Possibly stripped threads on my throttle body
- Thread starter GregBelleville
- Start date
Hmm, I'm learning a lot about fasteners with this little project.
So if the max tq on these screws is basically 80 in lbs, and the tq spec for the TB is 90 in lbs, should I be ok to just torque these zinc bolts to 80 in lbs, or should I be shopping for the same bolts in another material that can handle 90 in lbs? I couldn't find anything at home Depot in this exact size other than zinc plated...
If it were me, I'd want the fasteners under proper tension (through elastic deformation). Following the proper torque for the fastener will do that. You should be good as long as the paper TB gasket seals down and the fasteners hold. Even if you weren't concerned about strippling threads, tightening too much can cause the fastener to lose tension (and clamp force) if it goes from elastic to plastic (permanent) deformation. This is why it's important to follow torque specs wherever possible.
T
Those extra threads are good. It looks like you may get away without having to put in a time-sert or heli-coil.
Ok, here's an update. I went to home Depot and picked up this m6 1.0x30 mm cap screw which matches the size and length of the TB bolt, however, you'll notice the end of the bolt isn't tapered and Threadless, so it's the same length but has a few mm of extra threads.
I was able to thread the new bolt in to the TB and according to the FSM it looks like the torque spec is only 90 in lbs which I was able to torque it to just fine. Does anyone see any issue with not having the taper at the end of the bolt for done reason?
On a side note I attempted to torque down the other 3 bolts and a second hole stripped on me, so I think this TB got over tightened at some point.
If there aren't any concerns with this bolt then it looks like I'm heading back to home Depot for 3 more.
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Those extra threads are good. It looks like you may get away without having to put in a time-sert or heli-coil.
T
Those extra threads are good. It looks like you may get away without having to put in a time-sert or heli-coil.
Yep, they did the trick! I was able to replace all 4 TB bolts and get them torqued to 80 in lbs per @MikeE024 recommendation. So happy I didn't have to go down the thread tapping rabbit hole.
As for the high idle, it's a little bit improved, but still hovering around 1000 rpms. I tried backing out the screw on the throttle that it rests on at idle per a yt video I saw. It helped bring the rpms down a couple hundred, but still a little too high.
Just want to say thanks for all of the helpful suggestions and information!
Just throwing this out there...
I've only addressed this issue on my 2005, but I wanted to ask if you've cleaned or replaced your Idle Air Control Valve.
Also, have you tried doing a proper vacuum leak test? Using a smoker that utilizes merely 1-2 lbs of compressed air will tell you if you have a vacuum leak somewhere. I used this method to find a leak off the intake manifold and discovered that both ends of my TB's butterfly valve shaft were badly leaking at the bearings. The smoker tool took out the guesswork and saved me a ton of time and headaches.
I've cleaned the IAC both by pulling it off the TB as well as by spraying carb cleaner into it while the engine was running with no improvement. I have not done a smoke test yet, which I think will be my next step.
I've cleaned the IAC both by pulling it off the TB as well as by spraying carb cleaner into it while the engine was running with no improvement. I have not done a smoke test yet, which I think will be my next step.
Good deal man.
Might even be worth trying a new Mopar IAC if they are still available...in the event it's bad even after cleaning. Not sure how often they go bad, just throwing that out there as a possibility.
Just letting him know he can go to 80 inches instead of 90 for the plated 8.8 bolt, which reduces his chances of further stripping threads.
@MikeE024 I'm still chasing this high idle and wanted to confirm where you were getting a vacuum leak on your throttle body. Is it from the areas I've circled on mine? Did you buy a whole new TB?
Yes sir, that's the area.
Here's a link that discusses it more (post #6). The video that Kinkaid sent me is also linked to where i first saw it.
I used a tiny bit of silicone grease for lubricating the o-rings...don't want to use much.
I recently found out that I had a vacuum leak even though my manifold tested good...it was my brake booster and the one-way check valve prevented me from checking if the booster was good. Just throwing that out there. I didn't have a high idle like others have reported from the TB or due to the brake booster, but did have a high idle when I had a line popped off of the manifold, which I'm sure you already checked.
Best of luck and feel free to reach out.
Edit: post #20 in the link refers to the o-ring info a little bit more
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@GregBelleville have you done a pressurized smoke test? It could expose something like a leaking intake-manifold gasket. Just a thought.
Yes, did a smoke test using a hand pump and a cigar thru a vacuum port on the manifold that didn't show any leaks.
I actually may have solved it yesterday, see this thread.
A leak at the TB mating area can certainly cause a high idle! I had that happen to me when I didn't connect the TB properly (couldn't tell you what I did wrong, but I'm sure it was something basic).
You didn't see smoke coming out of that area during the smoke test?
I didn't, but I also don't think I removed the intake tube from the TB when I did the test, so it's possible I'd leaking and the smoke never showed because it was trapped in the intake maybe? I pumped a fair amount of smoke through it, I would think I would've seen smoke coming out of the intake at the air box?
I can't say because I never tried that exact method. Nowadays, I do it through the intake tube that way there's no way for smoke to get out anywhere it shouldn't. And I've only done it using compressed air and burnt mineral oil.
My gut tells me that a proper-pressured smoke test would have exposed any leaks at the TB (e.g., at the butterfly valve seals or mating surface).
My method has advanced through experience...I don't do it the same way I originally did because the smoke would just poor our of the intake. But your results would likely be accurate as long as the intake side is plugged well.
I have to be a little more critical in how I do it now since I'm also ensuring I don't have boost leaks.
All that said, it's also possible that your method worked just fine.
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