Time for overhaul?

[Bill Hart]

Bummer huh?


I sent my engine in for overhaul and this is what they found. [/img]

[tshort]

Ouch!

So what made you decide to overhaul? How was it running? Did you have any idea there was a problem?

A guy a few hangars down from me has a straight tail 172 and he has some of the pistons that were taken out when he overhauled it ... a couple are unbelievably damaged, with bent rings and deformed tops - they actually scored the cylinders. He had no indication (that he was aware of), and overhauled the engine because it was high time and he had the money. He says he can't tell any difference in the power after the overhaul ... feels like it was running fine before!

Thomas

[cessna170bdriver]

OUCH

Any leaks or oil pressure problems before teardown? What does the bearing and crank look like?

If you can't find a case closer to home, give me a call or PM. I have a runout C-145 with a case and bottom end I could have checked out.

Miles

[jrenwick]

I've got a case that looks exactly like that. The left side is cracked, the right is OK. The crankshaft appears to be fine. The fellow I bought the engine from said the case cracked because a main bearing wasn't seated quite right, and when the through-bolts were torqued, it cracked the web. The engine ran just fine that way.

Best Regards,

John

[johneeb]

That is sad Bill, I don't have much to offer like Miles and John except maybe some "Gallows Humor" have you considered J B weld?

[johneeb]

Bill,
At least you did not have a failure in flight like a friend did last October. He was 20 minutes out from landing his Shrike Aero Commander when one of the connecting rods let go. The real irony was he was droping off the airplane to have both engines majored.

Sorry about the quality of the picture, I took it with my Dick Tracy wrist telephone.

[Bill Hart]

Here’s the rest of the story…………I did have low oil pressure. It was running about 20 psi at 180 degrees. I tried several things to ensure that what I feared was true. I installed a new gauge, new relief spring and plunger, and my personal favorite bad idea washers behind the spring. When after every change the pressure settled right back down to 20 psi. There were no other indications that there was anything wrong.

When I exhausted all ideas of what could be the cause of the low pressure I decided to pull the engine and have a look in side and this is what was there.

I spoke with Paul Kline of Kline Aviation who is doing the overhaul he said that it could probably be repaired. After I spoke with him I called DIVCO and spoke with someone there and described the crack to them and was told if it can be repaired it would run $650.00 or if needed I could get a case outright for $1200.00.

All in all I must say I am happy to have a smoking gun and am happy so far with Kline. I will update everybody here when I get the engine back.


Oh yea go ahead with bad jokes with my friends I have heard them all.

[blueldr]

For what it's worth, I wouldn't even think about welding a crankcase with a bearing journal broken as the one pictured. I'd never feel confident flying it, and wouldn't want to pass ti off on someone else. Case halves are not that hard to come by. Turn that case half in to salvage with your old beer cans.

[cessna170bdriver]

I'm with Dick on that one. It would never have occurred to me that damage like that would be repairable.

Are those prices for a ready-to-use (yellow tagged) case, or are they for just the repair or core? I paid $875 to have my undamaged case brought up to spec a bit over year ago.

Miles

[Bill Hart]

For what it's worth, I wouldn't even think about welding a crankcase with a bearing journal broken as the one pictured. I'd never feel confident flying it, and wouldn't want to pass ti off on someone else. Case halves are not that hard to come by. Turn that case half in to salvage with your old beer cans.

I am with you on the case exchange. Personaly I don't think this will be repairable.

[johneeb]

Bill,
What is the total time and time sence last overhaul of your engine?

[Bill Hart]

It has a touch over 700 hrs SMOH but that was in 94. The company who did the overhaul is a well know overhauler.

[53B]

How can you be sure an exchange case didn't get the same repair?

I am starting to gather parts and info as my engine inches closer to an overhaul. I have no reason to think that my case can't be reused but have always been cautious of using exchange parts that you can't be sure of the previous damage/repairs.

[blueldr]

A thorough cleaning and a simple visual inspection of a crankcase would certainly reveal any welding repairs. I've seen a good many crankcase weld repairs, but, so far, none of them have been invisable.

[HA]

depending on the engine model, you will very often see welding in the bearing bosses during case overhauls - they fix fretting damage that way and then assemble the case and line bore it again (that's the last machining done anyway because they have to make everything round again after facing the parting surfaces). I've never done an O300 so I don't know how they are there, but you see it constantly on bigger TCM engines like 520's.

but it will be obvious if a major web repair (like to fix the above engine) was performed. I'd set the ground rules with your case supplier before it ships but inspect it anyway when you get it. if they have an approved repair process then they won't consider repairs that you don't necessarily like to be a problem.