Heater Glow Plug Preheat

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Prototype
Not Quite Blue Yet
Posts: 14
Joined: Thu Jul 19, 2012 11:30 am

Heater Glow Plug Preheat

Post by Prototype »

My Dexta doesn't have the injector in the inlet manifold, It has been removed and blanked off with a bolt or primer pump near the fuel tap.

Odd thing is although the primer and injector are missing someone has gone to the trouble of rewiring the heater plug which heats up perfectly. I guess the plug on its own doesn't produce enough heat to make a difference?

Question is do I need to reinstall the primer, injector and pipework or is it not necessary with an engine with decent compression?

Bensdexta
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Joined: Mon Sep 15, 2008 12:59 pm
Location: N Wales

Re: Heater Glow Plug Preheat

Post by Bensdexta »

If she starts OK without the primer, I wouldn't worry.

Quite a few Dextas have no fuel primer or fuel feed to the inlet manifold. They just rely on the inlet heater to warm up the inlet air to be all that's required to start. But in very cold winter weather the fuel primer does make starting much easier. There's a few posts on here about it. :wink:
Bensdexta - 1961 working for a living!

Brian
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Location: Norfolk, England.

Re: Heater Glow Plug Preheat

Post by Brian »

The heater plug is not to heat the air in the manifold, it is to ignite the jet of diesel from the spray nozzle. The resulting flame is what is drawn into the cylinders and ignites the diesel from the injectors starting the engine.

Because of the engine design, indirect injection, some form of pre-heat is required. A good engine will start without it in warm conditions but as the temperature drops, with no preheat, starting becomes a problem. Prolonged cranking without firing washes the bores with diesel, the next step is to reach for the dreaded ether and before you know it, you have an expensive engine repair. :cry:

If it were mine I would sort out the preheat system.
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Brian

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