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How ro measure the generator/alternator on a 1998 Elise S1 Rover K? And a few more issues/wishes. - Engine & Ancillaries/Gearbox - The Lotus Forums #ForTheOwners Jump to content

How ro measure the generator/alternator on a 1998 Elise S1 Rover K? And a few more issues/wishes.

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Hi all,

I am normally an Esprit guy, but this time around, I am asking on behalf of a friend who recently bought a Series 1 Elise (Rover K engine), as He is having a series of problematic issues, and trying to repair, overcome these.

1/ So, first of all, he's got the impression, that the generator, or alternator, is not working correctly.

Normally, on my cars, I would start off by having the engine off, ignition off, and then measure the Voltage between + and - on the battery.

Next, I would repeat that, but with the engine running, to get a picture of the performance of the generator. There are of course, wires and earth wires in between, but still there should be a measurable difference between the two readings.

He is right now using a normal closed type H2SO4 acid battery.

So, what is the the expected normal voltage to see on these cars? and how many Volts are to be expected when running?


2/ Secondly, are there any known issues of the generator/alternator on these cars melting down for example the voltage regulator, such as can happen on the Esprit cars? The black goo on the diodebridge melts and drips into the alternator, preventing the spinning copper parts to be read and send voltage to the regulator's diode bridge.


3/ Does anyone know if there's a compressor kit that can be installed on to this Rover K engine? No turbo thanks. Only compressors, such as for example a twin scroll or others. He would like the car to have more omps at low revs, not needing the engine to be spun up to 5000 rpm to deliver. The car is currently running some emerald box, seperate injector houses etc. Apprx. 185 hp. He did not tune the car, but bought it in this state from a previous owner who had driven the car, but never done anything to the car.


4/ The exhaust manifold is flapping pretty loud when cold, slowly becoming a bit more subdues when warm. Have to be corrected. Any know issues on this? 

And any good advice before risking breaking the studs? (method of releasing them).


All advice are much appreciated.

Kind regards,




Nobody does it better - than Lotus ;)

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  • Gold FFM

This is not going to too helpful.  I recently had my alternator replaced when replacing the water pump. So this is a part that wares.  

i could do a voltage test in the way you described this evening so you can compare results.  Would that be helpful?

undoing corroded bolts.  Not an expert but if you watch George kerelis youtube channel working on his esprit he uses a product like wd40.  If that fails a heat gun is then used. I get the impression wd40 can take some time to take effect.


let me know if you want a voltage comparison check.  Mine is an s2 k series enginr.

All the Best


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  • Gold FFM

Also try to measure the current going from the alternator to the battery. If the battery isn't completely charged you want to see around 20A from a healthy alternator at idle. I just fitted a rebuild one to an Esprit and that's giving 30A, as is the one in my Range Rover. A modern, electronically controlled alternator can put out as much as 100A at idle if there is a large current draw from electric seats etc.

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.


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I've used one of these very useful 

Place a Cross the battery and type on what type of battery you have ie lead acid or EFB or AGM.

And then punch in the batteries CCA and it will test standing CCA and CCA on start up.

Standing voltage and starting voltage and then place a load on the system via headlights and interior fan etc and it will also check the ripple so you can see if the diodes are ok.

about £35/£40 20210905_153932.thumb.jpg.aec50fd9a60628d9bf1c9abe37d7cf6a.jpg

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