Taimar Starter Original & New intermittent cranking !

Taimar Starter Original & New intermittent cranking !

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Fixanything

Original Poster:

222 posts

130 months

Thursday 29th April
quotequote all
Original Ford/LUCAS starter motor had an intermittent cranking problem i.e. sometimes it would not crank unless I manually rotated the engine to a non compression area of the cranking cycle.

Replaced today with a new HT starter motor......same thing !!! relay seems good, can hear starter solenoid kicking in but no cranking unless I move the engine to a non compression part of the engine cycle, then try, it will crank every time.

Notes:
a) 2 different new batteries fully charged tried, same result.
b) When it does crank its fast / very good.
c) Compressions and Oil pressure all good.
d) Once engine has started it idles well and achieves operating temp without issue.

Thinking of making up dedicated Earth/Ground & 12v cables from battery terminals to directly to Starter motor, any other suggestions would be much appreciated.

Many thanks

plasticpig72

1,646 posts

116 months

Thursday 29th April
quotequote all
Replace Solenoid corroded inside too much resistance
Alan

Stigproducts

1,555 posts

238 months

Thursday 29th April
quotequote all
try a jumper cable between the battery -ve and the block to rule out the earth strap. I once had one that looked find but the strands on the underside of the braid were all broken. When I took it off and folded it, it just snapped, it was only held together by the strands I could see from above, and they were corroded underneath.

Penelope Stopit

8,718 posts

76 months

Thursday 29th April
quotequote all
If the engine earth and starter motor main positive supply are proven to be good.............

Tooth to tooth abutment may be the problem, the flywheel will more often than not stop at one of 3 positions (I think it's 3 for a V6)

Over time the flywheel ring gear wears at the above positions

You could remove the starter and check the condition of the flywheel by slowly turning the engine through 360 degrees, check for wear by feeling the teeth with a finger or use a mirror to view the wear

If tooth to tooth abutment is proven to be the problem you could adjust the pinion lever to gain a bigger gap between the pinion and flywheel teeth, a 6mm gap is pushing it to the limit, standard gap is often found to be 3 to 5mm

Gap is worth checking as it could be too small

Edited by Penelope Stopit on Thursday 29th April 23:40

Fixanything

Original Poster:

222 posts

130 months

Friday 30th April
quotequote all
Thanks all

1) Don't think solinoid contacts are the issue as Starter motor (solinoid is new comes fitted to the new starter) is brand new and what's the chances both new and original starter motors/solinoids having exact same problem.

2) Will try jumper cables.

3) Tooth abutment.... I looked at flywheel ring gear while starter was off, looked original and in very good condition ie no signs of wear.

Q) which of the bulkhead relays is the relay that supplies the Solinoid +12v ? , thinking this relay may have high resistance contacts, I guess if I jumper solinoid direct from battery should prove if relay or not.

Have a great weekend and thanks again for the help.

timelord

305 posts

250 months

Friday 30th April
quotequote all
I've been having the same problem with the pre-engaged starter on my Vixen, it had been doing it since I replaced it last year then it appeared to fail completely, bought another starter,while I was fitted it I noticed a poor connection on the main earth lead, repaired that and its been spot on since. So check all the earths thoroughly before buying another starter!

Fixanything

Original Poster:

222 posts

130 months

Friday 30th April
quotequote all
Made up some nice battery to starter motor cables (Braided copper earth/ground with crimped and soldered terminals & +12v cable) and connected in parallel with the original cables. Turned key........ No improvement, did not crank unless I manually moved the crank off the compression phase !

Connected a jumper cable between the spade terminal on the starter solinoid and touched it directly to the positive terminal on the battery and it cranked faster than any car I have ever owned every time, no matter what position the crank is in. GREAT.

I guess I just need to follow the wire back to find we're the weak point is.

Is there a diagram that shows what & Where the different relays are ? Specifically the starter relay ?

Cheers

TwinKam

1,903 posts

62 months

Friday 30th April
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Just pull each relay in turn until you get no response whatsoever from the starter...

Fixanything

Original Poster:

222 posts

130 months

Friday 30th April
quotequote all
Found the route cause

Along the back of the bulkhead some PO had put an in-line 35amp fuse on the 12v wire from the starter relay to the starter solinoid not only was the fuse and fuse carrier very corroded but it had been spliced in by just twisting the copper wire ends together!

I removed the fuse and holder, made the connection good, tried starting and it worked every time.

Sorted.

Penelope Stopit

8,718 posts

76 months

Friday 30th April
quotequote all
Fixanything said:
Found the route cause

Along the back of the bulkhead some PO had put an in-line 35amp fuse on the 12v wire from the starter relay to the starter solinoid not only was the fuse and fuse carrier very corroded but it had been spliced in by just twisting the copper wire ends together!

I removed the fuse and holder, made the connection good, tried starting and it worked every time.

Sorted.
Nice fix

One of life's mysteries as to how the solenoid crank wire circuit decided to have a volt-drop large enough to prevent the pinion engaging only when the flywheel was in certain positions. As you no doubt know, the flywheel doesn't turn until after the starter pinion has engaged

It sure is a good one

This video is funny, someone forgot to show the solenoid pull-in coil circuit, the solenoid worked when it couldn't






Fixanything

Original Poster:

222 posts

130 months

Friday 14th May
quotequote all
I suspect in reality it was more random positions than specific positions and was just a matter of luck due to the dodgy 12v connection being marginal in its ability to supply adequate volts/amps to the solinoid in order to hold a strong high current connection. Using a wrench to rotate the engine each time sure felt like it was on the compression stroke and moving on to less resistive area of the crank cycle before it would crank/start again, I guess an engines natural stopping position would be on a compression stroke.

Or as you suggest could just be mysterious.

timelord

305 posts

250 months

Saturday 15th May
quotequote all
Ah! You had an airlock in the wires you just needed to bleed the electricity throughnuts