How to "kill" a 3B (1 Viewer)

[Texas bj-42]

Thanks Guys and Gals

The knowledge of this board always amazes me. On a tangent... I have been wanting to mount a 2" receiver below my pintle hook. The 47 link was GREAT. I am home with the flu so I have spent hours reading here.Justin

 

[shinny]

Yeah. I'm the same as you Brownbear. I'm having trouble with the concept of shutting the air to kill a diesel but it must be an acceptable way of doing things.

Not just acceptable - it's required where I work. Google "positive air shut off" for more.

 

[Dougal]

Yeah. I'm the same as you Brownbear. I'm having trouble with the concept of shutting the air to kill a diesel but it must be an acceptable way of doing things.

As long as the fuel pump gets the message that there is no air and cuts the fuel, you should be fine.
Otherwise you'd be running the engine silly rich until it ran out of oxygen to burn.

 

[lowenbrau]

As long as the fuel pump gets the message that there is no air and cuts the fuel, you should be fine.
Otherwise you'd be running the engine silly rich until it ran out of oxygen to burn.

Shutting the air off will shut down the engine right quick even with 20 lbs of boost and a wide open over fueled injector pump. I do it about one time in ten on highway on-ramps when the airflow forces the shutter closed. Its a real pain and super hard on the turbo but I haven't found a better spring yet.

Shutting off the fuel is the better choice I think. Toyota got it right in the 3B connecting it to the oil pressure. That has saved my but twice when I tore oil filters off. You can also shut down the engine with the key if you happen to get it running in reverse (it goes to the rev limiter, regardless of throttle position and gets quite scary). You tend to be hurtling backwards down a tricky trail while in a forward gear. With an intake shutter you have to stall it in gear against the brake.

 

[brownbear]

I'm thinking the air shut down on the turbo motors might be of benefit if you had an oil leak from a turbo causing the eng to keep running uncontrolled. Like a seal let go. Where the engine eats it's own oil till seizes... LOL

I never before realized the VSV was an air control device. I always imagined it to be fuel....why I don't know. Probably cause I have not dug around a 13b-t

I've seen some very simple fuel solenoids on big equipment. That might even be better.

On airplanes, piston or turbine, we always cut the fuel to shut them down. Piston you have two choices..ignition or fuel cut off. Turbine only one choice, fuel. Not ignition, no starving it of air

 

[lostmarbles]

I'm thinking the air shut down on the turbo motors might be of benefit if you had an oil leak from a turbo causing the eng to keep running uncontrolled. Like a seal let go. Where the engine eats it's own oil till seizes... LOL........

Shinny had an interesting point too

If I understand correctly, it looks like where there's a danger of a diesel engine breathing "flammable gases" (and thus running out of control), authories insist on it being fitted with a "positive air shut-off safety system". (Such regulations may apply near oil wells for instance.)

 

[Dougal]

There are several guys on 4BTswaps.com who've fitted emergency air valves to their rigs.

A warning in a similar vien, don't wash out your air cleaner with kerosene, diesel or anything similar.
If you do, leave it to dry for a couple of days. I met a guy who washed it, reinstalled and started.
Quite an expensive lesson.

 

[lowenbrau]

I'm glad this conversation came up. These guys have plenty of solutions. I think I might simply add one of these 24v shutdowns pre turbo and pull the guts out of my factory setup.

Also, an EDIC performs another function that many people don't know about. It over fuels when starting and makes the 3B start much better than without it. Remember that your foot is not actually connected to the IP and you have no control over fuel until air starts moving past the venturis.

 

[lostmarbles]

Shinny had an interesting point too

If I understand correctly, it looks like where there's a danger of a diesel engine breathing "flammable gases" (and thus running out of control), authories insist on it being fitted with a "positive air shut-off safety system". (Such regulations may apply near oil wells for instance.)

I've been thinking about this some more. And I don't think a diesel like mine/ours could in fact "run out of control" through breathing flammable gases. I think these regulations were based on the "standard diesel set-up" which has no air control butterfly (and where the accelerator controls the fuel directly).

If my engine breathed in "fueled air" and my foot wasn't on the accelerator pedal, that butterfly valve would still starve the engine of the "fueled air" and thus prevent any serious over-revving. (I think at worst it would just idle at a higher speed.)

But of course I'm sure the authorities wouldn't recognise this and would still insist on a separate "positive air shut-off" being fitted. (Likely location would be upstream of the existing butterfly.)

 

[lowenbrau]

I've been thinking about this some more. And I don't think a diesel like mine/ours could in fact "run out of control" through breathing flammable gases. I think these regulations were based on the "standard diesel set-up" which has no air control butterfly (and where the accelerator controls the fuel directly).

If my engine breathed in "fueled air" and my foot wasn't on the accelerator pedal, that butterfly valve would still starve the engine of the "fueled air" and thus prevent any serious over-revving. (I think at worst it would just idle at a higher speed.)

But of course I'm sure the authorities wouldn't recognise this and would still insist on a separate "positive air shut-off" being fitted. (Likely location would be upstream of the existing butterfly.)

You can disprove that theory by pulling one of the lines that connects the butterfly to the pump and listening while the engine revs to the limiter with the butterfly closed. It apparently doesn't make a very good seal or is forced open, I'm not sure which.

 

[Vanny]

You can also shut down the engine with the key if you happen to get it running in reverse (it goes to the rev limiter, regardless of throttle position and gets quite scary). You tend to be hurtling backwards down a tricky trail while in a forward gear. .

I thought River Shiver 2007 was lost in our memories? Could I have gone in reverse in all 5 gears?

 

[Tapage]

Also, an EDIC performs another function that many people don't know about. It over fuels when starting and makes the 3B start much better than without it. Remember that your foot is not actually connected to the IP and you have no control over fuel until air starts moving past the venturis.

this an important issue, most if you are selecting the manual kill way .. It's pretty much more dificult start an IDI engine without over injection.

 

[lostmarbles]

You can disprove that theory by pulling one of the lines that connects the butterfly to the pump and listening while the engine revs to the limiter with the butterfly closed. It apparently doesn't make a very good seal or is forced open, I'm not sure which.

By crikey. That's a challenge (if I ever heard one) Lowenbrau.









............................................And - (What do these one-legged birds mean?) Ye gods!!! You're right too.

The smoke is still clearing from my neighbourhood as I type this!!

First I pulled off the hose that connects to the upstream side of my butterfly, and, as expected, -- there was no change in idle speed. So I put that one back on.

Then - The more dangerous step - The dreaded vacuum venturi!!!!!!!!!!

Cautiously does it..................................Yeeeee Goddds


My lovingly-cared-for little engine screaming its ring out (and I hadn't even warmed it up). Wow! From "idle" to "maximum revvs" in the blink of an eye (and I've never seen my engine put out smoke like that).

And I didn't just do it once. Hell no. I had to experiment further. Putting my finger over the open venturi port made no difference to the engine scream! hhmm:So it isn't sucking the extra air it requires through there.) And blocking the hose to the vacuum side of the diaphragm didn't stop it screaming either (not that I can see how THAT could).

So I now believe a diesel doesn't need much air at all to achieve combustion. (That's the only thing it can mean isn't it?)

OK - I retract all that stuff about our diesels not being at risk of running out of control in a "fueled atmosphere".

Thanks Lowenbrau

 

[Henry James the 47th]

I'm glad this conversation came up. These guys have plenty of solutions. I think I might simply add one of these 24v shutdowns pre turbo and pull the guts out of my factory setup.

Also, an EDIC performs another function that many people don't know about. It over fuels when starting and makes the 3B start much better than without it. Remember that your foot is not actually connected to the IP and you have no control over fuel until air starts moving past the venturis.

Here's another interesting point, I think: the over-fueling while starting. If you take a look at the different configurations of 2H and 12H-T engines, it quickly becomes apparent that with the auto trans installed, the injector pump is configured to deliver more fuel at a given rack setting, when compared to the manual transmission set up. So, when Toyota put the auto trans on the 2H, they chose the pneumatic governor-controlled injection pump. It seems that this set up facilitates and even greater fuel dump than the EDIC-controlled set-up.

If you scrutinize the charts below (taken from the Nov. 1985 FSM for 2H and 12H-T engines), you can see that at every injection rack setting the auto trans type of injector pump puts out more fuel than the manual transmission/EDIC system. Also, for the 12H-T, whether M/T or auto, the pneumatic governor is the choice of the factory.

 

[amaurer]

And I didn't just do it once. Hell no. I had to experiment further. Putting my finger over the open venturi port made no difference to the engine scream! hhmm:So it isn't sucking the extra air it requires through there.) And blocking the hose to the vacuum side of the diaphragm didn't stop it screaming either (not that I can see how THAT could).

I admire your stoicism, when confronted with your engine screaming to the limiter you think of experiments to try! I'd be fumbling with the hose trying to jam it back on as fast as i could.... i guess loud noises scare me?

here's a question: how does the rev limiter work? how is rpm sensed?

 

[lowenbrau]

I admire your stoicism, when confronted with your engine screaming to the limiter you think of experiments to try! I'd be fumbling with the hose trying to jam it back on as fast as i could.... i guess loud noises scare me?

here's a question: how does the rev limiter work? how is rpm sensed?

I agree. I was hoping he wouldn't call my bluff and make me go do it to my truck. I would have had the camera rolling for it though.

The rev limiter is simply three ball bearings between two plates connected to the camshaft in the injector pump. as the speed increased centrifugal (or is is centripetal?) force moves the balls apart as thus the plates. One plate forces the fuel rail closed.

 

[Dougal]

I agree. I was hoping he wouldn't call my bluff and make me go do it to my truck. I would have had the camera rolling for it though.

Now that's dedication.
Setting up the video when you know it could all quickly turn to custard.