Stripped upper intake threads | Ford Explorer Forums - Serious Explorations

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Stripped upper intake threads


August 13, 2019
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Year, Model & Trim Level
1997 explorer 4.0 sohc
I have a 97 4.0 sohc explorer that i replaced injectors, upper and lower intake gaskets on however i have 3 out of 8 stripped threads when screwing down the upper intake, the other 5 i didnt torque to spec because im afraidof stripping them to. How can i go about fixing this? Will a helicoil work with plastic threads? I tried teflon tape but that didnt help. Id rather not take the upper intake back off but i will if i need to.
Seems like a poor design to use course thread wood screws into plastic and torque to 23 ft/lbs

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It's a horse-s**t design...same as the plastic t-stat housing. In the course of removing my upper intake several times to fix the leaking t-stat housing, I stripped a couple of those intake screw holes, too. Fortunately, I have a U Pull 15 mins away and I ran down there to get another lower manifold (BTW...I've gotten pretty darn good at removing and replacing those intakes). I have no experience with, can't help with that. Another idea that might work is to put a little JB Weld inside the holes. I've only had limited success mending plastic with it, but placing it inside the confines of a hole it might hold up. Of course, this would require removing the Upper Intake again and allowing the JB Weld to dry overnight. Then, probably drilling a pilot hole for the screw.

I have had varying degrees of success using a short length of weed eater line inserted into the hole. It's not really that good, but in a pinch, better than nothing.

I had relative success using a slightly longer coarse threaded screw (with a Phillips screw head).

Good luck.

This is why I never try to torque bolts into plastic. I just run them in with a 1/4" ratchet and get them tight by hand. Once they stop, maybe give them another 1/8 of a turn. There's no reason to be trying to tighten coarse thread bolts into plastic to 23 foot pounds. The O-ring gaskets provide the required seal. As long as the bolts are tightened down until they stop they're tight enough. To me it's like when people tighten the s**t on oil filters and drain plugs. Why? It's just a drain plug, it's not like anything is will be trying to loosen it. If it leaks, put some sealant on the threads or change the washer. Also you have to be careful with pipe-thread drain/full plugs screwed into aluminum. If you over-tighten them you can crack aluminum cases.

FYI - Intake manifold bolts:
...Thru 2000: Lower: 13 lb-ft, Upper: 62 lb-in

Well sorry then btw that wasn't a broken part

I think ill take a break here for a while

The best way I found to avoid stripping out the lower intake manifold is to drill a larger hole in the upper intake manifold with a 1/4" drill bit that way the screws just fall in until they meet the lower intake manifold. Seems once you remove the screws from the upper intake manifold they won't mate up with the lower intake manifold. I solved a stripped out throttle body hole with thread inserts. Haven't had a problem since. You can try this on the lower intake manifold as well. Lots of "how to" videos on youtube to show you the procedure.

Here's the bolts I used along with small washers to hold it all together.

M2 X 30mm Socket-head Cap Screws

M2 Thread Inserts

US Stock 50x M2 L4mm OD3.2mm Brass Cylinder Knurled Threaded Insert Embedded Nut | eBay