rover v8 engined stag cooling

richardw · Post by **richardw** » Mon Jun 01, 2009 9:36 pm

hi, hope someone can help,i have got a auto 72 stag with rover v8 engine . i have always had cooling issues with it, i have changed the water pump,radiator,rad cap,fitted a electric fan had carbs set up,compression test all ok.when bought it had a 10 inch electric fan with a shroud fitted to front of engine-thought that was restricting air flow so then fitted a 14 inch pacet type tothe front of radiator and this has made things worse,temp now creeps past the 120 degree mark b4 i switch off.Before it would tick over all day with fan on and never go past 90 degree,it would get hot when i am driving...........!tried all the tricks for air locks,but i am just getting so deflated

top hose gets red hot. flushed engine out had taps off the blocks.any ideas b4 i drive it into a lake. cheers rich (mansfield)

bones · Post by **bones** » Tue Jun 02, 2009 6:36 am

Hi, just a daft question, but does the fan pull the air through,as on mine it depends on how its wired as to how it rotates.

rich

RoverP6B · Post by **RoverP6B** » Tue Jun 02, 2009 7:02 am

Hello Richard,

What temperature thermostat are you running? At what temperature are the thermo fans set to come on?

120 degrees is much much too hot,...you might end up blowing head gaskets.

Ron.

Ian Anderson · Post by **Ian Anderson** » Tue Jun 02, 2009 8:23 am

14 inch pacit will not move enough air in my opinion

I believe it is about 1100 - 1200 cfm
If is "pushes" the air through the rad it will be more efficient than "pulling" the air through but I would think a minimum of a 16 inch would be required (I run 2 11 inch high volume fans 1100 cfm each as an example)

But I would also consider your set up is not correct as when the temperature of the water increases the amout of heat removed via the airflow increases exponentially (Rad at 35oC in a 20oC day will loose substantially less heat than a rad at 100oC as works on the difference in ambient to rad temps)

I would suggest you have an air block / bubble somewhere or even a blockage / bad head gasket that does not allow the water to flow correctly through the heads

Perhaps an experiment
Remove the rad hoses and put them both in a bucket of water - (same as an old stationary engine) and once the engine is running see how much flow you get - it should be a good amount - if not it suggests a blockage somewhere

One last thing before stripping apart CLOSE the cockpit heater valve (molegrip the hose feeding this to ensure no flow) and try again - some systems have so little restriction in this circuit that the water readily passes through here and thus avoids the radiator

Is your radiator getting really hot all over? - if not may be a bad radiator - even new ones can be duff

Ian

Darkspeed · Post by **Darkspeed** » Tue Jun 02, 2009 8:26 am

bones wrote:Hi, just a daft question, but does the fan pull the air through,as on mine it depends on how its wired as to how it rotates. rich

Not only that but fans are designed to run in one direction only - the motor will run the fan in two directions but the fan will only work effectively in one. So would be a good idea to check if you have a pusher or a puller and checking its going in the right direction.

I personally run a 74C stat - and always make sure it has a 4mm hole drilled in it shift air and allow low circulation through the rad. Also run an electronic adjustable stat set at 90C - would never have my engine above 100C

Andrew

richardw · Post by **richardw** » Tue Jun 02, 2009 9:33 pm

thanks for all suggestions,fan is on front of rad pushing air through ihe ia a pusher or puller 100% fan is working right way.I was only running a 10 inch one b4 and that did a betterjob than the one thats on now.rad is a nice even temp - a bit cooler at the bottom.Not got astat in at the moment,is this not a good idea? it was a 82 degree one i think.Just been out in it temp sat between 90 degree and 120, but rises when you push on.fan is on a switch and i tend to have it on all the time.............the water in expan bottle is only luke warm is this normal?? thanks again im on my knees .! this just spoils a cracking car..............rich

RoverP6B · Post by **RoverP6B** » Tue Jun 02, 2009 9:42 pm

Hello Rich,

Not using a thermostat could well be a large part of the problem!

As the thermostat slows the coolant leaving the engine, the coolant is able to absorb heat out of the engine and then transport that heat to the radiator for removal, but without one the coolant does not work any where near as efficiently, leaving most of the heat still in the engine!

Ron.

richardw · Post by **richardw** » Tue Jun 02, 2009 10:08 pm

cheers ron,i know what you mean but i have the same problem wether there is a stat in or out-it doesn't seem to make any differnce.Top hose is red hot and so is the radiator.I will try another stat in it and try again, perhaps drill some holes in the stat.With the hose getting hot i just presumed its taking heat from engine............rich

RoverP6B · Post by **RoverP6B** » Wed Jun 03, 2009 12:22 am

Hello Rich,

Use either a 74 or an 82 degree thermostat. The Waxstat units usually have a jiggle pin, but if not drill one small hole at 12 o'clock.

I assume that your engine is fitted with twin SU carburettors?

Which Rover V8 water pump are you using? The pump pulley must be the correct size else the coolant will either move too slowly or the opposite, with the result that you are experiencing.

Where does your expansion tank take the feed from? Is the radiator top hose level or sloping up from the engine to the radiator? Both are fine, but not the other way!

Ron.

Ian Anderson · Post by **Ian Anderson** » Wed Jun 03, 2009 9:52 am

Are you sure your gauge is reading correctly?

You could be worrying about nothing

Ian

harvey · Post by **harvey** » Wed Jun 03, 2009 11:29 am

RoverP6B wrote:I assume that your engine is fitted with twin SU carburettors?.

If that is the case, check that the bleed pipe from the top of the manifold to the top of the rad, (or the expansion tank) is clear, the metal pipe that goes into the manifold gets blocked and causes exactly the problem you've got.

Paul B · Post by **Paul B** » Wed Jun 03, 2009 1:14 pm

A pull fan is apparently more efficient than a push fan, or so I have been led to beleive.

Some fans will work as either, but you have to reverse the blade on the shaft, as well as reverse the wiring.

Have you checked the temp of your bottom hose? Is it too getting hot? if it is red hot it indicates the rad is simply not cooling. If it is fairly cold it might indicates the rad is simply not flowing water very fast. Could your rad be blocked?

Also, shrouding around the radiator, not just the fan. Is there something to stop the hot air simply pulling back around the rad and going back through from the front, time and again?

I've seen it on a friends race car, massive rad, two massive fans, but their was nothing around the radiator, it just sat in the front of the engine bay. Some shrouding was fitted to seal it against the surrounding bodywork (flip front) and bingo, job sorted.

richardw · Post by **richardw** » Wed Jun 03, 2009 9:08 pm

hi folks, some interesting ideas there,rad is 6 months old after being re -cored standard stag rad.Is the temp gauge working right?, i am going to try and gethold of one of the temp guns and see,but it does fell really hot when it reads hot!-if you know what i mean......Been out tonight in stag air temp about 13 degrees and the gauge read just over 90 degree and didn't waver much until i gave it a bit of boot.I just know that come warm weather it will be back up in the hot zone,i'm still running with no stat.Rad sits sort of level with top of engine and i'd say the top hose falls slightly down to rad,there is a small hose from the middle of the carbs to exp bottle where it tees off to another small hose that goes to the radiator. the engine is out of a mid 70's sd1 i think with a standard water pump - ichanged this about a year ago,pulley is about 6 and half inches in dia.It was an interesting idea about the shrouding,but it seems pretty well enclosed as it is but will have anotherlook at it....Thanks to you all for taking time out to reply

cheers rich

RoverP6B · Post by **RoverP6B** » Thu Jun 04, 2009 2:11 am

Hello Rich,

Given that the coolant temperature increases when you give it a bit of stick to me seems to suggest that the heat just can't get away. I know I am stating the obvious here.

What are the dimensions of your radiator? How many cores does it have?
Are you using a 15 psi radiator cap?

The standard radiator as used in the Rover 3500 P6B measures 670mm from end tank to end tank, (that is the total width) and 470mm from the base of the core to the top. The standard radiator ran a dual core, which in anything but cool weather was largely inadequate. A triple core is by far the way to go.

How much space is there between the back of the radiator and the water pump pulley?

Ron.

topcatcustom · Post by **topcatcustom** » Thu Jun 04, 2009 9:23 am

I would try putting the fan on the back of the rad as that's where most cars have them, then the air being pulled through the rad will be less dense which should give better heat dissipation, with a fan on the front you are compressing the air going through the rad which is not good, this is why racing cars etc have the opening of the air duct to the rad approx 1/3 the size of the rad surface, a bit like a funnel reversed, if it were the other way you would be compressing the air going in which takes longer to absorb the heat from the rad.

Also maybe you could try a slightly smaller pulley on the water pump, if makes it worse try a slightly larger one!

TC