K Series Starting

[AdamQ]

I know this has been done to death, but even after a searching I'm at a bit of a loss.

K series Elise.  On turning the key to start the car, there's an initial effort from the starter motor to turn the engine which is very half-hearted - as if the battery was flat - then there's a pause for a second or two after which the starter motor turns the engine 'normally' and it starts. 

It seems to be slightly worse when the engine is hot.

I've done the starter relay modification and the battery is new and healthy.

I assume I've got some high resistance somewhere - does that sound right?

As ever, any ideas greatly appreciated ...

[SM25T]

I would start by undoing, cleaning and reconnecting all of the fat cables .. especially earths to chassis and engine. Are battery cells topped up if a serviceable liquid type. Have you measured battery voltage at rest and while cranking ?

[Jonathan Kay]

Edited: Crossed with Ian's.

... and the battery is new and healthy.

I'd start by checking that it's up to the job.

Do you have a multimeter?

What's the voltage across the terminals:

1. At rest
2. Minimum during cranking
3. At 3,000 rpm?

If you're using a duff battery to diagnose an electrical problem problem it can make things very difficult. And there are several reports of new batteries being duff.

...

Then check all of the relevant electrical connections: inspect, wiggle, disconnect, clean and reconnect. That's all the fat ones to the battery and starter including the engine earths. And everything in the feed to the starter.

... 

Any work done recently?

Jonathan

[SLR No.77]

I had similar with my SLR, swapped to a WOSP starter and it now turns over brilliantly. 

[Nick Bassett]

Stu,

Is this what you have fitted?

https://www.ccw-tools.com/WOSP-LMS430---Caterham-K-Series-Hitachi-PMGR-Reduction-Gear-Starter-Motor__p-39894.aspx

Also, did you have to purchase the multi-drilled end plate they mention?

Cheers

Nick

[SLR No.77]

I bought it from AES ... same but cheaper:

https://www.autoelectricsupplies.co.uk/product/1184

Stu.

[Nick Bassett]

Thanks - did you need the extra plate?

[SLR No.77]

The 3-bolt mount as supplied with the starter mounts directly to the existing spacer that's used with the Caterham install ... unless you don't already have the spacer fitted?

This one:

Stu.

[Nick Bassett]

Gotcha - thanks.

Yep I have one of those, so that's good to know.

[AdamQ]

Thanks for the replies.  Battery readings are

13.0V at rest, 9.7V during cranking and 14.2V when running.  Battery is a PVR Clubsport so not serviceable.

No work done recently.  

I'm working my way through the supply and earth connections - nothing that looks horrendous so far, but a couple more to go yet ...

That's interesting about duff batteries.  I ordered a Motobatt MB18U for a Seven recently.  It was duff.  The supplier said he'd send me a replacement, but he couldn't find one in his stock that wasn't duff.  I naively ordered another one from a different supplier and that too is no good.  It's a pity because they looked like excellent batteries for Sevens at a reasonable price (AGM for ~£70).

Thanks again ...

[Jonathan Kay]

13.0V at rest, 9.7V during cranking and 14.2V when running.

It's desirable to see at least 10.5 V during cranking and as well as the starter not getting enough oomph some electronics will drop out below that. Charging side looks fine.

Let us know if checking the connections helps.

I'd now also try starting with a good external battery jumped to the existing one. Usual precautions. Preferably in another vehicle with the engine running fast. Does that affect starting the Elise? (And I'd measure the voltage during cranking with that attached.)

Jonathan

I ordered a Motobatt MB18U for a Seven recently.  It was duff.  The supplier said he'd send me a replacement, but he couldn't find one in his stock that wasn't duff.  I naively ordered another one from a different supplier and that too is no good.

That is extraordinary, but it's assumptions that so often cause problems of explanation. As I've discovered today!

[AdamQ]

Just to 'close the case' so to speak, a new starter motor has cured the problem so I guess the original one was on its way out.

Thanks for all the help.

[Jonathan Kay]

The cranking voltage was 9.7V. What is it now, please?

Jonathan