question: why would my temp go down when in reverse?

[ari666]

i have a running battle with overheating, but thats a story for another day. what i DID notice today is that when the car is in reverse (automatic) the temp guage drops down significantly. i.e. it was on full and dropped to just above half.

any clues?

[codfishface]

Ahh, that's an easy one!

When in reverse, your motor is spinning the other way, so you'll be pushing air through your rad, rather than pulling.

Have you got your fan on the right way?

0_o



Sorry about that........been a long day.

[moose man]

Quite a few brands of cars (unsure about commodore - maybe do the test) will do two unusual things when reverse is selected.
1. Turn on the cooling fans as no cooling air is being directed over the radiator when driving backwards
2. Turn the air conditioning compressor on to circulate oil around the system to keep seals wet.

[Darren_L]

how quick does it drop ?

[ari666]

thanks for the replies fellas:

twin thermo fans so yeah/no the fan isnt on backwards(good lol though, thanks mate ), no AC, thermos hard wired to ignition 'on' and the temp drops to quarter immediatly then down to half in 20 or so seconds. as soon as i put it back in P or D it goes straight back up to full. im thinking its some sort of weird wiring thing, but the temp guage has nothing do do with reverse as far as i know.

edit* i do have a transmission cooler fitted and the radiator is bypassed. does the trans fluid flow differently when in reverse? i fail when it comes to anything trans related.

[VK SL 3800]

This sounds more like dodgy wiring somewhere as driving in reverse makes your cooling system have to work harder as it only gets air flow from the fans, instead of both fans and fresh air coming through. Does your fuel gauge drop when in reverse as well? if it does it could be low + power to the instument cluster or something, and the oil pump on the transmission is driven of the input shaft and will always spin the same way as the engine so the oil is always getting pumped the same way but is directed though the gear box differently.

[1SIKR8]

hang on i just really got confused from the first post ..... in reverse your motor is spinning the other way ? .... umm don't think so

[ari666]

hang on i just really got confused from the first post ..... in reverse your motor is spinning the other way ? .... umm don't think so

^^^^lol.

electric fuel pump also, but no, the fuel level doesnt go down.

[codfishface]

hang on i just really got confused from the first post ..... in reverse your motor is spinning the other way ? .... umm don't think so

My job here is complete.

Carry on chaps!

[Tree cutter]

Try hooking up another gauge to the engine to see if your temp gauge is at fault. It could be just a bad earth to your dash that is helped when your reversing lights come on. If your engine is actually getting hot. then try taking the fan blades off the motors and turning them over because they normally work better one way than the other, depending if you want them to suck or blow.

[VK SL 3800]

You always want you fan to suck as otherwise it trys to stop air flowing through when your driving along.

[Tree cutter]

What i meant with the fans is some are designed to fit infront of your radiator and blow through while others are designed to fit between your engine and radiator so they suck through your radiator.

[vk.jonno]

i still stick with the throy the fans are on wrong..

[ari666]

i still stick with the throy the fans are on wrong..

lol, you think im a complete nonce hey? this has nothing to do with the fans. craig davies fans are designed to go upstream (in front of the rad) but i installed them down stream (behind the rad) which means not only did i have to take the fan off and turn it around (as tree cutter suggested) i also had to reverse the polarity.

anyways, the fans blow the correct amount of air in the correct direction, the fault is in the wiring of my dash/sender somehow. i was just looking for someone that may have found a solution to this problem.

(soz for the old thread dig, im bored)

[DerekP]

I don't suppose your inhibitor switch wiring has somehow earthed out on your dash instruments?

[ari666]

I don't suppose your inhibitor switch wiring has somehow earthed out on your dash instruments?

ok, now you can call me a nonce. whats an "inhibitor switch"?

[DerekP]

ok, now you can call me a nonce. whats an "inhibitor switch"?

Sometimes called a neutral start switch. I believe it also controls reverse lights (I could be wrong on that one....)

[ari666]

ah ok! "neutral safety switch" in my lingo. not a bad thought really. put the reverse lights on and it messes with the signal wire to temp guage. might have to check it out, good thinkin'

[vk.jonno]

..im sorry

[ari666]

*smooch* .