Bl**dy truck won't start

[Chris]

Well as it says, I got home tonight and the 80 won't start. It is NOT the batteries, they are fine and all four connections are solid. When I tun the key, I get a Schuuump noise like a piston in a tube. The lights don't dim and it doesn't buzz, clack or anything else. So, to me it sounds like the solenoid is activating, but there's no power going across the copper terminals to the main motor. It did this after an off road session last month. I took the thing off, had a look at the solenoid and it was spotless but the contacts were very burned. I think that this is a symptom of 24v start and an engine that fires on the turn of the key - the contacts spend so little time together that they spark and erode rather then clamp together firmly. I cleaned the contacts back to shiny copper so it can't be that in one week. I know little about the change over relay but I am starting to think that this is a 24v starter trying to turn on 12v. Yes, I have knocked the thing with a hammer (1960's style) and it has made no difference. Was deeply off road on Sunday and jet washed the engine as you do. Not moved it since then. Went back to it just now and the drive threw in very weakly a couple of times but never reached the starter ring.

So any words of wisdom chaps? No, It's not the batteries. Change over relay? I really don't suspect the actual starter motor if I'm honest.

Chris

 

[Ben]

have you tried starting it by putting power directly to the starter motor from the battery?

 

[Chris]

Not easy Ben, nor particularly safe with it being 24v. Access isn't bad but you'd need two jump leads and four arms. You still need to get the power across the solenoid which means doing it with the key turned. Pop round and we'll give it a go

Chris

 

[Towpack]

Check the voltage at the main terminal on the starter solenoid. You should have 12v with everything switched off and 24v when the key is turned to crank the engine. To check this without cranking/starting the engine I disconnected the small feed wire to the solenoid (plastic plug) and , curiously enough, got a noise very similar to what you describe so check the voltage here also.

 

[Chris]

Cheers Phil, will look at that tomorrow. What does that actually signify though? Maybe wiggling the plugs is not a bad thing to do! They do seal well and were clean last time I looked, but I bought some special electrical greases today. One that allows current and one that doesn't. Insulating and conductive I think that should be.

Chris

 

[Towpack]

If you get 24v at the main terminal when the key is turned then the changeover relay is operating. The thinner wire in the plastic plug is the feed from the starter relay which 'fires' the starter solenoid, bridging the large copper contacts and supplying power to the starter itself. A problem in either circuit would cause a starting problem. If there's a break or bad connection in the thin feed wire you will hear the starter relay operating but not the main solenoid, hence, no engine cranking. I think this is what you may be hearing from your description and from what I heard when I tried it. If the starter solenoid IS operating but the changeover relay isn't, again, you will get no or VERY slow cranking as the starter will, at best, be getting only 12v not 24.

 

[Chris]

C

 

[Jon Wildsmith]

Did you clean the plunger hat as well as the contacts? I shall be ditching the 24v start just as soon as my 12v starter turns up, one less complication to diagnose.

 

[Charlie]

I shall be ditching the 24v start just as soon as my 12v starter turns up, one less complication to diagnose.

Did the same late last year, 1 less possible problem……..

 

[Chris]

I did Jon. Had a pretty good polish around the rim in fact. I get the feeling that it's not getting the 24v goodness that it needs.

Chris

 

[nivapilot]

Mine turned with only 12volts at the starter as well.
Cured it by running another small earth wire from solenoid to engine ... connect a small jumper wire from the solenoid terminal that has the earth cable from secondary? nearside battery to engine block...and mine works a treat now.

 

[AndycruiserguyLomas]

If you need a spare starter motor let me know.

Andy

 

[Chris]

Cheers Chaps. Having had starter woes before, I really don't think that it's the unit. Remember it's only done 70k miles and is genuine. Plus I have stripped it and it was so good I reassembled it without any work being necessary. I think it's related to the change over relay most likely.

Chris

 

[Chris]

It's running again. Had to take starter off twice hence getting sod all else done today. Checked out the lekriks first and they were fine. Replaced copper contacts then finally took the whole thing to bits. It was the bendix drive that wasn't throwing out. Jammed with something. Back at 100% again

Chris

 

[Graham]

Well done Chris,

Glad you sorted it and it wasn't a gremlin electric thing, but a good old mech thing.

Gra.

 

[Chris]

Yeah, bearings sounded all very dry I have to say. It's on the list for another day.

Chris