Engine temperature once warmed up. Faulty thermostat?

[alanfp]

Hi

What should my engine temp settle at once fully warmed up? (2.0 Diesel 140BHP 2013).

Typically I'm getting 65 degrees looking at the needle on the gauge, 68 on the test menu and 66 using a cheap and cheerful infra red thermometer pointed at the top hose.

I think this all points to a faulty thermostat (i.e. always open) but would be grateful for confirmation before instructing my garage to change it. I know it's not a 10 minute job like it was on my Morris Marina!

[Tdci-Peter]

1 hour ago, alanfp said:

Typically I'm getting 65 degrees looking at the needle on the gauge, 68 on the test menu and 66 using a cheap and cheerful infra red thermometer pointed at the top hose.

If it was winter and you had just been trundling around at 30mph or less, then 65 to 68C could well be normal. But in this weather, or if the engine has been working hard, then it is certainly low. My stat is marked about 90C (Can't recall the exact figure), and I get 80C recorded on the outside of the rubber hose to the heater at the point when my stat opens. I suspect that 10C error is due to the insulation of the rubber hose, not to a 'stat fault.

I know it is a different engine, but all 'stats I have ever know anything about open at over 85C.

Another test is to check the top hose to the radiator near the radiator end some time during the warm-up, before it gets to say 50C, using the IR thermometer. This should still be cold. If the heater hose and the radiator hose are at the same temperature, the 'stat must be open,

[RMurphy195]

Does it take a long time to warm up?

[alanfp]

1 hour ago, RMurphy195 said:

Does it take a long time to warm up?

It NEVER warms up properly! 

Gets to about 65 - 70 degrees after about 10-15 minutes, I guess, but doesn't get above that.

[fugleman]

Hi,

 When i had a 2013 focus 163hp TDCI - first 3 years always midway 80-85c then slowly i had ongoing temp issues i.e. would never reach normal temp (about 80c) only when thrashing it on a warm day.

Always tended to sit about 60-70c complained to Ford dealer as under warranty and given many excuses(needed de carboned-head temp sensor etc) finally after writing a firm letter of complaint they checked it again and confirmed thermostat faulty replaced it and since had always sat midway near 80-85c for the next 4 years till sold.

so sounds like thermostat not closing or sticking? car always took a while to warmup as egr blanked and mapped out.

[RMurphy195]

23 hours ago, alanfp said:

It NEVER warms up properly! 

Gets to about 65 - 70 degrees after about 10-15 minutes, I guess, but doesn't get above that.

Classic failed thermostat symptoms (fails open). Will affect fuel consumption and all sorts of stuff. On a petrol engine warm-up should be a couple of minutes, diesels take longer (at least, that's my experience).

[alanfp]

4 minutes ago, RMurphy195 said:

Classic failed thermostat symptoms (fails open).

Thanks, Richard. You have confirmed what I suspected.