Got about 3-5 likely stripped threads in valve cover & upper plenum bolt holes. Permatex Thread Repair kit seems like a much easier DIY than helicoil. Recommendations from anyone who has used either/both? For those who have used helicoil on the above components, what size kit(s)? (I discovered the stripping when I put mine back together or I'd just measure them & I'm waiting for some parts to arrive before I take it apart again).
Never used the permatex kit, but have used the helicoil. The helicoil works very well. Costs a bit more but well worth it. most of the ones you'll run into are 10mm or 12mm bolts so 6M and 8M kit will do.
Any sdhesive kind of filler repair would be best viewed as a temporory repair. Helicoils are a far stronger than stock, permanent repair. if its an M6 x 1.25 bolt, you buy the same kit. Its going to cost you tho as each kit comes with the coils, coil installer and correct helicoil tap and you need to have the correct drill for the job. Many years ago was the last time I bought a kit and it was in excess of 70 bucks. IIRC the only ordinary metric tap you can use is an M8 x 1.25 which is used for M6 x 1.25 threads. I have yet been able to buy just the appropriate helicoil tap alone but you can certainly buy bags of loose coils. E
I have used the permatex repair kit on a Seadoo jet ski. I was very sceptical but let me tell you it worked a treat. Just follow the instruction to the letter. I used it on a striped bolt that held the exhaust ( blood enormous and heavy ) and I can tell you that a jet ski cops a hiding bouncing over waves so it would be a very extreme test. Now on a spark plug thread may be a bit trick as you do not want any epoxy going in the cylinder. Maybe get a price from a mechanic to helecoil and go from there. Cheers Dave
You could always call your friendly neighbourhood thread repair service if you're not confident with the helicoil option
No, I don't currently have any taps. Also, the helicoil kits I've seen come with the right tap (& bit) & I'd prefer to keep using the same bolts.
Usually with a good helicoil kit you get a drill bit, a tap (to tap the thread for the helicoil), helicoils and a helicoil insertion tool. If it's been chewed out enough that it won't rethread I doubt there'd be enough meat left to retap to the OEM thread size.
Fortunately, it's not the spark plugs I have to worry about. Permatex themsleves actually recommend it not be used on spark plug threads or brake parts (probably probably because of the possibility of liability in the US).
Yes, but I'd have to disassemble a lot more of the engine. I'm looking for something I can do in my own garage. The Permatex option offers flexibility (don't need multiple kits for different size bolts). The helicoil kits probably offer more economy in the longer term though. The bulk of the initial price is for the bit, the tap & the insertion tool, the coils themselves are much cheaper.
Ive used both and i sell both at my work. The local reputable mechanics buy helicoils very regularly. To put it politely, the few mechanics who use the permatex crap look like they just got off a boat from somalia, and their personal vehicles are in a condition that appears to mirror the quality of products they use. A few of these mechanics dont speak great english, but they all use the word "cheap" like they were born with it embedded in their brains. In my experience the thread repair glue is basically a glorified thread locking glue. Its strong, but when push comes to shove it is still just a glue. A helicoil screws into the material, and then your bolt screws in the coil expanding it against the material its in. This is a far safer, stronger fit and i would use again if i had to. Also, for anyone who buys helicoil kits just to get a few coils from it: YOU DONT HAVE TO. I sell the coils (no tap or tools) for between about $1.50 each depending on size. Im sure auto stores elsewhere would too.
Lots of people use to drill out the original spark plug threads in alloy heads and fit Helicoils on high comp motor race bike engines because it was a stronger thread witch never blows out a spark plug with thread and all.
id only use helicoils, its a permanent proper repair that is stronger than the original fixing, as you have a larger diameter thread in the aluminium and a steel thread against the bolt gluing is cheap and daft, really only designed to get you home.. or bodge it up because you dont have the right tools or skill to do it properly.. its like radiator stop leak.. sure you can go on forever like it and it might be ok.. your problems will only result in an oil leak and boost leak.. so its not critical they dont fail like brakes or a rod bolt. at the end of the day your replacing your aluminium thread with a plastic epoxy thread or a steel thread.. your call
I also think you have to use a molybdenum grease when using stainless steel bolts so that it doesn't bind the helicoil.
Kit/Insert sizes For anyone else who wants to know... Upper plenum: M8 x 1.25, 1L insert is just long enough. Upper fuel rail & intake valve covers - M6 x 1, 1.5L insert Exhaust valve covers: M6 x 1, 2L insert
