keeping 4.3 engine cool
Discussion
having lubed the pistons, started my babe 
despite heater end heater fan set to max, temp grew to edge of red before Otter woke up, then cycled with fan on and off just under red (heater still on and bonnet wide open)
where do you get low opening Otter from?
Any favourite heat gun with laser and probe?
Yes v old antifreeze now, but car has always behaved like this - rad looks like new, no leaks - heater running hot
despite heater end heater fan set to max, temp grew to edge of red before Otter woke up, then cycled with fan on and off just under red (heater still on and bonnet wide open)
where do you get low opening Otter from?
Any favourite heat gun with laser and probe?
Yes v old antifreeze now, but car has always behaved like this - rad looks like new, no leaks - heater running hot
Otter switch is about £8-£15 from any decent car spares place. They may not call it an otter switch (that name comes from the company that devised it) so you might need to refer to it as a bimetallic thermostatic switch.
You can buy them with any on and off temperatures you like. I have a later Chimaera and mine is a Ford one, on at 92 degrees, off at 85. That's what I chose when replacing it. And to fit it you will need a big socket while you are shopping - somewhere around 27-30 mm.
You can buy them with any on and off temperatures you like. I have a later Chimaera and mine is a Ford one, on at 92 degrees, off at 85. That's what I chose when replacing it. And to fit it you will need a big socket while you are shopping - somewhere around 27-30 mm.
i am assuming it is at bottom of header tank cylinder on 4.3? - any idea what the thread dia / pitch is as i shall try and slide new one straight into place with no regard for any potential bleeding (being the bottom of tank and engine that could be a concern? (even though that is what tank is designed to remove (at top)
I imagine an overide switch simply needs to bridge these two wires and that they are low current relay trigger wires?
I imagine an overide switch simply needs to bridge these two wires and that they are low current relay trigger wires?
Count Vampirski said:
i am assuming it is at bottom of header tank cylinder on 4.3? - any idea what the thread dia / pitch is as i shall try and slide new one straight into place with no regard for any potential bleeding (being the bottom of tank and engine that could be a concern? (even though that is what tank is designed to remove (at top)
There is a good chance you'll be able to swap the otter switch without having to bleed the system. Yes its at the bottom of the header tank with the blue cap (VW Polo that BTW should you need one)Count Vampirski said:
I imagine an overide switch simply needs to bridge these two wires and that they are low current relay trigger wires?
I carry a short wire in the glovebox with a male spade connector on each end specifically for bridging the otter switch should I need to.Chuffmeister said:
I wouldn't go for the lower temp large bore stat as it is designed for hot countries and for the most part, the UK just isn't hot enough. You may find that the car doesn't get sufficiently warm in the milder weather.
Not quite the case- the thermostat will open only when it reaches the correct temp, so it wont run any cooler than its opening point. The bigger bore hole simply allows less of a restriction in the cooling system so the flow rate to the rad increases.Count Vampirski said:
having lubed the pistons, started my babe
despite heater end heater fan set to max, temp grew to edge of red before Otter woke up, then cycled with fan on and off just under red (heater still on and bonnet wide open)
where do you get low opening Otter from?
Any favourite heat gun with laser and probe?
Yes v old antifreeze now, but car has always behaved like this - rad looks like new, no leaks - heater running hot
Before you do anything, establish it IS overheating.Shine the infra red guage on the black pipes going to and fro the thermostat housing, this will give you an accurate enough reading.As I previously said, mine was a faulty sender value. If the fan is cutting in and out, the Otter is likely to be ok.despite heater end heater fan set to max, temp grew to edge of red before Otter woke up, then cycled with fan on and off just under red (heater still on and bonnet wide open)
where do you get low opening Otter from?
Any favourite heat gun with laser and probe?
Yes v old antifreeze now, but car has always behaved like this - rad looks like new, no leaks - heater running hot
i quite favour removal of stat as I dont drive in cold conditions and would always drive v sympathetically until fully warm - this would at least eliminate that - the lower temp Otter is clearly helpful, though I prefer natural cooling - I have an Alfa GTV that never uses its fan and happy to sit around 85 deg (50 in winter with no stat!)
I may remove stat and fit lower Otter to at least help (and of course take heat readings before and after changes as necessary - personally I would have liked a larger radiator with all that trapped underbonnet heat
I may remove stat and fit lower Otter to at least help (and of course take heat readings before and after changes as necessary - personally I would have liked a larger radiator with all that trapped underbonnet heat
mk1 - good idea! - wasnt familiar with product - i have dropped them a line as i cannot see a temp adjustment control for cab - i fear that the adjustment is on their Otter with only a garish overide switch
Using this to drive an aux fan and set at low temp with original fan playin catch up at higher temp must surely work
I find that, like aircon (not fitted) the engine idle stabiliser seems to cut in with original fan and the lazy offbeat idle is replaced with a character free slightly higher idle - i prefer to avoid that loss of character if possible
Using this to drive an aux fan and set at low temp with original fan playin catch up at higher temp must surely work
I find that, like aircon (not fitted) the engine idle stabiliser seems to cut in with original fan and the lazy offbeat idle is replaced with a character free slightly higher idle - i prefer to avoid that loss of character if possible
I did not realise TVR made use of the idle up facility on the ECU- there are a could of inputs for heavy idle load like heated screen, or air con that lift the idle speed if switched. The heated screen input simply needs a 12 volt line on its input to lift the idle, that you can take from a fan relay. If you want some control over the temp the fan comes in without a lot of messing about, the Pergeot 205 GTI fan switch is suitable, (thanks Steve Sprint for this one) and comes in various temps. Nice thing is it has two switches inside for different temps, so you can simply use the cooler one, or if you want to get clever you can use one to switch the fans in series on the first switch , and then in parallel on the second switch, but it does require at least two extra relays to do this. This unit switches on at 88'c and off at 83'c on the first switch. The second comes on at 92'c, and goes off at 87'c, so these are good temps for the RV8- not too hot.
http://www.ebay.co.uk/itm/88-83-92-87-C-Range-Fuel...
Interestingly the ideal temp to run the RV8 was increased over the years, and the 90'c plus point used on the Serp' engines was only to reduce emission, and it does reduce the power significantly for some reason the power drops about 10% between 80'c and 100 ' c. so the best temp for both power and reliability is no more than 80'c so a 78'c stat is just fine.
There is a cooler single switch available as well, but id suspect the fans would be on most of the time once the stat opened;
http://www.ebay.co.uk/itm/PEUGEOT-205-Mk-II-1-6-GT...
http://www.ebay.co.uk/itm/88-83-92-87-C-Range-Fuel...
Interestingly the ideal temp to run the RV8 was increased over the years, and the 90'c plus point used on the Serp' engines was only to reduce emission, and it does reduce the power significantly for some reason the power drops about 10% between 80'c and 100 ' c. so the best temp for both power and reliability is no more than 80'c so a 78'c stat is just fine.
There is a cooler single switch available as well, but id suspect the fans would be on most of the time once the stat opened;
http://www.ebay.co.uk/itm/PEUGEOT-205-Mk-II-1-6-GT...
Edited by blitzracing on Friday 17th April 19:00
all great stuff...will read and digest shortly - what do i disconnect to avoid the 'idling up'when factory single Spal cuts in - would like to have the choice..cant see fan current putting too much drag on the alternator
Interesting that you agree that an 80s C is kinder to the engine efficiency - I would v much like mine running at that than peaking at what appears to be well into nineties as fan cycles
Interesting that you agree that an 80s C is kinder to the engine efficiency - I would v much like mine running at that than peaking at what appears to be well into nineties as fan cycles
Count Vampirski said:
though I prefer natural cooling - I have an Alfa GTV that never uses its fan and happy to sit around 85 deg (50 in winter with no stat!)
The thing to bear in mind is that metal is great for conducting and radiating heat so a metal bonnet and wings will absorb engine heat and then radiate it out, helping to keep the engine cooler. GRP however is very poor at doing the same thing. You are relying on airflow and the cooling system to control the temperature almost entirely.
Count Vampirski said:
I would prefer to add additional water volume and natural cooling (regulated by stat) than have annoying fan cutting in most of the time - has anyone added an additional small radiator in series
Blitzracing said:
If you want some control over the temp the fan comes in without a lot of messing about, the Peugeot 205 GTI fan switch is suitable, (thanks Steve Sprint for this one) and comes in various temps. Nice thing is it has two switches inside for different temps, so you can simply use the cooler one, or if you want to get clever you can use one to switch the fans in series on the first switch, and then in parallel on the second switch, but it does require at least two extra relays to do this.
CVYou need more airflow not more hot water and as you don't like annoying fans cutting in/out I suggest you start by fitted that extra fan you have and wiring it as Blitzracing suggests with a 2 stage fan switch (thermostat, otter switch) from a Peugeot 205GTi. The 1st stage with the fans in series reduces the noise and fan speed which reduced the initial load on the alternator. The 1st stage is not annoying as I can't hear them cutting in and out while the engine is running and also provide more air flow across the whole of the radiator especially with a radiator cowling. The Peugeot Citroen thermostat fan switches have the same standard thread and come with various different spade connectors and temperature settings.
To run twin fans with 2 stages on my Precat Griffith I only had to fit this one extra relay that performs the 2nd stage serial to parallel change over and I left all the original TVR wiring, fuse and fan relay in place to bring on the 1st stage.
Count Vampirski said:
i am assuming it is at bottom of header tank cylinder on 4.3?
Correct, as in this picture plus you can also see the three spade connectors of my 2 stage thermostat (Ottter) fan switch.Valeo 819773 (Quinton Hazell XEFS40) 1st: 93-88, 2nd: 97-92 degree.
Count Vampirski said:
thanks guys - does changing stat involve any bleeding in that position, if so how?
No, When I change my fan thermostat switch I would have the new one ready in one hand and swap them over so quickly I would only loose minimal coolant that just requires a small top up.Count Vampirski said:
My fan bearing screeches sometimes when starting up - presumably a little rust from lack of use
Screeching is usually caused by the alternator/pump belt slipping on the alternator and therefore it sounds like your alternator belt may need tightening up or you may need a new belt as they loose their grip with age. Does it screeches more when you blip the throttle or fire up with the full/main beam headlamps on?WinstonWolf said:
Fit a splitter and a smaller front plate. Mine struggles to open the stat when it's cool and I'm driving. The temp will rise in traffic but the splitter/small plate allows the airflow to bring the temp back down as soon as you get going again.
Do not underestimate the benefits the splitter has on the radiator air flow.Here’s a thread with a few splitter pictures
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I personally have and recommend an aluminium splitter as its self-adjusting/levelling as you drive over speed bumps and doesn’t break like fibreglass.
Count Vampirski said:
I imagine an override switch simply needs to bridge these two wires and that they are low current relay trigger wires?
Correct, just run one wire into the cockpit and earth it with a switch. However, with the correct fan thermostat switch you won't need an override switch but I also found it re-assuring to have one. My Peugeot 2 stage thermostat switch has been so reliable I actually forgot I fitted an override switch and now never thinking about the engine temperature or hear the fans.blitzracing said:
I did not realise TVR made use of the idle up facility on the ECU-
Mark, I’ve always had a hunch TVR made use of the heated screen input with zero idle increase because when my fans kick in the 1st stage you can hear the idle note momentarily increase but instantly drops back down to the same speed again, the base idle (base idle + neutral idle). I've never investigated as it actually works really well but I’m pleased you've brought it to my attention as you know how much I enjoy experimenting with the 14CUX. The next time I'm playing with the software I increase the heated screen input idle and see what happens, I’ll also test pins 8 and 21 on the ECU loom.blitzracing said:
This unit switches on at 88'c and off at 83'c on the first switch. The second comes on at 92'c, and goes off at 87'c, so these are good temps for the RV8- not too hot.
Although there are numinous hotter and cooler 2 stage thermostat fan switches to choose from I run a slightly hotter one than Marks suggests because when I first installed the cooler one without a splitter the temperature struggled to come down enough while on the move to turn the fans off. I’ve since fitted a splitter, vented bonnet and an alloy radiator but stuck with the slightly hotter thermostat switch as my engine now very rarely reaches the 2nd stage in the UK with normal summer driving. I think the last time I heard the 2nd stage was on the Growl rolling road and now consider the 1st stage of 93 degrees as normal and the 2nd stage of 97 degrees for emergencies only.If you want to check your engine temperature accurately I would suggest you buying a RoverGauge cable as they only cost £35 and come with the free RoverGauge software thats a huge help when diagnosing engine issues.
Colin RedGriff said:
The thing to bear in mind is that metal is great for conducting and radiating heat so a metal bonnet and wings will absorb engine heat and then radiate it out, helping to keep the engine cooler. GRP however is very poor at doing the same thing. You are relying on airflow and the cooling system to control the temperature almost entirely.
I totally agree and that’s why Fibreon vented bonnets work so well on a precat with a splitter, have a look at http://www.damagedtvrs.co.uk/products/part/16CV
I’m sorry if I’m over whelming you with projects but I’m sure you realise we all have matured our Griffiths over many long winters. The priority should always be to make sure your Griffith is on the road for the precious summer months as that stimulates your Piston Head hormones and fuels the enthusiasm. Therefore quickly slap on that extra fan and leave the precat heat box project for the winter.
Please do not hesitate to ask if you require further information to wire up the series to parallel fan relay, as I'm sure I can work out again how it did.
Best Wishes, Steve Sprint.
wow... I am humbled by your energy, generosity of spirit and diligence ...thx
Whilst it sinks in and later i check out links, i would just mention that it was the fan that squealed due to being too long laid up - now seems ok - yes belt could do with replacing as i have run out of tensioning range and it is too loose
I shall definitely need your expert guidance on how to effect series / parallel mod - something i would have managed in my sleep when younger, but following illness find all a bit heavy going - If i have definitive instructions, I can definitely do the wiring mods - finding and mounting the aux fan, ....
Whilst it sinks in and later i check out links, i would just mention that it was the fan that squealed due to being too long laid up - now seems ok - yes belt could do with replacing as i have run out of tensioning range and it is too loose
I shall definitely need your expert guidance on how to effect series / parallel mod - something i would have managed in my sleep when younger, but following illness find all a bit heavy going - If i have definitive instructions, I can definitely do the wiring mods - finding and mounting the aux fan, ....
"finding and mounting the aux fan, ….
Hi CV, my 4.3 came with twin Fans and as far as I can tell from the extensive history may have been original. So, I may be able to help with the mounting as I manufactured a new pair of fan mounting plates when I had the rad recored some three years ago. If you can please look to see if you have any mounting bushes on your rad (mine had a set of 4 on top and bottom) this is how the plates are fixed. I did make two sets, one as spare, but would be willing to part with the spare set to help you out! You will need the M6 bushes that connect the fans to each other and the mounting plates. Let me know? Reards, Pete
Hi CV, my 4.3 came with twin Fans and as far as I can tell from the extensive history may have been original. So, I may be able to help with the mounting as I manufactured a new pair of fan mounting plates when I had the rad recored some three years ago. If you can please look to see if you have any mounting bushes on your rad (mine had a set of 4 on top and bottom) this is how the plates are fixed. I did make two sets, one as spare, but would be willing to part with the spare set to help you out! You will need the M6 bushes that connect the fans to each other and the mounting plates. Let me know? Reards, Pete
hi Pete will get one of the mice to check it out
all is in mint condition down there - the existing fan appears to have clips or similar top and bottom - may be mount flanges into which bolted? - however being singular it is perhaps larger fan and mounted just off centre, with no room for second fan without first moving original one - my new fan if i can find it is a little smaller
all is in mint condition down there - the existing fan appears to have clips or similar top and bottom - may be mount flanges into which bolted? - however being singular it is perhaps larger fan and mounted just off centre, with no room for second fan without first moving original one - my new fan if i can find it is a little smaller
Count Vampirski said:
thanks guys - does changing stat involve any bleeding in that position, if so how?
No, When I change my fan thermostat switch I would have the new one ready in one hand and swap them over so quickly I would only loose minimal coolant that just requires a small top up.
Sorry for any confusion - I was referring to the traditional main water thermostat on top of the engine
thanks guys - does changing stat involve any bleeding in that position, if so how?
No, When I change my fan thermostat switch I would have the new one ready in one hand and swap them over so quickly I would only loose minimal coolant that just requires a small top up.
Sorry for any confusion - I was referring to the traditional main water thermostat on top of the engine
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