Thermostat Replacement

[nigelj77]

Since the weather has turned colder I notice my 450 is running much colder when at speed, barely off the bottom of the gauge, having owned a couple of chimaeras in the past I'm sure it's the thermostat stuck open so I've bought one with a gasket from my local dealer.

I read a how to guide on here which makes it sound really complicated, I then read that some people manage the job in 10 minutes, so wonder which it is.

Do I need to take the dizzy out or do I just put up with the poor access to the bottom fixing bolt?

Cheers

Nigel

[Chuffmeister]

http://www.rv8r.co.uk/thermostreplace.html

[swallet]

As said no need to remove dizzy.

You could manage just by removing the dizzy cap, HT leads etc. I also had the alternator off at the same time so even better access.
Mine is non-pas though. Not sure if that puts further things in the way.

Easy job.
The thermostat has a bypass hole in it - I was told to make sure that this is on top when fitting - not sure how critical this is.

[nigelj77]

Cheers Chuffmeister, I'd seen that link and that was what worried me, looks more like a few hours work than a quick half hour job?

[nigelj77]

Cheers Swallet, I hoped this would be the case, was worried about water draining into the dizzy drive hole, will have a go this weekend in that case, fingers crossed

[stueyp34]

I replaced mine on a PAS car with just the dizzy cap removed and all HT leads out of the way. As long as you have an extension bar for the bottom bolt you can get to it, getting it back on is a bit more fiddly but definitely do-able with the distributor and alternator still in place.

Presuming all comes off ok it should be a half-hour job really, then another 20 mins to bleed the coolant. Mine (450) was stuck open too and now warms up within a couple of minutes, bliss in this weather!

[WOO5IE]

Hi Nigel

Is the heater just as hot as normal.

My gauge is always as you described this time of year but the heater works a treat.

I believe the gauge reading low is just that the sender location is in a cold air flow.

And I have a lower temp stat fitted.

May save you some trouble in the cold by not changing it

[PRTVR]

WOO5IE said:

Hi Nigel

Is the heater just as hot as normal.

My gauge is always as you described this time of year but the heater works a treat.

I believe the gauge reading low is just that the sender location is in a cold air flow.

And I have a lower temp stat fitted.

May save you some trouble in the cold by not changing it

mine is just the same, if you look at the location of the sender unit it is located in a dead leg, this causes it to cool and not give a accurate reading, some people have moved the wire on to the old RR sender with a resistor to calibrate it, was thinking it might be worth insulating it to prevent the cooling.

[Chuffmeister]

nigelj77 said:

Cheers Chuffmeister, I'd seen that link and that was what worried me, looks more like a few hours work than a quick half hour job?

It's always like the first time you do it!!! The second time, you'll have it done in a flash.

[spend]

Fitting studs & nuts makes it much simpler; trying to keep stat + gasket + housing lined up whilst inserting bolts is the hard bit & studs overcome this as you just slide everything on.

IIRC I use 5/16"UNC studs & flange nuts out of my sump collection (2 different lengths if memory serves).

[nigelj77]

Cheers for the advice folks, thought I'd update on thermostat replacement which turned out to be a nightmare.

Got everything apart and cleaned up no problems, reassembly was the pain, top bolt no problem, bottom bolt an utter pig, there were hoses and what looked maybe parts of wiring loom in the way and no way could I get that bolt in without it trying to cross thread, after a few hours of cursing and trying to get it in, I gave up, dropped the alternator off and had in back together in no time.

In terms of access I'd advise anybody doing the job to take the alternator off, it's 2 bolts and means you can easily see what you're doing, dizzy can stay as long as the cap is off.

Good thing is I now have hot air in about 2 minutes and am up to temperature in around 5 :-)

[Chuffmeister]

nigelj77 said:

Cheers for the advice folks, thought I'd update on thermostat replacement which turned out to be a nightmare.

Got everything apart and cleaned up no problems, reassembly was the pain, top bolt no problem, bottom bolt an utter pig, there were hoses and what looked maybe parts of wiring loom in the way and no way could I get that bolt in without it trying to cross thread, after a few hours of cursing and trying to get it in, I gave up, dropped the alternator off and had in back together in no time.

In terms of access I'd advise anybody doing the job to take the alternator off, it's 2 bolts and means you can easily see what you're doing, dizzy can stay as long as the cap is off.

Good thing is I now have hot air in about 2 minutes and am up to temperature in around 5 :-)

Well done… what is your next project?

[nigelj77]

Next project, who knows....

Needs front pads and discs and the callipers freeing off I think, investigate rattle and slow window in drivers door, headlights could do with a strip and clean up inside and maybe a re-chrome, diff output seals and I think that's about it.