Some diesels don't use glow plugs. Normally they are direct injection and
have higher compression than engines that use glow plugs. Requires a more
powerful starter, faster crank speed, they are harder to start but easier to
get compliance with emissions standards.

 

Engines with glow plugs are normally indirect injection. Plug heats the air
in a pre-combustion passage in the cylinder head and hot air ignites the
fuel. Easier starting (as long as the plugs work), lower injection pressures
on pump and injectors, harder to get emissions compliance and complete
combustion on cold start.

 

There are other systems as well. The new Ultra High pressure common rail
Cummins engines (like you find in your pickup truck) have a heating grid in
the air intake that heats the air in the intake manifold until the engine is
up to temperature. DO NOT DO NOT DO NOT USE STARTING FLUID ON ONE OF THESE
BECAUSE IT WILL FLASH BACK IN YOUR FACE.

 

The strangest system I've personally seen is on older Perkins 6-cylinder
engines used in construction equipment and larger forklifts. It had a
thermostatically controlled solenoid that bled hot fuel into the intake
manifold. This enriched the mixture and aided starting. It also smoked like
the devil and smelled like a refinery when the solenoid valve leaked - and
they all leaked after a relatively short while.

 

Glow plugs or not is an engineering tradeoff made by manufacturers depending
on costs, philosophy, and engine application, I don't think any Yanmar
marine engine I know of uses glow plugs, but the 65HP 4 cylinder industrial
engines do.

 

 

Rick Brass

Washington, NC

 

 

 

From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of David
Risch
Sent: Thursday, May 16, 2013 7:58 AM
To: CNC CNC
Subject: Re: Stus-List Starting a Universal

 

OK...I gotta ask.

I have a 1981 3QM30.  Purrs like a kitten.

No glow plug.  Start up cold just fine.  Just a few more cranks.    Before
this engine  I thought all diesels had glow plugs.

What gives?


David F. Risch
(401) 419-4650 (cell)



 

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