Cooling system circulation.

[Alex.]

Hi Guys,

We're having a couple of problems with my wifes 340, rough running and general unhappiness both at idle, low speed and on the motorway!

One thing I noticed this morning is that there is no jet of water coming into the expansion bottle. I seem to remember that the circulation should be into the bottle at the top and out at the bottom, with the incoming water visible as it is above the water level.

Am I remembering correctly, or is my mind playing tricks??

Alex.

[Speedy88]

Heater needs to be on hot for this to circulate into the expansion tank

[Chris_C]

1.4s dont circulate, only 1.7s. Does it take forever to heat up?

[Alex.]

It is a 1.7 and in the past has taken ages to warm up, with the temp guage hardly moving even on long runs.

Recently the guage has been moving up more and quicker, we just put it down to the slightly warmer spring weather!

What problem would taking ages to warm up point to?
The radiator was replaced with a brand new item sometime last year.

Alex.

[Ride_on]

Thermostats are really a service item, change them every 5 years or so. Still doubt it would cause your running problems, even open circuit thermostat should allow enough carb heating to work ok.

[Chris_C]

Sorry, was on the phone earlier. Taking ages to warm up is a sign that your thermostat is siezed. They are only about a tenner so in the grand scheme of things... change it anyway

I agree with Mr Ride On though, I think there is something else as well. Have a nose at:

Carb and airfilter tight
Spaceman tubing from exhaust to the airfilter in tact with no splits
Dizzy cap condition. These really are a service item so if it's been in the car more than 6,000m put a new cap and arm on.

There are other likely things, but it's going to be a bit at a time as ever The bits above are either so common it's untrue, or cheap. Best move onto the the more expensive stuff later!

[Alex.]

Thanks for the replies guys.

Most of the ignition system was changed less than a thousand miles ago, dizzy, arm, leads, plugs.
I had a poke around this afternoon, before driving home and most of the coolant hoses got warm quite quick, followed by the others after a while. Wouldn't this suggest that the thermostat was operating ok?

As for the circulation in the expansion tank, it made no difference if the heater was on hot or cold, the flow into the tank was a trickle at idle and only a little better when rev'ed. I'm sure this was quite a gush when I changed the radiator.
Could a duff water pump cause running issues?

I drove the car home, with no apparent problems. I'm going to drive her with the wife sat next to me tomorrow, just to see if she can see if I am doing something different to her when driving!!

Alex.