Otter Problems?
Discussion
I am having some problems with my cooling system and can someone please help, I have had the leven cooler running kit fitted, and it is fan are cutting in earlier ( as expected ) at around 80 degrees running for approx 30 secs and stopping, the temp goes up to 83 degrees fans start for 30 ish second and stops temp goes to 85 degrees fans start and after 30 ish seconds stop again, this carries on happening till I turn the car off at 95 degrees. I have phoned leven and they have been great and sent a new otter which I fitted, and told me how to bleed system by removing the blue cap from header tank and running engine till you do not get any bubbles, I have done this about 5 times and have to replace the cap when temp gets to about 70 degrees and coolant starts over flowing the top of the header tank.
any ideas
Please any help gladly taken as I as scared of getting court in traffic.
Malc
any ideas
Please any help gladly taken as I as scared of getting court in traffic.
Malc
pretty much everything i have gathered about the cooling system has come from this forum, so credit must go to steve heath, peter v8s etc.
as i understand it, when bleading the system you should let the thing run at 1500rpm, until no more bubbles come out, as you say, but keep going. the tank does overflow, but when the thermostat opens ( and it doesn't sound as though you have reached that point if you switch it off at 70c ), it sucks a load of water down as the radiator fills.
when that happens keep topping up until the fans kick in. wait for the fans to go off, then screw the lid on, then continue to run until the fans go on and off once more. at this point you should be bled. ( so to speak
).
if it doesn't go like this, or you hit 100 during this process then it might be worth reverting to the original configuration, and then checking that the system works as normal. there could be a problem with the extra bits you've fitted, and you would need to exclude that possiblity before you go any further.
good luck.
as i understand it, when bleading the system you should let the thing run at 1500rpm, until no more bubbles come out, as you say, but keep going. the tank does overflow, but when the thermostat opens ( and it doesn't sound as though you have reached that point if you switch it off at 70c ), it sucks a load of water down as the radiator fills.
when that happens keep topping up until the fans kick in. wait for the fans to go off, then screw the lid on, then continue to run until the fans go on and off once more. at this point you should be bled. ( so to speak
). if it doesn't go like this, or you hit 100 during this process then it might be worth reverting to the original configuration, and then checking that the system works as normal. there could be a problem with the extra bits you've fitted, and you would need to exclude that possiblity before you go any further.
good luck.
It almost sounds like the thermostat isn't working right. Something that would explain it would be that the radiator is cooling the water enough to turn the fan off, but that not enough water is being allowed through to the radiator to *be* cooled.
My fans do this to a smaller extent. They seem to kick off too early, and kick in a little late. It's never (touch wood) overheated on me, but the first time the fans kick in is at ~87, they go off without seeming to have made much difference, then kick back in at ~89. This goes on until it stabilises in the high 90s.
What I think is happening is that the water coming out of the rad at the start is too hot. The fans cut in the the radiator sheds a load of heat. The water coming out is now about 80 (guess) The fans cut off thinking "yeah, got that under control" but there was only a small amount of water that was cooled.
The rad quickly picks up heat again, and the fans eventually cut in when the water is ~87 coming *out* of the rad. This slight lag means that the water isn't cool enough for long enough to keep the engine at 87.
Seems the issue is that the fan should wait for a lower temp to cut out again, or perhaps wait until 85 has been reached for a longer time. But that would require electronics.
Interestingly if I kick the fan override in, then evenentually after about 3 to 5 mins it can get the temp right down.
Does that explain any of the practicalities, or am I just blathering?
So actually my theory is that the otter switch is cutting the fan off at too high a temp. It's almost like it has *no* hysterisis. It needs to get the temp well below the cut-in temp if the cooled water is going to be cool enough to carry the excess heat away.
Nothing like contradicing yourself. :-)
My fans do this to a smaller extent. They seem to kick off too early, and kick in a little late. It's never (touch wood) overheated on me, but the first time the fans kick in is at ~87, they go off without seeming to have made much difference, then kick back in at ~89. This goes on until it stabilises in the high 90s.
What I think is happening is that the water coming out of the rad at the start is too hot. The fans cut in the the radiator sheds a load of heat. The water coming out is now about 80 (guess) The fans cut off thinking "yeah, got that under control" but there was only a small amount of water that was cooled.
The rad quickly picks up heat again, and the fans eventually cut in when the water is ~87 coming *out* of the rad. This slight lag means that the water isn't cool enough for long enough to keep the engine at 87.
Seems the issue is that the fan should wait for a lower temp to cut out again, or perhaps wait until 85 has been reached for a longer time. But that would require electronics.
Interestingly if I kick the fan override in, then evenentually after about 3 to 5 mins it can get the temp right down.
Does that explain any of the practicalities, or am I just blathering?
So actually my theory is that the otter switch is cutting the fan off at too high a temp. It's almost like it has *no* hysterisis. It needs to get the temp well below the cut-in temp if the cooled water is going to be cool enough to carry the excess heat away.
Nothing like contradicing yourself. :-)
What temperature did it use to settle at before you added the cool running kit? I wouldn't particularly panic at 95 degrees, the gauge may not be particularly accurate so you can't really tell whether this is 90 or 100. If the problem continues at higher temperatures, this suggests that you have insufficient water flow through the rad (stat faulty/incorrectly fitted?), or the water is not in thermal contact with the air. An air lock in the rad is one very common reason for this. I would expect to find a bleed vent on top of the rad, when bleeding the system you should use this to let any air out of the rad. Also not sure about your procedure for bleeding via the blue pressure cap. Don't you have a brass bleed screw on top of the swirl tank? Finally, if you find water overflows when you run the engine with the cap off as the engine warms up, you will find that picking the revs up helps with this. Once the air has been purged, it should run happily with the pressure cap off.
GreenV8S said: What temperature did it use to settle at before you added the cool running kit?
it would stick at a max of 90 and seem quite happy.
Don't you have a brass bleed screw on top of the swirl tank?
there is a brass screw on the swirl tank and a blue pressure cap on the header/expansion tank I have been leaving this cap on when bleding system.
Finally, if you find water overflows when you run the engine with the cap off as the engine warms up, you will find that picking the revs up helps with this. Once the air has been purged, it should run happily with the pressure cap off.
This is intresting I will run it tonight and report back tomorrow.
Thanks all
Malc
>> Edited by Count Duckula on Wednesday 21st May 13:56
If I may add a few words to Pete's i) Try bleeding the system cold, before you even start the engine. Do this with the blue cap off, to relase any back pressure then loosen the rad bleed screw (probabaly needs a 11mm spanner) until water comes out and close up, then remove the brass cap to the swirl tank, this is (almost) the highest point in the system so air will collect here. Try squeeing the heater hoses etc. to push any air out, etc. I then re-fit the brass cap and warm the engine up and then take another look, in the header tank, by the way if air comes out put some coolant in. until it is full etc. Finally never let the expansion tank get empty else you may draw air back inot the system, keep it half full. It's really not rocket science just a bit like blleding your house central heating system, a bit of a bugger but easy once you understanfd where the high points are for the air to collect. p.s. If it ran ok at 90 deg previously why did you change it? p.p.s. Like Pete I would just run it up to 100 deg + to see what happens 90-95 isn't that hot. Rich...
Count Duckula said:
GreenV8S said: What temperature did it use to settle at before you added the cool running kit?
it would stick at a max of 90 and seem quite happy.
Duckula
if it reached a maximum of 90 degrees then you really have nothing to worry about, assuming that the guage is reasonably accurate!
Chims are at their peak efficiency at around 90 degrees anyway...
Rich... Except that the earlier cars have effectively a combined swirl/expansion tank with a blue cap on it. So both could be right or wrong depending on which viewpoint is taken. Maybe.
Steve
www.tvrbooks.co.uk
PS In some cases the blue cap is actually black.
Steve
www.tvrbooks.co.uk
PS In some cases the blue cap is actually black.
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