Chopshop85

iTrader: (4)

Now I've got the zetec all set up I have been out racking up some miles and smiles.

However, I have a strange temperature issue. I have just tested it driving back from a friends house which was mostly motorway driving. Got on the motorway about 4-5 minutes after leaving his and sat the car at 70mph
For the first bit of my motorway drive the temp gauge would go back and fourth from point 1 to point 2 only stopping at each point for a few seconds. (excuse the crummy drawing)


After about 15-20 minutes of driving the needle then dropped to around point 1, about midway on the gauge, and stayed there for the remainder of the drive even when applying a bit of boost and driving through slower speed limits and traffic light stops.
(I know these gauges are old and not the best but the change is so quick and drastic on the scale of the guage its hard not to notice)
I know the Cold start for the ecu has not been fine tuned yet and the car can be a touch lumpy on start up, also I'm using the CVH thermostat housing with a brand new standard thermostat.

So and ideas what this could be?
Thanks.

matthart

The gauge sensor is only a 1 wire thing, it relies on a good earth to compare for the signal. Check it earths well into the head, and that the engine is earthed well to the body.

What management? Plug your laptop in and see what the ECU thinks the water temperature is.

Chopshop85

iTrader: (4)

Just seems strange that it will fluctuate to begin with then after 15-20 minutes it's fine.

Its on Omex 600 and I dont have a laptop or software sadly.

matthart

If it's moving around within a few seconds then it's really likely to be an electrical fault as I doubt your engine can change temperature that fast.

And faults like dodgy earths can easily clear up after a while because things get hot and expand and make a better connection.

Chopshop85

iTrader: (4)

ahh I'm with ya.
I will check the earths tomorrow and report back.

The engine bay was painted during the engine swap so there might be an earth painted over or something.

studabear

Where have you mounted the temp gauge sender?

Chopshop85

iTrader: (4)

We've already spoke stu but i thought I would update for others. The temp gauge sender is mounted in the side of the head, roughly the same place as on the CVH.

Havent had a chance to look at this yet, been a bit busy. Hoping to get a few jobs done at the weekend.

Chopshop85

iTrader: (4)

Ok. so I checked the earths and also moved one of the earths to body to a better place and added another on for the head.

This seemed to clear up the issue of it going up and down quickly. However, it will still be all over the place. I had the gauge shoot up to red after 2 miles of driving, pulled over incase it was over heating only to find that the fan's hadn't even come on yet. Switched of the car, started it up again and the temp gauge jumped straight down to the middle!?!

I bought a new sender but the issue persists.

studabear

Faulty gauge unit? Or could the wire have rubbed through anywhere or be damaged in some way?

Chopshop85

iTrader: (4)

Thats one thing I'm going to test next time I'm out in it. Wait till it's all over the place, then unplug it and see if it carries on.

UPDATE. tried this and the needle just dropped off the bottom of the gauge. So now i'm really confused.

Karl @ FPT

It does sound like a faulty gauge or more likely a poor connection, possibly to the back of the clocks, could even be the wire is damaged in the engine bay as it see's a lot of heat over the years making it brittle.

Chopshop85

iTrader: (4)

Tried re-wiring it. Must be a faulty gauge. (no doubt age related)
Got myself a VDO water temp gauge and sender plumbed in to give me a more accurate reading.