Stiff Throttle plates

[cptbill]

Anyone out there ever use one of those kits to put new bushings in/on tbi throttle plates. Mine have gotten really stiff and I'm not in the mood to spend Big Buck on new TBI units If these can be repaired. IN case it matters there on Volvo Penta 5.7L GSI PWTR 1999/2016 (Repowered)

 

[alldodge]

Haven't found the need for one of the kits, but what about removing it and use some PB Blaster or suck to free it up?

 

[Scott Danforth]

are you sure its not the cable?

 

[Bondo]

Ayuh,... The cable was also My 1st thought,.....

'n I thought a bushin' kit was to tighten up loose sloppy shafts,...

Like AD says, take it apart, clean it up, 'n loosen it up,...

 

[cptbill]

Sorry, not the cable,TBI unit throttle shaft was frozen in place so I took it apart and with a little extra extra fine sand paper cleaned it up and put some anti seize seams to be fine at this point. I took my measurements and it's a 3/8 shaft so if it happens again I'll try one of the kits I found for Rochester carbs w/ 3/8 shaft

 

[jimmbo]

Those bushing kits probably are not USCG approved for use on marine engines. Marine carbs and throttle bodies have to have some means of keeping fuel from seeping/leaking along the shaft to the atmosphere side of carb/throttle body. Bushings kits would probably disable the measures incorporated to accomplish that.

 

[alldodge]

Marine carbs and throttle bodies have to have some means of keeping fuel from seeping/leaking along the shaft to the atmosphere side of carb/throttle body

Not going to disagree because I've never heard or looked into this issue, but also have never seen any differences on the shafts

 

[jimmbo]

Not going to disagree because I've never heard or looked into this issue, but also have never seen any differences on the shafts

Did you ever compare the throttle shaft bores between an auto motive carb and a USCG certified marine carb?

 

[alldodge]

Did you ever compare the throttle shaft bores between an auto motive carb and a USCG certified marine carb?

No sir, but sounds like you have. I've only rebuilt many (carbs) over the years and never noticed anything differences in that area. Could you post some pics, spec sheets, part numbers, any thing at all would help. Would be nice to know the differences so I(we) will be able to provide better info

 

[jimmbo]

Some have a little circular grove machined into the shaft bore and a grove at the bottom of the bore machined from the circular groove to the venture bore. The circular groove interrupts any gasoline seeping along the shaft and the bottom groove returns it to the venturi. Sometimes the shafts themselves are grooved, but that does weaken them

 

[alldodge]

Pretty cool, thanks. Guess I'm just to old but don't remember seeing the multiple groves in the carbs I've done. Are these the same years, and what model carbs?

Can you advise as to why this would also be with a throttle bodies? If it was an MPI, then gas is no where near, and if its TBI then the gas is controlled by the injectors above and only pass by during air intake. Still a puzzler because if there was a leak then air would be getting sucked in while the motor was running

 

[jimmbo]

It doesn't matter on MPI engines, but TBI is has fuel above the throttle blades/shaft and is subject to the same type of fuel leakage upon shut down or if an injector leaks. These just sone of the little things that are different in Marine parts. However a lot of people's eyes glaze over and their ears go offline when differences are pointed out. They don't want to hear it because they think it is just a ripoff. Low volume parts do cost more, ask anybody who owns a less common car.

 

[alldodge]

OK so its not the bushings but the actual shaft that has the groves, bushings should all be the same. Will still be looking around for the differences as they show. Sure appreciate you going to the trouble to try and explain your point of view

 

[jimmbo]

Reread my post.

"Some have a little circular grove machined into the shaft bore and a grove at the bottom of the bore machined from the circular groove to the venture bore. The circular groove interrupts any gasoline seeping along the shaft and the bottom groove returns it to the venturi. Sometimes the shafts themselves are grooved, but that does weaken them"

shaft bore = holes

 

[alldodge]

Thanks, but I'm going to have to see a TBI with this set up, and carb bushings with the grooves. The USCG regulation (183.526) is a test for carbs

Fuel injection is now prevalent in marine engines. The regulations specifically addresses carburetors, as fuel injection was not commonly available in the mid-1970s when the regulation was written. This test is to confirm the integrity of the fuel metering equipment ...... Max leak of 5cc

http://www.uscgboating.org/assets/1/AssetManager/ABYC.1002.01.pdf

There are other sections which cover the fuel over flow back into the carb, pump and other items. I don't see an area where the same compliance issues impact the TBI. The way the regulation is written leaves it up to the manufacture to determine how this will be met, guess this may be why I haven't seen/noticed the grooves on the shaft

 

[cptbill]

Just to clear this up the casting # on the TBI body is a GM part# and there are no seals, groves or Bushings on the shaft or the unit it self. I've seen groves, seals and bushings in Rochester carbs before but after extensive research TBI units are the same as automotive

 

[Bondo]

TBI unit throttle shaft was frozen in place so I took it apart and with a little extra extra fine sand paper cleaned it up and put some anti seize seams to be fine at this point.

Ayuh,.... For frozen seized shafts, what you did is the cure,....

Bushin' kits are to fix a worn out loose fittin' shafts that can leak air, or gas,......