Talk Morgan

Main Fuse

Posted By: IcePack

Main Fuse - 09/02/19 04:41 PM

Interesting article in MOG magazine this month re main fuse corrosion & failure.
I did not know there was one as have never seen it, despite changing the battery fairly recently. In terms of servicing & preventative measures, what would my learned friends recommend to prevent/arrest any corrosion. My first thought is WD40, but I know long term it can actually attract moisture. Not sure of using ACF50 on an electrical component either.
Thanks
Posted By: +8Rich

Re: Main Fuse - 09/02/19 05:21 PM

I use Dow Corning MS4 grease as I have some left over from a previous occupation but this stuff is half the price with the same electrical properties. It also has the side effect of making the fuses easier to pull and replace.

silicon grease

In a similar preventative vein if you have the new type electronic pcb behind your dash it's well worth giving it a good coating of this conformal coating to prevent an expensive happening when the water finds it's way in there. conformal coating

This prevented a disaster when the licquorice tubing washer pipes fell off soaking it all on my 4/4 Sport.
Posted By: andymot

Re: Main Fuse - 09/02/19 05:38 PM

ACF50 is fine for electrics and is just what I'm going to use on the said fuse - after reading the Mog article.

I have used it on fuseboxes ( cars - not domestic!) and even PCBs on old Rover sat-nav units where water ingress is possible/likely.
Posted By: Burgundymog

Re: Main Fuse - 09/02/19 06:22 PM

Originally Posted By IcePack
Interesting article in MOG magazine this month re main fuse corrosion & failure.
I did not know there was one as have never seen it, despite changing the battery fairly recently. In terms of servicing & preventative measures, what would my learned friends recommend to prevent/arrest any corrosion. My first thought is WD40, but I know long term it can actually attract moisture. Not sure of using ACF50 on an electrical component either.
Thanks


You should speak to Cain who had a catastrophic failure of this nature on the Wolf Cafe Racer on an unlit stretch of the A14 at night.
Posted By: Gambalunga

Re: Main Fuse - 09/02/19 08:59 PM

Which fuse is this and where is it located?

Photo?
Posted By: Richard Wood

Re: Main Fuse - 09/02/19 10:30 PM

Originally Posted By Gambalunga
Which fuse is this and where is it located?

Photo?

On the latest +4 and Roadster (maybe 4/4) there are two approx 35mm2 red cables from battery positive terminal. One feeds stater motor directly and the other the common positive battery stud at front of car via an 80 amp maxi fuse in holder located close to battery. These two cables follow a similar path to the front, secured internally to wood frame underneath right hand door.

On mine the fuse is clearly visible when the battery access plate is removed.
Posted By: IcePack

Re: Main Fuse - 09/02/19 11:15 PM

+8Rich thanks for those links. Andy thanks for info on acf50.
I still have to find my fuse it seems well hidden. I will be lifting the tool tray next week & will have a look then.
Posted By: Gambalunga

Re: Main Fuse - 10/02/19 12:03 AM

Thanks. I too will check it out in due course.
Posted By: MOG 615

Re: Main Fuse - 10/02/19 08:24 AM

Originally Posted By +8Rich
I use Dow Corning MS4 grease as I have some left over from a previous occupation but this stuff is half the price with the same electrical properties. It also has the side effect of making the fuses easier to pull and replace.

silicon grease

In a similar preventative vein if you have the new type electronic pcb behind your dash it's well worth giving it a good coating of this conformal coating to prevent an expensive happening when the water finds it's way in there. conformal coating


Rich

Conformal coatings are a great idea providing that you are sure that the substrate is 100% clean. I used to work in the chemical cleaning industry and we sold far more chemicals to help people try to remove conformal coatings because they had trapped water or dirt behind them than we did cleaning fluid to clean the PCB in the first place. Because the coating is designed to stick , it is the very devil to remove entirely and most of the components ended up being used for spares only.

The other issue is that once applied any maintenance of the electronics is impossible, so dry joints etc became an issue.
Posted By: smudger1

Re: Main Fuse - 10/02/19 10:11 AM

Just a word of caution. WD40 has excellent insulating properties ( which is why people spray HT leads to stop electrical tracking in wet weather). If you get this on an electrical contact i.e. Fuse and Fuse Holder there is every chance you will eventually end up with a high resistance.

There is a copper rich grease available ( not coppaslip) which is specifically designs to preserve / prevent water ingress which is used in the marine environment but my old brain has ran out out of memory but I'm sure one of you can find it online.
Posted By: +8Rich

Re: Main Fuse - 10/02/19 10:24 AM

Originally Posted By MOG 615
Originally Posted By +8Rich
I use Dow Corning MS4 grease as I have some left over from a previous occupation but this stuff is half the price with the same electrical properties. It also has the side effect of making the fuses easier to pull and replace.

silicon grease

In a similar preventative vein if you have the new type electronic pcb behind your dash it's well worth giving it a good coating of this conformal coating to prevent an expensive happening when the water finds it's way in there. conformal coating


Rich

Conformal coatings are a great idea providing that you are sure that the substrate is 100% clean. I used to work in the chemical cleaning industry and we sold far more chemicals to help people try to remove conformal coatings because they had trapped water or dirt behind them than we did cleaning fluid to clean the PCB in the first place. Because the coating is designed to stick , it is the very devil to remove entirely and most of the components ended up being used for spares only.

The other issue is that once applied any maintenance of the electronics is impossible, so dry joints etc became an issue.


Andy

Interesting and valid points, when I was using it professionally it was on clean PCB's that were exposed sometimes to a marine environment and it was very effective but they were small replaceable units and non repairable.

The spraying of the Morgan PCB seemed to have saved my bacon (£500 if in stock) so I guess I was lucky in that the area was clean. Thanks for the information.

I did once try and clean off a PCB with this applied and it was not an experience I would care to repeat, I think the Morgan PCB are non serviceable items - I could be wrong.
Posted By: Richard Wood

Re: Main Fuse - 10/02/19 11:00 AM

It seems the main (maxi) fuse suffers from its damp and dirty location. It does/should have a cover though.



Checking the integrity of same and sealing out the damp should pay dividends without affecting the actual fuse contacts.
Posted By: Deejay

Re: Main Fuse - 11/02/19 12:43 AM

Seem to recall Dave W. finding an unexpected main fuse behind the dashboard on one of his Mogs a few years back, which was half out. He secured it with a cable tie.
Posted By: DaveW

Re: Main Fuse - 11/02/19 08:54 AM

That was Mr Bumble (2012). The main fuse was up in the top right corner under the dash.

On my Roadster, its next to the battery behind the nearside seat.
Posted By: Esprit

Re: Main Fuse - 11/02/19 11:35 PM

Dave, what is your recommendation for protecting this fuse please? We don't seem to have a consensus view on this thread. I assume / hope that failure of the main fuse is rare. Cain's experience sounds alarming!
Posted By: DaveW

Re: Main Fuse - 12/02/19 08:20 AM

I'm reasonably relaxed about this Tom. My Roadster has the main bank of fuses on the bulkhead. Recently I pulled them (eight) and just polished the contacts, which were slightly tarnished.

The bank of twenty fuses under the dash is hard to get at so I only go there when I have to, such as when the horns stopped working.

The single main fuse in the rear cavity I would only check if I was in there.

I found the problem under the dash of Bumble (2012 4/4 75th Anniversary) when I was tracing a hiccup in the engine over bumps. The fuse was half out of the holder and I added cable tie to hold it in. That wasn't the cause of the problem though, which was a loose connection on the engine.
Posted By: Rog

Re: Main Fuse - 12/02/19 08:55 AM

It does seem quite vulnerable just poked in the corner next to the wheel. Perhaps a squirt of acf50 before putting it in a small but rugged plastic bag and securing around the cables with a couple of zip ties might help?

Posted By: Richard Wood

Re: Main Fuse - 12/02/19 09:29 AM

Originally Posted By Esprit
Dave, what is your recommendation for protecting this fuse please? We don't seem to have a consensus view on this thread. I assume / hope that failure of the main fuse is rare. Cain's experience sounds alarming!


I don't think there can be one size fits all answer to fuse issues Tom. This due to variation on location of main fuse if one is fitted at all. All the latest cars have this fuse located close to the battery which makes sense as it offers protection to the cable as a whole. Ironic that there is a similar cable direct to starter with no fuse at all, although this is the norm. Fusing for the stater circuit would require a very large fuse in the order of 100's of amps and add unreliability. Fortunately the physical size hence rigidity and thickness of insulation on such cables, together with care in routing makes them less vulnerable.

It should be noted that only in the past few decades battery located fuses were added to cars in general. The fuse is there to protect the cable and attached equipment assuming as with most, they don't have their own internal fuse.

Careful routing and physical protection of cables is just as important as fusing them. Interesting to note my 55 year old Land Rover managed with just two 30 amp fuses and still retains the original loom although past its sell by date wink

Since the 90's most cars use blade type fuses which come in a range of physical sizes. Current Morgans use the mini type with the exception of the maxi battery fuse. Although blade fuses fair better long term than the various earlier types, they do benefit from simply being removed and replaced as the method of contact offers a self cleaning action. If the fuse slides in too easily its socket is worn or damaged. It may be possible to very carefully bend the socket contacts but otherwise replacement required. Dave's issue mentioned above springs to mind.

Finally be wary of squirting any product in the direction of fuse contacts if it has insulating properties.
Posted By: Esprit

Re: Main Fuse - 12/02/19 11:24 PM

Richard, thanks for taking the time to write such a full reply. I suppose there is always the risk of a failure, and additional protection and good maintenance are just reducing that risk. It could be that my X3 has a main fuse and I've been blissfully unaware of it but I feel a bit more vulnerable in a Plus 4 of course.
Posted By: Deejay

Re: Main Fuse - 13/02/19 06:48 AM

Originally Posted By Rog
It does seem quite vulnerable just poked in the corner next to the wheel. Perhaps a squirt of acf50 before putting it in a small but rugged plastic bag and securing around the cables with a couple of zip ties might help?


IMO, unless you can hermetically seal the plastic bag around the cables, (near impossible), then it is likely to do more harm than good. Any water that enters, or condensation that might occur will not be able to escape, and corrosion may be worse than if left open to the air.
Posted By: IcePack

Re: Main Fuse - 13/02/19 07:54 PM

Found it, same place as Rog found his. But having cut the cable tie attaching it to the other +ve cables, their is still very little slack to allow access to the fuse.
Cleaned it up with some ACF 50 & put a cable tie around it to hold it together & returned it to it’s original position with a new cable tie. (Stops it contacting the frame)
Posted By: Lowflyer

Re: Main Fuse - 14/02/19 10:27 PM

I've wrapped a plastic bag around my maxi fuse with a bag of silica gel inside (oh, and a spare fuse) Wether or not i ever remember to dry out the silica gel or not is another question....thjs post has just reminded me !!!!
Posted By: Esprit

Re: Main Fuse - 15/02/19 11:14 AM

Quote:
I'm reasonably relaxed about this Tom. My Roadster has the main bank of fuses on the bulkhead. Recently I pulled them (eight) and just polished the contacts, which were slightly tarnished.

The bank of twenty fuses under the dash is hard to get at so I only go there when I have to, such as when the horns stopped working.

The single main fuse in the rear cavity I would only check if I was in there.


Thanks Dave. I just realised I hadn't acknowledged your response so apologies for my bad manners. I've realised that this is probably also a feature of my other cars so the only issue is that the fuse may be less protected in the Morgan due to it's traditional construction. I would worry about completely covering it in any way that might trap condensation, so I think the preventative measures are to ensure it is reasonably shielded from dirt and water and then inspect it once or twice a year. Interesting though that protecting the car's electrical circuit might put the occupants at risk if the fuse pops at the wrong time and place!
Posted By: CBY

Re: Main Fuse - 15/02/19 06:07 PM

For remote boat (models) we insert the receiver in a small balloon (like used for birthday by exemple) in order to avoid water inflow.
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