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Discussion Starter #1
Made another brief run at the oil, water, gauges and heater motor.
No luck.
Verified that the gauge to sender wires do have voltage.
Tried grounding them but it made no difference to the gauges so the senders may actually be good.
Not sure how to get the gauges out to check the wire connections at the back side.
Seems unlikely they would both die at the same time so I suspect a bad ground?

Fuel gauge is working.
Varied indicator lamps and Tach/Speedo all work.

It may be worth mentioning that it appears the PO removed the original fender mounted fuel filter, no idea why.
Some funny business with the wiring and a relay as he also took out the fuel pump inertia switch which should probably be kept with the Spica in place.
I can replace them with unneeded parts from my '78 as it's using Dellorto's.

Really need to get to a Kinkos and get the wiring diagram printed large enough to read.

Dead heater motor looks even harder to get at, too bad I really need it.
Still trying to find a spot to jump it to try to get the fan to run.
Also looking at a way to manually turn the fan blade in case it is just stuck from sitting unused.
Appears to be a real PITA to remove the fan for replacement.
I do not do well twisting around under a dash for very long.

Tried to search the forum about this but did not find what I need as most post were for much newer or older cars and had few replies.
 

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Trained (ex)Professional, , 1953-2018 RIP,
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Seems unlikely they would both die at the same time so I suspect a bad ground? Fuel gauge is working.
Alfa daisy chained the grounds to the minor gauges with the fuel gauge getting the first ground. A ground wire was then run from the fuel gauge to the oil pressure gauge and then another ground wire continued on to the water temp gauge. An open in the ground wire between the fuel and oil gauges would account for both the oil and water gauges going out at the same time.
Still trying to find a spot to jump it to try to get the fan to run.
Under the left side of the dash, just to the right of the gas pedal, will be a yellow wire and a yellow/black wire going to the heater box. These are the high/low speed power inputs coming from the blower switch. You could either check for voltage at these wires with the blower switch on (verifying switch and wiring operation) or pull the wires off the heater box (simple spade connectors) and supply battery voltage to each terminal on the heater box. If no joy, checking the motor ground would be next. If the 79 is like earlier 105/115s, then the single black ground wire is attached to the painted trans tunnel with a sheet metal screw usually through the shift boot surround on the right side on the tunnel.
 

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Discussion Starter #3
So it seems I have power at the yellow and yellow/black wires.
Ground is even worse than the trans tunnel as it's crammed up under the dash.
Going to have to obtain more tools to get any chance of loosening and cleaning that ground.
I did try to jumper an additional ground with no effect.
Lots of black/ground wires going nowhere, or attached to the underside of the console, which of course is not grounded when it's off to check wires!

Speaking of wires to nowhere.
Some DPO added an on-off-on switch at the end of the console.
Of course they did not label it in any way for function.
So I followed the wires, up under the dash, along the drivers sill, and under the parcel shelf behind the seats.
Where they cross all the way to the passenger side and attache to NOTHING!
I've blown up the wire schematic and looked for a likely device that would fit there, nothing there makes sense for such a location.
So I think I'm safe to delete all this unless some one has a clue what should be there?
 

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Discussion Starter #4
Update time.
Finally figured out how to remove the oil pressure sending unit without having to pull the starter.
I was able to loosen it with a crow-fit open end.
Probably the first time I have USED a crow-fit to actually remove a part.

With the new sender in place I now have a working oil pressure gauge.
Not thrilled with the reading, sabotaged by the seller?
I have some more work to do before making any final judgements on this car.
Idle may be too low, I have some fuel injection issues to sort out.

Bought a self powered test light so that I may find out where the sending wire for the water temp has lost continuity.
Find that and I think I will have a full set of working gauges.
 

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You mentioned your fan motor as a project - I just replaced my '76's blower fan.

I managed to get it out and back in without removing the dashboard - thanks to clues from this post: 132059-s3-heater-fan-r-r-drain-holes

Two key items: there are 4 nuts (on semi-captive bolts) that can be removed (7mm, I think?) with some acrobatics under the dash, which allows the bottom of the heater fan tray to be removed - with the blower motor. Second, once it's out - DRILL HOLES in the fan motor pan to let the water out!! It's 99% likely that the fan motor is corroded from accumulated water.

I cut out the sound/carpet padding attached to the transmission hump around the base of the fan enclosure - it made it FAR easier to get in and out.

I got my replacement motor from Classic Alfa - since the British pound is kinda low compared to American dollar right now, the prices look nice there :) (Shipping is high though)
 
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