Heat or Biggier Issues

[1stTimeV8]

Hey Guys,

I took my baby for a spin today first time in a while with my gearbox issues. Today was a stinking hot day and the old girl ran so badly i though i was going to need a tow.

She was fine for the first 5-10 mins but then would stall out, bounce like it was on kangaroo juice, idle much lower than normal, unable to take any load rev as you would expect with clutch in then nothing. It reminded me a lot of before when i had air hole and secondary problems since then i had an electric fuel pump put in, dyno tuned re jetted, and throttle arm replaced and carby serviced.

It did become drivable if i turned it off for a while, the temp gauge was higher than i had ever seen it but not in the red or anything. the car hadn't been used in 2 weeks, so could be bad gas, fuel block?? i only put BP ultimate in her.

Summer is coming and this is a worry...

[ari666]

so to start with, how high did the temp guage get up to?

secondly, has any of the tuning changed since the dyno? is there a chance you have knocked a vacuum hose off something or moved the dizzy by accident?

thirdly, what fan is on it? how is the radiator, any leaks etc. did you try turning the heater on while it was playing up?

[1stTimeV8]

Man you are quick off the mark Ari,

temp was over 3/4 of the gauge but no measurement on it, i can tell you it was f$%ken hot to touch
there is always a chance something has changed but nothing intentional or accidental as the bonnet has been shut. but it is a Holley so could have de-tuned itself or a screw loosened.
And thirdly fan is an electric radiator has no leaks water is full and green had a flush 2 months ago 3 hours later top pipe is still hot bottom pipe is cold and has a lot of hard things like thermostats maybe but 3-4 of them. heater and AC have been removed by previous owner. also fan is always on

took air clean off, this evening as i could often smell fuel though maybe it has been running a little rich, top of air cleaner and carby are very black and sooty.

cheers

[ari666]

rich should mean it runs a bit cooler, but it couldnt hurt to spray a tonne of carby cleaner on and see if you cant knock a lot of the gunk off. i wouldnt stress too much about carby causing overheating unless it was running lean as f'k. might pay to recheck everything though, floats, fuel pressure, check for leaks etc. what i WOULD be checking is your timing. too far retarded will overheat. not usually in traffic, usually more on fwys, but it will have an affect on temperature. check that the vacuum advance hose hasnt fallen off or perished cos' if thats missing itll ramp temps up pretty quickly.

electric fans are RUBBISH. i have dual craig davies on mine and have a never ending battle with temperature in summer. i would advise taking it off and fitting the factory clutch fan and shroud back on, but having said that... i still run thermos, so a bit of a hypocrytical comment. but i would place the blame squarely on your fan TBH.

[VK SL 3800]

Were you highway driving or cruising around town?

[1stTimeV8]

Thanks guys, I had the biggest problems around town, took her out tonight for a good drive and she drove like a dream!!! so either fuel block or too hot i guess
Ari thanks for the tip on the fan, i have been thinking of replacing as it comes on with the battery and can give me grief starting which i solve by pulling the relay out so might be time to upgrade to an aftermarket radiator and increase the effectiveness of my cooling. turns out when i had my problems it was 37 degrees so temp is getting up there.

[DerekP]

I flushed my radiator quite a few times and put good coolant in and still had over heating problems (the bain of my existance but that is another story...) I then put a brand new three line radiator in with new (original) clutch fan plus a very large electric auxillary fan for those extra hot days and / or when using the A/C. It seems to have done the trick but am waiting for that 38+ degree day to test properly. What I'm saying is that sometimes a radiator is too far gone to flush and there is little option but to replace it. You only really notice this on the hot days when the heat just can't be circulated fast enough away from the engine due to a calcified radiator - as a result it no longer has the same volume.

[ari666]

also. and this is gonna sound weird, but bear with me... coolant doesnt necessary cool. lol. all you need in an early girl is an anti-coagulant (spelling) to stop the water from turning into algea, the anti-freeze they add to general use coolant actually makes things run hoter. i have found that plain water with a dash of anti-coag has been the best solution so far.

[DerekP]

^^
Agreed. I have found that to be true about coolant running a little hotter - I thought I had f*ckd up inititally.... However I use it as a rust inhibitor - to try and maintain clean internals - buy new radiators and welsh plugs less often.

[Drewie]

We have the original clutch fan and shroud on our VC, it had a brand new radiator put in several years ago, I assume it is just an original size unit, but our VC runs very cold all the time,
it can be a 40 degree day and it never goes over about a quarter to a third on the gauge, I thought maybe the gauge was not working so last winter I blocked off part of the radiator and the gauge read higher so I guess the gauge is actually working. So maybe revert to the original fan set up as ours is brilliant temp wise even on the hottest of days. Our VC has air cond so whether it has a different radiator I am not sure. I probably should change the coolant as it has been in there for many years could be as long as 6 or 7 years but the coolant is still nice and green and clean.

[DerekP]

Is your VC a 6 or an 8? The 8's are renowned for overheating, six's not so much.

[Darren_L]

if the bottom radiator hose is staying cold, whilst the top is hot then there is a blockage in your cooling system
you said you've replaced the thermostat several times, so I think we can safely rule out that.
As suggested, I would look at a replacement or reconditioned radiator.

as for the fans, I tend to agree with most of the comments here. You really can't beat the airflow/cfm of the factory engine fan.

[Tree cutter]

It sounds like you are getting a vapour lock in the fuel system when your engine gets hot. The best way to fix this is to run a return line from the carby to the fuel tank so the fuel keeps circulating and doesnt get hot enough to boil. You need to run a restricter in the return line so you still have fuel pressure. You can also wrap your fuel lines in thermal wrap to keep heat off them.
I would go back to a fan driven off the front of the waterpump and put a shroud on the radiator so the fan can pull more air through the radiator.