Extreme Throttle Body Frustration

[Bad Ass Black Trucks]

So, a few weeks ago I did the old bicycle inner tube attached to the Intercooler inlet trick and checked for vacuum leaks. Discovered that the shaft was leaking on the linkage side pretty badly and sure enough there was a fair amount of play. I heard about people having their TB's rebuilt and Matt Blum was the guy to go to, but from what I could tell he is out of the business. I didn't get a good feeling from the e-bay companies and didn't like the steep core charge or the cost of shipping back and forth. By the time I went through that expense and hassle I might as well buy an upgraded 52mm or try to find a good stocker.

I posted up looking for a good condition TB and a member offered me a "new" stock TB for a reasonable price so I jumped on it. I got that TB and it looked new-ish with a couple of signs that it may have been used. Upon further inspection and to my great dismay, there was a good bit of shaft play on the linkage side. In fact, it was on par with my 100k mile TB. I asked the seller about it and he was adamant that it was brand new and that some play is normal. So... I went to the garage and checked two aftermarket 58mm LT1 throttlebodies and they were nice and tight on both sides with no perceptive play at all. The seller offered to take back the TB and refund my payment but I will have to pay for the ride... leaving me out $20 some odd dollars for shipping a paperweight back and forth.

In the meantime, I found a shiny new old stock TPI TB. It came in an AC Delco box with gaskets in a new AC Delco envelope. Even came with new sensors. But upon inspection, the new throttle body had a good bit of play in the shaft on the linkage side as too! I was thinking that maybe I was wrong and the TPI throttle body has more play. Well, tonight I decided to go ahead and install the new Delco TB with a fresh VR gasket annnd... it leaks. In fact, it leaks like crazy. Soapy water sprayed on the linkage makes some nice bubbles when I apply pressure. The 100k mile TB seemed to leak less.

I feel like I keep getting screwed over. I have hundreds of dollars in bad throttle bodies and I hope the parts warehouse takes the new old stock TB back.

What aftermarket 52 mm TB's are guys having luck with? I heard the linkage on the Holley doesn't work on SyTys but the BBK worked well for people that have built transmissions. Anyone tried a TPIS or professional product Throttle body? At this point I might like one that can be rebuilt easily versus stock which has been peened in place.

 

[BoostedSUV]

Re: Extreme Throttle Body Frustration

I use a 52mm BBK and still have the stock trans, and cruise control hooked up. Just had to use part of the linkage from my stock TB (which I still have).

 

[Bad Ass Black Trucks]

Re: Extreme Throttle Body Frustration

Anyone else had this much trouble with their throttle body? Seems like every OEM TPI TP that I see is loose on the linkage side.

 

[ItsMyTy]

Re: Extreme Throttle Body Frustration

I wouldn't worry about the leakage. If your IAC isn't sitting on 0 counts while it's idling you do NOT have a vacuum leak to be concerned with. I doubt the small amount of leakage is causing you any problem at all. Being these trucks are speed density fueling small leaks aren't a problem like MAF systems.

 

[Beavis]

Re: Extreme Throttle Body Frustration

I had a chat with Jim Stokes years ago about the TB's, and he said they all leak. That the amount they leak isnt worth worrying about. Of coarse that was after I ordered a new BBK that has been sitting on the shelf since. According to him, you could have a 1/4" hole in the intake and not loose enough boost to make a differance. Vacume on the other hand, just make sure everything else is intact and good shape and it will be fine.

 

[jpz06]

Re: Extreme Throttle Body Frustration

58mm bbk works well, no problems......yet.

 

[Bad Ass Black Trucks]

Re: Extreme Throttle Body Frustration

I had a chat with Jim Stokes years ago about the TB's, and he said they all leak. That the amount they leak isnt worth worrying about. Of coarse that was after I ordered a new BBK that has been sitting on the shelf since. According to him, you could have a 1/4" hole in the intake and not loose enough boost to make a differance. Vacume on the other hand, just make sure everything else is intact and good shape and it will be fine.

Interesting. I could see that the resolution a MAF vehicle has could make it more sensitive to vacuum leaks, but was also under the impression that any vacuum leak throws a speed density vehicle for a serious loop as MAP is the ONLY 'airflow' sensor it has to lookup values in the tune.

On the topic of vacuum, I sprayed carb cleaner all around the upper and lower intakes with the engine running looking for vacuum leaks. There was no change in idle and I have replaced nearly every vacuum hose with new silicone. But when I sprayed the TB linkage the idle the RPM audibly went up. If that happens at a gasket, everyone will tell you to replace the gasket to fix the vacuum leak. I get that unmetered air leaking in at the TB is less likely to create a lean condition in a given cylinder than say a leak on the lower manifold gasket, but is the consensus really to ignore leakage at the TB? Maybe I am just too much of a perfectionist.

And while Jim Stokes was the man, I can only agree with that statement under one condition. Having a 1/4" hole in the intake doesn't matter when you are at maximum set boost and the wastegate has opened. At that point you have too much exhaust energy to utilize it all and boost leaks don't matter because you have already achieved the set point to open the wastegate. In all other operating parameters except perhaps idle, a 1/4" hole would make a difference. Efficiency and time to achieve maximum boost are two areas I can think of off the top of my head that would take a hit.

Folks with aftermarket throttle bodies, is there much play on the linkage side of your TB?

 

[Bad Ass Black Trucks]

Re: Extreme Throttle Body Frustration

...is the consensus really to ignore leakage at the TB?

Anybody agree/disagree?

I also got out the dial indicator and measured the slop on the 100K mile TB = 40 thousandths. The "New Ish" TB I got from a fellow member = 20 thousandths. And I do have to say that I now believe that particular TB probably is new. I had my doubts because there was some oil residue on the back of one of the throttle blades and there are some marks on the adjustment screw which I thought were sure signs it had some miles on it. I took it apart expecting to find more oil residue under the plate but it was clean as a whistle. I apologize member who's name I will not mention.

 

[Beavis]

Re: Extreme Throttle Body Frustration

When I did the innertube thing mine leaked fast. I went through my vacume lines, and eneded up with an idle around 800 in park at 18" of vac on my autometer gauge. I'm good with that.