Why does my BMW overheat?

[iliad]

I have been having this problem for a while now.
My car gets hot very quickly. If I drive over 2k RPMs for over 15 min, the car will get hot. I'm having to add about a quart of water/coolant every week or so. Anyone know what the deal is?
I rewired the secondary fan to be always on yesterday, but the car still runs hot.
The water pump seems to be working fine.
And there is no leak in the head gasket.
And I don't think I am leaking the fluid, unless its leaking only when I am driving, b/c there are no puddles under my car when I park it.
Thank you.

 

[Big Daddy]

You seem to rule out everything that could cause your car to overheat! It has to be one or more of; the radiator, water pump, a blown head gasket, or the thermostat, which I doubt because your adding coolant. You lose coolant due to a leak, blown head gasket, worn out water pump or boiling the coolant. Is there any oil in your water or coolant in your oil? Does the oil filler cap have a frothy brown foam on it? Is the water pump leaking at the weep hole? When was the last time a water pump was replaced? Is there air in the system? I would start with a flush and refill bleeding the air from the system. If that fails to resolve the issue I would replace the water pump and thermostat. Should that not cure the problem I would think maybe your radiator is plugged? Some ideas!

 

[iliad]

You seem to rule out everything that could cause your car to overheat! It has to be one or more of; the radiator, water pump, a blown head gasket, or the thermostat, which I doubt because your adding coolant. You lose coolant due to a leak, blown head gasket, worn out water pump or boiling the coolant. Is there any oil in your water or coolant in your oil? Does the oil filler cap have a frothy brown foam on it? Is the water pump leaking at the weep hole? When was the last time a water pump was replaced? Is there air in the system? I would start with a flush and refill bleeding the air from the system. If that fails to resolve the issue I would replace the water pump and thermostat. Should that not cure the problem I would think maybe your radiator is plugged? Some ideas!

Thanks for the help.
The oil is clean, I changed it 3 days ago.
I don't know when the water pump was last replaced, I have had it for 3 years and have not done it myself.
There might be air in the system though, I'll flush it then.
I would really like to not have to change the water pump, but If I have too...
I will be adjusting the valves too and see what happens.
Thanks again.

 

[Big Daddy]

Air alone in the system can cause overheating, hopefully this will be the issue that resolves the overheating.

 

[Doughnut]

Make sure you mix the correct coolant to water ratio (50/50) too, adding too much coolant to your water can also make your car overheat quicker.
Air in your system, can contribute to overheating, and a big air pocket can make your overheat really quickly! (done it )
Whats your primary fan cluch/viscous coupling like?

Does it over heat when you going at speed?
I think its either:
A faulty thermostat,
A huge air pocket,
Or your "owned it for 3 years not changed my water pump"
Peace.

 

[325i_Pilot]

The problem, 90% sure, is the fan clutch mounted to the engine crankshaft. I just had this problem with my car, my engine would overheat no matter what I tried , until my brother asked me about the fan clutch , the radiator hose clamp on top of the engine broke loose allowing the hose to come in contact with the fan blades thus preventing the fan from turning freely. This burned out the clutch!! Do the old newspaper trick , with your engine running; try to stop the fan with a few pages of rolled newspaper and light pressure, as not to break a blade . Alot of pressure will stop the fan for sure but light pressure should only slow it slightly if any at all. If that is the problem, the clutch is easy to replace and available at most automotive stores I.E. AutoZone around $65, and its not a hard job, just a pain in the arse to get the fan free from the crankshaft output. It is a tight area to work and is counter rotated threads. Left is tighten, right is loosen. While your changing your fan clutch, if it is the culprit, you already have the radiator out, flush it out with a high pressure water hose or take it to a radiator repair shop for a cleaning and flow test. Oh and replace the water pump while your down there !! Hope this helps you out, I fought this for 3 months..

 

[325i_Pilot]

Oh yeah, and also it overheats because it is a classic BMW, and its a BMW classic problem from our era. [bmwdance]

 

[Big Daddy]

Unbelieveable, you tell everybody we are getting in over our heads in another thread where a member's car won't start and in this thread your 90% positive it is his fan clutch. In another thread you tell another member to "Hold up" after some good advice by Kirby. I had a fan clutch go out and totally removed it (No fan) for several weeks until my new one arrived, at highway speed you do not need it, assumming everything else is working! And whats with

Oh yeah, and also it overheats because it is a classic BMW, and its a BMW classic problem from our era.

I have owned six BMW's including and 80's era model and overheating was never an issue in any of them. As many of us have suggested it could by any of the items connected with his cooling system. Everybody STOP posting and wait for the new self appointed Guru 325i Pilot to offer up the exclusive and only answers! Geez...

 

[325i_Pilot]

Thats It For Me Here!!

They don’t have to stop and wait I will get to this before they do! My BMW had the same problem, no matter what I changed or fixed, and the fan clutch is something that is easily overlooked by many weekend warriors and professionals alike. BMW's of the E30 M20 era and models have been notorious for cooling problems since day one! Why is there always a thread where someone says to replace the water pump?[read] Bleed the air out of the cooling system? "Because these water pump impellers in BMW's were made of plastic and frequently succumb to dryrot cracking and stress cracks that cause the pump to fail prematurely. If the pump is replaced with an alloy or alluminum impeller pump, then replacing it every 3 years would be a little much. The circulation problem that historically has haunted BMW is the dreaded Tufnol water pump impeller and overheating due to coolant non-circulation." Source undisclosed.. The only mechanic in town that I trust for an opinion and diagnostic analysis is Exclusively Bimmers, Mount Pleasant SC. Dennis, the owner/operator/manager is a BMW factory ASE master mechanic with 23 years under his belt. He and I have done all that we can to bring the operating temp down, but he has assured me that there is only so much that I can do in stop and go traffic because of "poor air circulation through the radiator and around the engine compartment" hence the BMW has 2 radiator fans one on each side for added cooling, while the rest a the worlds automotive market usually relies on only one fan to do the job. Also I have 7 years of vehicle restoration, painting (in a downdraft booth with Sata Jet gravity feed paint guns shooting Sikkens paint, which is the factory paint for both BMW and Porsche now), and mechanical work under my belt as an automotive restoration specialist while I was training and saving my hard earned dollar to become a pilot. Now that I am a 3000+ hour commercial pilot with type ratings in Cessna, Dassault, and Lear jets, I think that here I would be the authority on airflow and circulation, especially in and around engine nacelles and their enclosures. I have had my 325i for 4 years and I am in the proccess of restoring it now, its always runs warm if not hot!! There are plenty of BMW forums out there that I can post on and submit threads, advice, opinions that don’t include your mouth.. This is my final post here... and all the threads I have started here were for opinion only, not as a source of mechanical wisdom, just wanted a second opinion. For those of you that did give meaningful insight and opinions, I thank you, But now I will go somewhere else for that. OH AND BY THE WAY THAT MIATA IN THE PICS WAS WAXED BY A HIGHLY SKILLED PROFESSIONAL AND STILL HAD A CLEAR COAT ON IT!! YOU EVER WAXED A FADED AND OXIDIZED RED CAR?? SEND ME PICS WHEN YOU DO, I AM ALWAYS UP FOR A GOOD LAUGH!! SO LONG.[shake]

 

[Big Daddy]

Wow, got your panties in a bind?

You said, "They don’t have to stop and wait I will get to this before they do!" Huh? this makes no sense. Than you go off, "Why is there always a thread where someone says to replace the water pump? Bleed the air out of the cooling system? "Because these water pump impellers in BMW's were made of plastic and frequently succumb to dryrot cracking and stress cracks that cause the pump to fail prematurely. If the pump is replaced with an alloy or alluminum impeller pump, then replacing it every 3 years would be a little much" Reread my post, I never said to replace the water pump I said to check for a leak at the weep hole, and who said replace it every three years? Than this, "hence the BMW has 2 radiator fans one on each side for added cooling, while the rest a the worlds automotive market usually relies on only one fan to do the job." MY wife's Dodge has two fans, my truck has two fans, in fact a lot cars with A/C now have two fans. And yes I have waxed many faded and oxidized cars in my almost 40 years of car ownership, even red ones. My son restores Alfa Romeos and other Italian cars at Vintage Customs where he works, I have some knowledge.

I have no idea where this came from because I did not post a picture of a Miata or any other car? "BY THE WAY THAT MIATA IN THE PICS WAS WAXED BY A HIGHLY SKILLED PROFESSIONAL AND STILL HAD A CLEAR COAT ON IT!!" So I went back and looked, Kirby posted the Miata link, this is what the poster said about the RED oxidized paint he resotred, "first off, this is my first time doing a full detailing process on the exterior..." Nope NOT a professional...go figure!


And what has this got to do with cooling systems, "while I was training and saving my hard earned dollar to become a pilot. Now that I am a 3000+ hour commercial pilot with type ratings in Cessna, Dassault, and Lear jets,"

lastly, "There are plenty of BMW forums out there that I can post on and submit threads, advice, opinions that don’t include your mouth.. " Owe but[thumbd] if you insist on moving on....well bye!

 

[Kirby]

WOW! ! !! Lovely rant CANDYAPPLE7, you started it....

there is only so much that I can do in stop and go traffic because of "poor air circulation through the radiator and around the engine compartment" hence the BMW has 2 radiator fans one on each side for added cooling, while the rest a the worlds automotive market usually relies on only one fan to do the job.

If this is such a design flaw as implied by your expert mechanic, how did BMW sell tens of thousands of new E30s without overheating problems? And how about the thousands out there running today with no problems? You only see the PROBLEMS on the forums and in the shops which can lead to false belief that a huge problem exists. How many people post "MY BMW DID NOT OVERHEAT TODAY OR EVER" threads???

Now that I am a 3000+ hour commercial pilot with type ratings in Cessna, Dassault, and Lear jets, I think that here I would be the authority on airflow and circulation, especially in and around engine nacelles and their enclosures.

THE AUTHORITY HERE ON AIRFLOW? Oh of course, a commerical pilot CLEARLY knows more about car engine airflow and cooling than the ENGINEERS and MECHANICS that visit this board. Aren't we impressed with ourself!!! I know quite a few pilots, including my company's corporate pilots. Grow up dude, the fact that you are a commercial pilot doesn't impress anyone here but you.

OH AND BY THE WAY THAT MIATA IN THE PICS WAS WAXED BY A HIGHLY SKILLED PROFESSIONAL AND STILL HAD A CLEAR COAT ON IT!! YOU EVER WAXED A FADED AND OXIDIZED RED CAR?? SEND ME PICS WHEN YOU DO, I AM ALWAYS UP FOR A GOOD LAUGH!! SO LONG

Ah yes, you are also the expert on waxing red cars, you wrote the book, obviously! I've never owned and waxed my 3 red cars and boats, have I?

As Dan said, in the thread the person stated it was his FIRST TIME doing this! Can't you read? I hope you pay more attention to your departure read backs!

With your attitude, you'll fit in quite well at certain other boards, hehe.... Thanks for the entertainment!!

 

[Big Daddy]

WOW! ! !! Lovely rant CANDYAPPLE7, you started it....

Aahh Haaaa Candyapple7....oh goodness... I can't stop laughing

 

[echothreezero]

This is my final post here...

That's a bit of an over reaction. This is the internet dude, get over it. If you don't want people to disagree with your opinions, don't post 'em up.

Take a chill pill and a deep breath, realise that this is just the internet, and enjoy the board.

 

[iliad]

The problem, 90% sure, is the fan clutch mounted to the engine crankshaft. I just had this problem with my car, my engine would overheat no matter what I tried , until my brother asked me about the fan clutch , the radiator hose clamp on top of the engine broke loose allowing the hose to come in contact with the fan blades thus preventing the fan from turning freely.

^^^
My fan works fine. And my BMW does actually have 2 fans.
I rewired the second fan to be always on, but it still seems to over heat.

I didn't know there was this much bitching on this site!
But thanks to those that have helped me.
I'll replace the coolant and make sure there is no air.
Thanks again.

 

[Big Daddy]

didn't know there was this much bitching on this site!

There isn't, we get the occasional know-it-all who has to be reigned in . Sorry your thread got hijacked. Do the cheapest simple things first, like replacing your coolant and do what Doughnut said, make it a 50/50 mixyure, than bleed the air form the system and see if that helps. If not look for moisture under the water pump shaft to see if it is weeping. Let us know how it goes.

 

[E30m42cab]

There isn't, we get the occasional know-it-all who has to be reigned in . Sorry your thread got hijacked. Do the cheapest simple things first, like replacing your coolant and do what Doughnut said, make it a 50/50 mixyure, than bleed the air form the system and see if that helps. If not look for moisture under the water pump shaft to see if it is weeping. Let us know how it goes.

You're right Dan, cheapest thing first. Test the mixture, flush it, bleed it for a while, check your bleeder hole on the water pump, and check oil and coolant to see if they're mixing. The thing about head gasket failure is that those two fluids don't need to mix... you could be burning off the coolant in your combustion chamber. Have you checked for the white smoke?
Your thermostat could be the problem, but I've found that they usually seize open for me, rather that closed. However, testing the car without the thermostat's presence is cheaper than buying a new one, free in fact.
Your next free thing would be to test the fan clutch, but here's where I need a lesson; How do you test a fan clutch? If you can drive above 2k rpm and it's still overheating, I'm going to assume it's not your fan clutch.
The water pump would be your last resort, and barring a clogged radiatior, might just be the problem.

Point being I don't see how you're losing fluid if it's not your headgasket (burning off the coolant slowly) or your water pump being ineffective, all other things (theremostat, fan clutch, clog) aside.

...and I'd still love to know how to test a fan clutch!

 

[echothreezero]

Using a rolled newspaper in the spinning blades as the guy suggests does actually work. But not the only (or necessarily best) way. Plus you should do any test when the engine is warm as the clutch is a viscous job activated by heat.

I would fell the resistance of the fan by hand with the engine off when cool and then repeat when off and warm personally - less chance of injury or damage. Note the difference. If none - bad clutch.

 

[Kirby]

...and I'd still love to know how to test a fan clutch!

Stick your arm in the path of the fan. If your arm gets chewed up, the clutch is good!

 

[E30m42cab]

Stick your arm in the path of the fan. If your arm gets chewed up, the clutch is good!

I'll get right on that!

 

[E30m42cab]

okay, but you should be testing the fan clutch at idle speed right? Because fan should have the most "grip" at idle right? The faster the engine turns, the easier it should be to stop it right? Or does the fan clutch hold the fan with the same amount of resistance all the time? (I sound like I don't know anything, but I really don't know jack about fan clutches, except how to make the tool that holds them).