Topic: BMC glow plugs

pirate    -- Aug-16-2021 @ 10:19 AM
  In an emergency i.e starter switch faulty would it be possible to connect the glow plugs directly to the positive terminal on the batteries to get them to operate?


annville    -- Aug-16-2021 @ 11:23 AM
  Hi Andy Yes BUT! be very careful if using jump leads connect battery end first then plugs. there will be a big spark do make sure the area is well ventilated, better to connect/bridge the two large terminals at the heater relay and dont leave connected for to long. Why do you need to do this? John

This message was edited by annville on Aug-16-21 @ 12:23 PM

Dilligaf    -- Aug-16-2021 @ 1:16 PM
  When I had bmc's there wasn't any relay for the heater plugs just big spades on the back of the switch that did them direct, I used relays when I changed the engines.

Formerly 'LeoMagill'

pirate    -- Aug-17-2021 @ 9:05 AM
  Thanks guys thats what i thought.
John i was asking cos was out on parents narrowboat at weekend and the newly replaced (by boatyard)glowplugs failed.
Dave this had a relay which is probably what failed but had nothing to bridge it with.

Not sure of set up on my Alpha will check at weekend.



MandA    -- Aug-17-2021 @ 10:37 AM
  Was the carbon build up cleared out  of the glow plug holes prior to fitting new, it was a very odd sized drill that was needed according to the service Manual it made a huge difference to the efficiency of the glow plugs on the 1.5 in our last boat.


L'sBelles    -- Aug-17-2021 @ 10:58 AM
  John wrote "be very careful if using jump leads connect battery end first then plugs"

Sounds like an ideal way to weld the leads to the connector or another part of the engine or earthed part of the structure to me.

Whenever connecting flying leads to anything you should always connect the "dead" end first then the "live" end whether 12v, 24v or 240v to avoid accidents.

I know you will worry because batteries are known to release hydrogen and you don't want to replicate the Hindenburg disaster but the quantities of hydrogen are small, the battery compartment will be open to access the terminals so what hydrogen there is will be vented quickly, and the batteries will not be charging (when most gassing occurs) because at that point the engine isn't running.

warrior    -- Aug-17-2021 @ 11:08 AM
  A cheap little trick to clear glow plug holes is to use the Question mark shaped wire hook from a coat  hanger.  Works every time and is exactly the diameter required.  I have done it loads of times.   Smile  


MandA    -- Aug-17-2021 @ 1:48 PM
  I think I am correct in saying you need a 11/64 drill bit to clean out the  glow plug holes it does give you the size in the manual,it made the starting of my last boats .1.5 so much easier especially in the winter,only do it by hand though.


essexboy    -- Aug-17-2021 @ 7:58 PM
  I always coat the drill in grease to catch at least some of the carbon, clean the drill between each cylinder.

George Sims

Dilligaf    -- Aug-18-2021 @ 6:56 AM
  A 4.3 or 4.4 mm drill should be an easy find on fleabay, doesn't need to be anything special, treat yourself to a pin vice and it will be even easier.
Get engine hot before removing and they will likely come out easier, if starting is an issue in the first place blow a heat gun into the inlet manifold.

Formerly 'LeoMagill'

L'sBelles    -- Aug-18-2021 @ 8:33 AM
  Dilligaf wrote "if starting is an issue in the first place blow a heat gun into the inlet manifold."

Or alternatively fit a flame thrower like the contemporary Perkins diesels have!  Smile

pirate    -- Aug-18-2021 @ 8:50 AM
  HI all

The holes were cleaned by the yard and the plugs worked well for first 2 days so it looks like it will turn out to be the relay hopefully !! They are checking this week, thanks for all the advice i will check my set up this week and make sure I have gear ready should same happen to me.


annville    -- Aug-18-2021 @ 9:55 AM
  Hi Andy You could use a open ended spanner to connect the terminals, the ideal way is to connect a meter or large wattage bulb across the plug terminal to earth to check that there is currant at the plug, also make sure by measuring the length of the electrode as there are different lengths  for the same engine depending on build date, engine no should be used along with checking against the old ones if not original head fitted, and connecting a lead to a battery terminal that will spark is a recipe for a explosion, battery gas has a wide spectrum for ignition, this is lead acid one's not other types. John

pirate    -- Sep-3-2021 @ 4:59 PM
  Just an update

It turned out to be relay that was faulty so all good now.

Will have on board a short cable with connections so can bypass if happens again.



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