the way there...

That does sound like what I experienced. Have you checked to see if you have air in the cooling system?

In case anyone's interested, this is what my thermostat looked like before I changed it.