Starter slow to crank at times?

[Condor]

Hi All. (3b 1991 Coupe) I fitted a reconditioned Bosch starter a couple of years back to replace the original, from the begining at times the starter sounds slower than normal, if engine doesn't fire immediately and I turn to ign key off then on again the starter most of the time turns the engine over at the correct speed, the Bosch battery is fine, I had it tested, I've replaced the ignition switch, is there a relay somewhere which may be causing this to happen? Any ideas what maybe causing this? Thanks in advance.

[K Simmonds]

The starter's high amp supply is powered directly from the battery and alternator so I'd start by checking all the connections and grounds in this circuit, the ignition switch just activates the motors control wire so as long as it's working shouldn't be a problem

[Condor]

Thanks K Simmonds, I've checked ground cables,(I'll check again when I get time) does the ignition switch switch the solenoid direct ..ie no relay in that circuit? could the cables going to the alternator cause the problem? I was wondering if theres a main relay which disconnects other heavy loads (like lights, heater blower motor etc) when ign switch is turned to start to allow the starter to get top voltage/current ..? I've spent several hours on this starter problem over months now on and off.. ...Cheers Al.....

[K Simmonds]

No problem Al, happy to try and help, sound like an annoying issue but should be an easy fix.

There's no relay in the system to disconnect other loads, the light's will dim considerably and the blower motor slow's right down when trying to start the car with them on but they remain connected. I always switch off all electrics just before shut a car down, it's easy to forget about the blower and rear screen heater both of which draw a fair amount of current, however this isn't essential I simply do it out of habit to make life a bit easier for the battery.

The most likely causes of a lazy sounding starter are either a problem in high Amp circuit, so bad grounds or positive connections or an issue with the starter itself which shouldn't really be a problem with new a Bosch unit. Normally it's either a bad ground or poor battery or starter positive connections which I'm guessing you've checked... It's also worth cleaning the live's on the back of the alternator as well as checking the condition of the brushes on the voltage regulator but this shouldn't be the issue, I'd expect it always sound too slow if that was the case. The alternator doesn't produce much power until the engine fires up, the starter depends directly on the battery being in good condition for it's power at start up.

Have you tried bridging the connections on the starter with a short screwdriver from cold to see if it spins any faster? If it does then there's a poor connection between the solenoid and the motor which should be an easy fix.

How old is the battery and have you got another one from a different vehicle you could try to rule it out completely? Sometime's an older battery will pass an output test but still cause this issue especially if you only do a lot of short journeys. If you don't want to disconnect the battery from either vehicle to retain stored info like stereo code etc then simply hook up jump leads to see if the problem goes away, if it does then it's the battery or it connections.

[newsh]

Kit, I think my 3B has an X relay, turns stuff off while cranking?

[K Simmonds]

Kit, I think my 3B has an X relay, turns stuff off while cranking?

Thanks John, I can't recall my 3B having one but it's been 10 years since I had that car so happy to be corrected... Do you know which No it is so Al can check his?

I still doubt that circuit is the problem, as long as the solenoid is getting triggered the starter should see direct battery power. The only other thing's that require power while cranking are the fuel pump, ECU and ignition. The fuel pump is fused at 15 amps so shouldn't be drawing much power, I guess the coil require's a but of juice but if that was failing I'd expect there to be other problems.

[K Simmonds]

Just had a look at the Hayes manual for a 7A Coupe which should share the same starter arrangement as a 3B. It appears there is a relay, but it still shouldn't be causing a lazy starter....

I'll be down the workshop this afternoon and see if I find my old 3B fusebox cover which should give it's location unless it's under the dash.


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[newsh]

Relief relay
In the fuse box, back row, second from the right.

[Condor]

Relief relay
In the fuse box, back row, second from the right.

Hi Newsh, I think I read somewhere about ''a relief'' relay, like you mentioned it temporarily disconnects loads while starter is engaged.. I was wondering if this is the case and that relay is playing up? I will check the alternator connections when I get time.. thank you all for all your suggestions.. most appreciated.. would anyone know part number for 3b passengers door part which I believe has 2 micro switches in it.. there are various on AutoDoc... but I need a part number .. Cheers guys... regards Al....

[Condor]

No problem Al, happy to try and help, sound like an annoying issue but should be an easy fix.

There's no relay in the system to disconnect other loads, the light's will dim considerably and the blower motor slow's right down when trying to start the car with them on but they remain connected. I always switch off all electrics just before shut a car down, it's easy to forget about the blower and rear screen heater both of which draw a fair amount of current, however this isn't essential I simply do it out of habit to make life a bit easier for the battery.

The most likely causes of a lazy sounding starter are either a problem in high Amp circuit, so bad grounds or positive connections or an issue with the starter itself which shouldn't really be a problem with new a Bosch unit. Normally it's either a bad ground or poor battery or starter positive connections which I'm guessing you've checked... It's also worth cleaning the live's on the back of the alternator as well as checking the condition of the brushes on the voltage regulator but this shouldn't be the issue, I'd expect it always sound too slow if that was the case. The alternator doesn't produce much power until the engine fires up, the starter depends directly on the battery being in good condition for it's power at start up.

Have you tried bridging the connections on the starter with a short screwdriver from cold to see if it spins any faster? If it does then there's a poor connection between the solenoid and the motor which should be an easy fix.

How old is the battery and have you got another one from a different vehicle you could try to rule it out completely? Sometime's an older battery will pass an output test but still cause this issue especially if you only do a lot of short journeys. If you don't want to disconnect the battery from either vehicle to retain stored info like stereo code etc then simply hook up jump leads to see if the problem goes away, if it does then it's the battery or it connections.

I had the bosch battery tested when it started the problem when I fitted the new/recond Bosch starter, I tried a new Bosch battery but the problem still existed.. ..

[Condor]

Relief relay
In the fuse box, back row, second from the right.

Is it back row 2nd in from the right as you look in the fusebox?..got 213 written on the top..

[johne]

Unless you're trying to start the car with the headlights on full, heated rear window and fan motor on etc. the "relief" relay isn't going to make any difference to how the starter motor operates.

There's several relays with 213 on them in the car so just swap with one of those temporarliy to prove the relief relay isn't your problem.

[newsh]

Is it back row 2nd in from the right as you look in the fusebox?..got 213 written on the top..

Yes exactly, I'm sure it's not your problem though, I was just correcting Kit saying it didn't have one!

[K Simmonds]

Yes exactly, I'm sure it's not your problem though, I was just correcting Kit saying it didn't have one!

I never mind being corrected, I don't wish to spread misinformation intentionally... My brain does fart more often these days than it once did and I've become a little forgetful... That said it's really quite amazing it's still functioning at all.

I'm also 99.99% sure that relay is not the problem, assuming all the high Amp cables and connections are in order then as soon as that solenoid control wire see's 12V at pretty much any amperage it should almost instantly let the motor have full battery power via an un-fused non relayed direct circuit, which was kinda my point in the first place.

If it's not that then I'd have the starter off and bench check it.

I don't wish to put the *****s up Al but I've dealt with an early 80's big Merc four pot with K-Jet that was doing this as well point blank refusing to start hot randomly at work some year's ago, even with the jumper pack a fully charged brand new battery and Easy Start. After a whole day of F'in about testing all the electrics and fuel system my suggestion of a leak down test revealed a micro leak between the middle two cylinders.

We still don't fully understand why this was causing the problems to this day as it passed a compression test okay, though the middle two pot's were just a tiny bit down and it ran fine once it was away. But suffice to say I changed the gasket and rebuilt the head, that fixed all the weird problems the owner had been having for a couple years and it's still on the road to this day.

I very much doubt that's what's happening here though.