temperature guage....

[95bimm3r]

my temp guage is doing funny things. after warmed up im drivin and the needle drops down to cold?????stays there 1/4 (cold) then all the sudden it goes to normal (middle). then drops back down. :help doesnt seem to stay at one place. i mean if its heating up i understand but cooling down????

[thejlevie]

Does this happen when you are driving at a steady speed?

If the temp goes to normal at low speeds or when idling and drops down to cold when the car is moving faster I'd suspect a bad thermostat (stuck open). However, if it happens at steady speed and especially if the movement is very quick I'd suspect an electrical problem.

[95bimm3r]

steady speed ya. well first time it did it was today. so idk. i had problems heating up but thats when its 90+temp and idle for 10+minutes only if AC is on. as soon as i turn ac off it goes down then when i start driving the temp is normal. but the cooling down today was the weridest thing yet

[thejlevie]

Overheating in high ambients with A/C on points to a problem with the fan clutch and/or aux fan.

Having this happen at steady speed sounds electrical to me. Tapping into the sensor circuit and monitoring the signal with a meter will tell if it is a sensor or cluster problem.

[themadhatter]

check three things in this order:

1 - air in the system, if it hasn't been played with recently, this shouldn't be an issue.

2 - water pump - could be toast and working inefficiantly causing hot spots in the motor since it's not pushing enough fluid through the system.

3 - thermostat - could be on it's way out and sticking shut, this could be VERY bad.

not following up on this issue ASAP could result in an over heated motor and warped head.

you can run your car with only one working fan, it's not the greatest or most safe idea but it can be done. I don't believe your issue is a fan issue since your temp sensor would react slower. this issue is directly related to fluid temps inside the head.

[95bimm3r]

about a month ago when it heated up a little bit i then took it to two different shops. both said everything is fine. i know its not. i might have to drive it 100 miles to this place i use to go to. that guy really knows his stuff. would it be safe to drive 100 miles?? i will watch the needle the whole time.:help luckily i have another vehicle so the M is sitting in the garage.

[thejlevie]

The idle overheats are a bit bothersome. I don't think I'd want to drive a car that distance that I knew was overheating. As has been mentioned in this thread, the fan clutch, aux fan, thermostat, or waterpump could be causes.

If the car has the original plastic impeller waterpump I'd highly recommend its replacement with the upgraded composite impeller pump, whether it is a culprit here or not. Those pumps are known for impeller failure as they age. When the impeller fails the car will almost instantly go into the red and may blow the radiator. Also, if original, the thermostat housing and stat should be replaced along with the water pump.

[95bimm3r]

the stealer replaced the t-stat, radiator, belts about 2 yrs ago. i see no leaks. my friend thinks its air in the system idk. it doesnt heat up by driving. but ONLY when ac on when 90+temps in traffic over 10min. im waiting on rear control arms, tie rods, etc so im not driving it. i jsut drove it yesterday bcaz i was tired of drivin the dam civic. it didnt heat up yesterday just cooled down which i thought was weird

[thejlevie]

Okay, you should be okay w/respect to the pump. The replacement would have been the composite impeller pump.

That brings us back to a fan problem being the most likely cause of the high temps at idle. Can you hear the aux fan running at idle when the A/C is on and the temp is beginning to climb? It should be noticable if you roll down a window. If it isn't running the thermoswitch, relay, resistor pack, or aux fan could be bad. It would also be a good ide to verify proper operation of the engine fan clutch.

When the temp gage goes from normal to low or low to normal does it move quickly (like in a few seconds or less) or does it slowly move? The former is likely to be electrical and the later is likely to a cooling system problem.

Air in the cooling system will usually cause problems w/wo the A/C in use. And it certainly wont cause the low temp readings.

[95bimm3r]

Okay, you should be okay w/respect to the pump. The replacement would have been the composite impeller pump.

That brings us back to a fan problem being the most likely cause of the high temps at idle. Can you hear the aux fan running at idle when the A/C is on and the temp is beginning to climb? It should be noticable if you roll down a window. If it isn't running the thermoswitch, relay, resistor pack, or aux fan could be bad. It would also be a good ide to verify proper operation of the engine fan clutch.

When the temp gage goes from normal to low or low to normal does it move quickly (like in a few seconds or less) or does it slowly move? The former is likely to be electrical and the later is likely to a cooling system problem.

Air in the cooling system will usually cause problems w/wo the A/C in use. And it certainly wont cause the low temp readings.

yes i can hear the aux fan. i had the fan clutch replaced a little over a year. and yes the temp goes quick from low to normal vice versa. dam you know alot mad props

[thejlevie]

Well shucks, looks like most of the usual suspects have an alibi. I suppose it is possible that the replacement fan clutch or thermostat, or even the water pump could be bad. But that seems to me to be a lower probability. The fan clutch is pretty easy to test. On a cold engine it should be easy to stop the fan at idle by dragging a rolled up newspaper against the blade tips. With the engine fully up to temp and lots of hot air being pulled from the radiator it should be much more difficult to stop the fan.

As I recall, the aux fan on this car is a two speed unit. There's a resistor pack for low speed operation. Probably be a good idea to make sure that both speeds are available by jumpering to the fan leads. After that I'd tend to suspect the thermoswitch that brings on high speed fan operation or maybe a partially plugged radiator.

That said, it is just possible that you don't actually have an overheating problem and instead have a problem with the temp sensor or cluster (based on the other fault). I would want independent verification of the engine being in the normal temperature range before I'd be willing to risk the well being of the engine. On an OBD I car that probably means verifying the accuracy of the temp sensor (or replacing it with a known good unit) and directly metering the sensor output and converting that to temperature. I don't think a diag system can pull up live data from the DME on an OBD I system (but I could be (and frequently am) wrong).

[95bimm3r]

well when i get my suspension parts in ill ask my mechanic about this. he usually gives me right answer. but we'll see. thanks for all your help

[al@bmp]

my temp guage is doing funny things. after warmed up im drivin and the needle drops down to cold?????stays there 1/4 (cold) then all the sudden it goes to normal (middle). then drops back down. :help doesnt seem to stay at one place. i mean if its heating up i understand but cooling down????

The thermostat needs to be submersed in coolant for it to open and close correctly. Double check coolant level. If there is an air pocket it will close because there is no hot water to open it. You may want to us a cooling system pressure tester to check for leaks. This tool will also help chase the air pocket to the radiator to allow it to get to the coolant tank.

[95bimm3r]

The thermostat needs to be submersed in coolant for it to open and close correctly. Double check coolant level. If there is an air pocket it will close because there is no hot water to open it. You may want to us a cooling system pressure tester to check for leaks. This tool will also help chase the air pocket to the radiator to allow it to get to the coolant tank.


yes the coolant is normal. im just about to say screw this and order all cooling parts i.e. radiator, tstat, and housing, water pump, hoses, etc

[thejlevie]

yes the coolant is normal.
But have you checked to see if there's air in the block by cracking the bleed screw?

[95bimm3r]

But have you checked to see if there's air in the block by cracking the bleed screw?

where exactly is that:help

[themadhatter]

where exactly is that:help
oh my.....:eek:

it's the plastic phillips head screw located next to the over flow cap.

twist it open to bleed off air, some fluid may come out. becareful not to scald yourself.

[95bimm3r]

oh my.....:eek:

it's the plastic phillips head screw located next to the over flow cap.

twist it open to bleed off air, some fluid may come out. becareful not to scald yourself.


rofl i knew that:devillook

[95bimm3r]

k i just did it. i didnt hear any air nor did any fluid came out

[themadhatter]

was the motor running? was the motor hot?

if not, do get it hot and running and try again.

[95bimm3r]

was the motor running? was the motor hot?

if not, do get it hot and running and try again.

no it was dead cold. ill get on it an try it again when its hot

[95bimm3r]

was the motor running? was the motor hot?

if not, do get it hot and running and try again.

alright i did it this morning. coolant did come out. im not sure if i heard air or rush of the coolant. so what now?:help

[themadhatter]

coolant should have come out. if nothing came out them you have air in the system and air was probably seeping out.

if you squeeze your hoses (when cold) do you hear water squishing through the open bleeder? can you squeeze them or are they firm?

[95bimm3r]

alot of coolant came out. i didnt sqeeze the hoses i didnt know i was suppose to. i have class in lil bit but after class i will. what else should i do besides that.

[nmoe]

I could be misunderstanding, but it sounds like your thermostat is just stuck open. Easy to replace as well. Just to be sure, this is what you are saying right.

-sometimes the temperature gauge goes from normal to cold and then back to normal
-sometimes it won't heat up to normal unless you have the AC on full blast

[paul e]

When my thermostat went bad, the way I noticed it was that the needle never got to its normal, halfway position.. It took alot longer to warm up, and it never warmed to the middle like it always did.. kind of hovered around 1/3 ... That was symptomatic of a bad thermostat, and it was proven by replacing it, and all returned to normal :)

[95bimm3r]

I could be misunderstanding, but it sounds like your thermostat is just stuck open. Easy to replace as well. Just to be sure, this is what you are saying right.

-sometimes the temperature gauge goes from normal to cold and then back to normal
-sometimes it won't heat up to normal unless you have the AC on full blast

basically yes. like today i drove it to school. the needle stayed at cold the whole time. not once till it hit normal (middle). as soon as i pulled up to school it did then.

i also check the hoses. i pressed firmly and i heard the "whoosh" sound. i hope the t-stat fixes this. i just looked at my radiator and seems like original. i did get it done from dealer about 2 yrs ago and dont remember them changing it. they did change t-stat, fan, hoses, water pump and i got charged around $500. so im not sure if they did replace the radiator or not. all said and done im going to order some cooloant parts. what do you guys think about the "coolant overhaul" that bimmerworld sells?

[themadhatter]

time for a new cooling system.

got a link to that kit from bimmerworld?

[95bimm3r]

time for a new cooling system.

got a link to that kit from bimmerworld?

yuppers. some ppl might think its a bit pricy but i think its worth it.

http://www.nexternal.com/bimmerworl/Product474