running hot/clearance above distributor cap/Splitfire plugs

[kabaman]

All, having fixed my annoying alarm problem I'm on to my next task...

I suspect that the Griff is running slightly hotter than it should. I'm not sure how reliable the temp gauge is anyway but it sits on the white line above 90C on my gauge even when moving along. I'm going to replace the thermostat in case somehow the wrong one is fitted. I've replaced the water pump and I don't believe that there are air locks...Although I could be wrong. But I have noticed whilst checking the cooling system that there's almost no clearance above the distie cap. In fact the HT leads are all crammed under the hose that goes between the block and the header tank. Looking at some pics of Griff engine bays most seem to have a reasonable amount of clearance above the distie cap - does anyone know if the later tanks were lengthened to provide additional height in this area? It's all bolted up correctly but it's just not quite high enough?

Lastly has anyone moved to Splifire plugs on their Griff? I changed to these on my BMW 528 and the change was noticable even to my wife - so that really is proof. I'm going to change the plugs and it looks like a bit of a chore so I'd be prepared to spend some more on plugs if it was really worth it. I'm also thinking of replacing the coil. Any suggestions on ignition mods would be welcome.

Thanks, Neil

[dnb]

I've never found the standard temp gauge to be particularly accurate. Mine always tended to under-read and have a lot of lag in the readings - but they are all different, so yours may over-read a bit..

If all is reading OK, it does sound like you might have the 88 degree thermostat in there. This is normally fine, but not so good if your radiator is not as efficient as it could be. I have an 84 degree stat in mine, since this seemed to be the best compromise to me - the colder one let the car run too cold and the hotter one didn't give enough headroom while sat in traffic. 90 degrees C is a good temperature to run the engine - most modern cars in fact do this, but sometimes Griffs need a helping hand to not cook themselves.

As for Splitfire plugs, I have to say that I've not seen any real benefit over simply fitting a new good quality standard plugs. Admittedly they were in various euroboxes and Japanese cars, not Griffs. NGK make pretty good plugs after all.

[Simon.b]

I have always stayed with the NGK plugs and most of the V8 TVR specialist recommend these. Until recently the engine has run smooth, started reliably and felt like it was delivering good levels of power. However just as important as new plugs, in my opinion, are new extensions as my recent problems are demonstrating.

Cheers,

Simon.

[ruaricoles]

90degC on my gauge is really about 80degC, so likewise mine usually reads over 90. I have an 88degC thermostat. I'd check the real temp before starting to replace thermostats and water pumps! Does the cooling fan come on after the car has been idling for a while, and can you see what the temp gauge says when it does?

Do you have a multimeter with a thermocouple so you can get a real reading by pushing a thermocouple under a radiator hose? If you're anywhere near Warwick you're welcome to pop round and we can easily check it.

Ruari

[kabaman]

Ruari, I replaced the water pump because it was leaking, I mentioned that just in passing as I know that's doing it's job. I guess I should actually measure the real temp and maybe calibrate the gauge. The easiest way that I can think of doing this is by calibrating the resistance of the temp sender by heating it in water and measuring/mapping which will be quite time consuming. Then I can determine the real temp (when re-fitted) and if necessary calibrate the gauge to suit. Is there a quicker way than this. A thermocouple I can "pop in" to one of the hoses for example?

I'm in Cambridge so not on your doorstep - thanks for the offer though :-)

Cheers,

Neil

[dnb]

I used the approach you describe with heating the sender in a bowl of water. It was pretty close to being the same as the ECU temperature sender, but not in such an ideal location. If I can find them I could send you the excel files with my sender data in. Putting a thermocouple in the blanked off pipe stub for the throttle body heater seems a good idea to me.

I am now running the gauge on a second ECU type sender with the inlet manifold suitably modified. This seems to work better than the OE location because the sender now sees better water flow.

If you're only interested in calibration around the 75 to 95 degree area, you could simply put a potentiometer in line with the signal to add an offset to the gauge. It only works over a narrow range of temperatures - outside of this, it makes the problem worse.

[Uncle Fester]

dnb said:

I am now running the gauge on a second ECU type sender with the inlet manifold suitably modified.

What modification have you done?

If I understand the problem, we can't get a get a sender that matches the gauge and fits the thread for the 'other' sender. Have you had the manifold rethreaded to take one that does fit?

Can we get the gauge recalibrated to suit the original sender? Who would do that?

If you have an aftermarket ECU then you can rig an overheat buzzer off the ECU as a backup. You configure the ECU to ground a spare pin when the ECU temperature sender reaches a value of your choice. Mine is set to 95C.

[kabaman]

Thanks Fester, the buzzer idea could be done without the ECU but with a few cents of components hung off the back of the current set-up but I don't really think that's my problem. My real problem I think is knowing if the car is running too hot or whether the gauge isn't accurate. The only way I can know this is by testing which is a bit of a pain :-(

Where is the standard temp sensor located?

Cheers, Neil

[shpub]

Simplest way is to get a IR thermometer and measure the temps under the bonnet and compare to the gauge. Point and read the value. Its as simple as that.

[350Matt]

Just one thing tho' the IR types do get confused by shiny surfaces so a bit of marker pen applied to the surface helps here

Matt

[Pasco]

350Matt said:

Just one thing tho' the IR types do get confused by shiny surfaces so a bit of marker pen applied to the surface helps here

Matt

Hello Matt nice to have met you at the growl

My motor is reading around 90 deg even at a steady 70 leptons on a A road is that too hot do you think Matt ?

What is the ideal temp for our engines to run efficiently

[dnb]

Uncle Fester said:

What modification have you done?

I drilled and tapped the original gauge sender hole and the outlet for the redundant throttle body heater to fit 1/8" BSP blanking plugs. This made room to drill and tap the hole where the original range rover gauge sender went to the same thread as the ECU sender. The snag is that there isn't room for a junior timer plug on the top of the sender since bits of engine are in the way. So I used some of the small crimp connectors and filled the rest of the plug with black silicone.

It so happens the ECU sender has the same resistance curve as the TVR gauge sender, so no recalibration woes.

I did have a warning LED driven by the ECU for over-temperature indication, but since the car is well behaved in the cooling department (in others it's still a complete so-and-so...) I reused the output for something else.

[kabaman]

dnb said:

I drilled and tapped the original gauge sender hole and the outlet for the redundant throttle body heater to fit 1/8" BSP blanking plugs. This made room to drill and tap the hole where the original range rover gauge sender went to the same thread as the ECU sender. The snag is that there isn't room for a junior timer plug on the top of the sender since bits of engine are in the way. So I used some of the small crimp connectors and filled the rest of the plug with black silicone.

This sounds very useful but I'm too ignorant to understand exactly what you've done and where. Could you please spell this out as this is my first dealings with the Rover V8 and I'm yet to discover wher everything is and where everything *should* be. Where does the Range Rover sender sit etc. Do you mean that you now have two "ECU type" senders, one for the ECU and one for the gauge? Would you havea part number for this? You wouldn't have any pics would you?

Cheers, Neil

[350Matt]

Pasco said:

350Matt said:

Just one thing tho' the IR types do get confused by shiny surfaces so a bit of marker pen applied to the surface helps here

Matt

Hello Matt nice to have met you at the growl

My motor is reading around 90 deg even at a steady 70 leptons on a A road is that too hot do you think Matt ?

What is the ideal temp for our engines to run efficiently

First off I wouldn't treat the gauge as gospel truth, on mine (a '92 4.3) it overreads by about 5-6°C.
Ideally for best power block temps should be about 75-85°C with oil temps of about 90-100°C in the sump.
You do get a small gain (3 to 5%) in fuel efficiency from having the water temp slightly higher ( 90- 95°) but with our cars keep it as cold as you can I say as the system is marginal as it is

On my car with an ally rad, partially lagged manifolds and a genuine TVR large opening stat of 82 i get gauge readings of about 90° when the IR thermometer reads about 86 on the gauge sender body.

Matt.

[Pasco]

350Matt said:

Pasco said:

350Matt said:

Just one thing tho' the IR types do get confused by shiny surfaces so a bit of marker pen applied to the surface helps here

Matt

Hello Matt nice to have met you at the growl

My motor is reading around 90 deg even at a steady 70 leptons on a A road is that too hot do you think Matt ?

What is the ideal temp for our engines to run efficiently

First off I wouldn't treat the gauge as gospel truth, on mine (a '92 4.3) it overreads by about 5-6°C.
Ideally for best power block temps should be about 75-85°C with oil temps of about 90-100°C in the sump.
You do get a small gain (3 to 5%) in fuel efficiency from having the water temp slightly higher ( 90- 95°) but with our cars keep it as cold as you can I say as the system is marginal as it is

On my car with an ally rad, partially lagged manifolds and a genuine TVR large opening stat of 82 i get gauge readings of about 90° when the IR thermometer reads about 86 on the gauge sender body.

Matt.

Cheers Matt

[dnb]

kabaman said:

Could you please spell this out as this is my first dealings with the Rover V8 and I'm yet to discover wher everything is and where everything *should* be.

I'll try... Mine's probably not the best car for knowing where things *should* be due to the amount of things I've changed.

kabaman said:

Where does the Range Rover sender sit etc.

Next to the ECU temp sender. Look at the inlet manifold between the dizzy and the LH rocker. You should see a small sender with a screw thread top next to one with a Bosch style connector on it.

kabaman said:

Do you mean that you now have two "ECU type" senders, one for the ECU and one for the gauge?

Exactly right.

kabaman said:

Would you havea part number for this?

I do somewhere in my paperwork. It would probably be faster to look at the Griffith Pages alternative parts list.

kabaman said:

You wouldn't have any pics would you?

Probably. If not, I can take some if the area isn't obscured by one of the plenums.

[ruaricoles]

kabaman said:

Is there a quicker way than this. A thermocouple I can "pop in" to one of the hoses for example?

Neil,
Yes, if you can find a thermocouple from somewhere (some multimeters come with one which is handy) then just loosen a hose clip on your hose from expansion tank to radiator (top hose) and poke the thermocouple in before tightening up again; not a very robust long-term idea but it's fine to run engine up and check the temps. When the thermostat is open the coolant in the top hose is essentially engine temp, and the point at which the temp suddenly increases (if warming a cold engine) can be used to check your thermostat is working roughly OK. IR guns are very handy but you ideally need to know the emissivity of the surface you're pointing it at, plus fluid temps will be a few deg higher than the outside of the pipework. Very easy though to diagnose big errors, such as a gauge reading 100degC when the engine is at a normal 80-90degC. Good luck with it anyway.
Best wishes,
Ruari