Engine very slow to turn over

[oakleydad]

I have a 69 Elan +2 and the engine is very slow to turn over. I have jump started from a car with a running engine with about 13Volts measured on the solenoid, with a digital multimeter. When I try to start the engine the starter just about turns the engine over once then stops. The voltage on the starter motor side of the solenoid is about 6 volts when when the starter is engaged. Does this mean my solenoid is faulty? Any ideas greatly appreciated.

[mbell]

Have you checked the Engine to chassis earth strap for good electrical contact? The the chassis to battery connection?

[EPA]

I'm not clear from your description if the engine started when you fitted jump leads or if the 13volts was also at the starter side of the solenoid. Also if it did start, where in the circuit did you connect the jump leads?
If you check the battery side of the solenoid it should have the same voltage as the starter side when the solenoid is activated, if this is not the case then you have a faulty solenoid , assuming you were connecting your meter to the solenoid terminals and not the cable lugs.
If the engine turned ok and started when you used the jump leads then you need to work back from the point you connected the leads to find the problem.
Assuming the battery is ok it's likely to be the connection to the chassis as mentioned or the battery connections themselves.

Ed

[PeterK]

When my engine turned over over slowly, despite having fully charged the battery, I connected jump leads directly to the engine (Earth) and to the solenoid (live).
If there was still an issue, then I would look at solenoid and starter.

However, all was good, so I swapped the live lead to the battery and re-tried. If that had introduced an issue, then I'd have cleaned the battery connections.

Then I swapped the earth jump lead to the battery. For me, this is usually when the issue appears, indicating a poor earth somewhere. Eleven times out of ten, it was the battery ground connection to the chassis on my Plus 2. Paid it some attention and not had a further issue for a while.
Pete

[Famous Frank]

I've said this before so my apologies if you have seen my words before. These cars are give or take 50 years old. Most of the wiring harnesses have never been replaced. Assuming the battery is good and all the connections are good, it is very possible to have substantial corrosion within the wiring loom itself, especially within the positive and negative cable going to ground and to the solenoid and starter. My best friends Sprint would turn over slower but not horribly so. There appeared to be some green on the positive cable near the battery clamp. If the car had been sitting for a long time, you would have to crank the engine to get fuel to the carbs. When doing so, the positive cable would get very warm. We replaced that cable. Afterwards we cut off the insulation in numerous places across the length of the old cable. Guess what? It was green with corrosion through and through. The resistance must have been astronomical. Plus it becomes a fire hazard. Make the investment. Buy new cables and harnesses!

Frank

[oakleydad]

Thanks everyone for your suggestions. tried the jump start lead across the solenoid and that didn't make any difference. I new the battery was on the way out, but since I had been doing all these tests by jump starting from another battery in a running car I had reckoned on another problem. Anyway I went to Halfords this morning and bought a Yuasa 12V Silver Car Battery HSB057 (which only just fits - will need to do small modification to fix the battery in place) and guess what the engine turns over properly now - still took a little while to start with the help of "quick start". So I can only assume that the old battery was putting some additional load on the 12V supply when I was trying to jump start it.
Thanks again and a Happy New Year to you all and the kind offer to loan me a solenoid (btw I live just outside Basingstoke in Oakley)