Hello, I have a 84 300cd and my #8 fuse keeps blowing. this problem has just started recently. I have read that for some, the brushes on the blower motor have been the issue. Mine however are in very good shape. I took the motor apart and found that the brushes(both) are not worn down.

My fuse box is not burnt or melted in the #8 area or any other area. My CCU has been functioning ok. I will take it out again and inspect it for broken solder.

I have read a number of threads but I haven't seen any other causes for this problem other than the brushes in the blower.

Any other suggestions or links that could help?

Did you do anything like clean up the copper armature which the brushes ride on ?
Otherwise it sounds like normal ' shorting out ' electrical testing to find the problem....

Always start be making sure the negative ground straps are clean and tight..
you may have three... pretty sure you have at least two.... engine to body, etc...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Failing motor bearings will cause this too. And the brushes/commutator can look fine.

Drag increases on motor due to bad bearings
Motor current goes up since it's doing more work
Fuse blows since the current is greater than the fuse rating (16 A is pretty close to the normal full load on the motor, that is why there is nothing else on the circuit).

There is a Bosch motor that was meant for a Volvo that will work in a 123 and is much cheaper.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for the replys.

Jay-Bob do you have any other info on that Bosch motor (i.e. which yr and make on the Volvo)? I try not to buy URO or any other off brand parts and the prices I've seen has been $130 to $300 for this motor.

leathermang I don't have any other problems with this car(I say that now) and I thought the blower motor was on that fuse by its self.

Found it about halfway down on the page

everybody better take care of their 123 blowers!!!

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for the link, very good read.

OK, here is what worked for me.

The brushes in my motor were fine and I had no issues with the wires, clamps or solder.

The little clip on the end of the shaft(under the fan) that keeps the shaft in the housing had a little end play(it only slightly back and forth). I am not sure if this was caused by me tapping the fan off or just 30 years of use. I add some light machine oil to each ends of the shaft(where the bearings are) and tapped the clip back down so there was not as much end play. I did not measure the end play before or after.

I reinstalled the motor and drove it for an hour without the fuse blowing. So I think I'm good to go.
Thanks for all the help

I think they increased the amperage for the #8 fuse from 16 A to 25A. At least that's the case for my car, an 82. The replacement fuse card has a 25 A fuse listed for #8.

__________________
Marshall Welch
Seattle, WA
1982 300D-T

Be careful here, the wire has to be able to support that.

The latest 123s did go to 25 A fuse, but they changed the wiring to match. I think on the 300D/300SD they upsized the blower to provide better air flow. I know my 83 240D had a 16 A fuse.

Earlier 123s do not have the wiring to support the 25 A fuse.

The 16 A fuse is correct for a properly functioning blower motor if the car came with a 16 A fuse according to its fuse card. If the 16 A fuse blows it is doing its job and should not be raised to a 25 A.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech