Race Engine Forum UK

Over the winter I rebuilt the engine in my 1978 Beta 2.0 TC. Since the engine was out and the water pump's condition was unknown I replaced the water pump.

For various reasons I've only just started to drive the car. It's still a very tight engine so I'm using 3000rpm as a limit for the first 300 miles. It appears to be running to cold. I say appears as I'm relying on the dash gauge and the cars feel. It behaved like this on the original thermostat which I replaced thanking it was stuck open. The new thermostat has been tested by the pan of water and thermometer method.

Here are the symptoms:

On the open road the dash gauge reads only just into the 'normal' zone
At this point the car pulls poorly and stutters from low revs, clearing a bit as rev's rise. If I pull the choke out a little it clears and goes pretty well.

In town the gauge rises to 1/2way. The car runs great like this pulling smoothly in high gear at low revs.

Left for long enough the fan cuts in at about 2/3 scale on the gauge and it boils (airlock - whoops !) at over 3/4"

Given that the running problem could be carb/fuel supply how do I accurately ascertain the actual running temperature I was thinking of a thermal strip on the top metal hose ? If it is running too cold (which would be odd) what can I do about it ?

Thanks-Stuart

Have you had the radiator rebuilt or uprated at some time?A radiator with too many tubes can cause running too cool or in certain circumstance ,if over efficient ,overheating. In both circumstances a restriction placed in the bottom hose can improve the situation by keeping the water in the radiator long enough for the heat to be removed / increased.
Likewise was the water pump exactly the same, as the number , and shape of impellors can have a big effect on the engine temperature.

Often a similar looking , but not rated ,temp sender may have been installed at some stage giving a false reading.I would personally fit an aftermarket matched unit to ensure there is a fault to chase before proceeding further.

Stuart,
You did not mention whether or not the thermostat passed the pan of water test. But if you're having boiling in the overflow tank, you either have an incorrectly installed or defective thermostat or an obstruction in your radiator. Does your heater blow hot? If not, it's got to be one of these problems or a clogged heater core. Flush the radiator and try another thermostat. It goes without saying, make sure you have the thermostat installed correctly, machined side toward the water pump. After you run the car for awhile,until the fan kicks on, carefully grab the top and bottom hoses on the radiator, both should be warm/hot. If the bottom one is cold, you still have some sort of problem as discussed above. Good luck.

Yes the thermostat passed the test !

The boiling was a one off as a result of me forgetting which way was hot on the heater and causing an airlock. The thermostat is fitted correctly.

The rad is new(ish) but looks standard and I must admit I didn't check whether the water pump was the same. I rather assumed that the thermostat would take care of things - perhaps not.

I found that RS do self adhesive thermal strips with a range of 60-90 deg in 5 deg steps, accurate to 2 deg. I'm going to stick one of these on the top metal hose and use it to calibrate the dash gauge. I hope to find that the engine is running at 80-90 deg.

I use a laser thermometer to help to determine hot spots and temperatures drops on radiators. Also useful for working on mixtures and exhaust manifold design . Cost about ‚£25 and worth it's weight in gold on problems like this.

That's interesting - do you remember where you got it from ?

Stuart

From E Bay, though most larger motor factors such as Lucas, Partco etc will hold them though price probably isn't as 'keen'.

Also available from Maplins, here:
https://vault1.secured-url.com/chimney/ ... eters.html

And your local plumbers merchants do them aswell.

I also find them very usefull - checking which cylinder isn't firing (on the exhaust runners), setting up the camber on the track car (by measuring the heat in different parts of the tyre), etc, etc, even checking if your dinner is thoroughly cooked!

They are handy yes, but unless I'm mistaken, the laser thingy only tells you where you're pointing it though, and the accuracy of the reading is worse the further away you hold it.

GC

So,

was there an answer for this problems,

Ive meet exactly the same probs last week in a rally day : slow speed, high rpm and very good temp and car holding, but fast speed (ralliement road, highway) low rpm and very low temp, and bad engine condition. The thermostat seems good and the fan radiator sensor do the job......

the consumption of the car was 18liter for 100 km......

The head gasket was replace 3 weeks ago, after twice heat problems. The gasket was worn on the cylinder 4.

I am sorry but I cannot offer an explanation because:

1. I would want to see some good quality photos of the engine and radiator

and

2. I am not at all clear what the exact problem is..

G