Runnin hot

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cookbw

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So my car has been running hot ever since I got it a year ago. I warmed up the car this afternoon and looked around with an infrared temp gun (an awesome tool!) and saw that the radiator temp varied from 180 degrees on the driver side, down to 110 on the passenger side. I also took the cap off the coolant reservoir right after starting (engine cold) and saw that the fluid was completely still. I'm not sure if the water pump should have been running, but the still water makes me think it wasn't.

So I'd guess either the radiator is plugged up or the Water pump isn't working. Any ideas how to easily diagnose the problem would be appreciated.
 
If you have a thermostat in your car, you will not see coolant movement through the radiator until the engine is warm. When cold, the thermostat bypasses the radiator until the car warms up. When warm, the thermostat opens, allowing the water pump to circulate coolant through both the engine and the radiator to keep the vehicle cool.

Hope this helps.
 
not the pump

Water pumps don't "fail to work". As long as the belt is there, driving the pump pulley, the impeller is spinning and pushing water. As noted above, it isn't until the coolant heats up that the thermostat opens and coolant is routed through the radiator.

Only pump failure I can think of (and I've been there) is when the seal on the pump shaft starts to leak. Then there is a drip hole on the underside of the pump and you can see a drip or trickle of water there. The pump is still pumping at this point (it always is) but the leak allows water into the bearing on the shaft, quickly destroying it. "Quick" may mean over several months, or less time - it all depends. When the bearing is gone, the impeller and pulley shaft starts to wobble and make a knocking noise. At this point you can usually grap the fan and rock it back and forth - it no longer only spins in the fan's plane of rotation.

So where does this leave you?

Possibility one: the radiator core is plugged and water isn't circulating fast enough. You can remove the rad, have someone unsolder the top and/or bottom tank, and rod it out (clean the tubes internally), resolder, reinstall. This helped me quite a bit.

Possibility two: Park the car nose up on a slanting driveway and, engine running, open the bleed screw until only water is coming out. Close the screw, refill the coolant system, AND REPEAT THE BLEEDING PROCEDURE. You may have to do it three times, but ensure all the air is gone from the system through the bleed hole.

P3: Leaking head gasket causing a block of vapor in the system. Check and adjust timing and dwell to stock.

Possibility 4: not enough coolant in the cooling system. Fill, bleed per P2, run and report.
 
180 fahrenheit equals 82 celsius, thermostat most likely is and 80 degree celsius thus 182 coning out of the hot side is not extremely hot. put ypur hand on the valve cover after car is warmed up It should be Warm to very warm to touch but not hot enough to burn your hand. Where does your temp gauge needle sit?
 
some ideas

I agree with most of the previous comments

I had myself a problem with the cooling system, that was the reason for the upgrade of the whole system, you can find an explanation thread here:
http://e9coupe.com/forum/showthread.php?t=6020


the difference of temperature in the radiator does not seem to be really a big issue, the radiator has an entry way and an exit way runnig water from left to right and top to bottom, this means that differences of temperature are normal, I can not tell you in which ammount shoud be the difference, but a 39% of difference can be possible, or even a bigger one, depending on the position of thermostat and the moment in warming up process you meassure

I assume that when the system is working in steady condition after everything has warmed up, the temperature difference will be smaller

I agree that the pump is "always" working, you may have dirt or deposits that block in some extent the system piping

I made a complete renewal including the pump, but you should start step by step with simple things:

1- bleed the system as has been detailed before, this is a key thing, if you have air in the system, the temperature will go up for sure

if this is not working:

1- empty the coolant, completely, including the screw in the engine block (see my thread)

2- clean the circuit of cooling system with a mixture of Water+Oxalic Acid (250gr in 10liters), you pour the mixture into the cooler bottle, close, and bleed the system,

3-and you drive the car over 100 or 200 km, then you empty it again, and when the engine is cold you pour water until it cleans the hole circuit, you will see a brown dirty mud going out from your engine, when clean water comes out, you stop, and let it dry for 2 days with all the holes opened, then close holes, and refil with adequate coolant (don´t use a cheap one)

4- before the last refill, change a new thermostat (it is unexpensive and it might be faulty in your case)

5- finally bleed it and there you are !


another easy check is this one: you might know that you have a visco-clutch inside the fan that allows the car to engage and disengage the fan when needed, maybe your visco-clutch is not working well, to check that:

1- with the engine stopped, check that the fan can be turned with your finger easily

2 then start the engine, you should warm up your car and let the temperature go up

3- when the engine is really hot, the clutch will progresively block the fan making it solid to the engine, then if you stop the engine, you can check that you can not turn it with your finger

p.s.: sorry for my english

hope it helps

regards
 
Keep in mind that if the small hose from the radiator to the expansion tank becomes blocked that your engine will overheat within minutes. A check of your cooling system should always include verifying that the small hose is carrying coolant to the tank.
 
Wow...Thanks for all the great tips!!...and DeQuincey your English is actually quite good.

The fan hub is pretty tight...not quite siezed. I can turn it by-hand with engine off (cold), but it doesn't turn easily. The fan is always turning while the engine is running. So if all else were ok, then I guess the car would run cooler than normal.

I re-ran the test today with the temp gun. The highest temp I found was 190 at the radiator inlet and about 135 on the outlet - hotter than what I saw yesterday. The temp indicator was at about 2 o'clock - so pretty hot but not quite in the red zone. The temp indicator doesn't hold steady with normal driving and it rises quite a bit if I'm driving in hills or if I am idling around after cruising at freeway speeds.

So I checked the small hose running from radiator to reservoir and it is clear - flowing fine. So for next steps, here's what I'm thinking (in order)...

1. Bleed out any air in the system and top-off coolant.
2. Replace thermostat and seal.
3. If that doesn't work, then try coolant flush with Oxalic Acid (does anyone know of a good product for this? Prestone super flush perhaps?)
4. Then, if it still runs hot, have the radiator cleaned internally
 
cookbw said:
Wow...Thanks for all the great tips!!...and DeQuincey your English is actually quite good.

The fan hub is pretty tight...not quite siezed. I can turn it by-hand with engine off (cold), but it doesn't turn easily. The fan is always turning while the engine is running. So if all else were ok, then I guess the car would run cooler than normal.

I re-ran the test today with the temp gun. The highest temp I found was 190 at the radiator inlet and about 135 on the outlet - hotter than what I saw yesterday. The temp indicator was at about 2 o'clock - so pretty hot but not quite in the red zone. The temp indicator doesn't hold steady with normal driving and it rises quite a bit if I'm driving in hills or if I am idling around after cruising at freeway speeds.

So I checked the small hose running from radiator to reservoir and it is clear - flowing fine. So for next steps, here's what I'm thinking (in order)...

1. Bleed out any air in the system and top-off coolant.
2. Replace thermostat and seal.
3. If that doesn't work, then try coolant flush with Oxalic Acid (does anyone know of a good product for this? Prestone super flush perhaps?)
4. Then, if it still runs hot, have the radiator cleaned internally
Click to expand...


hi

some feedback:

the fan should not turn easily when engine is cold, the idea is that you can just turn it with your finger but when you stop the pressure it will stop immediately,

then I assure you that when it is engaged (hot) you will not be able to turn it even with all the strenght you are able to make

after that driving up hills you should check this engagement of your fan (please turn off the engine always), because it should be engaged afterwards

anyway, independent of the situation of the visco-clutch, the fan will always turn, the point is that when is not engaged (cold) it will be a different spin velocity between the engine and the fan, because not so high air request is needed for cooling, and when it is engaged after warming up, the fan will spin at the same velocity than the engine (more air suction by the fan will provide higher cooling)

consider that when the cooling effect is reached the visco will be fluid again, and the fan will be dissengaged

this is a key question, the visco-clutch is critical, you might get it checked in a garage, but I think that few brands are installing this type of solution, you should go to BMW. Spare part for visco-clutch is available in walloth&nesch or in BMW

take care if your car is as old as mine (1971 to 1973), then the visco-clutch can no be found anymore as a spare, so a renewal including new fan will be needed (as I did in my thread)

the other point, oxalic acid is sold as raw material (hope the explanation is ok) in a chemical store, or by those products distributors for laboratories, (this happens in europe, and I suppose you can find it also in usa)

it comes as a white powder, cristalized, usually in 1kg bottle, It is safe for aluminium and rubber tubes and gaskets, I use it in my restoration, 250gr dilluted in 10 liters water, and then add the rest to the adequate level

always bleed the system after changing the coolant !!!!!!

always run the car after filling with oxalic for some kilometers, because the effect is improved when it is hot, not less than 100 or 200 km

also consider that the whole cooling system has a volume of 12 liters aprox in a 3.0 CS (is my case), you will think me a fool, but you have to remove the bottom engine screw for a complete empty, otherwise some liters will remain inside the engine

happy to help, do not hessitate to make questions

regards
 
Lots of ways to see if your fan clutch is working- I do it the easy way.

Run car til temp gauge is at 1/2 mark AND!!!! the lower radiator hose is nice and warm.
Open hood- stare at fan and turn engine off. Any more than 2 revolutions and you got proplems.

Another tip for you- I never ever replace a thermostat without drilling it and making sure it is properly clocked in the housing. The clocking makes the cooling system more effective and the drill hole makes it self bleeding.

Note that BMW started producing their thermostats with arrows and holes in the 80's.
 
sfdon said:
Lots of ways to see if your fan clutch is working- I do it the easy way.

Run car til temp gauge is at 1/2 mark AND!!!! the lower radiator hose is nice and warm.
Open hood- stare at fan and turn engine off. Any more than 2 revolutions and you got proplems.

Another tip for you- I never ever replace a thermostat without drilling it and making sure it is properly clocked in the housing. The clocking makes the cooling system more effective and the drill hole makes it self bleeding.

Note that BMW started producing their thermostats with arrows and holes in the 80's.
Click to expand...


hi, sfdon

I never hear about drilling a termostat, where do you drill ? and with which diameter ?

what do you mean by clocking ? you mean to install it in a certain position ?

regards

dequincey
 
"On many vehicles, the recommended refill procedure is to fill the cooling system at the cap, run the engine until it warms up, then shut it off, let it cool and add more coolant to the reservoir as needed until the system is full. This can be a time-consuming procedure that may have to be repeated more than once to make sure the system is completely filled. One alternative here is to install a thermostat that has a "jiggle pin" vent. This type of thermostat is used on many import applications, and allows air to vent past the closed thermostat valve when the cooling system is being refilled."

I drill a 1/16" hole on the outer flange of the t'stat and rotate the t'stat until the hole is at the top.




Try looking at a t'stat before you install it- do you want water flowing through the metal supports or at the metal supports? That is why later t'stats came with an imbossed arrow pointing up.


e34 web site quote-• When doing the thermostat the arrow on it needs to be pointing straight up and if you want to make the job of bleeding easier drill a 1/16 hole directly through the thermostat where the arrow is located (tricks from BMW tech's) which allows the thermostat the bleed easier. Trick from LINGLE

Google :"drilling hole thermostat".
 
sfdon said:
"On many vehicles, the recommended refill procedure is to fill the cooling system at the cap, run the engine until it warms up, then shut it off, let it cool and add more coolant to the reservoir as needed until the system is full. This can be a time-consuming procedure that may have to be repeated more than once to make sure the system is completely filled. One alternative here is to install a thermostat that has a "jiggle pin" vent. This type of thermostat is used on many import applications, and allows air to vent past the closed thermostat valve when the cooling system is being refilled."

I drill a 1/16" hole on the outer flange of the t'stat and rotate the t'stat until the hole is at the top.




Try looking at a t'stat before you install it- do you want water flowing through the metal supports or at the metal supports? That is why later t'stats came with an imbossed arrow pointing up.


e34 web site quote-• When doing the thermostat the arrow on it needs to be pointing straight up and if you want to make the job of bleeding easier drill a 1/16 hole directly through the thermostat where the arrow is located (tricks from BMW tech's) which allows the thermostat the bleed easier. Trick from LINGLE

Google :"drilling hole thermostat".
Click to expand...


hello

so you propose to drill here upon the arrow ??

mh38ro.jpg
 
The arrow becomes a problem because the tstat cover and inlet angle precedes the tstat design.

It looks like you have it clocked just right.

Drill hole location is in red in the attached pic.
 

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sfdon said:
The arrow becomes a problem because the tstat cover and inlet angle precedes the tstat design.

It looks like you have it clocked just right.

Drill hole location is in red in the attached pic.
Click to expand...

thanks for answering

oh, yes I see the correct point for the hole, and also I understand that this i the right position for the hole to work as a way of passing the pressurized air bubbles, but,...

...I beg your pardon, the termostat in the picture is not correctly clocked !!! it can not be if we look at the arrow !!!

you identify the position of the upper side of the termostat, that is exactly where the red point is, so subsequently the arrow should be there !! that means to turn the t´sat 90 degrees

is this ok ?, the arrow is assumed to point upwards !!

in this moment I do not understand your first sentence, "The arrow becomes a problem because the tstat cover and inlet angle precedes the tstat design."

what do you mean ? may I guess that you say that there is a contradiction, because the arrow should point upwards, but also the support metal strip should be vertical ??

regards
 
"what do you mean ? may I guess that you say that there is a contradiction, because the arrow should point upwards, but also the support metal strip should be vertical ??"


Exactly correct!

The inlet angle to the thermostat changed over the years from:

11531714861
to
11531268650

The arrow was meant for later covers with the different inlet angle.
 
sfdon said:
"what do you mean ? may I guess that you say that there is a contradiction, because the arrow should point upwards, but also the support metal strip should be vertical ??"


Exactly correct!

The inlet angle to the thermostat changed over the years from:

11531714861
to
11531268650

The arrow was meant for later covers with the different inlet angle.
Click to expand...


hello,

If this is the case and "there is a contradiction", what should I do ?

1- maintain the support metal strip vertical ?

or

2- position the arrow pointing UP ?

please advise

regards
 
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