Oil leak on EC300 expansion pipe
 

Guys, got one ride on my 06 ec300 having just had the piston and rings done, as well as lots of other planned maint type stuff. I notice there is oil leaking from the flange the front pipe mounts onto, on the front face of the cylinder. Did i read on here that one of these holes is not blind and needs sealed when the bolt goes back in? I also get the impression that that mounting spiggot/flange that the pipe slips onto can crack and leak(as i see Nth Tahoe m'sport offer a ss version). Any ideas would be welcome before i tear it down.

Sorry one is a bit blurred, but its the bolt at the 3 oclock position. I have added a couple of bigger pics in the gallery.

Any comments would be greatfully received.

The stock spigot is somewhat fragile. I would suggest replacing it with the LTR unit even if it's ok now. It's cheap insurance.

Maybe your O-rings on the spigot need to be replaced. I replace mine once a year as I do not like oil leaks.

Also you could have had a few hard impacts that resulted in deforming the part of your pipe that goes over the spigot.

I thought the spigot on the older bikes were a weak link if your pipe took a hit,I was pretty sure in 04 or 05 they started making them stronger?

Not '04. I broke mine and don't even know exactly when it happened.

Is the flange tight on the cylinder? The '06 should be a steel flange.

Do you have the GG pipe?

I noticed that my '07 seems to leak a very small amount of spooge from the spigot/pipe a lot quicker after an o-ring swap than my '00 and '03 did. I think the pipe flange is just not as snug a compression fit on the o-rings as the FMF. All I did was clean everything up perfect with contact cleaner, and use hi temp RTV on the o-rings instead of grease. Seemed to solve the problem so far.

I imagine if the pipe is even slightly tweaked at teh spigot this situation will be aggrevated.

If the pipe is a very loose fit, its most likely that the next size up O-ring will fit tightly.

You can always just spin a few thou of the spigot in the lathe if necessary, to get the oversize O-ring to fit neatly.

I know, PITA, to have non standard parts.

K

There was no issues with the set up on there for the last 8 months i have owned the bike. I spoke to the tech today who did the recent work and he says he replaced the oring. But he is happy to take it back and put it right, as it was not leaking prior to him having it.

It is the stock GG pipe by the way. i will get him to check it all out and try and get it resealed.

What about this business of the through hole needing sealed? Is that one of these holes?

Cheers guys!

Colin,

It's a common problem. Sometimes the bolts on the spigot work loose, unfortunately this usually means the gasket gets damaged so tightening does not fix. I tried loctite but unless you can really clean out the threads in the barrel it doesn't work very well with so much crap in that area. The spigot is Aluminium so does break easily. I broke 2 of them with a Gnarly pipe that is very tough and didn't fit very well. Although many people suggest using the LTR steel one I shied away from that on the basis that spigots are cheap and I would rather that broke than the pipe or barrel. More likely the bolts would shear off in the barrel though. So I decided I'll just replace them. However ... since using a Doma pipe which fits better and is thinner I haven't broken any.

I have also found the o-rings that seal the exhaust on often get pushed out of their grove when fitting the pipe. I now use Silicon RTV as well to help seal the pipe on.

Ian.

You will wad up any pipe good before you break spigot bolts on a steel spigot.

About o-rings: Silicone hi-temp orings have poor abrasion resistance. Ever notice how they are worn flat from vibration and pipe movement? Buna N (common black rubber compound) is better but less heat resistant, and tends to retain its compressed shape. Viton is good but also not too abrasion resistant. I buy a big bag of Buna N o-rings and change them if I notice a leak. Its not a big deal.