cooling system worries. with some data

[Chriskbmx]

ill do the news paper check, but those temps look fine? what are bad temps?

[Bmwb]

going into the red shut it off asap! , mine still scares me.. heats good but has air in the line still , and now mines back fireing .. and is a fully built stroker soo idk what to think , as for the heat replace the easy stuff or test the thermostat put it in hot water let it heat up to 80 degrees or what ur thermostat needs to be opened . i tested mine with both and it failed

[Chriskbmx]

it never gets into the red, and i was tlking more along of line of actual tempatures

[Komzorz]

Just to throw a wrench into the mix, I once had a faulty instrument cluster tell me my car was overheating (not just SI board, the whole thing). A new cluster proved the system was actually working in top condition.

That's pretty unlikely though, mine was sort of a special case since it had a decade of water damage.

[Quinthirty]

so i went out and was checking some stuff out and found a few things. i like the car get warm and get a bit past the half way mark on the gauge and this is what i found. rad temp was around 210, top house on thermo housing around 180-190, hose that goes to the bottom of the rad was around 160-170 and the other housing hose was 180-190. i also found that when the car got warm and i shut it off i could move the fan and spin it with no issue. does that mean i have a bad fan clutch?

Have you checked out the fans if they're switching on automatically or not? It seems that the fan is not switching on at 99 deg, that's why the gauge is going over the 1/2 mark. IIRC, its fuse #3 that should trigger the fan at that point. At 210, IIRC, the temp gauge is at the 2/3 mark.

[Chriskbmx]

What do u mean turn the fan on? I mean the fan spins and all. I'll check fuse 3 tomorrow and check

[Chriskbmx]

all the fuses are good from what i could tell. i checked 3 18 19 and 20. so i am afraid that is most likly not it, maybe the sensor that turns them on?

[jlevie]

When AC is not in use, the aux fan should never be needed. If it does activate then something is seriously wrong.

[Chriskbmx]

and those for fuses mentioned about are just for the aux fan?

[Quinthirty]

Check fan clutch (newspaper test) & CTS and thermo-switches.

Straight from the Bentley:

"Power to the auxiliary fan is controlled by thermo-switches mounted on the radiator. High coolant temperature closes a switch to start the cooling fan. When the coolant temperature is in the correct range, the switch opens. An additional circuit powers the auxiliary cooling fan whenever the air conditioning is on.

An otherwise sound cooling system may still overheat, particularly with prolonged idling, due to a failure of either the primary cooling fan or the auxiliary cooling fan. The primary cooling fan is controlled by a temperature-dependent fan clutch. A failed fan clutch may affect air flow through the radiator, resulting in overheating or possibly overcooling. The electrically operated auxiliary cooling fan should be switched on and off according to engine coolant temperature. If the auxiliary fan does not operate, see 4.4 Auxiliary Cooling fan for testing information."

[jeffnhiscars]

As jlevie has said, the fan clutch is intended primarily for idle temps and the electric aux fan should not kick in a properly functioning cooling system unless the AC is on (at which point it will run continuously).

If you do have an IR temp gun check the radiator at various spots at OT to see if there are blockages.

[Quinthirty]

^Are we sure that the aux fan is only triggered by the AC? Why does the Bentley say that it should switch on or off based on engine coolant temp? Isn't that what the thermo-switch is supposed to do? Just validating...

[Chriskbmx]

Yeah the aux fan is kind of confusing lol does it turn on by rad temps or not? And if so can I just omh the sensor out?

[jlevie]

When the AC is off the aux fan is controlled solely by the thermo switches in the radiator. The low limit switch trips at 91C and the high limit at 99C. That is intended to be a last ditch effort to avoid a damaging over heat. When the AC is on the fan's low speed relay is tuned on to run the fan at low speed. It the radiator temperature exceeds the high limit it switches to high speed.

But as I said earlier, if AC is not in use and the engine is running hot something is wrong other than a possible aux fan problem. That cause needs to be identified and corrected. The aux fan may need repairs, but it isn't the cause of the overheating. So forget about the aux fan for now and focus on the other possibilities. As a recap those are:

Bad thermostat
Clogged radiator
Cooling system obstruction (like a bad hose)
Bad water pump

A head gasket leak could also cause this, but I'd expect an inexplicable loss of coolant to associated with that.

[Chriskbmx]

there is no loss of collant and it doesn't get hot enough to cause any damage. does anybody know what temps i should get when i check the rad and the hoses coming off the thermo block? i will be changing the thermostat this weekend, i also have another rad i can use that is a 5speed one when i do my conversion nxt weekned.