914 Exhaust leak

Tyler Hathaway wrote:

MML 5-20-00, pg 3 also says, under "Recommended Inspections", to carry out inspection: Of the exhaust unit (where necessary, replaced application of LOCTITE Anti-Seize).  In that case, it doesn't get too specific about exactly where.

I think you're quoting the 912 manaul, not the 914.

May we all just agree that the unpublished Good Maintenace Practices Manual produced by the School of Hard Knocks recommends that these joints be relubricated every 100 hours, or more often as deemed necessary.

Why would you say that Bill?

I'm all for doing necessary or desirable maintenance, but as has been pointed out by some pretty smart people, doing unnecessary maintenance is not a good idea as it can lead to maintenance induced problems.

So far, the only thing I have found in the manuals regarding these joints is to use anti-sieze when assembling, if you need to. This leads me to believe that no lubrication of these joints is necessary. I really would like to know if there is any reason to lubricate these as I do own a 914.

No l have not been, as there is no service interval in the manual.

it just says to add anti seize when assembling.

Knowing, what l now know, l would have lubricated them.

Many times the exhaust pipes and knuckle joints just need to be lined up better. If they are off to the side a little they can leak. Sometimes I just loosen the exhaust stud nuts and tab the muffler over one way or the other about an inch to help realign the joints. Sometimes I've had to use header wrap around the joint to keep them from leaking because I can't get them to stop. This actually works pretty good. The hot exhaust blow-by can have bad effects on wiring, hoses and rubber engine mounts. I don't lube them every 100 hrs., but do them at the 5 year rubber change or when I take a muffler off for some other reason or when trying to stop a bad leak. Over the years I've become a believer in header wrap. The wrap Mfg's say it reduces heat by 70%. I don't always believe Mfg's, but even a 50% drop in radiated and convected heat under the cowl is huge. In 20 years I have never seen an issue using header wrap on any of my planes. When applied CORRECTLY it should never hurt a thing.