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Hi everyone, I'm a bit of a car noob so help me out on this one please.

When I turn my lights on (not high beam), my car noticeably idles rougher. With high beams, or spotties on, it gets rougher again.

Is my alternator on the way out?

I never seem to have trouble booting up the car, but lately I've noticed that my car runs hotter (above 1/2 and towards 3/5) when its night time or late in the afternoon. The only thing i can correlate this with is the use of my lights.

Could this be caused by a dying alternator, and could a dying alternator cause slight overheating?

Thanks,

*EDIT: I also get a bit of a wobbley speedo on acceleration. Could the alternator or a ground be causing the dash to display temperature incorrectly? Or actually cause the engine to heat up?

Andrew

Its normal for the revs to drop when you put the lights on, lights use electrical power from the alternator/battery, the alternator gets its mechanical power from the engine.

A bad ground can cause your gauges to do funny things, possiably display a different temp.

But an alternator cannot make the engine overheat

OK cheers,

It is possible that the idle is too low, will knock that up, but without a tacho its all a bit annoying (stupid 80's eco crap).

You can actually see the needle jump a wee bit in the split second between turning the lights off to on.

It's just part of my endless guest to find out what is making my engine idle rough and overheat on long journeys. I would say it is lacking power too, but as i have never driven another L, i cant tell if mine is a slug, or if they are all slugs.

Next stop is thermo, but the overheating seems quite random. Like some days it will do it and others not. A better squizz around for vacuum leaks might be the go too. Is there a diagram somewhere where i can check the hoses against where they are meant to go?

Either way, it never gets into the red or too close, im just paranoid.

my l series used to do the same thing before it was turbo'd. Switch the lights on & the temp guage would move instantly up a little (only tiny bit), nothing to do with the actual engine temp just another subaru quirk!

If you have any doubts about the alternator most battery places do a free check but even better the RACQ will come round to your house or work and test install and do the lot plus with a great garantee

I wouldn't be doing that. Sure fire way of frying the alternator for good.
There are many tests to perform before that sort of extreme.
Has the car got a big stereo or high power lights?, usually the reason for stock charging system failure.

theclick wrote: i cant tell if mine is a slug, or if they are all slugs.

*Bumpty chuckles*
Idles roughly eh, have you checked the oil level lately?

400 watt amp but its been out for the last 6 months or so, so that is not the issue.

Oil level is sweet. Could probably use a change though :P
Another thing to add to the list :S

Ok. So i have swapped out the thermo, new plugs, new oil (which bought on lifter tick.. bah), and the heat problem around town seems to be solved.

THOUGH, on longish highway drives, the car still heats up to about 3/4 of the guage to the start of the red, but it doesnt happen around town.

I cant figure it out

get rad serviced.

Alright. Now i am really worried.

Opened up the radiator cap this morning to check the level, there seems to be a brown/dark orange mud like substance built up around the cap and for about 5cm below it. I recently topped up the coolant, and i seem to have lost a bit as well (about half the overflow bottle in half a month).

I am starting to worry this is a head gasket, but as mentioned above, it could be a blocked radiator. Any suggestions? I am meant to be heading to fraser tomorrow, but with all this going on, doesnt look like its going to be happening

get your radiator pressure flushed to get out all that nasty crap.

The muck could be oil however when summer comes along my RX usually throws a bit of that stuff at me after a reverse flush it seem good again and then the year after i get the core mechanically cleaned out.

Hmm yeah, I'm gunna get it flushed out after i get back from fraser...taking the jackaroo now .

If it does turn out to be a HG, im pretty much gunna part this thing out. It's given me nothing but trouble in the 7 months I have owned it. Last time i trust RACQ mechanical checks on cars. Belt went 30,000 early, oil leaks, a bunch of vacuum leaks. All sorts of stuff i should have picked up on the test drive and inspection but was too damn dumb. Ahh well