VM glow plug timer/relay question

[outdoordan]

Hi all.

Rencently did some work on the top end of the engine. it's a 2.5 VM TD (95a) exaclty the same as fitted to the '89/90 range rover classic.

for reasons unknown (a short somewhere) the glow plug realy and a length of the wire from it to the battery burnt out.

The source of the short hasn't been traced... possibly the top of the dipstick (now well insulated) touching the buzz bar, possibly a nut shorting accross from the buzz bar to block, or something to do with liquid... anyway...

I've fitted a new relay and everything seems to be working fine. Before fitting it I soldered inline a slow burn 80amp fuse cos i dont want to for out for another relay if it happens again.

The question is... is an 80A fuse big enough. I seem to recall that glow plugs draw quite a bit each at first then that drops away at the end of the heating cycle.

can anyone advise.

Cheers

OD

 

[Rodger]

Hi OD,
I've only had dealings with one VM engine so sought advice and the best place to talk to are the guys at VM Specialist Diesels in Derby. Very helpful people, Sorry can't find their number but I found it originally via a 'net search.

Regards,

 

[outdoordan]

Thanks Roger

 

[SafariTecPeter]

Well. I told You in the past to ask Geoirge @ VM Specialist

As we have no idea whatsoever as to what relay You have fitted, I am hesitant to advise on the fuse size.
AFAIK the Range Rover Classic had an unfused feed to the relay.
& YES, the relay are consumables.

If I was to fit a fuse, I`d fit a blade fuse in a respective holder. With that size (80A) U are looking at mega fuses anyway.

Have U measured how much current it draws when glowing?

 

[StarCruiser]

Either measure the current when glowing with a DC capable clamp meter (tong tester) or look up the current drawn by each glow plug and multiply by how many you have.

Then size the cable and relay to at least the next size above the current drawn to give a good margin for error and fuse to protect the cable and relay to somewhere between the current drawn by the glow plugs and the current carrying capacity of the cable and relay used.

 

[outdoordan]

Thanks StarCruiser. what you said makes sense.