Very hot wiper motor !

[taylormj4]

Hi all,
So this morning went to start up the 450 to get to work but no wiper function on any of the switch positions.

Checked all fuses. Wiper relay can be heard picking up when the column switch is moved so suggests switch is working and relay is working. The washer jets still come on and the relay is heard to pick up for several seconds and then drop out so further evidence feeds, relay and switches are working.
Went to motor to waggle wiring and park switch to see if that would help, no joy. Went to inspect in fuse panel area for a bit, leaving switch on continuous position. After 10mins or so went back to motor for a final wiring wiggle and found motor casing to be so hot I couldn't touch it.

Rapidly turned off switch and pulled fuses (just in case motor still trying to park) and then finally disconnected the motor feed.

Motor obviously has feed but is stuck so windings now acting more like a heater !
Tried assisting the motor by lifting the blades from the screen and then manually assisting them to move but no use. Presume this is a dead motor or a failed gearbox.

Any ideas anyone ?

[FlipFlopGriff]

You did the right thing removing the power to it.
Speak to Adrian Venn (07956 956042) who can rebuild it for you.
FFG

[freeclimb]

I do not think that hints going elsewhere help DIYers.

I would say: The wiper gear box looks like blocked.
Probably the "bearings" outside to the wipers.
Common problem on any car.

Are you able to disengage the Motorunit from the gear?

It´s pretty simple.

Unscrew fitting of Wipermotor (A) (There is a second one behind the motor)

Please don´t amuse about my customized Left-Bonnet-Damper.

Then release the big nut between Motorunit and Wipergear (red arrow).



Open diecast of Motorunit gear (around 5 or 6 hex bolts)


Disengage Wipermechanics:
1.) pull clip and washers beneath (keep them carefully)
2.) release wiper gear from Motor unit


Then you have the motor itself:


Try to run it.

Any changes? Positive Changes?
Yes? Then you have to revise the wipergear.

If not: The you have to revise the Motor.
(well explained in forum)

Sleep well
freeclimb

Edited by freeclimb on Thursday 1st August 01:17

[carsy]

As above i bet one or both of the wiper spindle boxes are siezed. Pull out the drive gear to them and then see if they will turn by hand. Should be nice and free.

http://www.track-days.co.uk/gassing/topic.asp?h=0&...

Edited by carsy on Thursday 1st August 09:11

[taylormj4]

Folks,
Thanks for the tips. I had the motor out a few times last year to try to improve the running and to investigate the intermittent, intermittent wiper setting ! I followed some PH advice and lubricated the drive linkage and rotated the wheel boxes 180degrees to a less worn bit, cleaned and regreased the gearbox etc.

The car has been a daily drive since 2001 so the wipers get used a lot, including only last week. I'm expecting it to be wear or failure rather than seizing. I fitted the Leven wiper arm/washer kit several months ago and they put a lot more load on the motor I think, as they actually wipe the screen better so that may have caused something to go.

Will be stripping the motor / gearbox tonight and will post results with pics if I can.

I will keep Adrian's details handy, thanks.

[taylormj4]

OK so I stripped the motor/gearbox assembly last night and found this:

The gear and worm had gotten out of sync and jammed the gearbox. This appears to have caused some damage to a few of teh gear teeth and presumably the gear itself has lost material for this to happen in the first place. Also, I noted some play between the metal centre of the gear and the plastic outer that has the teeth. This is presumably why my blades have been travelling further than normal and hitting the scuttle at both ends of the wipe.





I think it will still work as is but it's going to happen again, so I'm looking for a new gear. Anyone know a supplier ?

Thanks.

[carsy]

If your going to keep the 29w i think there is only Adrian@ on here who can help. Those gearwheels are no more i'm affraid.

[taylormj4]

Hi Carsy,
Thanks for the reply. Are there alternatives to the 29W then ?

I looked at the 14W and SVC said it would be a replacement but the longest travel gear they come with is only 130degrees, whereas the Chimaera needs 170 degrees.

Have sent Adrian an email; awaiting a response.

Thanks.

[FlipFlopGriff]

taylormj4 said:

Hi Carsy,
Thanks for the reply. Are there alternatives to the 29W then ?

I looked at the 14W and SVC said it would be a replacement but the longest travel gear they come with is only 130degrees, whereas the Chimaera needs 170 degrees.

Have sent Adrian an email; awaiting a response.

Thanks.

Best to call him. He's a conversation person.
His number is in my previous post.
FFG

[carsy]

taylormj4 said:

Hi Carsy,
Thanks for the reply. Are there alternatives to the 29W then ?

I looked at the 14W and SVC said it would be a replacement but the longest travel gear they come with is only 130degrees, whereas the Chimaera needs 170 degrees.

Have sent Adrian an email; awaiting a response.

Thanks.

As far as i could see the only alternative is the 14W. unless that is you want to re design the whole setup with something more modern. The 130 degree wheel doesnt quite sweep as far but is perfectly usable.

[taylormj4]

carsy said:

As far as i could see the only alternative is the 14W. unless that is you want to re design the whole setup with something more modern. The 130 degree wheel doesnt quite sweep as far but is perfectly usable.

Hi Carsy,
Have you tried the 130 sweep then ? Sounds to me like you'd have to either sacrifice some of the driver's side screen being wiped or have them parking right in the passengers view, or a bit of both.

[debaron]

taylormj4 said:

OK so I stripped the motor/gearbox assembly last night and found this:

The gear and worm had gotten out of sync and jammed the gearbox. This appears to have caused some damage to a few of teh gear teeth and presumably the gear itself has lost material for this to happen in the first place. Also, I noted some play between the metal centre of the gear and the plastic outer that has the teeth. This is presumably why my blades have been travelling further than normal and hitting the scuttle at both ends of the wipe.





I think it will still work as is but it's going to happen again, so I'm looking for a new gear. Anyone know a supplier ?

Thanks.

Have you checked the top of the worm? There should be a little captive housing to keep the worm shaft in place and also check the adjuster nut on the top of the housing. Should be no play obviously. If there is then that could have let the housing slip and then you're where you are now. Very surprised if the nylon gear wheel has lost enough material for it to jump out.

HTH

Ryan

[taylormj4]

debaron said:

Have you checked the top of the worm? There should be a little captive housing to keep the worm shaft in place and also check the adjuster nut on the top of the housing. Should be no play obviously. If there is then that could have let the housing slip and then you're where you are now. Very surprised if the nylon gear wheel has lost enough material for it to jump out.

HTH

Ryan

Thanks Debaron,
On further inspection the drive gear doesn't look that worn so you could be right. There must be some play somewhere. The worm seemed well located but the drive gear bearings or its shaft may worn.

I spoke with Adrian Venn but he told me it was impossible for the the gear and worm to get out of mesh. I asked him to look at the pics on PH that showed this had happened but he remained adamant that it couldn't happen. Unfortunately, Adrian is not prepared to sell DIYers parts and only does complete refurbishments. To be fair to Adrian, it sounds like he has invested in these motors and had parts made etc and you seem to get your monies worth (the case even gets repainted) but if you have a motor that has been maintained, doesn't need painting or new windings & magnets etc as I do, then it seems a lot when probably only a bearing or two may need changing. When the motor does pack up, £170 odd for a complete refurb seems OK but not right now.

Adrian was helpful with information and mentioned that the motor is a source of fire on the Chimaera as well as the well know engine bay fuel pipe problem. Suggests that the electrical protection is not configured correctly for the motor, which should remove power in the event of the motor stalling. Maybe an additional smaller fuse in the supply to the motor is required ?

[spend]

taylormj4 said:

Suggests that the electrical protection is not configured correctly for the motor, which should remove power in the event of the motor stalling. Maybe an additional smaller fuse in the supply to the motor is required ?

The motor supply is clearly fused (in the fusebox) on all the cars AFIK, the only questionable area I can see is the extra pulse to get off park for the wash/intermittent/swipe if that fuse has already blown (and the motor has seized)? ..but I'd guess that circuit is still fused ~ just never looked where it is fused...

[carsy]

taylormj4 said:

Hi Carsy,
Have you tried the 130 sweep then ? Sounds to me like you'd have to either sacrifice some of the driver's side screen being wiped or have them parking right in the passengers view, or a bit of both.

Yes i now have a 14w with the 130 sweep. As you say you can park them slightly higher if you want to , to help with the sweep. I personally dont have a problem with the 130. Its perfectly usable. Mine however doesnt see much rain.

When my motor siezed the fuse went immediately.

[taylormj4]

spend said:

The motor supply is clearly fused (in the fusebox) on all the cars AFIK, the only questionable area I can see is the extra pulse to get off park for the wash/intermittent/swipe if that fuse has already blown (and the motor has seized)? ..but I'd guess that circuit is still fused ~ just never looked where it is fused...

Hi Spend,
From memory, there are three 20A fuses related to the wipers and some also have other circuits off them such as brake lights and tail lights. Putting additional loads through a fuse, means you have to select a fuse that can cater for all being on, e.g. both brake lights on=approx 3.5A + wiper motor starting up. My suggestion was to insert an additional in-line fuse in the final supply to the wiper motor. This would not see brake light loads etc so could be rated just above the normal motor running current with an allowance for a brief burst of starting current. Locked rotor current is higher as no back-emfs generated and should blow a fuse within 10secs or so before enough heat is built up to damage the magnets or winding insulation. This did not happen on my car, which suggests the 20A fuses are not providing the intended protection.

[taylormj4]

carsy said:

Yes i now have a 14w with the 130 sweep. As you say you can park them slightly higher if you want to , to help with the sweep. I personally dont have a problem with the 130. Its perfectly usable. Mine however doesnt see much rain.

When my motor siezed the fuse went immediately.

Hi Carsy, what age car is yours? Do you have three 20A fuses in the panel that are related to circuits for the wipers, like mine ?

[Sardonicus]

You will probably find the cause of any fires will be down to the ign switch position 2 parking 12 volt + constantly trying to park the wipers obviously it don't understand jammed/seized just I want to park the buggers no stalk intervention here will change this and unless the fault turns into a short circuit or draws more than the fuse rating then its likely to just get hotter and hotter until something gives

[spend]

taylormj4 said:

Hi Spend,
From memory, there are three 20A fuses related to the wipers and some also have other circuits off them such as brake lights and tail lights. Putting additional loads through a fuse, means you have to select a fuse that can cater for all being on, e.g. both brake lights on=approx 3.5A + wiper motor starting up. My suggestion was to insert an additional in-line fuse in the final supply to the wiper motor. This would not see brake light loads etc so could be rated just above the normal motor running current with an allowance for a brief burst of starting current. Locked rotor current is higher as no back-emfs generated and should blow a fuse within 10secs or so before enough heat is built up to damage the magnets or winding insulation. This did not happen on my car, which suggests the 20A fuses are not providing the intended protection.

All sounds good but the CRUX of the matter is that the fuses will stand up to double their rating for limited amounts of time ~ if in doubt halving the fuse rating should work just blow quicker / last less time / under possible permutations....

Reducing fuse ratings & carrying spares is probably the easiest 'fix', you could even consider circuit breakers? Circuit breakers are also far more sensitive to restricting current to what you want ~ strip fuses are pretty hit & miss regarding what you consider the current they limit compared to what they say on the label...

[taylormj4]

Sardonicus said:

You will probably find the cause of any fires will be down to the ign switch position 2 parking 12 volt + constantly trying to park the wipers obviously it don't understand jammed/seized just I want to park the buggers no stalk intervention here will change this and unless the fault turns into a short circuit or draws more than the fuse rating then its likely to just get hotter and hotter until something gives

Motors generally draw around 6 times their current on start up or under locked rotor tests as no back emf is generated. Not sure whether the wiper is a series or shunt but generally it should be possible to rate the fuse to blow under a stalled condition. As spend states fuse rating are for 'continous' currents so a 20A fuse could well take 100A for a very short time. Although you can get quick blow and other types which have different current response curves. What we need to know is the normal load current for the wipers in standard and high speed mode in order to determine whether the 20A fuses are suitable. I could also do with a wiring diagram too if anyone has one. There are numerous standard circuits on the internet but not sure which TVR used.