V12 overheating - ignition timing?

[DOF]

Hi Guys,

I hope you may be able to help.
Was out for the first time of the summer yesterday (an unwise hot day), and had two near overheat situations...
She would idle fine, temp guage reading R of NORMAL, but on the move, the guage just went up and up, and I'm sure if I hadn't stopped, she would have gone into the 'red'.
Giving that she idles without heat issue, I'm thinking maybe the advance mechanism has seized? Had a Luminition ignition fitted last year, don't know if that makes any difference? It has been too long since I had her out of the garage....

Any thoughts?

Many thanks

Simon

[PPV]

I would have thought you would either hear unusual noises like pinking or it would not be running the same if the advance system was not working. As it has not been out for so long then perhaps airlock in the cooling system as unsure why it should hotter when moving compared to stationary. Are any hoses collapsed or kinked?
Has the water level changed from before to after run (checked after cooling down)?
Regards,

[DOF]

HI Paul,

Thanks for your kind reply.

Yes, you are right. I have now checked in the distributor, and the centrifugal advance seems fine, not so sure about the vacuum retard, but I don't think that should cause an overheating issue. Hoses look fine, I changed over to Kevlar jobs a few years ago..

Have ordered two new thermostats , and a new radiator cap, and will try a good old flush and re-fill, in the hope it may just be crud in the system, where it hasn't been used much.

Thanks once again for your advice.

Simon

[RichardSEL]

Back flush by hose too, include the heater matrix on full.

Any slack or squeal heard from the belts at any time?
Remove the one that's around your water pump. Turn your water pump crank by hand, any lumpiness felt? Or does it spin freely? Any sound coming from it when you spin it? Child's toy stethescope useful to hear whether you've got any bearing rumble

When you re-fill with your water/antifreeze mix (I use 50:50 but that's just me!) "press-up" the system on engine idle by leaving the cap off, heater on full and then let the temperature rise to normal. You should see that there's no bubbling coming back into the resovoir. But should see the flow back with a new thermostat fitted. When that's happening then put your new resovoir cap on once topped up. Then you know there's no air in your system

[DOF]

That's brilliant, thanks Richard, you've just answered my next question before I asked it!
Hope it works, as there's less than 3 weeks before I'm due on Copse Banking for the Silverstone Classic...

[piman]

Hello Simon,

this is largely theoretical as I don't know from practical experience.

Assuming a stanrd car, the carburettors will be set weak for cruising and to get correct running, more ignition advanced is required. This is where the vacuum advance comes in. Should it not be working the engine will run lean and tend to cause greater heating of the engine. (More accurately it is the engine is running retarded as the mixture should be lean)

Alec

[DOF]

Hi Alec,

Thanks for coming back to me.

I thought that could likely be the case...am hoping my flush, thermostat and coolant change, will do the trick first, but if not, will def reconsider the timing...

Simon