Starter bushes slow cranking when hot

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thejinx

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I am getting slow cranking when hot. Battery is good timing is correct. I am thinking bad earth or bushes.
1. On my 72 the earth strap goes straight to body by the battery tray. Should it earth to the engine?
2. How hard is it to change a bush or bushes?

Checked battery
12.85 engine off
11.5 whilst cranking
14.84 ticking over
So battery seems fine

OHMS 5. So I think I have answered my own question. Bad earth

Cheers
 
As per Sparky - what is your gearbox earth strap like and are the contact points clean and oxidation free? Otherwise the starter is earthing through points that shouldn’t be carrying any considerable current, and won’t carry it very efficiently.


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When I had the "slow crank when hot" problem I eventually changed the starter bush in the bell-housing (1600 SP)
I replaced my earth straps first, but it made little difference.

It's a 10 minute job to unbolt the starter, then wind a 12mm tap (IIIRC) into the bush until it bottoms out and pushes out the bush.
Then press in the new one, being careful not to drop it into the void.

I couldn't believe it would fix the problem, but it certainly did.

The theory (as I understood it, and which may be nonsense) is that when everything is heat-soaked and expanded, the starter shaft can move more side-to-side than when it's cold, especially in worn bushing. Even a small deflection massively reduces the magnetic field, which kills the torque.

I believe you can now get self-supporting starter motors that don't need the bush in the bell-housing and therefore won't suffer the same problem.

But the bush is much cheaper than a starter motor.
 
Refer to my article about this problem. Also change bush in endplate of starter motor . Bosch part number 1-000-301-001. Changed both bushes on my starter motor and now like new.
Robert
 
c705ncp said:
Refer to my article about this problem. Also change bush in endplate of starter motor . Bosch part number 1-000-301-001. Changed both bushes on my starter motor and now like new.
Robert


Hiya Robert, how ya doin???

Ozziedog,,,,,,,, long time no see. :mrgreen:
 
Hi Ozzie, been quite busy latley building and rebuilding engines.Owners buying not only VW's but other makes with nice looking paintwork and wheels but soon finding out engine knackered. Last one, type 2, smoking like a goodn and rattling at over 2500 revs. previous owner told him to set valves at zero and put thicker oil in.ha ha Turned out one of cam followers had nearly quarter of an inch side ways play and valve guides were well and truly worn out. Had to supply line bored case and fit new guides and cam followers. No smoke ,no noise and engine going like a sewing machine.
Robert
 
Love that one, setting valves at zero, that would be the sort of thing I would say to an apprentice to try and catch them out if I had an apprentice that is. So where did c705ncp come from ? Is it something you got up to in a car park (ncp) at some time ? :shock: :? :shock:

Ozziedog,,,,,,,, don’t be a stranger :mrgreen:
 
Being this has been reopened, i did another thread on this. basically the bush was knackered there was play in the starter motor spindle and the stop washer (or whatever) on the motor spindle was broken. As the other thread stated. pulled off starter removed old bush. fitted new one dropped it into bell housing, removed engine, retrieved bush, fitted bush, fitted new starter all is good.
o, oil in bell housing, removing engine again this summer to fit new seal and check end play

all in a day of owning a VW Campervan
 

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