Big Dave

When attaching my belt tensioner last summer, the threads in the hole I've highlighted in the picture stripped. I've tried sealants on the threads of the bolt, but it won't tighten and I've gotten my clean engine dirty again due to the leaking oil. The hole goes into the oil passage, allowing the oil leak.

I need to decide how to repair this. I'm concerned that shavings from re-tapping the hole to a larger size will make it into the engine's internals since I don't know if the oil pathway here leads to the filter or to the delicate engine parts.

Does the pathway go to the filter, or does it first go to other areas where aluminum shavings will cause a problem? I may just seal the hole if the shavings will cause a problem....the other fasteners for the tensioner hold it well enough.

PorKen

The hole you've highlighted (for the bolt that goes through the TB cover) doesn't go into an oil passage. The one leaking oil, below, goes into one of the oil drains from the head, and requires RTV on the bolt to seal.



Once you have the old junky tensioner off...

Adam Geist

I had a similar issue with the lower bolt - it would not hold the specified torque value. The first few threads in the block were iffy (previous mechanic?) so I used a bolt 5mm longer and solved my issue. Based upon the depth of the lower hole in the block, I could have gone with a bolt 15mm longer.

Big Dave

Hmmm....maybe I'm thinking of the wrong bolt. Gotta go check again...

Bill Ball

Yeah, it should be the lower bolt Ken shows weeping oil. That's supposed to take a 45mm long M8 with sealant. Try a 55mm M8, which would be the bolt intended for the upper hole.

Big Dave

On further inspection, it is in fact the hole I've marked with the arrow that's stripped. Is it at all possible that this hole, too, reaches into the oil passage? If not, I have a substantial leak coming from somewhere else in the immediate vicinity of that hole. Unfortunately, the entire area is dirty with oil and grime, no doubt from oil blown by the cooling fan.

Big Dave

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Lizard928

I would use some cleaner and pressurewash the area off. Once relatively clean remove that bolt and have someone start the engine for a moment. If it goes into an oil passage you will be able to see a steady stream of air (with some atomized oil in it) coming out of the hole.

However if you dont then it is safe to helicoil that hole without worrying about shavings.

If it does then take off the rear crankcase vent on the passenger side valve cover, and plug the hole.
Once plugged take the small hose off the oil filler neck and hook up some compressed air (5-10 PSI, NO MORE) and tap the hole with this air hooked up, it should be enough to blow all shavings out of the hole.

dr bob

...Or grease the tap. Putting grease in the tap means that cuttings will be contained by the grease and not sent into the oil galley there. This is tedious work, since you get maybe a turn at a time on the tap, then pull it, clean it, re-grease it and start again. Use a Time-Sert insert instead of the Heli-Coil, per to the experts.