Engine upgrade

[Dave3066]

Ps i don't want it running with the ignition off , cant see the point in that as the water not circulating .

You should have it wired to run with the ignition off, as when you stop the heat builds up and the fan will cut the temp down and then cut itself out on the thermoswitch.

Ok I'll ask the obvious question then :twisted:

What happened to all that heat before the advent of electric fans? The engine driven fan stops when the engine stops. If the engine can handle the rise in temp when you switch off due to the non-circulation of coolant then is it really worth having the fan running that bit longer to allow the heat to dissipate quicker?

Dave

 

[harveyp6]

What happened to all that heat before the advent of electric fans? The engine driven fan stops when the engine stops. If the engine can handle the rise in temp when you switch off due to the non-circulation of coolant then is it really worth having the fan running that bit longer to allow the heat to dissipate quicker?

Dave

Before electric fans the heat built up after you switched off, and so after you came back from popping into the newsagents to buy your paper it wouldn't restart..... By the time you'd read your paper it would go again.

 

[Dave3066]

What happened to all that heat before the advent of electric fans? The engine driven fan stops when the engine stops. If the engine can handle the rise in temp when you switch off due to the non-circulation of coolant then is it really worth having the fan running that bit longer to allow the heat to dissipate quicker?

Dave

Before electric fans the heat built up after you switched off, and so after you came back from popping into the newsagents to buy your paper it wouldn't restart..... By the time you'd read your paper it would go again.

Seems we should all keep newspapers in the car then. Much cheaper than messing about with electric fans

Dave

 

[harveyp6]

The perfect solution! How come nobody has thought of that before?

 

[GrimV8]

Newspapers? Do they still sell them, or do you download them on your E book reader

 

[DaveHerns]

And doesn't the fan running after the engine is turned off also help to prevent the fuel in the float chambers evaporating , hence it will start easier ?

 

[Dave3066]

And doesn't the fan running after the engine is turned off also help to prevent the fuel in the float chambers evaporating , hence it will start easier ?

Isn't that what Harvey said? :wink:

Dave

 

[The Rovering Member]

Newspapers? Do they still sell them, or do you download them on your E book reader

I hope so, as I'm earning crusts by delivering them at the moment.

Talking of heat building up after switch-off, ask Harvey about our little P5B surprise a couple of weeks back. :shock:

 

[harveyp6]

Newspapers? Do they still sell them, or do you download them on your E book reader

I hope so, as I'm earning crusts by delivering them at the moment.

Talking of heat building up after switch-off, ask Harvey about our little P5B surprise a couple of weeks back. :shock:

Ah, such fond memories......(I thought you were going to post a pic of the offending item?)

 

[stina]

O.k guys , So i want to wire my fan up to the ammeter shunt as testrider says that coming off the battery stud in the foot well has the ammeter needle pointing the wrong way ( towards positive ) when the fan cuts in .
I've been studying the wiring diagram ( Workshop manual ) and found the shunt , and know where it is behind the dash , but can any one identify the wire i need to connect the main feed for the fan into ??? I'm not too worried about switching the thermostat relay , i can work that out , just need to know how to tap into the shunt .
Stina

 

[DaveHerns]

coming off the battery stud in the foot well has the ammeter needle pointing the wrong way ( towards positive ) when the fan cuts in .

- can't see why that should be , it's still putting a load on the battery

 

[stina]

Hmmm , Not much help Dave , i need to know how to wire it into the ammeter shunt

Any takers ???

Someone out there gotta be good with electrics !

 

[dmcsweeney]

What about the big spade on the solinoid?? It seems far easier than messing about going behind the dash :? . I found a large male spade on the permanently live side of the solinoid, unoccupied, on my car and took the feed from here up to a small fuse box on the wing, and a relay. The cable up from the spade has a heavy duty waterproof inline fuse to protect it about 3" from the solinoid and is contained in 10mm coplex just to be on the safe side. Rather than running cables through the bulkhead this seems a more straigh forward option. If the spade is occupied (don't know what it is for but it seems to be occupied on one of the other cars, you could come off the solinoid with a ring lug. Never get any strange ammeter readings. I'll get a picture of the setup Friday if required.
Regards,
Dave

 

[chrisyork]

I understand where Stina is coming from, Dave. She wants the current draw from the fan to be registered on the ammeter. Therefore, any function that is in line with the alternator before the current gets to the ammeter shunt is no good. Her pick up point needs to be after the shunt. It doesn't have to be directly onto the shunt, just so long as there aren't any thin wires between the shunt and the pick up point! So whilst I can see the wiring diagram for Stina's car, I don't have the practical reality to refer to (mine's a series 1). So I don't know the wire sizes and physical location of pickup points.

So we need someone with a late series 2 to have a furtle and recommend a practical pick up point after the ammeter shunt. You can win some glory here, because, once established, I reckon we all ought to be using it for any new wiring and / or ancilliaries! My suggestion, without having a car to check against, would be the live feed to the fuse box, at the fuse box. ie onto one of the permanently live feeds to the box.

Chris

 

[dmcsweeney]

I understand where Stina is coming from, Dave. She wants the current draw from the fan to be registered on the ammeter. Chris

Good point Chris, I missed that when doing my own . I've always had a habbit of 'going to the source' when working on older electrical systems if I'm in any doubt about the existing wiring and it's capacity, and I always chuck lots of fuses and relays at it .
Regards,
Dave

 

[stina]

I had a look under at the solenoid this afternoon and have to admit i can see the temptation of coming off the live stud on it , it's right there , and the fan has a ring connector on the live ! It may even be that i use it as a temporary supply . I want to go in behind the dash at some time to bypass the ballast resistor for the coil ,( running off washer bottle feed at mo ) so might have a weekend sorting it out after i've done the oil pump , and timing gears , and fitted the fan .
Got a mate with a scrapper , dash is stripped out , loom still in place . I'll have to get over there and have a look , might even be able to hook a battery up and see what goes where if their's enough of it left !

 

[DaveHerns]

I understand where Stina is coming from , too but I am trying to get my head around how the shunt works and whether the ammeter only reads if the load is applied "downstream" . I'm thinking the ammeter is not reading amps but the volts drop across a resistance ie the shunt but in that case how does it read + and - ?

 

[darth sidious]

I understand where Stina is coming from , too but I am trying to get my head around how the shunt works and whether the ammeter only reads if the load is applied "downstream" . I'm thinking the ammeter is not reading amps but the volts drop across a resistance ie the shunt but in that case how does it read + and - ?

The shunt is a very low ohmic resistor, but has a high current carrying capability.

If the current is flowing from the battery, through the shunt, to whatever is drawing the current, then there will be a small voltage dropped across the shunt, which the ammeter senses (yes, the ammeter is a small-voltage voltmeter in essence) and moves the needle in the - direction

With the engine running and alternator charging the battery, the current will be going through the shunt but in the opposite direction. This means that the small voltage drop across the shunt will be in the opposite polarity, i.e. the ammeter will move the needle in the + direction.

I'm under the impression that what the ammeter displays is predominantly the amount of current flowing to/from the battery.

 

[rockdemon]

Yes that's how they work.

 

[chrisyork]

ie absolutely no point worrying about registering the fan load - go straight for the starter motor stud. Is that right?

Chris