rover p5b

[lencottam]

Its Len p5b XYW 188 ,the car is just about ready for booking in for an MOT, and sods law.The ballast resistor near to the coil is overheating,and the voltage is dropping to abouy 3 volts .I had a fault on the resistor itself ,with a bad connection on it ,which I thought I had cured .The car cut out on tickover and the ballast resistor started to smoke so quick turn off.I havn`t had any luck in getting a new resistor.Can I change the coil for the later type and is there any rewiring to do .Any one help

Have just spent another 1/2 hr under the car .I find that if I take the feed from the starter motor to the coil off ,then the car runs and the ballast resistor doesn`t overheat.This contact feeds 12volts to the coils while you are starting the car,so why it is drawing current when not being turned over I don`t know.It is a recon starter as well.The next stage is I think to fit a modern coil and do away with the ballast resistor ,happy days .

[johnwp5bcoupe]

I don't know where my reply went Len it said there are two ways one to the shunt in the starter the other to the coil and to check them both but it looks like you got there anyway

I should think the shunt is knackered in the S motor ?

Thinking!! the ballast shunt in the S motor gives the extra volts to the coil during the starting then it drops out as the solenoid disengages and the ballast resistor takes over reducing the volts to around 9 to 10 volts so if what you are saying is correct there must be a -ve return path some where because in theory both are at the same polarity +-ve albeit one is lower voltage than the other

More thinking if you measure the terminal on the S motor if you have a meter Len? it should read open circut to deck in the none engaged position if it reads any ohms at all its a bit strange because the other side of that terminal should be +ve when the starter is engaged I would have thought there would have been a few sparks when the motor solenoid engaged

Even more thinking was the connector shorting to deck or the wiring some where near the motor? enough thinking for now

[johnwp5bcoupe]

Lens question on the 3Lt section

CAN SOMEONE PLEASE TELL ME WHERE THE STARTER RELAY IS POSITIONED.I HAVE A FAULT ON MY IGNITION WHICH IV`E TRACED TO THE AUXILLARY CONTACT ON THE STARTER .THIS IS DRAWING CURRENT WHEN THE ENGINE ISN`T BEING TURNED OVER ,AND THUS OVERHEATING THE BALLAST RESISTOR.THERE IS A MOD TO FIT A RECTIFIER OR EXTRA RELAY IN WHICH I SHALL TRY .LEN

There is no tie in with the start relay 6RA and the contact used for the coil ballast shunt, the 6RA is the relay which energizes the solenoid on the S motor there are two sets of contacts which make when the solenoid pulls in one which energizes the starter and the other is the coil ballast shunt supply! so if you are drawing current when the motor is not being energized you have a S motor problem or a wiring fault either of which are taking the shunt to earth somehow

[lencottam]

It must be the replacement starter,if you turn the ignition on then the ballast resistor overheats.If i remove the aux. lead off the starter then the ballast resistor is ok,it just means I suppose that you are not getting the full volts on the coil on turn over.I have seen this mod using a rectifier to bypass the aux contact I want to know where the starter relay is ,to take power off one of the contacts Len

[johnwp5bcoupe]

It sits on the bulkhead next to the heater unit Len, I am a little concerned if you have a connection to earth at the Ballast connection on the motor the other side of that contact goes to +VE so either the contact has come loose or something has or will burn out

If you bypass the contacts with a rectifier you will put 12v on the coil the ballast circuit is designed to increase the boost of the coil by the voltage drop across the ballast resistor I cant see where you are going Len

I have had a look at the circuit you could put a diode (5 amp one to be safe) from C2 on the start relay to the connection point that goes to the starter after disconnecting the offending circuit at the balast resistor the -ve side would have to go to C2 otherwise the current will not flow you will get 0.7v drop accross the diode

I would still be concerned about the short on the solenoid

[Phil Nottingham]

Steve Munford is finalising the wiring diagrams which correct errors/anomalies in the original wiring diagram but the ignition relay protects the the starter switch from havey loads of the starter motor soleniod. A similar relay handles the alternator field windings again to keep the ignition switch loads down. Connecting an electric pump , having wipers/heater/radio/HRS running really puts too much load on an old ignition switch which as with any switch that overheats ruins it permanently.

The wiring seems to have been well messed up!

[johnwp5bcoupe]

Welcome on board Phil if Len does the correct thing the motor should not be left as it is but if he fits a doide it will cure the problem he has with no extra load on anything as the same ammount of current will be drawn! which ever way it is done I have two concernes with this, it is none standard and you still have a fault

I have Steves latest PDF the boy done well

[Phil Nottingham]

I agree - either renew the solenoid cap (have you used the correct terminals?) or remove ballast/shunt/diode and revert to an unballasted standard 12v sports coil - its far more more reliable and uncomplicated. Those who have dispensed with armoured set-up like me run perfectly well and start easily without a ballast

The wiring seems to need careful sorting

[johnwp5bcoupe]

I agree Phil a sports coil would do the trick but I am still concerned about an earth connection on an open +ve terminal if Len has got it right looking at the diagram there is no way there should be any earth contact outside the casing on the S motor if Len is saying he removes the terminal and the fault goes away one can assume from the motor onwards it is ok! but it that terminal is -ve and the otherside of the make contact is +ve during the S motor ativation something is passing a large amount of current and it must be through the contact bar assuming all the info is correct

[Phil Nottingham]

Its likely to be an internal fault in the solenoid cap and shunt wire must be disconnected or preferably new cap/inspection of solenoid - perhaps its a blob of solder/copper shorting out.

As I said there is little advantage using ballast ignition as this engine just does not need it to start

[lencottam]

HAVE BEEN IN TOUCH WITH THE SUPPLIER OF THE RECON STARTER AND HE IS GOING TO SUPPLY A NEW SOLENOID CAP.I DEFINATELY PIN POINTED IT TO THE STARTER.THANKS FOR YOUR HELP.I SAW A MOD,WHERE YOU FIT A BRIDGE RECTIFIER IN THE CIRCUIT TO DO AWAY WITH THE AUX CONTACT.I HAVE READ SEVERAL REPORTS,WHERE PEOPLE SAY HOW UNRELIABLE THE LUCAS STARTERS ARE .LEN

[johnwp5bcoupe]

Good Len I am pleased the Diode (rectifier) from C2 would be an easy mod if there was no other option but if you are changing the solenoid that is the right way to go

[Phil Nottingham]

The 2 basic Lucas pre-engaged starter motors originally fitted were extremely reliable and many still have the original ones on. The modern compact high torque motors apparently work very well but their longevity is unknown and I have heard that their QC is far from consistent but then that is the case with most modern stuff

The problem is that only very early P5B's had the separate ballast and did not require the shunt terminal on the separately available solenoid cap.

There are therefore 4 different types meant to fit P5B's and a few others that can be made to fit.

I did not think your car should have had a separate ballast as these disappeared for 69/70 models - yours is therefore a 68/69?

Resisters/diodes and mods by Po's and there mechanics who do not understand the basic simplicity of these cars brings in teh unreliable element.

Let us know the outcome please

[johnwp5bcoupe]

philnottingham said:

The modern compact high torque motors apparently work very well but their longevity is unknown and I have heard that their QC is far from consistent but then that is the case with most modern stuff

If mine packs up I will go for a High Torque modern motor the name Nippondenso says to me they are reliable not to mention far smaller and better still much lighter I would only go for a Japanese derived motor myself there are a lot about made in India

[petervdvelde]

Len,

On your replacement starter there might be a wrong cap. Some years ago i had simular problems and I found out that there are differences in the solenoid caps on starter motors on different cars where the rover V8 was fitted. If i remember correctly some of the secondary (=smal) terminals are connected to earth and others to 12V depending on which car it belonged to. The solenoid cap itself can't cause much trouble.

Regards
Peter

[Phil Nottingham]

Peter -Your comment therefore confirms that is the solenoid that is causing the trouble as it is the wrong one?

John - I believe it is the Indian versions that are far from reliable (perhaps the Chinese ones as well)

Nippon Denso stuff was always better and more advanced than old JL stuff

[Kev]

johnwp5bcoupe said:

philnottingham said:

The modern compact high torque motors apparently work very well but their longevity is unknown and I have heard that their QC is far from consistent but then that is the case with most modern stuff

If mine packs up I will go for a High Torque modern motor the name Nippondenso says to me they are reliable not to mention far smaller and better still much lighter I would only go for a Japanese derived motor myself there are a lot about made in India

Nippondenso every time.
Big Kev.