Diesel thermoSTART Question?

Dougal

Dougal

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Perkins 4108

The thermostart housed in the inlet manifold (NOT glowplugs). Pretty sure mine has a problem UNLESS this behavior is normal...

If I rev the engine, it 'squirts' a small but visible amount of fuel into the manifold. I don't think this is correct???!!! Thus its probably why i get a little excess dark smoke when throttling up.

The heater coil appears to work correctly. What I don't understand, is EXACTLY at what point it SHOULD allow fuel to flow through. Should it ONLY happen while actually cranking the motor?

I do have a spare;-)

Thanks
 
Dougal said:
Perkins 4108

The thermostart housed in the inlet manifold (NOT glowplugs). Pretty sure mine has a problem UNLESS this behavior is normal...

If I rev the engine, it 'squirts' a small but visible amount of fuel into the manifold. I don't think this is correct???!!! Thus its probably why i get a little excess dark smoke when throttling up.

The heater coil appears to work correctly. What I don't understand, is EXACTLY at what point it SHOULD allow fuel to flow through. Should it ONLY happen while actually cranking the motor?

I do have a spare;-)

Thanks
Click to expand...

If I remember correctly (and its been a long time) the pipe is plumbed into the fuel filter line after the lift pump and before the injection pump and the thermostart only opens when energised, so it sounds to me like you have a duff thermostart.
 
Dougal said:
Perkins 4108

The thermostart housed in the inlet manifold (NOT glowplugs). Pretty sure mine has a problem UNLESS this behavior is normal...

If I rev the engine, it 'squirts' a small but visible amount of fuel into the manifold. I don't think this is correct???!!! Thus its probably why i get a little excess dark smoke when throttling up.

The heater coil appears to work correctly. What I don't understand, is EXACTLY at what point it SHOULD allow fuel to flow through. Should it ONLY happen while actually cranking the motor?

I do have a spare;-)

Thanks
Click to expand...

Its usually on return pipe outlet fitting of filter head with non return valve, its only meant to open when warm, if its leaking then change it, I have know of engines being condemned because of the noise they make when this happens, if it gets worse then serious damage could be done. New plug just over a tenner.
 
As already stated, it comprises 2 parts both electric 1 is a coil that heats up and 2 is a non return valve that opens when warmed up, normally fed from the filter housing, and operated by holding the ignition key at position three (or a push button), Hold key/button for 20 seconds and then crank engine should start and key will return to position two, (sprung loaded) or release button, if not running smoothly then re apply the key/button, but not for more that 20 seconds or you may burn out the unit, I fear that this what you have done, a new one on ebay £10 or less.
 
I had to try several of these before I found a non leaker ! All genuine Delphi , probably make in a far eastern sweatshop.
Mine used to dribble in whilst running, sounded like a lump of coal going through the combustion chamber ! The height of the reservior can make a difference, if it is fitted with one !
 
From what I understand they should be fed from a reservoir, which in turn is fed from the leak off union i.e the one that returns excess fuel back to the tank, I imagine there is very little /no pressure there, but if your on the engine feed side then you will have pressurised fuel. Why not just top up the reservoir by hand, as I say ours is just a length of pipe straight onto "flame heater". If you are referring to "coal burning" then you obviously do not have Ford 360's as your base engine. LOL
 
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omega2 said:
From what I understand they should be fed from a reservoir, which in turn is fed from the leak off union i.e the one that returns excess fuel back to the tank, I imagine there is very little /no pressure there, but if your on the engine feed side then you will have pressurised fuel. Why not just top up the reservoir by hand, as I say ours is just a length of pipe straight onto "flame heater". If you are referring to "coal burning" then you obviously do not have Ford 360's as your base engine. LOL
Click to expand...

There were several ways in which Perkins and Ford installed these, the 4-108 was fed from the second out connection on the cav filter, the earlier 4-107 & 4-99 had a gravity fed reservoir, Ford Sabre had a reservoir that was topped up by the fuel return.
 
Dougal said:
So, mine being a 4108 and being fed from the CAV filter, will I have to bleed the whole system after replacing the thermostart?
Ta!
Click to expand...

Just slacken off feed into thermostart and opperate lift pump until clean flow of fuel is there.
 
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