What the diaphragm does...

[bigcruiserhj]

Correct, with the 3B you are not directly linked to the fuel rack of the injection pump. The diaphragm controls the rack position.

Adjusting the HAC or "fuel screw" (BJ60s don't usually have a HAC in Canada) changes amount of fuel delivered right across the full range of the fuel map. The HAC is the high altitude compensator and is supposed to adjust fuel delivery dependending on elevation.

The HAC is supposed to drop down fuel flow on injection pump at high altitude.
Without HAC your engine will smoke a lot at high altitude.
This system is only for non turbo toyota diesel engine.
Turbo engine are less subject to smoke at high altitube.

 

[lowenbrau]

The HAC is supposed to drop down fuel flow on injection pump at high altitude.
Without HAC your engine will smoke a lot at high altitude.
This system is only for non turbo toyota diesel engine.
Turbo engine are less subject to smoke at high altitube.

If you are adding at turbo to a rig with a HAC you can plumb the boost into the vent of it and it works a bit like a boost compensator Not great but better than nothing.

 

[PressOn]

So as the diaphragm develops holes, the engine slowly goes rich as the diaphragm deflection decreases. Eventually, with enough holes, there will be no metering (or pinching) off the flow as it thinks the butterfly is wide open and you have massive black smoke.

Cool. Like I wrote earlier, very timely.

Thanks

 

[denis]

117 bar (1700Psi) with the 2H around 200 bar (2900Psi) with the 12 Ht.
Excuse me for my rookie english speach.

that's the injector opening pressure, it goes far beyond at peak injection rate

 

[bigcruiserhj]

that's the injector opening pressure, it goes far beyond at peak injection rate

I'have check toyota 2h/12Ht engine repair manual.
You are right :whoops:.There is nothing about pump pressure.
Only fuel quantity with pump RPM on the bench.

 

[lowenbrau]

So as the diaphragm develops holes, the engine slowly goes rich as the diaphragm deflection decreases. Eventually, with enough holes, there will be no metering (or pinching) off the flow as it thinks the butterfly is wide open and you have massive black smoke.

Cool. Like I wrote earlier, very timely.

Thanks

It actually ends up blowing grey (almost blue) smoke on descents. When the engine is getting a lot of fuel but no air. The same symptoms appear when your air cleaner is plugged. I once lost my snorkel top while traveling through thick alders and started to become concerned about the smoke I saw in my mirror. I eventially clued in and found my airbox completely filled with leaves.

 

[Tapage]

that's the injector opening pressure, it goes far beyond at peak injection rate

and the rate is .. ?

 

[bigcruiserhj]

It actually ends up blowing grey (almost blue) smoke on descents. When the engine is getting a lot of fuel but no air. The same symptoms appear when your air cleaner is plugged. I once lost my snorkel top while traveling through thick alders and started to become concerned about the smoke I saw in my mirror. I eventially clued in and found my airbox completely filled with leaves.

If your air clcleaner isn't plugged. It is a problem of mixture air/fuel.
Here in France some BJ owner with inline pump had same problems.
Pretty simple, The diaphragm was cracked, so air/fuel ratio wasn't good.

 

[duncanrm]

Old thread.. but there's an excellent description of this mechanism here (Google Books -
Fundamentals of Automotive Technology: Principles and Practice )

https://books.google.com.au/books?id=mJWAa-qbOQUC&pg=PA1878&lpg=PA1878&dq=diesel engine butterfly diaphragm&source=bl&ots=q26dvaCQB4&sig=GPYGfYRLTyzI32xH8-dBfxLwqtk&hl=en&sa=X&ei=y1WrVKHEOKPNmwWZiIHADg&ved=0CEIQ6AEwBw#v=onepage&q=diesel engine butterfly diaphragm&f=false

 

[Gengis]

OK
So I have a normally aspirated B Mark II ( Post 88 with a Denco rotary IP pump). I have always liked the " Basicness" of the system, but do have a bit more smoking at higher altitudes. My IP has no diaphragm devices at all but the manifold does have a butterfly. Is it possible to fit a HAC system with out too many problems.
Could I do this myself or must the pump "go In" for a retrofit.
Any idea of the part numbers to look out for?
Which donor pump should I look out for to steal the HAC components off?
Why do these engines even have a butterfly?

Regards and a happy new year to all.
G

 

[duncanrm]

Why do these engines even have a butterfly?

I believe the addition of the butterfly delivers some level of engine braking. Engine braking is largely absent in diesel engines unless an exhaust brake or jake brake has been added.

 

[keving]

Where on the IP is the HAC fuel screw on inline 3B's?? I have a Canadian spec 1985 BJ60. I don't want to mess with it but I would be interested to know where it is if my Canadian one even has a screw.

 

[Campagnola]

Hi,sorry for my bad english but your all wrong saying Mr Ricardo invented pre- chamber.In fact iT was een invention Made by Prosper l’Orange en adopted by Daimler in combination with Bosch inline pump.Swirlchamber is probabely invention mr.Ricardo.Most ID diesel engines have swirl chambers,a few bands used pre-chambers,I only know Mercedes diesel engines have pre-chambers before they changed to DI engines.Greetings from Campagnola