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-   -   suddenly starter motor wont engage (https://www.volvoforums.org.uk/showthread.php?t=291725)

2V8s Feb 12th, 2019 14:04

suddenly starter motor wont engage
 
Hi all,

having just got my 960 24v estate MOTd, the next time I went to use it, turn the key and nothing. It not the battery - thats fine and also I tried fully charging it - no difference.

I read somewhere else about dodgy ignition barrel - well that was already replaced once and also if I put the headlights on, they turn off when the key goes from pos 2 to start position so I figure that's fine?

The only sign of something going to be amiss was the day I took it to the MOT, when I started it initially there was a delay of a second or so when nothing happened and then it started as normal although the starter motor sounded a little sluggish.

Could it be the starter motor? do they suddenly fail in this way? Or could it be something else?

Im feeling a bit gutted because this has always been such a reliable car, dont recall there ever being a time it has failed to start (even when the fuel pump was playing up)

thanks

Aaron

Laird Scooby Feb 12th, 2019 15:26

Is it manual or auto? First thing i'd check is that the exciter/trigger wire (usually white/red) hasn't come off the starter terminal. :thumbs_up:

aardvarkash10 Feb 12th, 2019 19:58

Highly unlikely the wire has fallen off. However, if you can see the starter motor (not sure of layout on that engine), try this:
  1. With the vehicle in neutral or park, have someone hold the key in the start position.
  2. Assuming the engine is not cranking, rap the starter motor itself with a hammer (via a drift or similar if you cant reach it easily).
  3. If the starter springs into life, you have identified the problem - worn out brushes in the starter motor itself.

Laird Scooby Feb 12th, 2019 20:27

Quote:

Originally Posted by Laird Scooby (Post 2494935)
Is it manual or auto? First thing i'd check is that the exciter/trigger wire (usually white/red) hasn't come off the starter terminal. :thumbs_up:

What i forgot to say earlier is if it's auto, try holding the key in the start position and moving the gear lever through the entire range of movement (P to 1 and back again) several times and listen to see if the starter engages in N or P or tries to.

Could simply be a worn inhibitor switch or even just dirty contacts.

Still worth checking the exciter wire, if it's where it should be, not broken, clean and tight connection, give Ash's idea a try.

Also worth checking the relays are all pushed fully home in the electrical box behind the ashtray and/or under the bonnet depending on which model you've got - a loose start relay will also cause this problem.

loki_the_glt Feb 13th, 2019 09:36

An alternative source could be the engine earth strap!

Years ago I had a Fiat Mirafiori that refused to start; I became adept at starter motor removal and replacement but couldn't work out what the problem was as the starter was fine when off thecar.

It turned out that the earth strap between the rocker cover and bulkhead had an air gap. Remade with aircraft-specification braided cable and - problem solved.

Laird Scooby Feb 13th, 2019 10:50

Quote:

Originally Posted by loki_the_glt (Post 2495150)
An alternative source could be the engine earth strap!

Years ago I had a Fiat Mirafiori that refused to start; I became adept at starter motor removal and replacement but couldn't work out what the problem was as the starter was fine when off thecar.

It turned out that the earth strap between the rocker cover and bulkhead had an air gap. Remade with aircraft-specification braided cable and - problem solved.

Quick way to check for that is a jump lead fromthe bellhousing as near to the starter as possible to the battery -ve terminal. :thumbs_up:

cheshired5 Feb 13th, 2019 11:21

Quote:

Originally Posted by aardvarkash10 (Post 2495038)
Highly unlikely the wire has fallen off. However, if you can see the starter motor (not sure of layout on that engine), try this:
  1. With the vehicle in neutral or park, have someone hold the key in the start position.
  2. Assuming the engine is not cranking, rap the starter motor itself with a hammer (via a drift or similar if you cant reach it easily).
  3. If the starter springs into life, you have identified the problem - worn out brushes in the starter motor itself.

Not necessarily. In this scenario the problem could just as easily be a sticking solenoid.

Quote:

Originally Posted by Laird Scooby (Post 2495179)
Quick way to check for that is a jump lead fromthe bellhousing as near to the starter as possible to the battery -ve terminal. :thumbs_up:

..... or voltage test between the starter motor body and vehicle chassis/battery negative during cranking.
There'll be an over spec voltage drop reading if the earth strap is defective.

Laird Scooby Feb 13th, 2019 12:24

Quote:

Originally Posted by cheshired5 (Post 2495190)
..... or voltage test between the starter motor body and vehicle chassis/battery negative during cranking.
There'll be an over spec voltage drop reading if the earth strap is defective.

The jump lead does that and proves the starter at the same time if it is an earth strap fault. :thumbs_up:

cheshired5 Feb 13th, 2019 14:35

Quote:

Originally Posted by Laird Scooby (Post 2495214)
The jump lead does that and proves the starter at the same time if it is an earth strap fault. :thumbs_up:

Agreed but the jump lead trick is only good to identify that one fault but if you guess right first time, it's all good.
Using a multimeter to measure voltage drop on the live and ground side will identify many more potential faults though so a combination of methods is always handy.

Laird Scooby Feb 13th, 2019 16:16

Quote:

Originally Posted by cheshired5 (Post 2495249)
Agreed but the jump lead trick is only good to identify that one fault but if you guess right first time, it's all good.
Using a multimeter to measure voltage drop on the live and ground side will identify many more potential faults though so a combination of methods is always handy.

True but eliminating the simple faults first with a few simple checks is a lot easier to do than go through everything when you're at the side of the road in the pouring rain with a customer bleating "Have you fixed it yet?"


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