[Fot] TR8 Water temperature

[Duncan Charlton]

Chris,

It might be instructive to measure input/output comparison temperatures over a range of, say, 160˚F to 212˚F.  Everything I’ve read so far says that a 25˚F drop between inlet and outlet is pretty typical.  If it’s dropping more than that, I would think that the coolant is spending more time in the radiator due to slow flow.  I have read that the idea that the water is circulating too fast for an adequate temperature drop in the radiator has been discredited but I couldn’t find the source of that statement.  It does make sense to me, however, that if the water flow is completely unrestricted some areas will be cooled more effectively than others as friction loss drags down flow in smaller passages in the engine as flow increases to the larger passages.

Checking the temperature at various places on the block and intake manifold could yield some useful information too.

I just remembered something as I was typing this.  Some serpentine belt arrangements cause the water pump to turn the other direction on the BOP V8.   there are various types of impeller, some with straight vanes, some with curved ones, and I’ve seen both “directions” of curved vanes  — I wonder if your car ended up with one that is meant to turn the other way.

Duncan Charlton
Elgin, Texas USA



> On Jul 9, 2016, at 7:11 AM, MadMarx <tr4racing at googlemail.com> wrote:
> 
> Hi Duncan,
>  
> To answer your questions:
> 1-      I measure about the same what is measured at the head outlet. The gauge is mechanical and I’ve put the probe in boiling water and had read 210F. I think this is okay with being 200 meters above see level.
> 2-      The radiator core is new and came in at year 2014. I’ve also measured over the whole core temperatures and they are very even. It is also clean from outside.
> 3-      I do always my best to remove air.
> 4-      With the fan blowing the temperature is creeping up more and more. Fan blows in the right direction
>  
> The impeller of the waterpump has a metal plate so it should be independent of any distance to the housing.
>  
> The car had these temperatures already when I drove it at Road America. So this is not a new thing on the car, I just want to cure it.
>  
> Chri
>   <>
> Von: Duncan Charlton [mailto:duncan.charlton54 at gmail.com] 
> Gesendet: Samstag, 9. Juli 2016 13:51
> An: MadMarx <tr4racing at googlemail.com>
> Cc: FOT List <fot at autox.team.net>
> Betreff: Re: [Fot] TR8 Water temperature
>  
> Chris,
>  
> 212F at idle?  That’s interesting.  I’ll start with the usual questions: 
>  
> 1) What is the temperature you recorded at the radiator inlet?  (Having observed this, I assume you have already confirmed that the gauge is reading correctly.)
>  
> 2) Is the radiator clean, inside and out?
>  
> 3) Have you confirmed that there is not an air bubble trapped in the system?
>  
> 4) Temperature at idle remains this high even with the cooling fan blowing?  If so, is the fan blowing the right direction?
>  
> I don’t know whether the following applies to the Rover motor you’ve got, but some Morgan owners with Triumph motors have found that the impeller of their new water pump is improperly placed on its shaft so that there is a large gap between the impeller and the housing, causing it to be very inefficient.  One guy measured 0.075” end clearance, which he was able to reduce to 0.015” by use of a spacer.
>  
> Duncan Charlton
> Elgin, Texas USA
>  
>  
>  
>> On Jul 7, 2016, at 12:20 PM, MadMarx <tr4racing at googlemail.com <mailto:tr4racing at googlemail.com>> wrote:
>>  
>> Hi guys,
>>  
>> My TR8 is running way too hot about 212F at full speed and at idle the temps are getting that high also. I have no idea to get them down.
>> Radiator core is 68x48cm x 5 cm. I suppose that should be enough. I've experiment with different restrictor plates with no change. Changing pump speed didn't help either. The difference between radiator in and outlet is 10°C (50F). Not enough I would say. Maybe making the pump more slower? It was running on a ratio of 0.8 slower than crank, currently 1:1 speed. Any ideas? 10 Liters are circulating.
>>  
>> Cheers
>> Chris
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