Lotus Elan

Plus 2 Battery

PostPost by: potleyu18 » Tue Jul 09, 2019 7:37 pm

After a full engine re build i cannot get the engine to turn over fast enough to start even with the plugs out its quite slow in rotation.
Spark is there but not sure on the condition of the battery bought 18 months ago (Yusa) voltage across the terminals is 12.5 volts.

If its as suspected a faulty battery whats the best option available. Obviously space is not too much of an issue but want to keep the weight down if possible.

Other option is the starter motor is not man enough for the job any ideas on a high torque one?


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PostPost by: pptom » Tue Jul 09, 2019 8:21 pm

Recently went for an edge performance gear reduction starter, my inertia one would only just turn the engine over with the plugs out (rebuilt project which i'd never previously seen running). Tried 2 batteries and jumping it with leads from my other car which was running.
The old starter checked out, good electrical readings + brushes, just died from old age i guess.

Also just put a new battery on, odyssey pc680, not cheap but very small and light, no discernable difference from the massive van battery i was temporarily using
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PostPost by: mbell » Tue Jul 09, 2019 11:29 pm

I'd first try jump starting it, connecting via the solenoid and engine to confirm if it's a battery or wiring issue.

(If it starts you know it's battery or wiring, if it doesn't it's likely a starter issue.)
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PostPost by: 2cams70 » Wed Jul 10, 2019 12:19 am

If the battery may be suspect try and start it using the battery out of your daily driver temporarily. If it started OK with the same starter motor prior to the rebuild be very careful. Did you check the crankshaft for free turning during assembly? (i.e prior to installing piston/rods?) did you check it again after assembly of piston/rods? If bearing clearances are too tight it may have this effect. If it's tight don't just assume all will come good when the engine finally starts. Any metal to metal contact will result in a localized hotspot due to lack of oil film and will wipe the bearing surface. I know from experience that things are very critical here. During the first assembly of my engine I brushed some ARP bolt lube into the main bolt holes using the brush attached to the lid of the container it came in. When I assembled the crankshaft and before doing up the conrod caps I initially noticed a very slight bind in the crankshaft which improved after a couple of rotations. All the clearances had been checked prior to assembly and targetted to around .002". Being suspicious I pulled the crankshaft out again and lo and behold what did I find - a couple of very fine brush bristles from the ARP container embedded in one of the bearings! Once removed all was OK. I was anal of course and ordered a complete new set of bearings due to the slight damage done to one of them. Even though the bristles were only plastic the bearing material is very soft.
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PostPost by: Chrispy » Wed Jul 10, 2019 5:41 am

Are your earths good? Most of the troubles I've had around this sort of thing was because of electrical connections :?
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PostPost by: mikealdren » Wed Jul 10, 2019 7:36 am

As above, assuming the engine is ok, poor starting is usually down to:
1. A poor battery
2. Bad connections/earth
3. End of life starter motor

It may be daft but have you connected all the earth leads when you had the engine out? I once forgot years ago with a Viva and the engine tried to earth back through the clutch cable which melted and seized!

If you have a bad connection in the starter circuit, it is usually easy to find because the current is high and bad connections get hot, check for hot spots but mind you fingers.
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PostPost by: steve.thomas » Wed Jul 10, 2019 9:59 am

Check the main battery earth connection to the chassis under the boot floor - always seem to work loose after a year or so.
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PostPost by: potleyu18 » Wed Jul 10, 2019 2:56 pm

Thanks for the reply's,

The engine turned over freely before installing it, and was assembled using assembly lube. So don't have any concerns over tolerance etc.

Have run a separate jump lead form the battery negative to the engine with no discernible difference in rotation. Looks like the starter motor simply is not man enough to cope with the overall compression and tightness of the engine so have ordered a Hi torque one from Kelvendon Lotus.

Fingers crossed it works.

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PostPost by: Bigbaldybloke » Sun Aug 04, 2019 4:15 pm

Check you have the correct size gear on the bendix. Motor brushes may be worn or commutator may need skimming, check brush springs too. Check all connections for over heating after you?ve tried starting it, would highlight a bad connection.
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