Bedford TK

[knighty]

problem is the water coming out of the engine should always be 90'C (or close to that)

so the fan would run all the time

water coming out the bottom of the radiator is supposed to be cold all the time
(guess cold is the wrong term, but you know what I mean)

fan isn't needed most of the time, just when you're stuck in traffic etc.. with the temp sensor on the top hose the fan would run all the time once the engine is up to tempriture

 

[octo0072000]

so why do the electric fan kit say to fit senser in the top hose kenlow for one you used to slide the sender under the top hose and rad then seal with a jubilee clip and a bit of shaped rubber/plastic see picture

 

[knighty]

I've got no idea why they say that....

but look at every car/van radiator with the stat built into the radiator... they're all down low right next to the exit pipe

 

[mylesdw]

It does not really matter where you fit the switch as long as it is a suitable value.

Say the water entering the rad at the top is at 90 and leaving the radiator at the bottom at 80. Later, as the engine warms up the top temperature rises to 100 and the bottom temperature rises to 90. So a fan switch that operates at 100 in the top hose will have the same effect as a fan switch that operates at 90 in the bottom hose, that is, the fan will come on when the engine has reached a certain temperature.

 

[knighty]

thing is the bottom hose is supposed to be cold all the time,

if you're moving the radiator should be full of (mostly) cold water, then the thermostat regulates water flow to regulate temperature

at least that's what I read when I was researching building a combined heat and power system (generator that heats your hot water too)



with the sensor on the bottom hose the fan won;t come on until it's actually needed, which is what you really want

so if you're doing 70mph the water coming out of the engine might be over 90'C

but the 70mph wind through the radiator cools that no problem, so water out the bottom of the radiator is 50'C so no need for fan to run
(I plucked 50'c out of the air, I don;t know the actual normal radiator out temperatures)


EDIT: I did a quick google looking for bottom hose temperatures, didn;t feind any decent/reliable info.... but did find a lot of forum people saying "my bottom hose is cold, is that normal" with the replies saying yes that's normal

 

[mylesdw]

Spent Xmas in the UK with family which was great fun but did not contribute to this project one bit. I'd forgotten how dark it is in England in December!

Anyway...

Fitted the tank

First some closed cell rubber tape on the brackets



Then the tank and straps



120L that tank. Need to fit the new sender and plumb up the diesel feed and return lines.

 

[DAPPH]

I think I'm right in saying you'll need a canvas /thin webbing waxed strap on the inside of each of the banding straps against the steel tank to prevent vibrations wearing them through into the tank as it happens even on tightened up straps .

 

[mylesdw]

It doesn't show in the photo but there is more closed cell foam on the inside of the straps where they touch the tank.

 

[DAPPH]

Now you've gone all modern & posh on me ...... " Closed cell foam " .... indeed

 

[mylesdw]

Sorry Daph, I went all Waitrose on you there; now where's that organic humus...

Any idea why the switch for the oil light would have THREE connections to it? I wonder whether it is a change-over style switch with a common (C) and NC and NO connections. Is that likely? Putting a meter on it shows centre and left terminals shorted and all other combinations O/C

 

[fixedfixer]

I think one wire goes to pump then same light tells pressure and if pump working. I emphasise think on this reply.

 

[awemawson]

On the Land Rover 101 forward control a similar three terminal oil pressure switch doubles as an engine cut out, which always struck me as odd on a fighting vehicle

 

[colnerov]

Hi, The change over oil pressure switch is probably for controlling other items, if required, on the vehicle to only work when the engine is running, especially if the engine is used in another application like a bus or coach. On the bus company there was a similar set up except in the case of AEC and Leylands it was controlled from the alternator, for example the heater fans would only work if the alternator was charging.

Colin

 

[DAPPH]

Engine cut out if no oil pressure or low pressure sounds reasonable .
Have you had a close look at the terminations .. are they original or replacement Lucar crimps ? Are there any coded sleeves on the wires that you can find on a wiring diagram ?

 

[mylesdw]

Not a cut-out I don't think because the engine stop is purely mechanical and there is no fuel solenoid. I'm guessing it was something to do with the dual battery system; it was a horse-truck with a separate set of house batteries.

 

[colnerov]

Hi, Yes that makes sense, it probably controls a relay to disconnect the house batteries from the vehicle battery with the engine off. So that any demand on the house battery overnight doesn't run the vehicle battery down and then you end up with a non start in the morning.

Colin

 

[DAPPH]

I didn't realise that a simple charging relay would have been involved with an expensive to make & difficult to design NO /NC oil pressure switch .

As a result I've been trying to think it through , if the switch was earth for the warning light & the relay to operate to come on. For you'd only need one double terminal connection on the switch for both wires

I can see that a two stage normal & low oil warning light earthing plus a cut out fuel solenoid earth terminal within the same switch would work . Maybe the switch is not working like it should ?

Puzzled I put " three terminal oil pressure sensing switch into eBay ...
& found this item number
231341952249

Does that help any ?

 

[mylesdw]

I agree Daph, it can't be the reason that switch is there, but it does look stock. The original wiring loom appears to only have ONE wire to the centre terminal and this one coincides with the expected BS-AU7 colour code. If you look carefully at the photo you can see that the two outer terminals are wired to a cable clipped to the diesel line and obviously not part of the loom. That is what made me think it might have been some sort of split charging arrangement but that does not explain why the switch was a three terminal one in the first place. I'll try posting on the truck & bus forum and see if they have any ideas.

Also wondered whether it was a combined sender for oil light and oil pressure gauge? There is no gauge on the dashboard but maybe some did?

 

[mylesdw]

Added fuel gauge sender and diesel hoses

 

[Cobbler]

My feeling is that it's not for a split charging system, the normal way uses a relay from the charging circuit. If you wanted to run one from the oil pressure switch for some reason, all you would have to do is put a relay in circuit with the existing switch. You would need a relay anyway to switch the current the charging current, so why make it more complicated by using a special switch. Some early Golfs had 2 switches, one high & one low if I recall, not sure how it worked though, is this a similar system, but all done in one switch?