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car alternator belts - damage ?

Channel Hopper

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#1
the car I drive at present is a Mitsubishi Galant petrol 2litre inline four from 2000. Aircon as standard, there being two belts from the pulley on the crankshaft. Its done 80k miles in four years with no real problems.

Two nights ago the alternator belt gave up the ghost and self destructed. It had been reported as worn at the last dealer service, but the belt was not replaced at the time as there were none in stock.

The charging light came on the dashboard, and since I was on the motorway, it seemed preferable to travel on (using parking lights to save battery charge ) until the next exit, a few miles from home.

The car seemed to have no problem with doing this when on the motorway, and after I had confirmed it was simply the belt - stopping to check under the bonnet - I restarted the engine, and the oil light came on. I chose to walk home rather than risk the chance of damage, (the company issued recovery policy from EuropeAssist) is as much use as an ashtray on the motorbike.

Ive since ordered and fitted the alternator belt and everything runs fine, no warning lights on the dashboard, but is there any link with the lack of charging andthe oil light coming on ?. Does the belt also drive the oil or water pump ? or anything else that might bugger up an engine for fifteen miles of motorway driving ?

The drivers manual with the car confirms the car should be stopped immediately the light comes on , and a service agent called, but it does not confirm if the engine should also be turned off until the repair is carried out, suggesting running on for a few miles is not likely to do damage to any engine component.
 

brewby

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#2
I'm only a diy'er but it is possible that the oil pressure sensor takes its power from the alternator and not the battery as it only goes out when the engine and alternator are running and the oil pressure is ok. this would not nessesarily work on battery power alone.
Oil pumps are usualy driven from the cam or crankshaft and therefore are mechanicaly driven not belt driven.
hope this helps
Brewby
 

Channel Hopper

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#3
On the bikes I have , the oil and water pumps are geared directly inside the engine and so I would agree with you.

The oil light only came on once Id retarted the engine after checking under the bonnet, and so the sensors that govern this may have required a shutdown to initiate. On starting the car all lights come up as the manangement system carries out a check

I suppose i need an answer from a mechanic that has worked on this particular engine design, there is a third pulley that runs from the alternator belt, and I dont know if its an idle one, or one that has something critical on the other end.

Interesting to note as well that in the manual , it confirms the charging light is indicative of an 'abnormality in the charging system' only on the petrol engine, but on the diesil engine variants claim that the belt also has something to do with braking.
 

brewby

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#4
The oil light would stay on because the alternator was not running after snapping.
The other pulley maybe for power steering or a tensioner as on my volvo because flat belts sometimes need a tensioner whereas a V belt does not.
Its possible that on diesel engines that the belt powers the vacuum pump used to supply vacuum to the braking sysem servo and air inlet for the injectors as the crankcase does it on a petrol engine.
The management system will take its power from the battery as will the ignition system
Regards
Brewby
 

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#5
Thanks - you have put my mind at rest
 

Channel Hopper

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#7
Whereabouts are you ?
 

Channel Hopper

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#9
if its also windy then you will need something substantial to hold it on station, not your usual diseqc motors here
 

brewby

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#10
I have a stab hh120 which will be coupled to an 80cm dish in a fairly sheltered area, it will be mounted on 12" t&k brackets with a 40mm steel scaffold pole.I think it should be stable enough, I'll let u know when I get to put it together next weekend.
Cheers