Cooling fan

[Bandit1200]

Currently, my Stag is running with the standard viscous fan and Stroms.
I have no problems with cooling, in that the temp gauge rapidly reaches mid point and goes no further.
However, in warm weather, when the Stag is left for more than 5 mins it fails to start.
I have determined that the problem is caused by fuel vaporisation because if I open the bonnet when I stop and close it again after 5 mins she starts with no problem.
I don't want to continue with this as it invites comment from the experts that "Stags always overheat don't they".
Can you please advise the best electric fan/thermostat solution so that the fan runs after the ignition has been turned off until the under bonnet has reached a temperature where starting becomes no problem?
Thanks in advance
Steve

[StagJonno]

Hi Steve,
I've got a 14" UHP Kenlowe fitted, but removed the VC fan (aiming to improve mpg). It's thermostat sits in the top hose and currently is on an ignition controlled circuit. Am planning to change to a battery circuit and include a timer to run it for 5-min after stopping to reduce engine bay temperatures. Couldn't find any automotive timer relays, so have just bought a "Engine Run-On Turbo cool-down" timer from China for the grand sum of £8.36 which I hope to adapt to the function I want.

In your case, assuming you'll be keeping the VC, I'd connect to a battery circuit and route the thermostat sensor along the top of the bulkhead. Check first to see that the thermostat will cover the temperature range you're looking to achieve. Or you could use a timer. I'll post on here when I get my timer sorted out (may be a few weeks).

Jonno

[Nigel W]

Steve
Are you trying to cure the symptoms rather than the cause? I confess that I am no expert, but I am not aware that fuel vaporisation is a common problem with Stags. Mine for example always starts when hot. I just turn on the ignition and wait for a second or two to let the fuel pump work if needed, and when it stops clicking, turn the key. Could it be that there is something wrong with the carbs that allows the vaporisation to occur. Just a thought.

Nigel

[Jeff]

Not being an expert myself but I understood fuel evaporation on the Stag was common knowledge. Mine starts fine when hot but many don't and has been discussed at length on here.

I replaced my VC as I didn't notice or am bothered about 'extra' mpg or more power but do notice a more even temp gauge reading, again discussed at great length on here.

just saying

[mallardstag]

Steve,

I agree with Nigel that you may be trying to treat symptoms and not cure the problem. Have you checked the float chamber needle valves are not leaking and that the fuel pump is providing the correct pressure? Either of these can lead to flooding after shutdown and difficult starting until the excess fuel has evaporated.

Try switching the engine off by operating the inertia switch until the fuel runs out. Then restart after waiting a few seconds for the float chambers to refill. If this works then you may have a fuel problem.

Simon

[Ian F]

Steve - I agree with Nigel, and I used to have a similar problem. However mine would start and tick over fine when hot, but as soon as I tried to pull away it would seem to flood and "fluff" 3-4 plugs and need considerable revs to burn off the fuel and it would then run OK.

Unfortunately, not being an engineer, I changed several things at once, so I am unsure what cured it - but fitting braided under bonnet fuel lines (Silver braiding reflecting heat rather than black plastic absorbing it?), re- setting float levels very, very carefully having renewed needle valves (again!), and re-tuning the carbs - completely cured it, No problems since, hot or cold.

Ian

ps I do have an electric fan, that does/can run for up to 5 mins after stopping, but since fitting a TR6 spoiler and re-setting the temperature cut in for the fan, it hardly ever cuts in - or at least so far this year. Think it's a Kenlowe, but fitted when I bought the car.

[wilf]

I have a Kenlowe fan, but kept the VC fan as removing it, IMHO, simply increases underbonnet temperatures. What I do also have is some thermo- sleeving over the fuel lines from the filter on the suspension turret to the carbs.

I have no hot start problems.

[thebadleys]

The early Renault 5 Turbo's had an issue with fuel percolation, as it was dscribed as then, and the answer was a separate small fan which ducted cool air from under the front wing to the carburettor bowl, later cars had ducting from the radiator fan

[Lingen]

Steve. I am also lucky in having a stag that always starts cleanly when it is hot, and I have no modifications. It is known that vaporisation has become an issue on some cars since ethanol was added to petrol, and if the concentration is increased from 5 to 10% it will almost certainly get worse. However, you ought to be able to stop it happening by ensuring everything is correctly set up on the Strombergs. Float level, mixture etc. and that the compensator valves are opening correctly. Also that the 12v bypass of the ballast resistor is working when the starter is engaged.
I would check these before experimenting with an extra fan.
Mike.

[tonyh]

Hot starting problems is normally caused by stuck vent valves in the carbs, early MK1 Stags carburettors did not have vent valves and suffered hot starting problems, this was rectified by redesigning the float chamber venting by incorporating a vent valve operated by the throttle linkage. The other thing to check is the breather pipes from the air filter box to the carbs, it’s possible for the pipe entering the rear part of the T piece can be pushed in too far, blocking off the pipe coming in from the side, this shuts off any venting to LH carb, even if the vent valve is working, and can also cause bad hot starting. All this causes a vapour lock in the carb float chambers when the engine is shut down for a short while but only because there is no venting to the float chambers.

No doubt there will be people out there that disagree with me but over the last 40 od years I have cured hot starting problems by just freeing off the vent valves that other owners have spent hours of modifications that didn’t cure the problem.

Personally I don’t like the braided fuel lines, you can’t see when the rubber hose under the braiding is starting to perish and leak, I had one customer that had a small under bonnet fire for just that reason, luckily there was not too much damaged caused.

Tony.

[greystag]

ref evaporation

I run the webber and first day out it would not start when hot,heat was boiling the fuel,put an insulation pad under carb and hay presto no more problems.