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.

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.

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.

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.

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'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.

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?

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

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.

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.

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.