Thread: 300 tdi intermittently wont start

You can try pulling the relay apart - but nice to have a replacement on hand. Can only assume you can get them from auto shops - I have some spare on hand from wrecks.

Recently cleaned up the points on a Land Cruiser relay, attached to the fender inside the engine bay. The first symptom was lots of clicking before firing up in the drive way. The second symptom was thinking you're now fine you go out to do things - only to find you're momentarily stranded in every car park, with again lots of clicking before firing. A few people walk up to help and recommend hitting the starter motor - wrong solution for this problem.

Needed a hand lens to convince myself there was point corrosion; by eye the contact looked OK.

Try to completely remove the relay. The LCruiser wire connection wouldn't untether, so relay contact cleaned in situ - don't use a file in situ, use sand paper, otherwise with a metal file you could touch both sides of the contact and turn the engine.

Have popped a few Disco relays apart, the ones under the dash. Easy to determine if the coil is working (they are robust), and if working then check contacts and for corrosion elsewhere inside. They're usually in plastic housings. The base is released by pushing lock tabs, using small screw drivers, knife points etc. The Toyota relay was very large, in a metal case that required opening metal tangs to pop the base.

Haven't had to pull a Disco starter motor apart yet, but assume much the same as another Land Cruiser unit I had trouble with many many years ago. The massive solenoid attached to the side of the electric motor had a copper bridge that was pulled down by a magnet, onto positive and negative points. allowing current to flow to the electric starter motor.

The bridge had badly corroded at its ends, and most times had no interface with the negative and positive terminals when pulled down by the magnet - no start, but lots of clicking.

However, there is a little bit of play, or side to side movement in the bridge - so if stuck in a car park you could lift the bonnet and hit the starter with a wrench - this would knock the bridge, to one side, enough to contact the positive and negative terminals. Back then you could buy a replacement copper bridge from Toyota for a few dollars. Also used the 'bash with a wrench' on a LRover series 3 starter with same effect - but never owned it long enough to bother fixing it (replaced it with my first LCruiser).

Originally Posted by edddo

I have just had a look at the solenoid and cleaned the terminals.
It has 12.3 volts at the solenoid power lead with key in start position ( 7.5 with key on accessory?)
With the spade connector/power lead only on the solenoid clicked on and off with the key.
I couldn't recreate the non start state while I had it apart.
The earth from the side of the starter to the chassis is very tight.

If have further problems I might try a test light ( per Beeutey's post) connected to the solenoid.
Then if it wont start but the globe lights then that would indicate solenoid or starter failure wouldnt it?
Or if it didnt start and the globe was not lit then it would mean it was upstream, perhaps indicating an ignition problem. Is this logical?

I have hooked up a test light to the power lead on the solenoid.
So far today no starting problems. Turn key to start, light comes on and car starts.
Will just watch this for the time being. I don't think just cleaning the solenoid terminals will be the fix - life is not like that.

If I get no light and no start then I will power the solenoid by bridging the test light wire to the positive on the starting battery and hope that will get me going.
That scenario will help the diagnostic process.

Re the location of the starter relay - according to my Haynes manual it is " behind drivers footwell side panel". But I will listen for the click when I go looking for it.

I think I will put a new starter on anyway - it is 20 years old. Might look at renewing the ignition wiring as well. This car does go to out of the way places.

Originally Posted by Finnius

Are they a common relay to be bought at any auto shop or are they a LR only relay?

I would guess that they are a standard relay that you can buy "off the shelf" as are most of all the other relays and fusible links on the truck.

If it helps anyone - I can confirm that in my 97 disco 300tdi the relay that sends power to the starter motor solenoid is in the drivers side fascia/footwell area.
I pulled my relay apart this arvo and sure enough the contacts had some serious wear/pitting and the contact pad area that is meant to be convex was concave where the power presumably arcs.

Not sure if it helps but with my old r31 skyline used to have same issue. Was starter motor related, forgot what but my way around it when it didn’t start was to have a steel plumbing pipe next to my seat and lean into the engine bay and tapping starter motor whilst turning ignition. Worked every time. Not suggesting that as your fix but it might help you narrow down problem. Not familiar with inside of starter motor. Certainly would have looked entertaining to other people. My ex girlfriend used to go red and hide her face.

I had exactly the same problem.

check the connection on the starter motor first. It gets corroded making for a bad connection.
if this is not the problem you might be looking at a worn out starter motor.
the reason why it is intermitted is that over time the contacts wear out and if they are not exactly aligned the starter motor will not turn over..

short term solution (if you are stranded) open the bonnet and gently tap the starter motor with a screwdriver. This might re align the brushes just enough for contact. I used to slam my door real hard and that would do the trick 80% of the time.

I chose to bite the bullet and replace the starter motor. I had the old one repaired and keep it is a spare.

good luck
Jan

I too have this problem intermittently like you, but I believe mine has something to do with the transmission position switch. I've got the auto too and whenever it randomly decides it doesn't want to start even though it's in park or neutral I run it through the gears and back into park and try again. Sometimes it works first time others it may take a few attempts. I've been meaning to look further into it but since it rarely happens its not currently a priority. But might not hurt to check on yours.

I am going to pull the dust cover off the end of the starter motor tonight after work.

Anyone chime and tell me how to tell if brushes are worn too much or are fine? Is there a millimeter amount meant to be left?
I have pulled apart 1 other starter motor and the brushes had springs which pushed them down. So i guess the brush would have to wear completely out before it didn't make contact.