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Engine exhaust valve holes stripped

RTBS

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Nov 3, 2013
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<hr style="color:; background-color:" size="1"> I have a used sled I purchased and after cleaning the power valves a couple of the holes where the short screws go (top & bottom) are stripped. Any suggestions on what to do to repair the holes? I could tap them and use a bigger screw or use a helical coil or there is an epoxy that loctite makes that you can remove the screws after it hardens. Not sure if it the temperature rating would be sufficient. Anyone else had to repair stripped holes in the aluminum block?
 

XCaSSAULT

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Why not get a longer bolt and nylock nut on the backside?
 

RTBS

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Thanks for the responses. I like the idea to using a longer bolt and place a nut on the backside where I have access to do that.
 
L
Sep 6, 2011
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I had the same issue on the used sled I bought. I am a huge fan of using a timesert over the helicoil. I personally believe they work way better, the only downside is the price of the kit. I did the bolt and nut for a period of time, but ended up using the timesert to make a more permanent solution.
 

BeartoothBaron

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I used several Heli-coils on an aluminum Mercedes engine I did a top-end rebuild on. Through-bolts weren't an option on most of those, but I'd have repaired the thread either way. You could use a through-bolt if you're looking for something quick and dirty; I'd go with the thread insert just because it's a more elegant solution (actually better than new since the insert is stronger). I've heard of Time-serts: they're the preferred solution to a frequent problem of head bolt threads stripping on the engine I was working on (fortunately not a problem on mine), so I'd expect they're superior to Heli-coils.

On the topic of stripped threads, it seems like a question of not if but when on aluminum threads, but you can reduce the likelihood by using anti-seize and always torquing to spec. I had to replace the water pump on my truck because two of the three bolts for the thermostat were stuck so hard they just snapped, and ever since I've been religious about cleaning and putting anti-seize on aluminum thread. I don't think I've ever stripped threads that I've "treated" that way.
 

mountainhorse

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vote +1 for the Timeserts !

Helicoil->Better
Time Sert-> Best (IMO)

Good prices, fast/fair ordering (no.. im not 'sponsored')
www.mechanicstoolsandbits.com/time-sert

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