I have wondered this for quite a while and now I finally remembered to ask. Where in the temperature gauge are you guys running? Ever since I've had this car it's always ran between half and 3/4's up the temp gauge. Tonight as I walked in front of the car after a drive, it smelled hot. You know that certain smell of overheating? Not coolant, just hot engine. My 633CSi ran hot but my 535 didn't and my 2002 runs at about 1/3 up the gauge. Thanks in advance.

When I had mine, it stayed just a bit below half way, even in the heat of summer. When was the last time you changed your coolant?

Mine changed when I changed thermo and waterpump.

Has only ever reached a 1/4 of the way up the gauge since.

Stays on the second mark, and wont mover from there no matter how hot it gets outside...

my temp guage always stays at the 1/4 mark. It does matter if its freezing outside or a 100+ degrees.

I took a little romp through some of the back roads this past weekend when it was like 100 outside, and the temp never got above the half way mark on the gauge... Usually during normal driving, the gauge stays between 1/4 and 1/2.

Mine stays a hair over 1/2 unless I am in traffic in which case it goes almost to 3/4. I'm pretty sure I'll overheat in bad traffic this NY summer. I just got an 82 degree secondary fan thermostat so hopefully this will help.

When I switch on my (useless) AC the temp needle jumps a hair hotter. Anyone have any idea why this would be?

Stays on the second mark, and wont mover from there no matter how hot it gets outside...

Same goes for mine. I got a thermostat off BAVAUTO that opens up earlier than most for hot weather climates. Works great in So Cal.

Mine runs anywhere between 1/4 and 3/4 depending on traffic and weather conditions... alot like my old 2002. I think the new waterpump may be in order. I am planning on putting the cooler thermostat when it's due as well...

stock (with the old engine): 1/2 to 3/4 & occasionally near the red when stuck in bumper-to-bumper traffic in afternoon summer (where the air temp would be around 115 & asphalt would be around 160-degrees).

with the electric fan: mostly around 1/2 & occasionally near 1/4 & 3/4 (depending on the air temp)...never got near red, even in the same summer rush hour traffic.

with big radiator, fresh engine, & recent coolant modifications (http://forums.bimmerforums.com/forum/showthread.php?t=563504): just below the 1/4 mark (at around 175*F). Long idles raises it to the 1/2 mark.

When ran the stock fans and rad my car ran around 3/4, due to the poor grounding. When I turn on my blower motor the temp raises up. The temp gauge fluctuates alot with accessories. If you fix the ground on the gauge, it's a bit better but accessories still affect it. Now that I'm running a rad out of a 535i with a hayden 16" electric, the temp varies from 1/2 on the highway and speeding traffic to almost 3/4 when the fan turns on and brings it back down because I'm running an adjustable thermostat. My belt tension isn't the greatest so that might be a reason that it runs a bit hot at low rpm.

When I bought a new t-stat and the parts place sold me too high a temp of one, it ran super hot. Like to the red when driving in 60 deg weather.

Replaced with the 160 (or whatever the lowest one is) degree one and in 100 deg heat it usually only gets a touch over half. Too cold for cool weather driving, really, but in the summer its great.

After work today I did a coolant flush with new BMW coolant and Aquafina distilled water. On the way home, the hottest it got was almost 1/2. Usually it would go up to 3/4-7/8. Thanks for all the help!

When I switch on my (useless) AC the temp needle jumps a hair hotter. Anyone have any idea why this would be?

You're engaging the AC compressor. This means the engine has to turn another pulley; so in turn the load on the engine will make it run that touch extra hotter.

Also the electric fan in front of your condensor should come on when you turn on your AC.

I've actually pissed off all my A/C parts and just left the fan (and the condensor for now) and the wiring, so i can turn it on and off via a switch.

I'm always at halfway, on the hottest day maybe just above halfway, but then hit the highway and it goes back down.

well today it was 96/98 degrees ambient (felt like 110) and it cruised at 150*F; if I get stuck in traffic or let it sit it will go to 180* and stay there. I am only running the stock engine driven fan and radiator; no A/C condensor, no auxiliary fan, no nothing.
BaronOfIpanema, check if the electric fan in front of the radiator turns on when the A/C is on, if it doesn't try spraying some WD40 and lightly tap it with a hammer(it might be stuck) and check the fuse and relay. If the fuse and relay are good and it still doesn't turn on, look for a used one on ebay

Does anyone know the temp readings on the gauge? In other words what is the temp at 1/4, 1/2, 3/4, red.

I do not know the reading sorry, but I have a real gauge in my '80 iS, and it is running 185 to 205 right now with the 100 temps. and that is with the big aluminum radiator AC totally removed.

Both of mine run hotter on the freeway (3800 to 4200 rpm) then around town, my new one an '81 iS with prefect working AC, is at 3/4+ w/AC on, running down the freeway stock gauge.

Thanks, Slowe21 and Yonkers. I've got the feeling that my secondary fan is indeed out of commission. When I install my new thermostat I'm going to do a complete check up on it.

Aesthetics question: Has anyone with a dead A/C wired a 2ndary aftermarket fan to their A/C switch instead of installing an aftermarket toggle somewhere else on the dash? Imho that would keep the look of the interior a bit better (more stock) than adding new switches.

Mine is at half on the freeway. When I hit traffic it gets to 3/4 before i turn on the AC that is now just a fan. That seems to drop it back down to almost half, even in traffic.

CJ, the SDSEFI kit can show the water temperature via a bosch water temp sensor (it's mainly used for cold-start fuel enrichening)....but, the display only moves in increments of 6 to 8 degrees (so it's not very precise).
the first 1/4 mark is around 175*F, and the 1/2 mark is somewhere around 192 & 198*F.

THe Baur runs at 3/4 and hotter unless I run the fan I pulled off my 78 and wired in a switch. with the fan on it'll run at 1/2 all the time in our schorching 70 F degree heat. I used water wetter and a 50/50 mix, a fellow auto-xer told me to go with less antifreeze use some water wetter and use mostly water and the temp will drop. my car won't be used in the winter and will be stored in a heated garage so it shouldn't hurt it at all.

My problem is the motor is bigger than stock and I'm still running a stock radiator, I need to find a bigger radiator that fits in the hole...

Does anyone know the temp readings on the gauge? In other words what is the temp at 1/4, 1/2, 3/4, red.

I can read it off a diagram posted from 'The Complete Roundel' a few years ago, or next time you are in a book store you can look it up. I dont get home until next week...

John

As soon as I get my exaust back in my new 81 I'll run the car and use my temp gun on the top hose and chart it out. Maybe I can get together with a couple of other people and do the same and come up with some averages. I'm sure that not all gauges read the same.

I do know that the electric fan does not come on until the head gets to 205 or 210, with my gauge. This is due to the sending unit in the radiator being at the bottom of the radiator - it is being tripped by the cooled water and not the hot water coming out of the motor. So a unit that turns on at 170 or 175 will trip when the head is at about 190 to 195 if your radiator is doing what it is suppose to do.

Alaska - DO NOT MIX ANTIFREEZE AND WATER WETTER. They do not like each other. Water wetter is for racing where they do not want oily spills on the track, wetter does not work as good as antifreeze in a street app, it's just easier and quicker to clean off a racing surface. This is what I was told by two local race car biulders when I was looking into water wetter.

Aesthetics question: Has anyone with a dead A/C wired a 2ndary aftermarket fan to their A/C switch instead of installing an aftermarket toggle somewhere else on the dash? Imho that would keep the look of the interior a bit better (more stock) than adding new switches.

Why not, it's only wires :)

I've got mine hooked up to the ac fan, but didn't use the factory switch, coz I got rid of the A/C console in favour of a non AC... still trying to figure out where to mount this switch!

Sorry- phone pics:

http://i73.photobucket.com/albums/i235/slowe21/fan_switch.jpg
http://i73.photobucket.com/albums/i235/slowe21/fan_switch2.jpg

Hey everyone, new to the site and can't wait to put my two cents in! I have owned my 77 320i for over 12 years and had some strange things happen over that time. Here are some things I have noticed along the way, and by the way, the guage has never been a problem. If your thermostat is stuck open (always cooling) the car will run "at" or just below the first quarter mark and rarely rising above except under heavy load. With old antifreeze the car would generally run between the one quarter and one half mark. If idling for a long time the temp would climb above the three quarter mark occasioally going past the three quarter markuntil fhe aux fan would begin to cycle. With good antifreeze and a working thermostat the car would normally run between the one quarter to one half mark. My recent purchase (a 1982 320i) has it's thermostat stuck open. It has never exceede pasr the one quarter mark.....as I said before...just my two cents

Yesterday it got to like, 106 degrees, and my temp gauge was pinned all day. I felt bad for my little car.

for my car it doesnt matter at all what im doin how im driving or how hot it is outside my thermo always runs straight up no matter what and i just rebuilt the engine and put a new thermo on it

My 80 320i ran hot until several years ago I flushed out the radiator. Then it ran straight up most of the time (a/c non-functional). Last week I replaced the radiator due to leakage and so far around town in upper 90's temps the guage only goes to about one quarter. Now I'm thinking maybe getting the a/c up and running again......

oh ya i dont have ac so untill i get that fixed my car runs sttriaght up

Sorry to revive an old thread, but when is the fan in front of the radiator supposed to kick in? My 323 has always run right on the 1/2 mark, now in traffic its jumping up to 3/4 and I don't see that fan kicking in. Once I start moving it drops right back down.

It doesnt, you wont have it kicking in if you have a clutch fan fitted, the fan in front is for the air con only.

my temp

My temp normally runs just below half but on the highway in hot weather it will run up to 3/4, especially when in the boost.

Sorry to revive an old thread, but when is the fan in front of the radiator supposed to kick in? My 323 has always run right on the 1/2 mark, now in traffic its jumping up to 3/4 and I don't see that fan kicking in. Once I start moving it drops right back down.

There is a bypass temp switch that threads into the bottom of the radiator that turns the fan on. You can buy a lower temp sensor that will turn the fan on at a lower temp, I have the lowest temp available from Bavauto and the fan turns on automatically at the 3/4 mark. I wish it would turn on at the 1/2 mark but I also have a manual switch wired in that I use. For me its good to know that the switch will take over if I forget to turn the fan on though.

Water Wetter is a surficant, like soap. It improves the flow rate which allows more absorbsortion. I have been using it with antifreeze for years without a problem. The best way top use it is with straight water for summer. It has anticorrosives.

I'm running water wetter as well and I did notice an improvement.

It lowers the surface tension of water (like soap) which in turn raises the heat transfer abilities of the water and maybe the flow rate.

There is a bypass temp switch that threads into the bottom of the radiator that turns the fan on. You can buy a lower temp sensor that will turn the fan on at a lower temp, I have the lowest temp available from Bavauto and the fan turns on automatically at the 3/4 mark. I wish it would turn on at the 1/2 mark but I also have a manual switch wired in that I use. For me its good to know that the switch will take over if I forget to turn the fan on though.

Not when you have a clutch fan installed, the fan in front of the radiator is totally a air conditioning thing.

What does the external temperature have to do with the engine's temperature? Bruce said he uses water wetter in the summer. I use the stuff too, but not with straight water. But I've never heard of outside temperature affecting the temperature of a car.

What does the external temperature have to do with the engine's temperature? Bruce said he uses water wetter in the summer. I use the stuff too, but not with straight water. But I've never heard of outside temperature affecting the temperature of a car.

The outside temp affects the rads rate of thermal transfer.

I don't know if that is true or not. It just doesn't seem like the outside temperature matters--if it's 100 degrees or 60 degrees, what difference does it make to the engine which is hundreds of degrees hot?

I don't know if that is true or not. It just doesn't seem like the outside temperature matters--if it's 100 degrees or 60 degrees, what difference does it make to the engine which is hundreds of degrees hot?

LOL... that is like questioning gravity. The rad cools via the ambient air. The cooler the ambient, with airflow as a variable, the faster the rad can shed the heat.

You sold me, Bruce! It sounds like you believe in what you're saying, so I trust you! I'm out of my element. Take care

I'm out of my element. Take care

So am I but it sounded good didn't it?

So just to be clear (I'm just a stupid newbie) the fan in front of the radiator will never turn on if I don't have AC (and I don't).

What about the temp switch that JRCook has -- is that a bypass add on for cars that don't have AC? or is that just to lower the temp the fan will switch on at and again you need to have AC?

it is stock on US e21's with AC. It's a temp switch in the fan circuit to turn the fan on as a last ditch effort to cool the car down whether the AC is on or not. Lower temp switches are available than stock, I've installed the lowest bavauto sells and it turns the fan on at the 3/4 mark.

Look down the driver's side of your radiator. If there is a 2 prong plug hanging off the side about 3/4 of the way down you have a switch in your fan circuit. If the 323i's don't have that switch, why would a non AC car have the electric fan unless the ac has been removed?

my temp
+1
Here in Texas on a mid 90s day with high humidity and A/C on