12H-T bouncing idle at takeoff

[GooSe77]

Hi there,

in theory the 12H-T should be able to drive away in 1st gear without extra throtle. My doesn't and after reading a bit across the web I thing it is due to a worn out/soft damening spring unter that big 22mm nut.
Partnumber is:
22495-68150

I read somewhere that there is a stronger replacement out there ...
Or a least the original would help.

Who has a link for me to get one ? I tried some eoropean dealers, some ebay shops in australia ....

THX Bastian

 

[roscoFJ73]

You can attach your own springs fore and aft to control the bounce. I use to keep the idling high on mine

 

[GooSe77]

Thaths a work arround, not the solution - and the way I have it right now

What do you mean by "your own springs" ? The on I am searching is IN the back part of the pump, not the 2 that are pulling back the throtle ...

 

[roscoFJ73]

You will probably need to see Denso for the spring. Look for a site that converts Toyota part numbers to Denso part numbers

 

[relaxedcruiser]

Moin Bastian,
the rather bouncing behavior of the 12ht govenor is annoying me since ever, I managed to calm it down when driving slow over rough terrain using a setup originally found on a Mercedes OM 601 engine of an 308 D - I used the Mercedes shock absorber but build my own spring setup at the end of the throttle cable. That´s a spring with preload inside a double walled aluminium pipe. When you apply only a slow movement in to the throttle cable the spring is not in action, if your foot bounces a little - causing normally the engine to create a bouncing behavior - the spring comes in action and smothens out the actual movement of the lever at the IP. This setup works perfect since more than 25 k kilometres. The shock is single acting which means the lever is able to come back to idle without damping. Since ever I wanted to post this here to share my experience. Never came around to do it and also wanted to test it thoroughly before diplaying it out here. I don´t know whether I could help you with your bouncing problem which appears without touching the accelarator. You can play a bit with the preload on the spring behind the 22mm nut you mentioned. This alters the behavior no question. Just painstakingly record the original adjustement and every change you are making. As you up the preload you´ll find that you have to lower the idle rpm at the so called steering lever of the IP (just the lever your throttle cable is attached to)
Happy cruising ! Und schöne Grüße nach Leverkusen aus New Zealand...

 

[GooSe77]

THX for the input, sure, the dampener on the cable will help with the nervous throttle, might do that to if the new spring wont help. I turned the damepener screw in for 3-4 truns so I could just für the 22mm nut back on and the idle raised for maybe 50rpm, hard to tell without RPM gauge, but I did not need to reduce idle speed ..... so I think it is verry worn out ....

 

[Jentuh]

From what I heard, it's not the spring that's worn but all mechanical items behind it that are part of the idle controller.
Due to play in them little rods and hinges the mechanical behaviour of this regulator became slower.
Replacement of the spring won't solve it. Increasing spring pressure doesn't help either. The bouncing in rev's will only increase in frequency.
I've given my 12HT just a slightly higher idle rpm... I think the only permanent fix is a injector pump overhaul..

 

[relaxedcruiser]

I´m have yet to check my compression readings - but if the readings are very hopefully nice and even I have to attack the govenor.
I do not want to hijack this tread but have to say that the "govenor bounce" which is quite typical for the 12HT, is a constant pain for me.
I don´t expect a silky running straight six but every 4 cylinder is running calmer than my 12ht - and I´ve heard many others having the same behavior. I had the pump at a professional Denso Keiki Bosch shop to test it and they stated that it is in good nick. That´s on the test bench and the pump is propelled by an electro motor. In reality the pump is in conversation with the engine and reacts to the revs and loads. I suspect that the govenor is in permanent "discussion" with the engine like slowerfasterslowerfasterslower making the typical rumrumrumrum.
I have even though about fitting a distributor pump from an 1HD-T or the like to get an even and smooth running 12HT.
There is this rubber dampener between the mainshaft and the govenor in M/T govenors. Next thing to test is also whether the govenor has some play which would also could cause this unsettled running.
How is your experience ?
On take off my govenor is resonable calm - so I have realy hijacked the tread - I should start one with my special topic.

 

[GooSe77]

From what I heard, it's not the spring that's worn but all mechanical items behind it that are part of the idle controller.
Due to play in them little rods and hinges the mechanical behaviour of this regulator became slower.
Replacement of the spring won't solve it. Increasing spring pressure doesn't help either. The bouncing in rev's will only increase in frequency.
I've given my 12HT just a slightly higher idle rpm... I think the only permanent fix is a injector pump overhaul..

I've read from a well experienced engine builder that by raising the idle with the big screw and setteling it down again with the normal screw you move to another point on the rack with is not worn out .... well, it seems to bee a low budget test

 

[koxfarm]

what do you mean by bouncing? Does your rev go up and down? And within what range and what is your peak/low ?
I guess it is in your right foot.. try to learn giving a fat deep half way in the pedal type step and back to 1/4 and down again any time you begin to accelerate in first.
It is not a passenger car it is more like a tractor. So learn to deal with the pedal like if you were a drummer. You must have that rythm in your foot that is optimal for a heavy duty diesel like the 12HT. Once the turbo kicks in its irrelevant but before is I guess what you discussing.
I would NEVER put springs on the governor!! That is insane!

 

[GooSe77]

No, I mean when you yust use the clutch to start driving without extra throtle. Then the idle goes down/up/down/up and almost stalls. Ofcourse a little throtle helps, but it should work without .....
I'm not adding a spring, replacing it because it is worn out

 

[BJ4x4]

Hi, how did you finally solved the bouncing idle??

 

[kevin in okinawa]

Mine was really bad too before. I only had one spring attached to the linkage. I got two new ones from Cruiser World and it’s smooth now.

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[coldtaco]

now you got me curious about this. will have to try this when I get home. when I first got the engine the builder had one soft spring for the throttle thing and I had a hard time driving smoothly when driving slower. I found a place in Spain that had the correct springs in stock (both) and I installed these and that solved the problem.