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Discussion Starter · #1 ·
My '69 Silver Shadow's thermostat is stuck open. Is the thermostat a generic part or unique to R-R?

-rick
 

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The answer to this depends upon who you ask. There are those who insist that you must use the Crewe original part because there is a 5-degree (or so) difference on the opening temperature. The 180 degree thermostat is a tiny bit lower than where the Crewe thermostat opens, but I can't recall the exact temperature at which it opens.

See Rolls-Royce/Bentley Substitute Parts for substitute thermostat options.
 

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Termostat deceised

When the termostat stays open it has deceised and needs to be replaced, however it is possible to drive a long time with an open termostat. This is the safetyprocedure as there are many with deceised parts...

There are some replacement parts offered on EBAY.UK for a fair price, but i suppose the quality of the original will be best. I dont think the difference of temperature-opening is an important issue. It will be around 90' Celcius.

Only i wonder as there is no termometer in my dash (but just a warning light), how did you discover the problem :?:





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Hemmo,

One way you can generally tell that a thermostat is stuck in the open position is that it seems to take forever for the car to show signs of heating up on the standard temperature gauge. When all the coolant is in full circulation, including through the radiator, it takes quite a bit longer for all of it to heat up. The thermostat normally prevents the engine coolant from circulating through the radiator until it reaches approximately the 90 degrees Celsius you'd mentioned. You can check for a thermostat that's fixed in the open position using an IR thermometer gun on the hose between the thermostat housing and the radiator. Its temperature should remain steady for a while until the thermostat opens, when you should see a sudden spike. If it begins a slow climb shortly after starting the car and stays on that long, slow increase in temperature the thermostat is almost certainly stuck in the open position.

I didn't realize that there was no temperature gauge in the Shadow original series. It's part of the 4-way gauge in the Shadow II/T2.

It can be quite damaging for an engine (over the long term, rather than immediately) if it's allowed to run too cool all the time.
 

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The standard Crewe part has holes around the circumference filled with lead (or wax?) plugs. If it happens to fail shut, the lead/wax will melt and allow coolant flow. (It will then effectively be "failed open", but that's a lot better than failed shut.)

Do the replacement parts have the fail-safe plugged holes?

Jeff.
 

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jeyjey said:
The standard Crewe part has holes around the circumference filled with lead (or wax?) plugs. If it happens to fail shut, the lead/wax will melt and allow coolant flow. (It will then effectively be "failed open", but that's a lot better than failed shut.)

Do the replacement parts have the fail-safe plugged holes?

Jeff.
Several of the replacement options are "fail-safe" type thermostats that always fail in the open position (or default to it somehow if they fail). There are others that include bypass valves that will open if pressure gets too high.

In any case, regardless of the method used, you can get thermostats that will fail open or allow bypass.

Brian, who once owned a Chrysler Sebring convertible that "ate" thermostats and used an OEM thermostat design without fail-safe/bypass. I'd never replace a thermostat again without a fail-safe/bypass feature, as I hate being stranded. [And who will never pay $100 US or more for a thermostat - they're not rocket science]
 

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Discussion Starter · #8 ·
Thanks everyone, for the advice. Yes, my car ('69 Shadow) takes forever to warm up and even then, the temperature (gauge) stays low in our cold winter weather. I will replace the thermostat this weekend, time permitting. And hopefully, I will have photographs.

-rick
 

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rolindsay said:
the temperature (gauge) stays low in our cold winter weather.
I had the same thing last winter on my 97 turbo R. The thermostat was not brake, but a little tired ... :D

 

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Discussion Starter · #10 ·
>> the temperature (gauge) stays low in our cold winter weather.
> I had the same thing last winter on my 97 turbo R. The thermostat
> was not brake, but a little tired ... :D

Sorry, forum quoting doesn't seem to work for me.

LOL! I should qualify my usage of the work 'cold'. I live in Houston,
Texas where cold is 'cool' or 'fresh' in other places. Perhaps 12-14
degrees C.

-rick
 

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Northern Europe still freezing

Hmm, some people have all the luck.

Over here it's still freezing at night and an ice wind is blowing. Just repaired my Volvo 164 exhaust in that weather :shock:. Saved 200 Euro for now though :).




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Discussion Starter · #12 ·
Thank Hemmo. Then again, Houston's summer lasts about 6 months at temperatures above 32 degrees C with near 100% relative humidity. We pay in the summer for fine weather in the winter. :p

Friday's weather looks great but rainy Sat. and Sun.. Perhaps I can get the grand old lady out for a cruise Friday afternoon, after a thermostat-ectomy.

-rick
 

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Did you ever replace the thermostat, which did you use, and what about those pictures?
 
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