One of the four bolts holding the air box/throttle housing to the intake manifold must have been over-torqued at some point by POs, because I pulled it out today and there was aluminum nicely coiled in the grooves of the bolt. So I can only torque (14 ft lbs) three of the four bolts.
What are my options? Retap for bigger bolt? Will I have a vacuum leak if I leave it for now?
HeliCoil.
Is there room to get a drill into the stripped hole?
Possibly once I remove throttle body? I’ve never done a helicoil before, so it will probably be a couple weeks until I figure out what I need and get to it. Need to order gasket too.
You will have a major vacuum leak if you remove the bolt.Put the bolt in place using blue loctite, silicone sealer, weatherstrip adhesive, until you have a plan!
Not silicone: it’s not gasoline-proof.
All the others a GO!
Thanks, I’ll put some blue loctite on threads, let it dry, then put Teflon tape over that and reinstall bolt snug?
Greg,
I have done several helicoils on my Jaguars (but not for the bolt you are dealing with) due to errors made by prior owners or their shops. I purchased a kit from the local NAPA Auto Parts store. If you take your time and follow the directions they are no big deal to install although a straight line with a drill is needed.
Paul
Could it be that the spiral is not alloy, but a steel Helicoil, installed by a PO. Probably not quite correctly, as they are usually quite reliable.
No, I could tell it was aluminum that came out in the bolt. I didn’t hear any vacuum leaks from that corner, so will need to put this off due to other issue.
Thanks, it doesn’t seem too hard. I just need to get correct size and length now. I measured, it seems that its 3/8" deep of bite.
There is something else to consider.The helicoil insert has a tang at the base of the spiral which is used by the installation tool to screw the spiral into place. Then you are supposed to use a punch to break off the tang. Unless the design has changed since I last used a helicoil, this means that there will be a nasty little piece of metal flying around inside your intake manifold. Tread carefully.
I would use a Keensert in the intake. The helicoil does have a tang that needs to be broken off and retrieved.
A Keensert is similar to a helicoil except there are four tangs that need to be driven home and no loose pieces to find.
McMaster has them in just about any size you need under key lock insert.
Gordon
Thanks, I will look into those, since I am going to try this with manifold on.
While there, research Timesert or Bigsert, depending on the size. I’ve used them to fix stripped threads before with success. I forgot why I didn’t use helicoil, which I’ve also successfully used before. Maybe I needed to reach a torque the helicoil couldn’t meet?
Bodge solution: JB Weld a length of threaded rod into the hole and use a nut.
No way! And I’m surprised Kirby, you are usually the anti-bodge problem solver.
Good point! To boot, that is a VERY hard piece of nasty little metal.
If the part was off you could re-thread hole to a larger size and machine a stud that one end is original size and the other end for the larger size…if you are concerned about originality get a whole different part
Not concerned with originality, just want to use OEM bolt.
Thanks for all the help, i will research and fix soon. For now, car runs fine. 31 year old throttle body gasket is probably welded in place!
Finally got around to this job. Even with the throttle body off, no way I can fit my drill in there. I can fit my hand tap tool, but I need to tap 7/16" threads into original 5/16" threads for the insert. Could I tap without drilling?
The bolt threads straight and snug, I just can’t get enough torque on it. If I put some blue lock on it, let it sit a few hours, and then torque as tight as I can and let it sit overnight, will that be enough until one day I remove manifold and do a proper job?
Oh, and those pink/orange paper gaskets are a pain to scrape off! I’ve got new black non-paper ready to go.
I think that now that you have removed the throttle body and you are putting a new gasket the only way to insure that you will be leak free is to put a stud or threaded rod with gb weld or red locktite.