Overheating... Over it!!!

[V8 Middy]

Some of you guys may remember that I had to re-bulid after a fire under the bonnet last year. I thought that since then my cooling problems were over but alas no...

On the highway, haven't had a problem. If anything, it maybe runs a little cool so I'm guessing the radiator is good enough (correct me if I'm wrong)

Was doing a hill climb in Toolangi yesterday and it only took 5min at 3000rpm in 1st low and she was boiling, having started at normal running temp.

The current fan is the biggest single fan you can fit on the square 7x series radiator. From reading previous posts, it sounds like twin AU thermos are the buisness. Would it work having a shroud made up from the square radiator to the rectangular shape of the twin thermos so they end up pulling a large volume of air through the smaller space? If so, who would be able to create a custom shroud to do it?

All suggestions appreciated cos its pi$$ing me off!!!!!

Thanks

[midi73]

I know it may be a silly question, but has the thermostat been removed.
I know that if you run without a thermostat the cooling system will not work the way they are designed to. at low speeds and high revs the water will flow to fast through the radiator for the amount of air drawing through the radiator, therfore not allowing it to cool down.
If it does have one in, maybe it needs replacing.
Failing that if you say the radiator is good then maybe it is not big enough.
If it is the standard radiator for the middys, I am pretty sure that the 1hz out of a 75 series is bigger (taller).
Failing that have you got heaps of stuff ( winch, lights etc) in front of the grill blocking the airflow.

Cheers.
Dave.

[amtravic1]

Sound to me like not enough airflow at low speed. Also sounds like you are running just one electric fan. I have found in the past that one thermo fan will not be enough for low range work, especially on a warm day.
If you can fit the au ford setup with shroud or refit the engine driven fan. Thermo fans will never be the equal of an engine driven fan in hot conditions.

Ian

[bru21]

I am assuming you have a v8. I had a 350 chev in my bundera and it never came close to overheating. i fitted a 45series radiator from memory and a fixed fan mounted off the motor - they are the secret. I didn't even have a shroud.

mate had a 327 in a 40 series shorty, dual radiators with vl thermos and it overheated often.

also check its not running too lean

cheers bru

[Hally]

had a simular problem with mine . Was driving along a rough track everthing was fine ,then I tried to drive up a little bank gave it a few revs then the water temp went through the roof. I found out that my twin thermos had stopped due to the wiring earthing out on the body due to that bumpy road , soon as I replaced the fuse I had no problems flogging it for the rest of the day I run a 4.6v8 with an viscos fan and twin thermos no drama at all with water temp or oil temp I would maybe consider twin thermos

[bogged]

and it only took 5min at 3000rpm in 1st low and she was boiling

I would suggest that 5 mins revvin constantly like that at slow speed/low air flow it would get hot..

[V8 Middy]

and it only took 5min at 3000rpm in 1st low and she was boiling

I would suggest that 5 mins revvin constantly like that at slow speed/low air flow it would get hot..

So is it unrealistic for me to expect to ever do steep hill climbs, even with a higher flowing fan?

[booflux]

and it only took 5min at 3000rpm in 1st low and she was boiling

I would suggest that 5 mins revvin constantly like that at slow speed/low air flow it would get hot..

So is it unrealistic for me to expect to ever do steep hill climbs, even with a higher flowing fan?

I dont see why my Lux with twin falcon thermos and 1uz will rev like that all day in the heat and the temp wont rise by any more than 5 degrees the falcon thermos are a great unit

[midi73]

and it only took 5min at 3000rpm in 1st low and she was boiling

I would suggest that 5 mins revvin constantly like that at slow speed/low air flow it would get hot..

So is it unrealistic for me to expect to ever do steep hill climbs, even with a higher flowing fan?

No it is not unrealistic. you just need to sort the problem out. (which is what you are trying to do here).
I can go up and down fast and slow all day reving etc, and my temp barely moves. This is not a v8 midi, but it is in a midi that I had a lot of heating problems before I sorted all those problems.

[Loanrangie]

Maybe a larger capacity rad with twin thermo's is needed.

[shakes]

a shroud will definatly help... air follows the path of least resitance, even though you have a fan it still may be drawing air from around rather than through the radiator!

as bru21 said, if it is leaning out considerably on the climb that could be another reason.

[V8 Middy]

No it is not unrealistic. you just need to sort the problem out. (which is what you are trying to do here).
I can go up and down fast and slow all day reving etc, and my temp barely moves. This is not a v8 midi, but it is in a midi that I had a lot of heating problems before I sorted all those problems.

What problems did you have to sort out? I had hoped that a re-cored radiator on a re-co'd engine would be fine.

[midi73]

No it is not unrealistic. you just need to sort the problem out. (which is what you are trying to do here).
I can go up and down fast and slow all day reving etc, and my temp barely moves. This is not a v8 midi, but it is in a midi that I had a lot of heating problems before I sorted all those problems.

What problems did you have to sort out? I had hoped that a re-cored radiator on a re-co'd engine would be fine.

Mine were mainly radiator problems. Once I recored it the problem was sorted.
With my middy I have fit a 14b (4cyl Diesel) motor and I moved the radiator back about 4 inches towards the engine to give room behind the grill for winch etc. While I was doing this I consulted a radiator specialist about how far back to put it, because it is important to have the right spacing between the fan (viscous) and radiator. He, and a lot of other experts also said that alot of people that go and put thermos on and remove the engine fan run into a lot of trouble. There is quite a science to radiators and the airflow etc when you look into it.
If your radiator and thermostat are good and the system clean and you are running coolant and you are still having problems, Then my suggestion would be to remove the thermo, put the engine fan back on and put the proper shroud back on the radiator (if your middy was a petrol before the v8 conversion than this shroud wil be right, if not a 75 series shroud will be the right one). If you do this, the leading edge of the blades need to tuck about a third of the way inside the edge of the shroud. this gives the most effficient airfllow. see how this goes, I think you will find that it fixes your problem.
Hope this helps.
Cheers.
Dave.

[V8 Middy]

Is it possible to have a radiator that cools too much for the engine? I think my first move will be better fan / shroud. A mate of mine sourced a Ford Taurus Fan built into a shroud that fits the 7x Radiator almost perfectly. Apparently it moves a fari bit of air too. Failing that, I'm guessing custom alloy rad ($$$) is the only other solution. If I do go this way, it it possible that it will run too cool on the highway (given that it runs well below the fan turn-on temp already) or does the thermostat take care of that?

[chimpboy]

Is it possible to have a radiator that cools too much for the engine?

Nope, controlling that is what the thermostat is for.

I think my first move will be better fan / shroud. A mate of mine sourced a Ford Taurus Fan built into a shroud that fits the 7x Radiator almost perfectly. Apparently it moves a fari bit of air too. Failing that, I'm guessing custom alloy rad ($$$) is the only other solution. If I do go this way, it it possible that it will run too cool on the highway (given that it runs well below the fan turn-on temp already) or does the thermostat take care of that?

From your initial description it sounds like the problem is the fan/shroud, and not the radiator or the water pump - ie air flow not coolant flow.

None of these electric fans will pull as much air as the engine mounted fan would; is there a reason you can't use one of those?

Anyway, your plan with the Taurus shroud and fan sounds like a possibility, although I wouldn't have thought Tauruses needed anywhere near as much cooling power as your vehicle, so I wouldn't necessarily have thought that a Taurus fan would be up to scratch.

[bazzle]

a shroud will definatly help... air follows the path of least resitance, even though you have a fan it still may be drawing air from around rather than through the radiator!

as bru21 said, if it is leaning out considerably on the climb that could be another reason.

Ill 2nd the shroud. People underestimate their importance.

Bazzle

[bogged]

a shroud will definatly help... air follows the path of least resitance, even though you have a fan it still may be drawing air from around rather than through the radiator!

as bru21 said, if it is leaning out considerably on the climb that could be another reason.

Ill 2nd the shroud. People underestimate their importance.

Bazzle

Yup, GQs are prime example of this.

[vraamm]

ive had some similar problems with my 40series. i made shroud up which helped heaps. Tried a 16" electric fan, that was ok at idle but pretty much useless at high rpm even when shrouded. settled for a chev viscous hub, with a 10 blade fan from an EB i think. The fan only protrudes a few cm down the bottom of the standard toyota radiator. this has worked well so far.

[trains]

3 votes for a correctly fitted shroud, pack some 1' sq foam around it near the rad so that it has to suck air through the rad, not where the shroud rad gap can be.

T

[Ruffy]

You've got an air flow problem alright. Thermo's are shite. I'm guessing that your running a thermo because you can't run an engine fan on the V8?
If you can run a viscous fan then do it. Shroud it and fit a decent fan.
If not then go twin AU's. They move a fair amount of air. Most aftermarket thermos have shit fan design and dont move much air once on a radiator. Moving air free mounted is a lot easier than drawing it through a radiator so don't pay too much attention to CFM figures on packaging.
Good luck