T350 oil and water temperatures

[STE VR]

Just curious but I’m witnessing very erratic readings on both water and oil temperatures on the dash (water on ecu is fine and steady).

Readings once warm and engine running are flipping between 88 and 102 very quickly. (Both oil and water) Annoys me.

From reading previous threads my oil temp seems high. Oil measured at 102 degc with calibrated meter ( in oil tank as soon as engine stopped) Water seems ok. Fans kick in and out as they should. When engine off but still hot, readings are steady. Both new sensors. Have just changed oil again as fitted a new oil tank. Oil level is high so need to drain a bit.

Any ideas? Electrical issue? Oil level too high?

Just for info: 2003 3.6 fully rebuilt less than 2000miles ago. Everything is new except harness and ecu.

Thanks

[Penelope Stopit]

Before getting too involved, are you able to connect a voltmeter across the battery to check that the alternator isn't faulty and switching on and off charge or going to an on/off overcharging state

[STE VR]

Hi Penelope, it’s a brand new alternator and previous checks have resulted in everything being fine. I know there’s always a possibility something has changed but gut instinct tells me this is unrelated. All other systems are perfect.

[Penelope Stopit]

Ok, anyway you would notice sidelights flickering at the same time if it was a voltage problem (sorry, I should have mentioned this in my earlier reply)

Having now delved deeper I do know that their sensors share the same earth connection, what I don't know is whether several earths are joined in the loom and exit it as one main earth lead with an eyelet terminal on it that bolts to the engine somewhere .....or.....several earths exit the loom and join together at an eyelet terminal that bolts to the engine somewhere

I can delve deeper if you want me to but it will have to be Monday or Tuesday as it's difficult to trace through, takes time and I haven't got any more free time today

If you know your way around the engine, you may recall bolting earth points up to it and be able to check them

[Sagi Badger]

OP, can you explain what you mean by water on ecu is fine and steady? Do you have the software linked up?
J

[STE VR]

Yes laptop plugged in and water temp reading on there steady. Runs between 90-94 on there with smaller slower changes.

[robsco]

The ECU and dash work from different sensors, the dash temp will always be higher due to the location of the sensor, up to 15 degrees I was told. The ECU is the temperature you should trust, not the dash! I had the dash on my old T350 calibrated to the ECU temps therefore increasing the accuracy. I can’t offer you any more info than that I’m afraid as I cannot remember!

[STE VR]

Thanks for the replies.

When the engine is off and nothing flowing then the water dash and water ecu sensor tally up and are steady. Oil sensor is steady too but have no reference apart from dipping my temp meter into oil tank.

Only when engine running and oil/water flowing do the readings start jumping everywhere on the dash. Starting to think electrical but still not sure.

Oil temp still seems high though.

[fredd1e]

Check the engine/battery/loom earth points. one might be loose or corroded.

[STE VR]

Ok will check just to make sure. I have removed/cleaned/new nuts washers etc all the earth points but will double check.

Thanks for all suggestions so far.

[Penelope Stopit]

You could pull the cover off the temp sensor plug which will reveal 2 cables of which one should be Blue/Green and the other Black, now you could run an earth from the engine block or battery direct to the back of the black cables terminal to see if the gauge stops flickering about

The above test will at least prove that there is or isn't a fault on the earth side of the temp sensor

[STE VR]

Will check and test everything regarding earths. I’ll be disappointed if it is that after a 3 year rebuild!!