Cold Start Heater on Perkins 4-108

[Boracay]

My engine just won't start without ether.

A one second spray onto the intake filter and brrrrm.

I know I should spend $12,000 ++++ on proper engine reconditioning but three cans of ether came with the boat...

[jimisbell]

The Gasoline rag thing was told to me by to different "old Timers" one a top notch diesel mechanic who taught me everything I know about diesels so I trust it, but do think I will try it.

The WD40 I have used by spraying it directly into the intake on my 6-354 and it worked fine....even provides a little lubrication....#8-)

[Alan Wheeler]

Yeah the WD40 would be a great idea. It would lubricate, it would not detonate and it is safer to use.
Petrol, If it was a last resort and you just had to, then I think I would simply dribble some in to the manifold and bypass the rag idea.

[GordMay]

COLD START: Spray WD-40 directly into the air intake as you are turning it over. WD40 will not hurt the engine like ether starting fluid will - nonetheless use it sparingly.
If your compression and timing are good it will start with WD-40, regardless of bad injectors, fuel pump, or glow plugs.
If it stops when the WD-40 is burnt, then your fuel system is at fault. This could be injectors, injector pump, fuel pump or bad fuel lines or bad fuel.
If it does not start at all, with WD-40, you have other problems.

[jimisbell]

I know, I know, I said all my questions were answered. BUT....they are not. When I said that I had not yet removed the Thermostart from the engine. I now have it in my hands and that presents two new questions.

1) There appears to be no way to STOP the flow of fuel as the device does not seem to contain an electricaly activated valve so, What stops the flow of fuel when the engine starts???

2) If I did not connect the fuel line, would the heat alone be of any help in starting the engine?

Where I live on the lower Texas coast we rarely have really cold weather but on a couple of mornings when the temp was in the 40's it was hard to start. I am wondering if heat, but no fuel, would be enough to help starting or would it just be worthless without the heated fuel?

[jimisbell]

In reading the literature from Perkins is is obvious that they do NOT think starting with ether is a problem. They even provided an adapter for the intake manifold that would allow ether injection while starting!!!

I found in the literature that the fuel was often supplied to the thermostart from a small resivoir above the engine that was fed from the return line. In my case it is supplied directly from the return line. But still no indication of how it was shut off after the engine started. In one place they state that you should "turn on" the fuel supply to the thermostart before starting. But they dont mention turning it back off. Since it would be in the engine room on a boat I suspect these directions were for a tractor where access is better. They also say one should not operate the thermostart "dry" as it could damage the unit. This, however, flies in the face of the fact that the heater is run for 15 to 20 seconds BEFORE pushing the start button which would then supply fuel to the thermostart and that if the engine starts the fuel is immediately turned off by some mechanisum not yet discovered. Thus for 20 out of 25 seconds the thermostart IS running dry. That is assuming the engine starts in 5 seconds. Which it should if its operating properly. Mine never takes more than 2 or three seconds of cranking. So that would be a 90% time of running DRY in my case.

[teddy326]

In my youth I had a car in UK with a 4108. (built it myself from parts).


The Thermostart is not a Glow Plug. When it heats for 20seconds with from memory about 20Amps - the valve opens and it emits vaporised Diesel which is sucked in when you start cranking after about 20seconds.
Modern Glowplugs have been invented so you can get in a Diesel Car and start it more or less straight away. (and they are a pain because unless half finished harry put them in with antiseize you can lose the head or the engine).



It allowed my car to start when we had -10degC of a morning.
I put a reservoir on the firewall fed by the leakoff line that went back to the tank.



After that I built a 3kw water heater into the lower hose of the cooling system so I could get in a heated car - but I still needed the Thermostart because I could not plug in the car at work.
Never had to use Ether on that 4108 - maybe I should have got a can! - But you can blow head gaskets with it so try to avoid it.

One time it was -20degC and I parked it outside and forgot. I got it going by directing a gas blow torch down the manifold while my partner cranked it.


https://www.parts4engines.com/perkin...g-thermostart/

[teddy326]

This video shows the Thermostart working and a view of the fuel reservoir on the vehicle.
https://youtu.be/NeDvCVS38hk

[skipperpete]

Here’s a schematic of the whole setup. Usually there’s a momentary position on the keyswitch or a button to supply power to the heating coil which serves the dual role of first unseating the tiny ball valve and then setting on fire the fuel. If your 4-108 starts to use a lot of fuel, it could be that the little ball is unseated and allowing raw fuel to drip into the intake.

[Mickeyrouse]

It’s been some time since I heard about the WD-40 trick. Supposedly it used to work because of the propellant used to spray the contents from the can. The story goes that this trick is no longer as effective as it once was because the aerosol propellant was changed.
It is tempting to use gasoline engine starter fluid. That stuff is pretty potent. The higher diesel compression ratio makes it even more so. Too much ( how much is that?) can cause ignition at the wrong part of the compression cycle and damage valve stems. In other words, don’t use it.

[teddy326]

Originally Posted by skipperpete

Here’s a schematic of the whole setup. Usually there’s a momentary position on the keyswitch or a button to supply power to the heating coil which serves the dual role of first unseating the tiny ball valve and then setting on fire the fuel. If your 4-108 starts to use a lot of fuel, it could be that the little ball is unseated and allowing raw fuel to drip into the intake.

Thanks for the schematic

[skipperpete]

I got curious about what was inside that darned bonfire lighter so I sliced one in half.... a very delicate device, and seemingly, adjustable. It relies on the heating coils wrapped around an insulated copper rod to let the ball lift off the seat. Gotta be less than .005”travel, just enough for it to leak fuel onto the now glowing outer section of the same coil.
For what it’s worth, if you need to “give er a sniff” in an emergency you can use just about any non waterbased aerosol .....fly spray, hair spray, pretty much most of the WD 40 type sprays....... but only in an emergency ok!

[skipperpete]

Here’s a pic......it’s a rainy day at the workshop and not much else to do other than a bit of forensic archaeology.

[teddy326]

"a very delicate device, and seemingly, adjustable."


Thankyou Pete for the cross section.
Did you mean adjustable? if so how is it adjusted?

[skipperpete]

That little pin thingy has a thread and normally it pushes on the ball and physically holds it against the seat... so no leakage into the manifold. During the cold start, the tube it all screws into is heated by the small end of the coil... it expands a few thou, and the ball is unseated so diesel flows onto the very hot outer coil. Over time I guess the ball needs to be re seated using the screw. There is a chance that a leak could go un noticed and the only sign would be heavy fuel consumption and maybe a smoky exhaust.