How do you know your over heating?

[keada714]

I know you can look at the gauge but what if your temperature gauge isn't reading correctly?! I took out the cluster to see if there is anything wrong with the cluster and I accidentally moved the heat needle as well as the gas tank needle.. Now i'm not sure if the car is overheating. Before I pulled the cluster the heat temp was between the 1/2 and 3/4 mark. I'm about to change the bad clutch fan which I initially I thought was causing the problem. So I was wondering if there is another way for me to figure out if the car is over heating? Going to replace the clutch fan soon and would like an accurate rating.

[Simon S]

Well – you could go to an auto parts store and get a full-on temp gage kit and install it (?)
Don’t think there’s an easy, cheap way to get an accurate reading otherwise.

A ‘peace of mind’ route may be to purchase/install a new temp sensor.
part # 12621710512 ~$22
This would require pulling much of air intake system off to access sensor on head.

I’d think in terms of testing before/after ‘relationship’ of needle – and work from there. I don’t think bumping a needle will throw it off really.

1) Confirm/adjust gauge to its normal dead/resting position.

2) Run the engine. Does the gauge come up to the same position it used to? If so – I’d tend to trust it.


I read about how tricky it is to properly bleed the cooling system – so checking/re-bleeding the system might be good to do first.
– elevate front of car prior to bleeding
– if you’re flushing/installing new coolant, it can help to pour coolant into system via upper radiator hose

I think most m42 cars run at the half-way mark. If I was sure it was bled properly – and it was creeping up to 3/4 mark – I’d look into replacing fan clutch as well. (did you do the rolled-up newspaper trick on the fan?)

Noting that related “m42 overheating” thread is chock-full of good info..

[keada714]

Thanks Simon.. I guess i'm going to have to just trust the darn gauge for now. I didn't bump it but I moved it. The clutch and temp switch on my car is broken so I'm going to fix that for now. I already wired the aux fan to turn on high but the car is still over heating so hopefully the clutch fan does it. thanks once again

[Simon S]

No problem - glad to be of some help..

Keep reading, checking things out, and you'll get 'er.

Here's a pic of my gauges in hopes that it'll help you determine what yours should look like at resting position:

[keada714]

my gauge looks somewhat like that right now. At operating temperature it is slightly pass the half mark