Strange thermostat behaviour on 2.5

[endorfin]

As previously mentioned I recently replaced the main thermostat on my 2.5 after I had some slight overheating issues (nothing more serious than reaching temp of 100 deg at very high speed i.e. 100mph or working hard) However the new thermostat made things worse. It turned out to be a faulty stat that was stuck closed. I forgot to do a test in boiling water before fitting!

Back to motor factors for another, this one had a different design with the spring on the outside. Having learnt from the last faulty stat I placed it in boiling water and it opened up nicely. Fitted stat, refilled with coolant and bled the system. On test drive temp climbed in a timely manner and stayed on 90 degrees at high speed, sometimes even falling slightly below 90. Whilst stationary stayed at 90 deg with fans on.

All sorted. Or so I thought!

Drove back to Brighton today, started car from cold and it seemed to take a very long time to reach 90 deg, the temp gauge would rise, then fall slightly, rise again the fall slightly, a bit like 3 steps forward 2 back. I got onto the motorway and booted it and temp would not go higher than 80 degrees even at high speed, a lot of the time it would be on 65 & 70 degrees which I know is far too cool to be normal. Arriving into town and driving at a slower speed the temp rised to 90 deg but then curiously went slightly over, say about 93 degrees before settling back to 90.

Any ideas on whats going on here!! Since it worked fine when 1st fitted I'm thinking maybe the thermostat is stuck OPEN this time??

Maybe I should just buy a genuine Citroen one from Citroen? How much would one cost?

[endorfin]

Price for the stat from Citroen is only a couple of quid more than a non OE one!

Wish I'd checked before buying cheapo ones. Will fit it tomorrow and see if this solves the problem.

[Peter.N.]

Don't know anything about 2.5s but I would say that you new stat is faulty, unless the water is able to bypass it somehow.

Peter

[endorfin]

Yeah, worrying that 2 new stats in a row were faulty. Makes me wonder if non OE parts are worth the hassle.