Coolant not circulating ('74 Midget 1275)

[jameslowe]

I've recently bought my Midget out of storage after 4.5 years and am in the process of getting it back on the road. Leaving it standing for this time seems to have caused a couple of problems.

I'll restrict this post to the cooling system

The problem is that the cooling system is not circulating the fluid. The top hose is getting hot within a couple of minutes, the hose to the heater is getting warm but everywhere else is staying cold. To resolve so far I have tried

1. Flushed the whole system in both directions a number of times (including the heater matrix) In either direction the water is flowing freely and clean. Each time I have done this it has been at mains pressure.
2. Removed the thermostat
3. Checked for leaks and airlocks (I am pretty certain that I have neither)
4. Belt is correctly tensioned

Maybe the water pump? However this is running as quiet as it ever has and there is no obvious freeplay on the pulley

Any suggestions gratefully appreciated?

Thanks
James

[mr rusty]

Fit a new thermostat.....if the top hose is getting hot within a couple of minutes that's a sure sign it's either stuck open or not there at all ( you don't mention putting it back........) At this time of the year it'll take forever to warm the coolant up if the stat's not working or totally absent.

[jameslowe]

no I've not put it back. It will go back in when the problem is resolved but for now want to eliminate possible causes. WIthout the thermostat I still have the problem

[Luxobarge]

What isw the temperature guage reading?

As Rusty says, sounds to me like the engine just isn't getting hot enough. If the enging is overheating but the rad is still cold then you have a problem, but if it isn't overheating then I doubt you have a problem at all.

[Wicksy]

Yes the temp guage is a big clue but if it is also showing cold - it's already been said but here we go again.
At this time of year the thermostat can take about 5 minutes or more to open and then probably not fully.
If it's been removed or has jammed open, the rad/fan/circulation and any ram air will cool the water exiting the engine via the top hose so fast it will be cold at the bottom hose. In fact if you don't have anti freeze at the correct strenth you can easily freeze the rad at speed if it's really cold.
The heater gets a hot feed from the bypass hose on most engine designs, which in effect is a fast warm up well as a fail safe device, but it aint enough.
You can test the stat by putting it in a pan of water and bringing it gently to the boil, it should only open at between 80-90 deg C and the actual figure will be stamped on it. If it's opening early or already open or you aint sure, it's knackered - they are only about a tenner so this not a big deal

[JPB]

"At this time of year?"

Note the o/p's location! It's late Summer down there, so will be considerably warmer at this time of year.



Unless of course he's talking about St Helen's or Bishop.

[Luxobarge]

Note the o/p's location! It's late Summer down there, so will be considerably warmer at this time of year.

True indeed - of course, due to the coriolis effect caused by the opposite spin of the globe in the southern hemisphere, he should be using an anti-clockwise water pump - that's right isn't it?

[JPB]

Either that or one whose vanes have the hollow side facing the other way.

[bnicho]

Southern hemisphere jokes aside....


The water pump impeller may have come off. There was a bad batch of A-series pumps that were prone to that problem. Take the pump off and check the impeller.

Cheers,
Brett.

[grumpy2]

I had something similar with the spitfire eventually traced to an air lock in the pump. I cured it bu back filling the system using a funnel through the heater pipe

Took 3 weeks to figure it out though