Fans cutting in and not stopping!
Discussion
Help! Only a few days to go until Europe and the Chim is still playing up!
On an earlier post I described how the fans were cutting in too early then staying on. Even when coming back to the car once it had cooled down. I traced the problem to the otter switch (or so I thought) and replaced it. Still the same behaviour!
I took it for a test drive - fans come on at 60-65 degrees on the gauge and don't turn off again. The only way I can persuade them to turn off is going at 60 in 5th with the heater turned on full blast, and even then it takes ages for the temp to drop to the 65 degrees the switch seems to require.
I know that the temp guage is not particularly accurate, but the fans should definately not be cutting in so early. If I leave the car at idle on the drive, the fans don't cut in and out. Once they're on they tend to stay on. I should mention that I had a new (well, re-cored) radiator in recently. Although the car behaved flawlessly for the first 250 miles after the change.
So, i'm thinking either the new otter switch is up the duff (unlikely) or it's operating correctly, and the surrounding water temp really is 87 degrees. If the water into the radiator is hot, why is it so darned cool going out, and how does is heat up so much again?
The relays don't seem to be at fault - the otter switch is indeed "on" when the fans are - tested by disconnecting the wires momentarily.
Any ideas? It seems most odd to me. Could it be the thermostat sticking? I can't think how it would create this behaviour though.
Apart from this, the car drives well, the engine seems as smooth and as powerful as ever, it's just the constant fans and low temp gauge reading that are putting me off!
On an earlier post I described how the fans were cutting in too early then staying on. Even when coming back to the car once it had cooled down. I traced the problem to the otter switch (or so I thought) and replaced it. Still the same behaviour!
I took it for a test drive - fans come on at 60-65 degrees on the gauge and don't turn off again. The only way I can persuade them to turn off is going at 60 in 5th with the heater turned on full blast, and even then it takes ages for the temp to drop to the 65 degrees the switch seems to require.
I know that the temp guage is not particularly accurate, but the fans should definately not be cutting in so early. If I leave the car at idle on the drive, the fans don't cut in and out. Once they're on they tend to stay on. I should mention that I had a new (well, re-cored) radiator in recently. Although the car behaved flawlessly for the first 250 miles after the change.
So, i'm thinking either the new otter switch is up the duff (unlikely) or it's operating correctly, and the surrounding water temp really is 87 degrees. If the water into the radiator is hot, why is it so darned cool going out, and how does is heat up so much again?
The relays don't seem to be at fault - the otter switch is indeed "on" when the fans are - tested by disconnecting the wires momentarily.
Any ideas? It seems most odd to me. Could it be the thermostat sticking? I can't think how it would create this behaviour though.
Apart from this, the car drives well, the engine seems as smooth and as powerful as ever, it's just the constant fans and low temp gauge reading that are putting me off!
Have you confirmed that the fans stop when you disconnect the otter switch i.e. it's the otter switch which is causing this?
It's possible that what you're seeing is the result of a hot thermostat and a cold otter switch being used together i.e. they're both working correctly but they just don't suit each other. You can test the thermostat and otter switch to see whether they're both working correctly. Do you know the temperature rating of each unit?
It's possible that what you're seeing is the result of a hot thermostat and a cold otter switch being used together i.e. they're both working correctly but they just don't suit each other. You can test the thermostat and otter switch to see whether they're both working correctly. Do you know the temperature rating of each unit?
Hi,
Yes, confirmed that the otter switch is definately responsible for the fans being on (disconnect it and fans stop). I see where you're going with the otter/thermostat mismatch, although niether unit has been changed;(well, the otter has been changed now, but the old one was doing the same thing). The otter is the standard 87/78 (or thereabouts - the normal one), from my local Tiv specialist, definately not a lower temp one or a higher temp Landy unit.
I was thinking the thermo could be stuck or malfunctioning in some way. If it was limiting flow, then the lower flow rate would heat up more in the engine, but cool down more in the radiator(?) giving a higher rad-entry temp but nice cool water coming from it hence the low guage reading. Or have I got my wires crossed?
Either that or the thermal characteristics of the new radiator have completely thrown the thing out of balance. Well, here's hoping it will be a simple fix. Either way i'm going to rig up a fan ovveride so I can convert to "manual" if it all gets emotional.
Cheers. Ed.
Yes, confirmed that the otter switch is definately responsible for the fans being on (disconnect it and fans stop). I see where you're going with the otter/thermostat mismatch, although niether unit has been changed;(well, the otter has been changed now, but the old one was doing the same thing). The otter is the standard 87/78 (or thereabouts - the normal one), from my local Tiv specialist, definately not a lower temp one or a higher temp Landy unit.
I was thinking the thermo could be stuck or malfunctioning in some way. If it was limiting flow, then the lower flow rate would heat up more in the engine, but cool down more in the radiator(?) giving a higher rad-entry temp but nice cool water coming from it hence the low guage reading. Or have I got my wires crossed?
Either that or the thermal characteristics of the new radiator have completely thrown the thing out of balance. Well, here's hoping it will be a simple fix. Either way i'm going to rig up a fan ovveride so I can convert to "manual" if it all gets emotional.
Cheers. Ed.
Yes, a stat that is failing can give some of the symptoms of a hot stat. But the stat is easy enough to check and replace if necessary, and I assume you'll check this in due course. The point about them being mismatched was just another avenue to follow if they both turned out to be working OK.
Edited by GreenV8S on Monday 7th August 22:31
Just ran the engine up to check what its doing. The stat seems to open at 60 degrees (indicated) which seems a little soon, but then the guage may be under reading. It doesn't appear to be stuck open though, and there is a definate point where the pipes/swirl pot go from cold to hot. The temp then hovers around the 65-70 mark until the fans kick in. They come on for a few minutes, turn off, come back on, then they seem to stay on for ever (with the gauge still reading under 70). The heater air is nice and hot, so no problems there.
I can't seem to get the screw lid off the swirl pot no matter what I try - i've got some pretty hefty bits of metal round the garage, and all they do is bend! I tried loosening the hose that goes into the top, and got a flow of coolant as I loosened it, indicating it's probably full. I've taken the rad bleed screw off and the rad seems full to the brim. The water level in the expansion tank is healthy too.
Anyway, i'm taking it to my local specialits tomorrow to see whether they can shed any light on it. It's just bugging the hell out of me, because although the car is perfectly driveable, i'm not sure what will happen in REALLY hot weather next week.
Cheers!
I can't seem to get the screw lid off the swirl pot no matter what I try - i've got some pretty hefty bits of metal round the garage, and all they do is bend! I tried loosening the hose that goes into the top, and got a flow of coolant as I loosened it, indicating it's probably full. I've taken the rad bleed screw off and the rad seems full to the brim. The water level in the expansion tank is healthy too.
Anyway, i'm taking it to my local specialits tomorrow to see whether they can shed any light on it. It's just bugging the hell out of me, because although the car is perfectly driveable, i'm not sure what will happen in REALLY hot weather next week.
Cheers!
I have a low stat (75deg) and a lower temperature otter switch in my car. If I am stationary or just crawling about the fans are on pretty much all the time once the engine has got hot (but temperature is maintined and does not increase). If I then get some air into the radiator with some road speed then they switch off, basically it all works fine.
In the winter this is a different story though and they are on/off a lot more often (more off then on), do bear in mind that ambient air temperature is pretty high at the moment, some 15 degrees higher than in the autumn.
In the winter this is a different story though and they are on/off a lot more often (more off then on), do bear in mind that ambient air temperature is pretty high at the moment, some 15 degrees higher than in the autumn.
i would just fit a new stat 82 degree regardless dont bother testing it(why bother)at least that will be out of the equation.try flow testing the rad with a hose if its clogged it will give the cooling system weird behavoir,could be an airlock as the other guys have said also.i would also go for the wide orifice stat,there is a renault 16v stat same temp, as big opening & same dimensions works a treat cant remember part number though.looks a lot better quality also.
I had an almost identical issue with my Griff after it overheated (see www.pistonheads.com/gassing/topic.asp?p=1&f=&t=276363&h=0) so much so that the fans were even coming on first thing in the morning when I started the engine from cold.
After having the otter switch changed and the cooling system bled again (and again and ...!), it settled down to normal operation.
I can't prove it but I reckon there was an air gap at the top of the rad (where the otter switch is in my Griff) and this air gap became a 'steam' trap which was always hotter than the water and kept the fans running all the time. However, I reckon that the overheat kn**kered the otter switch which is what kept the fans running from a cold start.
After having the otter switch changed and the cooling system bled again (and again and ...!), it settled down to normal operation.
I can't prove it but I reckon there was an air gap at the top of the rad (where the otter switch is in my Griff) and this air gap became a 'steam' trap which was always hotter than the water and kept the fans running all the time. However, I reckon that the overheat kn**kered the otter switch which is what kept the fans running from a cold start.
Edited by griff50tvr on Tuesday 8th August 18:16
Hi Andy, nope, no air con fitted. I must admit i'm starting to think either there is an air lock in the rad or it's not doing the cooling business particularly well. Neither explains the low reading on the gauge, and whilst this has been pretty accurate for the time i've had the car, obviously a dodgy sender/gauge can't be ruled out.
The steam trap theory sounds plausible, with the otter switch getting hot quickly and turning the fans on. My old otter switch had the fans on from startup one morning (stone cold), prompting me to get the new one. This one doesn't seem to stick, and reliably comes on at the same (low indicated) temp.
My biggest worry is that if the fans are coming on in response to the otter switch reading a true 87 degrees, and then stay on for ages, struggling to cool the system, how will it cope with hotter weather+traffic?
I'll report back on what the garage say either way. They replaced the rad recently so they are hopefully in a good position to tinker with it and diagnose the problem. Fingers crossed!
The steam trap theory sounds plausible, with the otter switch getting hot quickly and turning the fans on. My old otter switch had the fans on from startup one morning (stone cold), prompting me to get the new one. This one doesn't seem to stick, and reliably comes on at the same (low indicated) temp.
My biggest worry is that if the fans are coming on in response to the otter switch reading a true 87 degrees, and then stay on for ages, struggling to cool the system, how will it cope with hotter weather+traffic?
I'll report back on what the garage say either way. They replaced the rad recently so they are hopefully in a good position to tinker with it and diagnose the problem. Fingers crossed!
I know that Ed is taking his car to the garage today, but if the problem is an air lock by the otter swtch I wonder whether the following would work?
The air bleed screw on the rad is on the O/S and the otter switch on the N/S.
If a block of wood perhaps 4" thick is put under the O/S/F wheel and the engine run at operating temparature, might this coax the air lock to move to the highest point and out of the bleed screw?
The air bleed screw on the rad is on the O/S and the otter switch on the N/S.
If a block of wood perhaps 4" thick is put under the O/S/F wheel and the engine run at operating temparature, might this coax the air lock to move to the highest point and out of the bleed screw?
Well, it seems to be sorted! The chap at the garage tried putting in an Otter switch with a higher temp trigger. The fans now cut in at around 80 indicated (gauge still probably reading a little low) and will cut out again no probs. Stationary, the fans cut in and out as normal, and on the move they only cut in when in traffic / crawling as they should do. Engine sounds as smooth as ever and no signs of overheating. Seems like the one I put in before had a lower trigger which wasn't really suited to the car.
I'm going to fit a manual switch anyway for peace of mind (plus I like having lots of controls to play with). I was thinking of mounting it on the lower RHS of the steering column.
Is there an easy way to pass the wiring through from the engine bay without taking out/resealing clutch reservoir covers etc? I was thinking of poking it through one of the existing rubber grommets that are near the grill and sealing with silicone lube.
I'm going to fit a manual switch anyway for peace of mind (plus I like having lots of controls to play with). I was thinking of mounting it on the lower RHS of the steering column.
Is there an easy way to pass the wiring through from the engine bay without taking out/resealing clutch reservoir covers etc? I was thinking of poking it through one of the existing rubber grommets that are near the grill and sealing with silicone lube.
Most people use the switch under the dash that turns the instrument lights out. It is possible to do all the wiring inside the car by the fusebox, but you need to be really sure what you're doing in there, so your method of using one of the existing grommets and sealing up the hole afterwards is fine. Just be careful not to run the wires close to anything [too] hot.
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