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Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 02:04 am: | 
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OK. I think my problem with not enough heat is actually a thermostat stuck open. Today was really cold and while driving, the temperature guage dropped below the lowest mark. Car ran great even on 87 octane but I do need some heat inside.
I searched the archives and found Paul using a SBC tstat. I just did not get the comment about drilling the flange for the jiggle pin. Was that the flange on the tstat? What jiggle pin?
Also, does anybody have the part no for the original replacement. I'll try local Canadian Tire or Auto Value to see if they even carry these.
Thanks... |
Paul T. Schram (Paulschram)
| | Posted on Wednesday, January 22, 2003 - 08:16 am: |
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Milan:
The thermostat has a flange that positions it in the recess. The jiggle pin is there to allow air to escape as the upper reaches of the water jacket fill and force air to the radiator. Without the jiggle pin, the air can't escape to the radiator and be displaced by coolant-this can cause overheating as the water jacket has air pockets instead of coolant everywhere it needs to be.
Not only can you use the thermostat from an SBC, the gaskets are identical (I bought a genuine gasket for comparison purposes).
Thermostats are simple devices and one doesn't need the genuine part. Stant probably makes them for Rover...
Peace,
Paul |
Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 10:50 am: |
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Thanks Paul. That makes sense. |
Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 12:16 pm: |
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P.S. How come the jiggle pin or hole are not needed on the SBC or other engines? |
Steve
| | Posted on Wednesday, January 22, 2003 - 01:45 pm: |
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Milan
FWIW, The thermostat needs to be in contact, mostly, with the coolant for it to work properly. The coolant on the engine side heats the lower chamber of the thermostat and the "wax" in the chamber expands opening the thermostat. If the engine coolant doesn't contact the thermostat then the thermostat is only contacted by air and some steam which does not transmit heat as well a water. (you put your hand in a 400 degree oven to remove a roast but putting your hand in 400 degree water would be a disaster) Some engine manufactures flow water past the thermostat with their bypass hose to cope with the problem, others use an air bleed hole or jiggle pin in the thermostat to eliminate air from the system. After fighting with getting air out of a couple of cooling systems years ago, I would drill air bleed holes in thermostats whenever installing new thermostats. Now many come with jiggle pins installed from the factory. Rover engines are among the engines which benefit from the use of jiggle pins or bleed holes.
JMHO
Steve |
Blue (Bluegill)
| | Posted on Wednesday, January 22, 2003 - 04:15 pm: |
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very informative Steve & Paul...oh the wonders of the tstat
OEM:
Motorad replacement part from NAPA:
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Blue (Bluegill)
| | Posted on Wednesday, January 22, 2003 - 04:16 pm: |
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Blue (Bluegill)
| | Posted on Wednesday, January 22, 2003 - 04:17 pm: |
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Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 06:39 pm: |
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Hey guys thanks!!!!!
I just picked up a SBC Motorad tstat with a jiggle pin. $8.09 CDN and $1 something for the gasket. It is also one of the ones with the "Safegurd" feature - little metal notches that lock the t-stat open once the engine overheats. I wonder if the one in our Disco is like that and got stuck open.
I still don't get the jiggle pin, or maybe I do. I know how the t-stat works but does the pin jiggle loose when the air is in the pasage and then plugs the hole once coolant level in the passage rises? I would say: "Obviously.". The reason I'm still a bit doubtful, is that I would figure that pressure inside the passages would push the pin in "closed" position (which would really defeat the purpose of having it) but maybe that pressure is not enough. I figure it must be the coolant that does that.
Obviously I have not had to do a tstat in a while (about 20 years) and back then I only bought the simple ones so I never noticed jiggle pins, though they probably existed even then. I don't remember "Safeguard" features either. Oh well, have to become old one day. Even if old means not remembering stuff from 20 years ago. |
Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 06:46 pm: |
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P.S. Should the pin be at the 12 o'clock position when installed? Or does it matter? |
Blue (Bluegill)
| | Posted on Wednesday, January 22, 2003 - 06:52 pm: |
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yes, jiggle at high noon
if you were in a bind and had to pick up a non-jiggle-equipped tstat, you can always drill a hole at 12 o'clock.
see also
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Milan (Milan)
| | Posted on Wednesday, January 22, 2003 - 07:05 pm: |
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Thanks Blue!
Here's the link I found in the archives:
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