More expense.

Not out of the woods yet. I ran out of daylight with the water pump still needing to go back on and the rad and plastic intake pipes off. The thermostat housing on mine is plastic? and was in perfect condition though the lip seal wasn't wanting to leave it's bed. I put the hot air gun over the thermostat and it did cycle but I'm not sure if that wasn't as a result of me having to pry it free having un stuck it? The design of the blades on the new pump impeller look much more efficient on the new pump, longer and more curved/aggressive like they will actually move water rather than thrash it about. When I have looked at the old and new rad caps it ie they that are showing the most obvious discrepancy the old one being quite nasty and a bit hard in the rubber, the new one almost pops when I undo it even with the rad on the bench so its not impossible that the old one was not sealing proper and allowed pressure to bleed more than it should? Anyway it should be tested by this afternoon and I'll be able to see if it has stabilized or is still spiking past 99 degrees in a quarter of a mile. If it is then it's a new viscous coupling and a temperature sensor because the rest of the system is cleaned or new.

Just so you know normal operating temperatures, my 2000 twin cam runs at 89' when cruising at 30 mph but increases to 92' when going up a hill or at speed. Sometimes when pushed it might get to 95' but no more.

Kirkynut

Thanks those are comparators to what I was seeing regularly on the autool until Sunday which is why I didn't like seeing 107. Not catastrophic but a significant increase on the previous normative range and more than enough to upset me. I suspect that if I do get a result I'm going to anxious about it for a while yet as so far nothing I have replaced has suffered a serious injury and replacing everything at once makes it difficult to isolate the culprit. Positive mental attitude, it's going to be fine in no time!

I certainly sounds like a stuck or jammed thermostat from the symptoms, I hope your work sorts the problem.
Looks like a horrible job for such a simple device., but at least you are nearly done and the other new parts should have all possibilities covered.
Good luck and keep that positive attitude.

Damn it. It's not holding a stable temperature. Into the middle 90s just on my estate side roads. And even with a good lump of revs on the fan is quite easily stopped using a cloth. Grrrrrrr.

Don't mainwearing captain panic. Speaking to a service department type and concluded that the radiator could be partially blocked so out with my spare one and I'm another step closer. The heater currently isn't so I have to think that there's still an air locking issue somewhere. Letting it cool over night and see if it takes some more water and then play with it some more. Just out of curiosity where is the temperature sensor?