Can someone give me some pointers please

Hi
Can someone please give me some pointers for my electrical and plumbing problems on my 94 200tdi defender 90. (Ex FFR if this helps, 24V not included)

Started out of the blue last week, lights were like very dim candles coming home and temp uage looked like it was about to explode.

Charged battery, checked earths, checked alternator is charging and all OK.

When I disconnect the earth lead from the battery and run a meter between the battery terminal and the disconected lead, I have a full 12v reading. No sparks whe the terminal lead is struck accross the battery either.

Engine tempreture is running a little high, and poor to no water flow, new pump and thermostat fitted, radiator clear, no crud and water running clear through all pipes and heater matrix OK. When connected up I have no water pressure at all, and no flow of water through the system as though there is a blockage somewhere, but it runs freely with the hose. I have not had it pressure tested yet, but have no smoke, emulsification etc in the oil, I am not using water either, and no loss of power so do not suspect head gasket at this time

Taking her out for a test drive yesterday, I noticed that the temp guage was sitting at about 3/4, but as soon as I put the heater fan or the lights on, the temp guage shot right over to the red so something is shorting out somewhere.

I have disconected all the fuses one by one and the taken the relays out, diconected the heater matrix and all other conections that I can see easily and still getting the 12v reading across the earth.

Checked Rad for cold spots and all ok, Top hose hot, bottom hose less so but warm, seems more like conduction rather than convection. Inlet and outlet Heater matrix pipes very hot, although no real heat in cab

The above two points may or not be connected but scratching my head now and would appreciate some pointers if anyone else has had this issue.

Thanks

Have to say you've done all the obvious stuff.

I'm stumped.

Someone with far more knowledge than me will be along soon

Check that the alternator isnt over charging the battery.

This could also be a symtom of a bad earth causing the current to flow via any earth connection it can find making gauges go haywire. I couldn't hazard a guess as to which earth is bad (if not more than one) so I'd maybe start by checking the earth connections at the battery, the chassis and chassis to engine. You could try a jump lead direct from the battery to the chassis/engine block which might help to narrow down the search a bit.

Good luck.

Ron

Thanks to all the comments so far, jump leads is a good idea and I will try that in the morning. I have checked for the alternator charging already and its all good at 14.5V at the battery.

Like to revise the above on the water issue though in case it triggers something to someone.

Although the temp gauge is telling me I am overheating the engine, in truth it does not smell that way and having just travelled 25 miles in her I emptied the cooling system ready for tonights frost as not putting antifreeze in at the moment while trying to sort out the water problems. The water in the expansion tank was cold and no pressure as mentioned, we have hot pipes from the heater matrix, hot top hose and cooler bottom hose. radiator is fairly cool overall but equal temp all over. When letting the water out of the bottom hose it was only luke warm still to begin with, then got hotter towards the end of the flow. Guess that was the stuff from the heater matrix, but far too cold for a journey of that length.

When I flushed through the water via the heater box with the thermostat removed everything was free flowing. The colour of the water is clear and almost good enough to drink, no crud or crap coming out with it no browning at all to the water

My point is that I am not overheating the engine, in fact I am probably running cold. As the temp gauge is telling me porkies, I have to assume anything it is telling me currently is lies and a symptom of the electrical issue. I did remove the fuses for the lights and the heater with the engine running and put the opposite appliance on to try and see if the issue was on one circuit or the other but made no difference, and still no blowing fuses. Also noted issue with raising temp gauge is effected by the indicators also, but not the brake lights

noel colledge said:

When I disconnect the earth lead from the battery and run a meter between the battery terminal and the disconected lead, I have a full 12v reading.

Click to expand...

Two things. Firstly, this is not how to check battery voltage. To test voltage, you have your meter in parellel to the battery terminals. I.e. red probe to positive, black probe to negative. You only put your meter in series with the battery to test for current draw. In which case you want amp mode (and never do this with the engine running, or attempt to start the engine when connected this way). Testing for battery voltage in the way you have is quite likely to give you an inaccurate reading. As you are creating a potential divider between the vehicle's electrics and your volt meter.

Secondly your problem is simply a bad earth. Behind where the radio would go there is a big blue connector with 20 wires going into it. 12 of these are black wires. They are pins 1 through 6 and 15 through 20. Pins 1 to 6 are connected internally in this connector, as are pins 15 through 20.

The black wires from pins 1 and 15 are both supposed to run through the bulkhead into the engine bay and connect to the earth point on the bulkhead at the back of the engine bay. I strongly suspect that yours are not connected to this earth point.

The rest of the black wires in that connector are the earths for all manner of things, such as heater fan, lights, dash illumination, hazards, gauges etc etc. Swiching on any of these these circuits is electrically pulling this connector up to some voltage nearer to battery voltage than ground. This is why your lights are dim (They are only getting a small voltage across them). Also this is back feeding your temperature gauge, so your gauge is seeing a much larger voltage across it than is it designed to (and actually in reverse polarity).

I'd imagine that switching on your interior light or hazards may also affect your temp gauge.

If my theory is right, you just need to connect these black wires to a good earth point. Ideally the one on the bulkhead as mentioned. If this doesn't work, make sure the bulkhead is earthed correctly to the chassis and battery.

If this doesn't work, bugger knows what the problem is, I'm stumped to.

The TD5 has a bleed nipple for the cooling system to remove excess air in the pipes (which might be causing an airlock,) I don't know if the 200tdi has this but someone will come along who will know.

As far as I know the method of use is to fill water and fit the cap, start engine to warm it up and pressurise the system, slacken bleed nipple to allow air to escape .. caution beware of hot water coming at ya.

Let everything cool down and top up the header tank (personally, I always overfill my header tank and let it spit out any excess once it's up to running temperature.

Gone through aall the suggestions above today, put two new earthing straps on from body to chassis and engine just in case, checked and cleaned the connections mentioned by Mundungus, all ok.

Confident it is not an airlock in system at this time. No water movement still but left on tick over small pipe between water pump and thermostat housing very hot hence I guess the warning indicator. Can only think the temp sensor is acting like a kettle in this area and warming the water up itself.

Electrical issues still raising the temp gauge then either or the lights, heater, indicators are used and increases the problem significantly when all three are on together such that it will eventually stall the engine if left running.

Absolutely no ideas left now but something must be shortng out on the engine, got to take it now for second opinion as seems to have stumped me and you guys too. Booked in for Tuesday so will report then in case it helps others

Ok developments since my last post. Amazing what 5 mins and a cup of tetleys can do.

Thinking about why the engine would stall after a full loading of the headlights and heaters being on for a little while ( Its a Diesel) Also thinking about seeing and smelling a little tell tail trail of electrical short circuiting smoke. Made me think again about the alternator for some reason, so I decided to go and check it out again. The main feed cables were connected correctly and tight, but what about that other extra small brown and white cable ( or brown and yellow wire I can't remember). It has to go into one of three terminals on the alternator

It then dawned on me that when I put the ignition on, I did not see a battery light come on. I disconnected the wire and with a little jiggling around I now have a battery light on with the ignition and seemingly no electrical issues across the water temp gauge.

A round trip test drive of about 10 miles for the school run with the heaters on full and the lights blazing confirms I think the issue has been resolved

I (think) know that one of the other terminals on that alternator connector is for a tacho which I do not have fitted, but does anyone know by any small chance if the third terminal is an Earth?, or for something that could be put to earth?. That being the case it would explain the short circuit if it was connected to this one by mistake.

Am I on the right track?

Does not explain the non circulation of water, but I have good heaters, (it was -1C in the cab yesterday) the engine is not over heating and it is time for another cuppa. Can only think this now is a faulty or blocked rad as even after that 10 mile journey cold spot from about 3" above the bottom hose, bottom hose and expansion tank cold but everything else hot (top hose, heater matrix top of rad).

Alternator earths through the mounting bolts - not aware of any separate earth terminal/wires as standard