OK, about four days ago, the battery was low so I placed on the charger to charge which took all night. I then took the 1984 300DT to a local parts store to check the alternator, I was right, the read out showed low charging so it appears there is a problem with the alternator. Also, after the car heats up, a squeel or high pitched whine is coming from the alternator side of the engine. Does this sound like time for a new alternator?

Could be. But check the belt tension first.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Belt appears to be about right. I'm thinking of going ahead and replacing it as I can't even remember when it was replaced last.

I assume it's a 300D unless it is a stationwagon and that is a 300TD. Check your trunk lid.

It is a 300D turbo charged sedan. my bad, sorry.

Squeel is usually a slipping belt. I'd try tightening the belt before replacing the alternator.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

it doesn't squeel until the car is good and hot (about thirty minutes of driving).

Still could be a slipping belt.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sounds like the belt.
Dont forget the fan clutch starts to grab when it warms up & puts much more load on the belt.
Try turning lights/heater fan/ rear demister on & see if it squeals more.
Even if the belt is tight, it still can be warn down so the belt is sitting on the bottom of the pulley groove.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Have you got oil on the belt?

Is the belt too tight?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Once the belt has been taken care of, the voltage regulator simply unscrews from the back of the alternator. Compare the brush length on the new one to yours once removed. Alternators are not known to fail but the regulator is a wear item and will eventually need replacement.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

thanks for all the answers; I am going to check the belt tension. question: how do I measure for correct tension on the drive belts?

PS I'm using contitech belts.

The belt should not flex more than a 1/2 inch between the 2 pulleys. Once a belt is squealing, it usually glazes the gripping surface requiring replacement.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

I've been told here that the best way is to go and buy a belt tensioner - but I'm still using my rule of thumb => shouldn't twist more than 90 degrees on the longest length. (Use firm pressure between two fingers - not a big long pair of pliers!)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!