Question for 250ED owners

[Bullfrog]

I suppose this question might also be for 250SL owners, but an interesting and rare situation was brought to my attention earlier this evening. One of my local Hodaka buddies called and asked if I'd mind taking look at his engine this evening, and the photo below shows what we saw.


The photo is looking between the 2nd and 3rd fins (from the top) of the cylinder on the left side. This is at a point above the transfer port. As you can see, the casting flaw is "wet" - indicating that it IS a "leak". The engine has been run for years without damage, indicating that the "leak" passage is long and convoluted and small. There is a matching casting flaw on the other side of the cylinder (same place, other side) - but it is "dry" - so almost certainly not a "leak". As if that wasn't enough, there is yet another casting flaw on the centerline of the cylinder at the rear (intake side, also between the 2nd and 3rd fins). Thankfully, this one appears to be "dry" too.

So here is the question, do any of you folks who have running 250 engines see the same sort of casting flaw on your cylinder? I would expect not, but I am curious. The engine in question has always been a "poor runner" for its current owner . . . perhaps now we know why. Unfortunately I'm pretty sure it is too late to file a Warranty Claim.

Ed

[bchappy]

We are looking at aluminum. So how is the compression getting through the steel liner? And why are you still up after midnight?

[Bullfrog]

You've just asked one of several questions my buddy and I threw out. Base gasket or head gasket failure allowing leakage to the joint between the liner and the alloy? Is there another "route" for the leakage? Is the liner cracked or porous? Whaaaaaat? (and I told my buddy I'd get the photo posted last night . . . editing and uploading photo took me into the wee minutes of this morning )

Ed

[racerclam]

well Ed I have a few 250s and never seen this .

Rich

[olddogs]

I have a Super Combat cylinder with similar casting flaws. The aluminum looks as though it puddled and never stuck. You can see the iron liner through the blemishes. They are in various locations mostly near the intake track.

[Hydraulic Jack]

Everyone's aluminum cast cylinder has flaws. In this case, itmos a problem.

The "bond" between the aluminum casting and the iron insert isn't a perfect one even under ideal conditions, but here you have clear evidence of casting omissions, at least one of which is continuous from inner liner to outer surface. The most likely place this originates is the port most closely in proximity to the obvious leak. The leak is not coming from the head gasket or base gasket, but from a port.

Fix this one of two ways: 1) thoroughly degrease the outer casting flaw and plug thoroughly with epoxy. If you can get the oil out of the aluminum pores, there is a good chance the epoxy will stick and stay. If in doubt, improve the flaw inner surface lightly with a dremel tip exposing clean aluminum (like preparing a tooth for a filling) and if you do this, do it so there is a slight taper inward, not outward; 2) pull the cylinder, thoroughly degrease the whole thing, inspect closely each and every interface between port and liner, and epoxy any such interface that is suspect, and then do the outside of the flaw as well.

Either way, fix it with 24 hour epoxy, not the quick stuff. JB Weld, Devcon, or equivalent.

Or, big buck fix, take it to a competent welder and have the flaw filled from the outside. I think that would be overkill, but it isn't my ride.