Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 2001 +8 Temperature gauge

The needle on my temperature gauge generally moves slowly between 80 and 100c, moving towards 110 in heavy traffic or when stationary. About a year ago it started randomly rising to the stop. Mostly it falls back to the normal level but can do this two or three times in a journey of 15 miles.

I’ve replaced the thermostat and temperature sender unit but this hasn’t helped. I have also replaced the radiator and fan due to a leak.

Any suggestions?

Has it got a voltage stabiliser? Check and replace, also the earths on the instruments.

It could just be the gauge. A couple of years ago my temp gauge started reading high. I replaced the voltage stabiliser, the sender, the thermostat, and the water pump. Coolant temp measured with an infrared thermometer shows it to be completely normal but my temp gauge shows around 110C. I've decided to just live with it as putting a new temp gauge into a 40 year old dash would look silly.

Alan, your 2001 +8 according to wiring diagrams doesn't have an old style instrument voltage regulator. The instrument signal grounds are directly shared with each other so unlikely to be an issue if other gauges displaying normally. There is a green/blue coolant temperature signal wire from instrument in dash loom that connects with same colour wire in main chassis loom and on to engine loom and likely to ECU. The coolant temperature sensor signal also feeds to ECU on green/blue wire but no further info due to missing intermediate wiring diagram.

As Tim suggests your issue is likely with the dash instrument itself although you could check wiring connections as above. A cheap infra red/laser temperature sensor could be used close to temp sensor to allay fears of engine overheating.

I spent over £2k chasing overheating on my 2001 Alfa 3 ltr Spider, it was the gauge DOH.

Thanks all for your prompt, and helpful responses. I’ll pick up one of the infrared sensors to ease my mind and get round to checking the wiring asap.
Alan

It was an infra red sensor that finally told me my Spider was not overheating, bloody gauge

They are really useful bits of kit - I also use mine to check exhaust manifold/pipes to see if I'm getting a consistent burn across cylinders. And for irritating my Mrs when she's not feeling well or I'm winding her up about her cold hands and feet.

I got one years back for racing (temp difference across the tyre width indicating camber and pressure settings) ... use it for all sorts around the house and workshop. ... really useful things and cheap as chips these days.

The cold-foot wind-up sounds like a wheeze worth trying ... having been married forever I'm running short of new ways to be an annoying arse!! 🙂

K

BTW, a codicil on the temperature reader. If they are pointed at a shiny surface, they are inaccurate.

Your observations are not happy ones. And it is odd behavior for a failed gauge..which we hope it is.

However, you have no less than three sensors reading your coolant temperature. One feeds your rad fan switch. You have a hearty SPAL fan from the Factory. Is it coming on and off and at what temperatures?

Frankly, I would do pressure[/b] test of all cylinders. Doesn't take long or cost much. At worst, a pressure tester costs negligibly or any honest local mechanic can do it in 20 minutes for 10 times as much with his own tester.

Lorne

Had the same problem on my 2002 +8. Check the connector block on the back of the gauge hasn't come loose, Simple fix of tightening the nut that secures it to the back of the gauge.