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The car was running good temperature (less than 1/4) but took ages to warm up so thought I'd buy a new thermostat and fitted a 82c one, along with new thermostat gasket. Once fitted it seemed to run hotter, up to about 1/2 when doing 60 - 70 mph so thought I'd go back to the original thermostat as I'd cleaned it up and after checking it looked like it was working properly again, and was the original deeper design with bleed/drain hole. No difference, still the same - up to 1/2 at higher speeds.

I decided to replace all the hoses and take the radiator out and flush it. The hoses were a little old with some crud inside so worth doing. All back together with about 40% anti-freeze and the car warms up as it should and stick at about 1/4 all day long when idling or doing less than 50 mph, but as soon as the revs are up and constant the gauge moves to 1/2. As you slow down the gauge drops a little again and when idling drops back to 1/4.

As it was all fine before tampering with do I suspect there's still air in, or a coincidence that something is restricting flow i.e. radiator or water pump? Certainly there's no noise from the pump and the radiator seems good when flushing water through it. When feeling the hoses, the top inlet is much hotter than the bottom outlet so would seem the radiator is doing a good job.

The heater works as it should from cold to hot so seems like good flow through that as well.

I also changed the oil & filter recently and there's no sign of any water contamination.

Don't want to throw money at a new radiator but apart from removing it again and getting it checked by a professional I'm not sure what the next step is?

Thanks for any suggestions.


Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">The car was running good temperature (less than 1/4) but took ages to warm up so thought I'd buy a new thermostat and fitted a 82c one<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">Hi, the temperature is not good: you should aim for 1/2 and the proper thermostat is an 88c. In keeping the temp at 1/4 (82c), you are not running at the most efficient temperature for the engine. In summary: you are trying to keep the engine temperature down from the designed operating temperature. Fit the proper 88c thermostat.

Looks like the original thermostat but will need to measure properly to know the operating temperature.

My main concern is that the temperature goes up when going faster which my other (near identical TR7) car doesn't do. Maybe the viscous fan isn't slipping enough and cooling too much when lower revs but running fine at higher revs?

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by paulheritage</i>

... My main concern is that the temperature goes up when going faster ... <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Check your fuelling first, might be running lean.

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If anything, running very rich as I don't need choke when cold. Got new needles to put in the SU's before I tune it up.

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

I would confirm operating temperatures and variations with an infrared thermometer. Remember the temp gauge reading is dependant on voltage which varies with temp of coolant at the temp sender. The voltage can also be varied by any resistance in the circuit (other than that provided by the sender) so some gauges will read higher or lower in a given car as well as different readings from differences in manufacturing. It's also dependent on voltage of the car, if your car's battery output is low the gauge may read low but go higher at higher RPM if the alternator is not putting out max voltage at low rpm. To take all this electrical variables out of the equation you need to know the temp of the coolant. A good spot to measure would be the metal cover spout where the hose is hooked to as the metal will give good thermal conductivity (better than rubber) and it will be at it's hottest (just before it goes to the rad) other than any hot spots that may be in the engine of course.

In other words it may not be a temperature thing at all but an electrical thing.



- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

Paul, when the impeller on my new water pump was slipping, & pumping little water, my inlet & outlet hoses were at very different temperatures. In fact only the top quarter of the radiator was hot, when the water in the thermostat housing was at boiling, [100C]. If the top is at near 90C, I would expect the bottom to be at about 60C, far too hot to hold a hand on for long. If it is too cool, you're not getting full flow.

I would change back to the old thermostat, & see what you get, & pick up an infrared thermometer, they're less than $20, then you know what you're talking about.

Of course, you may have interfered with the connection to the gauge sender so have changed the reading, The engine temperature may be unchanged as Spyder says. Still I'd be careful about too much difference between the top & bottom of the radiator.

Hasbeen

Will measure various heat points to get a better understanding.

Thanks.

p.s. the original thermostat is back in but haven't checked the opening temperature on it.

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

Had a quick check earlier with the temperature gauge showing 1/4.

Top of the thermostat housing = 75 degrees C
Top of radiator inlet = 70 degrees C
Bottom of radiator outlet = 50 degrees C
Water pump housing = 45 degree C

(CORRECTED THE F to C !)

Not sure what this means yet until I can get the temperature gauge up to 1/2 on a longer/faster journey and re-test.

Would be nice to know the temperature of the thermostat housing when the gauge is at 1/2 so I can be sure it isn't too hot and anything to be immediately concerned about.

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

Those readings must be on the C scale.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by FI Spyder</i>

Those readings must be on the C scale.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Correct!

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk

Back in the day when I had a 2.0L engine in mine, it was normal to have the temp gauge at or just below the 1/4 mark running the factory fitted thermostat. My pal's FHC was the same.

It only went north of the 1/4 mark when the water pump leaked at 33,000 miles and the water level dropped. A new pump and it was back at the 1/4 mark whatever the temperature or traffic.

On some forums they swear by filling a radiator with warm / hot vinegar (really cheap stuff in a gallon polybottle from Aldi or similar) to remove the limescale from the bottom, flushing out before and after.

Adam



TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, S/S Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes all round, Anti- Dive, Strut-Top Roller Bearings, Capri Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 14" 5 Spokes or Maestro Turbo 15" Alloys, Cruise Lights, S/S Heater Pipes, Replacement Fuel Tank. No Door Stickers. Mine since July 1986, V8 from 1991 courtesy of S&S V8 conversion and big brake kits.

It's only going up to 1/2 - probably the correct running temperature - when you give it some beans. What happens if you 'hammer' it for a few miles? As long as it doesn't go above 1/2, I say there's nothing to worry about........[:)]

It never goes above 1/2 but usually 1/4 when just tootling around town and A or B roads. Might get the water pump rebuilt anyway.

Cheers Paul,

1976 TR7 2.0 FHC, ACG 3115 - Java Green (on the road)
1976 TR7 2.0 FHC, ACG 2367 - Carmine Red (on the road)
1980 TR7V8 3.9 DHC, Orient Blue (on the road)
1977 TR7V8 4.0 FHC rally car, ACG 35005 - Tahiti Blue (complete, no MOT)

www.TR7.co.uk