where should the temperature gauge Read

C

casper171072

New Member
Where should the needle read on my 72 3500. Ive just overhauled the complete water system, new radiator, all hoses, water pump and heater matrix and now if anything my car runs too coo (it was like that before but it did overheat on one ocassion). It sits just at the top of the white and the heater is a bit pants (heater box has been out, cleaned seals done). Stuck in traffic the needle rises to mid way up the green and the heater gets good again and thats as hot as it ever gets. I know I should be greatfull it doesnt overheat like half the other classics Ive owned over the years. Thought may I should get a Kenlowe style fan that will let the engine run a little hotter before kicking in as I hear that running too cool can affect the fuel economy. I have another thread going about that as mine is only about 16-18mpg.

I know the engine is in rude health etc, exceptionally quiet, never uses oil, never rattles or blows any smoke.
 
What thermostat have you got fitted, and if you have the correct one is it opening at the correct temperature or opening early?
 
Did the gauge read 85 prior to the rebuild? All V8s I have ever driven read 85 when running, i.e. needle at 12.00 O'clock

Could be the gauge not reading correctly.

Richard
 
quattro said:
Could be the gauge not reading correctly.

Richard
Click to expand...

As the heater isn't working properly I'd be more inclined to think that it's not getting fully up to temperature, especially as the guage does rise when stuck in traffic, at which time the heater starts working properly as well.
 
I have a 3500s and have exactly the same thing, needle sits between white and green, in traffic will go to middle of green and has gone slightly higher, heater acts the same as well, keep meaning to check stat but have not got round to it.
Can the thermostat be bought from a local car shop, Halfords for example.
 
Immediate update, bugged me so went out to check the stat, removed the elbow and what fell out............. Nothing, no stat in their so no wonder it was running cool. Now why was it left out.
 
Ah.....The D*ckhead factor strikes again! Probably because with a stat in there it was running too hot, which was more than likely caused by the bleed pipe in the manifold blocked, but taking the stat out stopped the temp rising high enough for it to become a problem.
 
I got one from the local motorfactors. Dont know about halfords specifically. You need to make sure you get one with a jiggle pin too...


Rich
 
Think the temperature is 82 or 85 degrees but the workshop manual will tell you that I guess!
 
WSM says stat should commence expansion between 82 and 84 degrees centigrade. Harvey don't think I will that brave 82 sounds good.
 
Mick,
If you cannot get a jiggle pin one ( I couldn't), I drilled a 1/16" hole in mine, and made sure the hole went upper most when I fitted it. My car doesn't hit the green, but the heater works, I wouldn't call it red, strip to your Kalvin's, hot, just pleasant heat.
John.
 
The thermostat sets the minimum operating temperature for your engine. The marked temperature of the thermostat is the temperature in which it first begins to open, and will typically be fully open around 10 degrees C above that minimum temperature.

An engine should reach the thermostat opening temperature within a few short miles after starting as up until this time the thermostat is closed. Drilling a hole to prevent air locks in a thermostat that would otherwise not have one has the potential to slow down the warming up process. This will be especially so in cold weather.

I used to prefer to use thermostats with jiggle pins, but now I find that those with a calibrated bleed notch are a better option, allowing the engine to reach operating temperature more quickly and regulating coolant temperature much more efficiently.

If an engine does not reach the minimum temperature of the thermostat, then either the thermostat is not closing as it should hence coolant is circulating prematurely, or a hole has been drilled slowing the warm up time or the thermostat is indeed working correctly, but the gauge isn't.

I tested my thermostat prior to installation, and on my gauge 82 degrees C lies in the space between the white and the green when covered by the needle. I know this to be so by feeling the top radiator hose, which is pressurised from this point onwards. The engine will normally run a few degrees above the thermostat opening temperature, mine normally runs with the needle over the '8'. In hot weather it will move up and sit between the 8 and the 5 and on really hot days over the 5 or beyond depending on traffic conditions etc.

Ron.
 
Interesting Ron , mine has been sitting in the space between White and green with no stat in it. This under normal driving. In traffic it can go to middle of green very very rarely any higher
 
Ron's preference on thernostat type is interesting. I've not heard of this type before. What is absoutely critical, though, is to have some sort of bleed provision in the thermostat. Without it the V8 will effectively air lock and cooling performance will be all over the show! Hence why it is also critical to get the jiggle pin / bleed hole at 12 o-clock as well.

Do you have any links to an example of this type of thermostat, Ron?

My personal preference would always be for an 88 degree stat. Running a lower temperature stat will noticeably reduce the engine's efficiency leading to higher fuel consumption. In theory there will also be increased engine wear, although this should be marginal. If running the higher temperature stat leads to you having problems with overheating, then there are other problems with the cooling system that need fixing. A good general flushing, plus checking that the outlet from the carburettor "tower" between the two carbs is clear and running freely is a good start. If that fails to fix, then an upgrade of the radiator from 2 row to 3 row is the best solution. Any local radiator shop should be able to achieve that for you.

Chris
 
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