Are you running hot
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 Are you running hot?

 

This whole process started when I read an interesting article by Pat Lockyer some time ago. He discovered that there was a restriction on the driverís side of the timing case cover caused by the distributor shaft running through the water jacket. So I decided to measure the temperatures on each side of the engine with some temperature probes. Thanks to Bill Ebzery we managed to get our hands on such a device but with no running engine of our own to test it on we waited for an event at our place so that we had the two vital ingredients. The first was Bill Ebzery to run the device and secondly the most important was Sue with her Jupiter so we had a car to test. Firstly we had to rig up the car with the temperature probes as shown by the pictures at the end of this article.

 We then started the car and waited a while for it to warm up a little. The following results were taken with the car in neutral and revved between 2000 to 3000rpm. The ambient air temp was also measured at a lovely 23oc. One interesting note was that while the water pump temperature measured 65oc the cars temperature gauge read a much higher temperature which fluctuated between 75oc and 81oc. Looks like Bill has another job to do when he gets home. 

 

 

Time

Interval between readings (mins)

6

8

10

12

14

Passenger timing case

42

46

48

49

51

Driverís timing case

56

65

65

66

68

Driverís water transfer

58

69

71

73

76

Passenger water transfer

55

62

63

63

64

Water pump outlet

60

70

64

65

65

  

 

 From the chart above we can see that there is a substantial temperature problem on the driverís side of the car which is the side with the restriction, at the worst there is a 19oc difference between the two sides of the engine. We must now ask ourselves several questions. Does this affect the carís running? How do we go about fixing the problem? Is it worth fixing the problem? These cars have run for 50 years and the majority have survived intact. Although I canít answer all the questions above I do have a theory about how it affect the cars running. For an example letís assume you run absolutely no coolant in your engine, when the gauge on the dashboard reads 90oc you think thatís ok Iím not boiling yet, however while the passengers side of the car may be around 90oc the drivers side is 19oc higher at 109oc and has turned into steam which is not very good for cooling.

 Granted nowadays with the addition of coolant and the 4 PSI of system pressure the cars wonít boil till around 120oc however the problem is just delayed not cured. Also who knows what other affects the temperature difference may have on the engine? Hopefully this article has given you a little more insight into our beloved Jowetts. Whether youíre young or old its interesting learning about what makes our unique little cars tick. Finally, thanks to Bill Ebzery for the use of the equipment used in this experiment and his expertise in running it and Sue for being kind enough to lend us her baby to be poked and prodded.

 

By David Hood

See pictures below of the measuring points. Pat Lockyer's modification can be found here.

 

 

 


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