Spitfire 1500 severe overheating but NOT an evident coolant system fault

[Colin Lindsay]

I'm just going to bounce this one off you guys for a bit of a) moral support and b) brain picking.

Spitfire 1500, mid 1970s, hard to start and running very rich.

I've replaced the leaking coil (12v, it has been modified from 6v ballast) and converted to Accuspark electronic ignition. Timing was set to about 13 degrees as it ran better there than at the handbook 10. It's been quite poorly maintained so no antifreeze in the system, just rusty water; I cleaned the thermostat and replaced a manky gasket on the housing and replaced temperature gauge and sensor as the gauge has never worked. Brakes have all been rebuilt.

The driver picked it up today, took it for a short run, no issues, no leaks and temperature showing lower third of scale. It was idling quite high so I turned the idle down to 900rpm, the carbs have allegedly been tuned recently but it's a twin-box sports exhaust and very sooty.

40 minutes after it left me the driver phoned to say that he had broken down. He had taken a wrong turn so did some motorway driving but claims a maximum top speed of 60. So much for not thrashing it until the brakes bed in. At about 3000 rpm there was a loss of power, he dropped down to 2500 rpm then tells me he noticed the temperature gauge was in the red. He nursed it to a garage forecourt but on checking when it had cooled down the water is still full and with the radiator cap off can see it moving if the engine runs. So: it's not lack of coolant.

I did not check the oil but am assuming it's got some. I'm wondering if the timing system would cause the symptoms, if the timing had managed to go way out? 

He's 60-odd miles from me and I may drive over tomorrow to have a look, but if the car runs well and idles well at lower speed, what might cause serious overheating at high speed with no coolant loss? Any thoughts of what to look for when I next see it?

[Clive]

Sounds like a possible blocked radiator. As in the tubes. Had that on my Toledo, I fitted a modern smallish radiator, only to find the faster I drove the hotter it got. Rad was too small, and cured by a bigger radiator.

No amount of flushing will unblock the rad tubes, as teh water flow will always be down unblocked tubes. Only solution is to find an old radiator repair place, they can remove the top tank and poke each tube through.

I digress. To check, try a known good radiator. 

Also check the distributer advance is working correctly. Non-advancing ignition will cause hot running.

[poppyman]

Sounds like a blocked rad Colin, for some reason they always seem to block in a circle from the centre of the fan. You can feel it with the engine off, cold in the centre. Also a bad airlock can can cause problems. Retarded timing usually causes overheating. So same as Clive really.

Tony.

[Pete Lewis]

getting a bit hot for what ever doesnt make the loss of power is related

is the voltage stabiliser actually working as with a run the battery voltage will increase so would the temp and fuel gauge reading  as it seem it was not really over heated just the gauge said so 

power loss down to them darn rubber slivers especially if any hoses had been disturbed 

and is it still on wax stats ????

if it has not lost coolant and not blowing  steam i suggest its just the gauge reading that invited its overheating 

just thinking of another avenue to the problem 

Pete

[Chris A]

Maybe I'm being a bit obvious but have you used an infa red thermometer to confirm if it is actually too hot and where.

[Colin Lindsay]

Yes still on Waxstats, but has been running fine until now, just rich.

The driver has had a non-working temp gauge ever since he bought the car and never looked at it until the car started to miss and play about. I've been on the phone constantly today, they've flushed the system and are replacing the thermostat but I'll do it again tomorrow, and will check the radiator. I'm going to have to drive 60-odd miles in the morning as I feel bad now.   Large toolkit assembled and in the boot ready to go. Too many unknown quantities with this car; the distributor was also replaced a while back but at present I don't know why. I suspect it may not have been overheating but the gauge would have been in the top 2/3 and the inexperienced driver panicked, so that could be a red herring.

Thinking out loud here as usual; won't know until tomorrow.

 

[Patrick Taylor]

Hoses gone soft and pinching closed when hot & at high revs?

[PeteH]

I would not be surprised to find that the Issue had to do with the Distributer?. If its not advancing as it should then it will be retarded relative to the engine speed and potentially down on power. Is the replacement Distributer correct for the car? In terms of the advance curve?.

Pete

[dougbgt6]

I’ve just had something similarish, loss of power and unable to get the revs up. This was after breaking out of a 45 minute traffic crawl. No apparent engine overheating, but I think something electric didn’t like the heat and it affected the ignition timing. 

East Berks this evening suggest,

dodgy coil.

insufficient heat sink on electronic ignition.

dodgy earth in dizzy.

Running too rich.

I’ve already swapped the coil and it hasn’t happened again, but too early to tell if this is it. Certainly going to check the rest.

Doug

 

[Pete Lewis]

wax stats   time for the 2x 1p  conversion 

dont loose the small metal spacer its needed just prise the crimped cap off and remve the old wax capsule  , replace with two  1p peices and the small spacer 

tranforms silly running problems 

[Chris A]

1 hour ago, Pete Lewis said:

wax stats   time for the 2x 1p  conversion 

dont loose the small metal spacer its needed just prise the crimped cap off and remve the old wax capsule  , replace with two  1p peices and the small spacer 

tranforms silly running problems 

Is that classed as a bodge or product development? 

[Pete Lewis]

its a 2p improvement ..added value 

better than paying £60 for new jets and some badly bent linkages 

 

[Colin Lindsay]

Okay... just home, nightmare day - left the house at 9.10am expecting to arrive at 10.30, got there finally at noon due to roadworks, a diversion of over 40 miles and poor directions. The diversion was mostly due to me thinking I'd be a smarta$$ and find another route over the mountains. There wasn't one.

Timing spot on, car did not overheat on test runs, coil fine so didn't replace. There's quite a roughness in the engine at 3000 revs that goes away by 4000 rpm but no pinking, missing or hesitation evident. It's an FM 1500 engine. No noises on idle or when revved stationary but when driving, once at 3000 rpm there's a loud rushing / hissing almost as if the heater blower has turned on that goes away again at higher revs. Weird and no identified cause.

At least I'm happy now it's not down to anything I did...

[Chris A]

16 minutes ago, Colin Lindsay said:

Okay... just home, nightmare day

 

16 minutes ago, Colin Lindsay said:

At least I'm happy now it's not down to anything I did...

A trying day without a completely positive result. Treat yourself to a glass or two of your favourite tipple, you deserve it.

[Clive]

1 hour ago, Colin Lindsay said:

Okay... just home, nightmare day - left the house at 9.10am expecting to arrive at 10.30, got there finally at noon due to roadworks, a diversion of over 40 miles and poor directions. The diversion was mostly due to me thinking I'd be a smarta$$ and find another route over the mountains. There wasn't one.

Timing spot on, car did not overheat on test runs, coil fine so didn't replace. There's quite a roughness in the engine at 3000 revs that goes away by 4000 rpm but no pinking, missing or hesitation evident. It's an FM 1500 engine. No noises on idle or when revved stationary but when driving, once at 3000 rpm there's a loud rushing / hissing almost as if the heater blower has turned on that goes away again at higher revs. Weird and no identified cause.

At least I'm happy now it's not down to anything I did...

Did you check the dizzy is advancing OK? 

It isn't an intermotor coil is it? every one I have known of has failed.....always when hot but usually OK when cooled.

[Pete Lewis]

this is why garages charge so much to cover any unforeseen events 

you do a job for peanuts and get a guilt trip when things evolve into a wasted day 

and then you start to think why do i do all this 

but hats off you make the effort ,i hope he was a club member ????

whooshing noises    does it have a viscous fan ????  when a bit worn out  they can make some silly noises 

Pete

 

[AidanT]

1 hour ago, clive said:

It isn't an intermotor coil is it? every one I have known of has failed.....always when hot but usually OK when cooled.

Never knew that ! Time to chuck my spare coil !  😁

[Colin Lindsay]

2 hours ago, Chris A said:

 

A trying day without a completely positive result. Treat yourself to a glass or two of your favourite tipple, you deserve it.

Bottle just purchased... home now for the evening and I'll raise one to a trying day. Good fun, though.

2 hours ago, clive said:

Did you check the dizzy is advancing OK? 

Yes, base plate is moving freely and when the car is driven no pinking or other signs of lack of advancement. I adjusted it to about 9 degrees BTDC, it had been at about 13 and was running quite well but I decided on some very slightly lower idle in favour of more advance at higher revs. We had it right out to over 5000 rpm with no problems, just that strange noise at about 3000. No viscous fan, either.

One thing I did notice, and maybe the cause, was the original carb heatshield, a woeful thing of pressed card and tinfoil - the ends were all split and raggedy and when the engine reached a certain pitch, the air from the fan blew on it like an organ reed! It actually started to make strange harmonic noises, they way you used to blow on paper as a kid. It's coming off in favour of a metal version asap.