Short - burning!!!! 745

[ralnavman]

Oh dear, I decided to tax my 1987 MY 745 only for it to short!! Whilst I was in a petrol station!!
I'd appreciate if anyone can point me in the right direction but I think that the heater motor seized (I had it on to try & dry drivers side footwell.....another story yet to be resolved) and it just stopped. As I haven't used the car for a few months, thought it was just a bad contact.....I knew I was in trouble when smoke started coming from the scuttle and the wipers started off! Fortunately, I pulled the fuses and was able to drive it home ok. I think heater seized, started getting hot, burnt another wire, wipers. The heater fuse didn't blow surprisingly. Wonder if anyone else has had this and could point me where to look for burnt wires? Then I will have to look at wet floor, the heater valve isn't that old and since I changed, it has never been stiff/stuck since. Any ideas on that one too?

[nordmaschine]

Well, for what it's worth, wiper motor/wiring is on opposite side of the cabin to the blower motor and its wiring.

Take the scuffle panel out. Tray underneath might have been full of water, shoring the wipers...

[ralnavman]

Hmm, thank you....that is interesting. i will have to remove the scuttle

[stephend]

FWIW, I'd be slightly surprised if the heater fan seized without blowing the fuse: when the fan motor seized on a mate's Focus, it blew the fuse instantly. Is it definitely the right fuse?

[ralnavman]

With the mild weather, actually got to removing the heater motor & look at the wiring. Discovered that the motor is drawing too much which was my problem as I thought. And yes, it did NOT blow the fuse!! Which is of concern.

And as for the wiring not being close to the wiper harness........well they not only come together in the main bundle deep under the dashboard, their respective fuses are side by side in the fuse box!!!

Having removed the heater motor, for which I now need to get a replacement, I have reinserted the fuses & found that there is good supply to the heater motor plug, and intermittent wipe worked after feeling along the wires. But I couldn't find any melted together so I guess that there is a chance that the wipe function was just loose & that the smoke coming out of the scuttle was a wire getting hot & it was the nearest point for it to escape. Trouble is that all the wiring is so buried in under the dash!!

Hope this helps anyone else with a similar issue.

[Rversteeg]

Is the fuse amperage rating correct? Sometimes people replace fuses for higher amp rated ones to "solve" the problem of fuses blowing....

[monkeh]

Is the motor rusty? could the drainage channels have gotten blocked and allowed water to get into the motor. Check your carpets, if they're wet then it may have drained into the cab or the drain has unblocked itself.
You're lucky, Your motor just fried a bit of wiring, My motor went bad and took out the power module(resistor pack). Currently re-building the module...

Originally Posted by ralnavman

With the mild weather, actually got to removing the heater motor & look at the wiring. Discovered that the motor is drawing too much which was my problem as I thought. And yes, it did NOT blow the fuse!! Which is of concern.

And as for the wiring not being close to the wiper harness........well they not only come together in the main bundle deep under the dashboard, their respective fuses are side by side in the fuse box!!!

Having removed the heater motor, for which I now need to get a replacement, I have reinserted the fuses & found that there is good supply to the heater motor plug, and intermittent wipe worked after feeling along the wires. But I couldn't find any melted together so I guess that there is a chance that the wipe function was just loose & that the smoke coming out of the scuttle was a wire getting hot & it was the nearest point for it to escape. Trouble is that all the wiring is so buried in under the dash!!

Hope this helps anyone else with a similar issue.

[ralnavman]

Hmm, all interesting. Fuses are correct, but monkeh, as it happens, drivers side footwell is wet which I'm drying out. But where are the escape channel(s) as I thought it was on the passenger side, which is dry (I think!). I have to say that this is a car that is used infrequently but it is not that long ago that I replaced the heater valve or had the scuttle out. Having said that, I do seem to have a slight loss of coolant, only gone from max to just below min on the expansion bottle. Blower isn't rusty, the car has done over 220k miles!
Got another motor on the way after which I guess I will have to monitor it all, its just the carpet is a bit of a struggle to lift up

[ralnavman]

I could do with a couple of pointers as to where the drain channels are on the 745? I think that the passenger side is also a little wet but I've got plastic floor trays and they haven't got wet. Which makes me wonder just where the water is coming through.
I don't use the car that often which I must rectify, especially as I did drive it out today & it was just great. I mean, this car is virtually 30 years old & done over 232k miles!!

[monkeh]

You can pull the capets up by loosening and removing the front 2 seat bolts, removing the trim and lifting the carpets around them. I hate to say that, if they are wet on top, then theyre certainly going to hold a hell of a lot of water underneath. Youll need to trample the foam to squidge the water out.

Other points of water ingress would be the dreaded tinworm from underneath.

The drainage channels on a 740 without aircon are under the scuttle panel. Which means wiper removal etc...
As for heater drainage, Itll be a small rubber pipe with a plastic shroud over it, passengers side cabin. On the lowest point before it goes to the matrix. It might even appear over the transmission tunnel.
Im used to cars with a/c so I may be wrong.