Cracked Intake Manifold at Coolant Sensor

[rayhawk]

It looks like my intake manifold is cracked at the coolant sensor. Unfortunately I just did the lower intake manifold gaskets, I'm wondering if there is a way to fix this leak without removing the manifold again?

Should I just buy a used intake manifold, or is it likely to be cracked in the same place? Is this a common problem, or did someone over-tighten the coolant sensor?

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[rayhawk]

I should add that as I was tightening it, it got easier to tighten at a certain point. I'm wondering if I can get away with some sealant or threadlocker and a bit less torque since it looks to be a hairline crack that opens when tightened.

 

[RCFallis]

Good photo but the crack is not visible. If you can see it, take 1/8” drill bit and dimple the end of the crack. That will slow further progress. Teflon tape the sensor. Use adapters for your 1/4” drive ratchet to socket to tighten. (For nearly all sensors.)
Don’t use the 30” break over again.
Coolant pressure test while cold and up to operating temp. Leak free you’re lucky.

This crack will always be the weak link. One more way before you swap intake.
Because it cracked from the thread, a Polymeric Belzona Product cures like JB Weld but with a steel molecular structure that can be tapped and machined. Great stuff. Also, that ground wire terminal in the photo is green. Better clean it. Be Blessed.

 

[Schurkey]

"Teflon/PTFE" tape on a sensor is a really bad idea.

1. Thread tape shreds, and it's hard to get all the stringy pieces back out. This is real trouble on oil and fuel systems, cooling systems are more-tolerant.

2. Lotsa sensors ground through the threads, the thread tape acts as an insulator preventing them from working properly.

Whether that sensor screws into plastic, aluminum, or iron, a cracked sensor boss is likely going to require a replacement manifold.

 

[alpinecrick]

I cracked my intake tightening down the temp sensor “just little extra”. Bad move.
I was concerned about welding aluminum, especially because that seems to be a weak point around the temp sensor, and would fail over time because the temp sensor is putting “outward” pressure on the hole, especially with repeated heat cycles.
I bought a used intake. It was warped. Tried three times to get it to seal. Finally bought a brand new AC Delco intake. Definitely learned a hard lesson…..

And when the engine warms up that tiny, hairline crack opens up and leaks like a sieve…….I know this…..

 

[Boots97]

I cracked my intake tightening down the temp sensor “just little extra”. Bad move.
I was concerned about welding aluminum, especially because that seems to be a weak point around the temp sensor, and would fail over time because the temp sensor is putting “outward” pressure on the hole, especially with repeated heat cycles.
I bought a used intake. It was warped. Tried three times to get it to seal. Finally bought a brand new AC Delco intake. Definitely learned a hard lesson…..

And when the engine warms up that tiny, hairline crack opens up and leaks like sieve…….I know this…..

Agreed. I know it sucks, but I'd start over. coolant leaks are not good at all and trying to fix it any other way is just a band-aid at best or a disaster waiting at worst.

 

[cj8scrambld]

Personally, I'd take off the mani and have it welded up (Tig). It doesn't need to tightened that much....snug+ will be fine.

 

[rayhawk]

Thanks for the feedback guys. I decided to take it off and weld it up. It's all back together now although I'll have to put some miles on it before I claim victory.

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[alpinecrick]

Cool. I hope that works. Makes me wish I had kept my cracked manifold instead of takiing it to recycling.....