Discussion
here is the problem
I have 3 switches
number one switch - cut in at 96 C drop out at 91 C
number two switch - cut in at 97 C drop out at 94 C
number three switch - cut in at 102 C drop out at 97 C
so if you are giving the car a beating on the motorway the airflow is reduced as the under bonnet area has a build up of preasure and the temperature climbs to around 90 C (any thing over 100mph for more than 5 mins)
this means if I fit the low temperature switch the fan will cut in nice and early in traffic but may also run flat out on fast motorways (i't a 16" 12 vane job that from experience works great for cooling the rad but has a greatly reduced life if left running too long)
If I fit the high temp one the fan won't cut in for no reason on the motorway but in traffic the lump will be hotter than it should be
i'm tempted to fit the low temp switch with a manual over ride that switches it off on the motorway (not often you zip along for more than a few minutes)
or fit the high temp switch with a manual to turn it on in traffic
you see my dilema ?
bearing in mind the draining the cooling system to change the switch issue i'm inclined to go with the low temp and manual on option
all this may be bol*!*s of course as i've not yet thrashed it up the road with a bulb attached to see if it comes on or not
any idea what range your switch is ,if it works fine in traffic and doesn't come on on the motorway ?
reb
I have 3 switches
number one switch - cut in at 96 C drop out at 91 C
number two switch - cut in at 97 C drop out at 94 C
number three switch - cut in at 102 C drop out at 97 C
so if you are giving the car a beating on the motorway the airflow is reduced as the under bonnet area has a build up of preasure and the temperature climbs to around 90 C (any thing over 100mph for more than 5 mins)
this means if I fit the low temperature switch the fan will cut in nice and early in traffic but may also run flat out on fast motorways (i't a 16" 12 vane job that from experience works great for cooling the rad but has a greatly reduced life if left running too long)
If I fit the high temp one the fan won't cut in for no reason on the motorway but in traffic the lump will be hotter than it should be
i'm tempted to fit the low temp switch with a manual over ride that switches it off on the motorway (not often you zip along for more than a few minutes)
or fit the high temp switch with a manual to turn it on in traffic
you see my dilema ?
bearing in mind the draining the cooling system to change the switch issue i'm inclined to go with the low temp and manual on option
all this may be bol*!*s of course as i've not yet thrashed it up the road with a bulb attached to see if it comes on or not
any idea what range your switch is ,if it works fine in traffic and doesn't come on on the motorway ?
reb
Mine is 88/79 ive never had a problem when the cars running,when in traffic it can get a bit high so i have an override switcg to put the fan ON
I suggest you have your override switch wired this way,so should the otter switch fail you can put the fans on
Id be fitting the lowest of those as i know there is a delay between otter switch coming on and fans getting the temp down
The one ccutting in at 102,id bin its way too late
P.S are these temp measurements ,or otter markings
I suggest you have your override switch wired this way,so should the otter switch fail you can put the fans on
Id be fitting the lowest of those as i know there is a delay between otter switch coming on and fans getting the temp down
The one ccutting in at 102,id bin its way too late
P.S are these temp measurements ,or otter markings
High temperature under cruise conditions indicates that there is something wrong. There should be ample cooling air at high speeds. I suspect that either the radiator is clogged with limescale, or you have an air lock in the radiator.
The high temperature otter switch sounds like an air con switch - the temperature rating is far too high for the cooling fan. There isn't much to choose between the other two switches, they're both on the high side.
The high temperature otter switch sounds like an air con switch - the temperature rating is far too high for the cooling fan. There isn't much to choose between the other two switches, they're both on the high side.
ah the debate
well the rad won't be clogged now as it's brand new - it might of course have been knackered before
interesting that the highest of the three switches seems the least suitable as it was new yesterday from tvr car parts and they supplied it as the standard fitment for the v8
the markings on the switches is temperature not switch numbers etc as otter switch codes are 3 numbers eg 103 and these markings are 102/97 C etc
I'll stick the lowest one in and hook up a switch and we shall see
thanks for all the interest in my minor technical issues
reb
well the rad won't be clogged now as it's brand new - it might of course have been knackered before
interesting that the highest of the three switches seems the least suitable as it was new yesterday from tvr car parts and they supplied it as the standard fitment for the v8
the markings on the switches is temperature not switch numbers etc as otter switch codes are 3 numbers eg 103 and these markings are 102/97 C etc
I'll stick the lowest one in and hook up a switch and we shall see
thanks for all the interest in my minor technical issues
reb
the rad was fitted last week by me
i haven't tried running the car yet with the new rad
it didn't get really hot with the old rad - it was just leaking a bit so I stripped out the cooling system to powder coat the swirl pot and pipes,plumb up with silicone hoses and fit a new rad,otter switch etc
i haven't really got an over heating problem as such i'm just getting the benefit of others wisdom and experience to save me from doing things twice : )
perhaps tvr car parts made a mistake with the switch and sent me the wrong one - if the tower view one was different ........
reb
i haven't tried running the car yet with the new rad
it didn't get really hot with the old rad - it was just leaking a bit so I stripped out the cooling system to powder coat the swirl pot and pipes,plumb up with silicone hoses and fit a new rad,otter switch etc
i haven't really got an over heating problem as such i'm just getting the benefit of others wisdom and experience to save me from doing things twice : )
perhaps tvr car parts made a mistake with the switch and sent me the wrong one - if the tower view one was different ........
reb
Take the blanking cap 
off the swirl tank and run the engine up to temperature. With the engine still running open the 'bleed screw' on the top of the radiator, close it when water comes out. Switch off, fill the swirl tank to the shoulder just below the neck, refit blanking cap. If the system has been drained then give it ten miles or so to dislodge air pockets from the engine, then repeat the procedure.
off the swirl tank and run the engine up to temperature. With the engine still running open the 'bleed screw' on the top of the radiator, close it when water comes out. Switch off, fill the swirl tank to the shoulder just below the neck, refit blanking cap. If the system has been drained then give it ten miles or so to dislodge air pockets from the engine, then repeat the procedure.
You forgot the "sqeeze all the pipes trick". TBH I have drained the cooling system twice and refilled and never had a problem. Just remember to take a large bottle of water with you when out on the first run.
PS Peter is right about the high speed running, there should be more than enough air getting under the bonnet unless you are screaming along on the rev limiter. I'd bet a kitkat the new rad will solve your problems. Oh, and my otter switch cuts in at 90 deg.
Z
PS Peter is right about the high speed running, there should be more than enough air getting under the bonnet unless you are screaming along on the rev limiter. I'd bet a kitkat the new rad will solve your problems. Oh, and my otter switch cuts in at 90 deg.
Z
Gassing Station | S Series | Top of Page | What's New | My Stuff