Fans not cutting in properly ?

[windsorrob]

Just after some advice on this - have got the bible but not with me at present !

Out for a run today - all going fine until I got stuck in the school run traffic. Temp went from the usual 70 up to 90 when I expected to hear the fans cut it - but nothing. It then moved slowly up to 100 - by this time I was home, turned the engine off (but left ignition on) and lifted the bonnet. At 100 the fans cut in, but not very convincingly - i.e. kept starting very briefly, then off then back on again etc.

A few weeks ago I had a new temp sender fitted as my temp gauge was reading low - i.e. 50 - 60 never going much higher.

From reading through some other posts, it seems the device that reads the temp could be at fault (Otter switch ?) - Am I right in thinking this ? I know the temp gauge can read incorrectly and hence when it cuts in at 100 - this could be 90 - however, it feels a little hot i.e. more then 90 and the way the fans cut in and out very quickly does not seem right - its as though there is no difference between the cut in temp and the cut out ?

Any advice appreciated - if the jobs simple happy to do myself !

Rob.

[shpub]

Sounds like a duff otter or a bad connection on the otter switch or fans.

[windsorrob]

Read through the cooling section in the bible last night - just to check I'm understanding properly, on a 4.0 litre serp engine (year 2000) am I right in thinking the otter switch is on the swirl pot ?

Also - there are two wires leading into a connection on the radiator housing - just below what I think is the inlet at the top right hand side of the rad (viewed from the front). Is this the power to the fans or is this something else ?

Couple of Q's on the otter switch - Up to now the fans have cut in at 90 (Or at least 90 as indicated on the gauge that was fed from the temp sender that has now been replaced) - can the otter just go haywire like this, or are they the type of thing that either works or not ?

Also - having read the bible I'm keen to get a replacement otter that activates at a lower temp - where's the best place to get one, do most dealers have them ? Can I rely on them to give me what i want and not just a standard one ? Roughly how much do they cost ?

Finally - where is the temp sender that feeds info to the temp gauge on the dash ? Does this have anything to do with fans cutting in ?

Any info appreciated !

[chimpy_bob]

Might be worth you lookin at this thread:
www.pistonheads.com/gassing/topic.asp?f=8&h=0&t=62963

I'm in the same position as you at the moment but the fans are not cutting in at all.

I'm thinking of phoning HHC and see what they say.

Chris.

>> Edited by chimpy_bob on Tuesday 10th February 14:30

[shpub]

You might have a version where the otter switch is in the rad... Yours is a late car. Otherwise it is on the swirl tank. The temp guage sender is usually behind the distributor and buried. Nothing to do with the fans. Lower temp switches are stocked by most dealers. I got mine from Tower View.

[JonRB]

Quite possibly a loose connection or corroded contacts in the electrical connector near the fans. It tends to sit in a puddle of water when wet and the contacts rust.

Have a look at this thread for more details:
www.pistonheads.com/gassing/topic.asp?t=80769

[windsorrob]

Thanks for advice so far !

Eliminated the fan connectors - took apart cleaned etc, also bridged the otter fan contacts and the fans kick in immediately, hence think this now must be the otter switch.

Now trying to sort out the right switch. I was under the impression that the right switch cuts the fans in around 90c and lets them off at 85c ish.

Having spoken to a few dealers - they all seem to hold switches that cut in at 96/95ish and go off at 90ish. Also - having looked at the switch on my car it has markings suggesting 96on 91off - hence I'm now confused - these all seem too warm, yet I'm getting the same message from a number of different dealers. Only one dealer (a main one) has said that a lower temp switch is available ( I think 87on 82 off) and this comes with a lower spec thermostat that opens at 74c.

Don't quite know what to do now - just get another 'standard' switch, get the lower activating switch plus the thermostat - if I do this, do I have to fit the thermostat ?

Also - One really helpful guy, said that I may have air in the rad which means the current otter is not surrounding by coolant fluid and hence is not sensing properly - any thoughts on this ?

Any advice appreciated,

[spend]

Have a look at www.tvrcc-south-wales.co.uk/chimaeraparts.asp
I extracted the correct threaded fan switches from Intermotor parts catalog (please note not all switches listed have the correct connectors). IIRC Tim Lamont once advocated a 50250 (86/76) - it was fine in my swirl tank.

Dave

[just trouble]

Hello fella's.I never feel comfortable just relying on to otter switch to turn the fans on when hot,so had a fan overide switch fitted so when ever I am stuck in heavy traffic I just put the fans on.It costs about £50 fitted.I had a tip from an AA patrol man if your fans are playing up carry a spare high amp blade fuse, remove conections from sender and place contections with fuse.Fans will run non stop till you get home/garage and will save you cooking your engine.JT

>> Edited by just trouble on Wednesday 18th February 10:38

[shnozz]

have a look at leven technology website. I have just ordered their complete advanced cooling kit which consists of thermostat, low temp otter switch and water wetter.

Should assist in the cooling dept and if you need a new otter switch, might be worth a look.

[shpub]

The fuse trick doesn't work on all cars because the plug design is such that the fuse won't fit. A paper clip is a better solution as you can bend it to fit.

Details on how to wire up an override are in the bible and I would recommend it. Mod Wise does a conversion kit for less that £50 that simply plugs in if you don'y fancy a bit of DIY.

[mongoose]

Robby,take a look at the 'poosible temp sensor problem' thread running on here at the mo.it explains why the otter figures dont agree with the gauge,and what to do.where going to be making little jackets on the weekend,thanks to david beer of www.modwise.co.uk fame!

[MOD500]

From reading previous threads, people say the Leven kit does'nt do much good. I fitted the Mod-wise two stage cooling kit last summer for piece of mind.....there was nothing wrong with the cooling system, I just wanted some confidence when driving in traffic in the baking heat. Once set up right, the temp never once went over an indicated 85. The kit is easily installed by DIY, it took me 2.5 hours I think, but I spent ages routing all the wires out of sight and tidy.

HTH

MOD.

[leventech]

We are very interested in the comment 'people say the Leven kit does'nt do much good' as we have never had any adverse comments. Our kit has been sold in quantity for a number of years to owners and dealers worldwide. Its concept is firstly make sure it does the job well and then keep it simple, avoid adding additional items and keep the price down.

[MOD500]

Hello Leventech

I was going by the comments from people on previous 'what can I do about keeping my RV8 cooler' threads. I have never used your cooling kit.

My original statement on reflection is quite (read very ) sweeping. Some people have found it works well others not much it seems. The discrepancies in cooling performance might be caused by the kit being used to reduce the running temp in cars with cooling / engine probs to start with? Out of interest, does the water wetter work by increasing the specific heat capacity of the water in the cooling system?

I see your point about keeping the kit simple without adding (only replacing) components to a car. One of the reasons I got the mod-wise 2 stage kit was to reduce the strain on the fans; by them coming in at half speed first it removes the need for them to come on at full speed straight away from been stationary. As when the fans came straight on at full speed it used to drag the hell out of my electrical system, causing the engine to dip when they came on. With the half speed set-up, there is no engine dipping on them engaging, and the engine bay runs cooler. Hopefully the fan motors should last longer with this set-up? Just my opinions.......its horses for courses I suppose

BTW have you starting selling the Al surrounds to suit the two plastic heater blowers beneath the bottom dash, they were in R+D last summer when I got an Al cockpit kit.

Best Regards


MOD.