Just replaced the thermostat as I'm pretty sure it had never been done before even though the coolant was replaced last year as part of a service. I didn't want to drain the whole system and so I was expecting to loose loads of coolant.

Much to my surprise after emptying the header tank (nifty hand pump does the job) when I removed the thermostat housing and thermostat there was minimal coolant and I could easily catch it in a plastic container.

I guess many folk already know this but I didn't.

Having got it out I'm pretty sure the old thermostat was the original.

 

Thanks for sharing - I'm gearing up to do the same using the guide in the DYI section. I'm not sure if there's lower bolts that are hard to get to but having the thermostat up on top sounds like an 'easier' process. Glad it went smooth. Did you get a OEM thermostat?

(got another question though if and when you get a chance.. when you did change out the coolant.. did you fill things like half way? Last time I changed coolant in a miata the coolant was going all over the place as it gained temperature as I was waiting for the thermostat to open up..and then it quickly opened and sucked in everything in a big gulp along with a bunch of air.. anyway any tips on how you did it?)

 

Thanks for making it sound easy, I'm going to try it too. I'll look in the DIY section for the details.
Thanks.
Doug
1997 XK8 BRG Convertible

 

The bolt on the underside of the T'stat housing is easy enough to get to. I used a 5/16 socket on a small socket wrench with no problem. A small ring spanner (wrench) would work fine. Note the bolt is 5/16 not 8mm. 8mm socket will fit but it's a little loose and as the nuts are likely to be tight it might just flatten off the corners if it slips.

Yes, used an OEM T'stat - part number: AJ86484 (http://www.ebay.co.uk/itm/4010515948...%3AMEBIDX%3AIT)

For a complete guide to coolant change look no further than here: http://matt.zenfolio.com/xk-coolant-...tat---v1-1.pdf

I did not remove the supercharger coolant fill plug - I tried using the suggested method but it just would not budge and I was a bit "girlie" about damaging the casting. It might have if I could get a deep enough socket to slip over the 2 nuts and then use my torque wrench. Anyway, it's not essential.
Steve

 

Sweet thanks for the information - glad yours worked out easy, I was looking at that the other night thinking it's going to be hard to get to those lower bolts but I'll give it a go. And I agree.. I hope *cringe* I can get that Supercharger plug off :/ (i'd probably do the same.. just leave it if it's too difficult..)

But thanks for the thermostat part number and advice - hopefully mine goes smooth!

 

Try as a I might I can not get this pesky plug to unscrew. Even bought a longer 19mm spanner (wrench) but still no go. I reckon the ally threads are "cold welded".
Anyway, I've called it a day for fear of cracking the casting.

 

Hopefully I can get mine off as well.. I worry about air getting trapped up there. :/

 

Thanks for all the info above, including the 5/16" wrench size rather than 8mm. I've rounded off many a nut head and it does make things difficult. Not as bad as breaking iff the nut head and then trying to remove with an extractor. Have a good day all!
Doug
1997 XK8 BRG Conv.

 

I wish you all luck 'cos I'm beaten.
I'm not so concerned about trapped air as I have "burped" the radiator and supercharger hoses to expel air through the header tank - I'm more concerned that I can't inspect the inside as others have reported "gelling".

Going to have to wait until the next service and get the mechanic to loosen it. I'm still worried something will crack with too much force - it really is stuck.

 

I use an UltraGauge to monitor various parameters - not least engine temp. Since fitting a new T'stat the car is running around 4C cooler on the same run and same conditions. The reduction in temp when the fans cut in is faster and so far it has not reached the same high temp (98C) as before.
Definitely worth doing. Clearly, thermostats deteriorate over time.

 

I agree, best money I ever spent.

I managed to get my intercooler plug out. It is held in place by a special sealing washer (says to renew but I re-used the old one with no problems). I had no success at first, but had to get mine out as I had replaced the intercooler pump, then I found that if I applied a strong continual force for quite a while it suddenly released.

 

Thanks for this - gives me the confidence to have another go. Think I'm going to get one of the old fashioned long handle torque wrenches to get more welly on the pesky thing. My current torque wrench is one of the adjustable types but methinks a tad short for this job.
Steve