Help: Bonanza Oil Leak?

Can anyone offer some specific help? We have an oil and maybe fuel leak in my 1988 Be -36TC Bonanza.
The a&p is a Beech expert, but it it very hard to see some of the engine, it is dark and dirty and wet in more than one spot.
It it a Cont TSIO 520 U B engine, opposed horizontal 6. There is a small amount of oil at the top spark plug well, just a small spot, and it also looks like there is a small green area, like a fuel stain.
The mech thinks the cylinder might be cracked. He has looked inside with a borescope and is not sure; valves and plugs look good, but there is one little spot that looks almost like a spot of carbon, could be a crack?
I have some doubts about this. It seems that if fuel is only going into the cylinder just before combustion, it is not going to leak out as a green liquid. If there is any leak or any crack to be seen, it would be a black carbon streak from the combustion. Does anyone really know about this?
This is cylinder 5, the right front one. We noticed some oil leak coming out the air vents on the lower right side of the cowling and it is wet underneath the cylinder; just hard to see anything specfic there and it is right in the cooling air flow so oil is blown back and down; might even go up as far as I can tell.It seem to be pretty dry up near the alternator which sits in the right front air intake.
I am thinking about asking him to clean the oil off and then run it and see what we get. I don't want to step on his toes when he has 45 years of experience, but I'd like to be sure what is happening, before it is torn down.
I appreciate any solid answers.

I keep having to chase oil leaks on the O470 in our 182. The problem is if you notice a leak after a few flights the oil has blown all over the engine & you can't tell where it is coming from.

Has he cleaned the engine? If not, go to the local farm store, get a pump up hand sprayer & a couple gallons of mineral spirits. Spray the mineral spirits everywhere to get the oil off (above, below, reach under, etc, just soak the engine) then hose it down, use hot water if it is available.

Fly 3 laps around the pattern & pull the cowl & look again, you will probably be able to tell where it is coming from then.

A 1/4 cup of oil looks like a few gallons when it gets blown around under there.

Thanks, Mike, that is sort of my thought also. He has cleaning spray in hand. Unfortunely I just spoke to my A&P and he wasn't very receptive to the cleaning and then running it idea.He's very busy right now and trying to fit me in.

What about the fuel colored stain? Do you see anyway that the liquid fuel, still colored blue green, can appear on the outside of the engine at the upper spark plug hole even if the cylinder is cracked?

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Originally Posted by Bill Greenwood

What about the fuel colored stain? Do you see anyway that the liquid fuel, still colored blue green, can appear on the outside of the engine at the upper spark plug hole even if the cylinder is cracked?

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Someone on the AOPA board had a similar problem, I'm going off memory here but I think the head had a small crack starting either next to an injector or primer, but the engine really needs to be clean to find it, especially a small crack.

If the mechanic doesn't want to clean it & fly it you can clean it & run it up on the ground, the problem I have run into with our 182 is a ground runup doesn't build as much crankcase pressure as actually flying it with the engine under full load, and small leaks may not show up.

Hi Bill!
I use these things all the time to find leaks in planes and my cars.
http://www.amazon.com/Uview-413010-B...sim_sbs_auto_1

If you use just the yellow goggles and light you need to Varsol etc. all the old oil off the engine. Then run it and look for oil. Looking at the oil using just these tools the oil will appear yellow/greenish and will stand out pretty well in the shade.

If you use the dye pack (which is safe for ALL engines, transmissions, etc) you don't need to clean the engine, just pour in the dye, run the engine for a minute or so and look for your leak. Using the light and goggles the old oil will look yellow/green like before but any leaking of the now-dyed oil will be neon orange!


My kit is in constant demand at the airport...maybe I need to rent it out???


Hope this helps.

Chris

Hiper , thanks for the suggestion. A leak detector in the oil sounds like a good idea, but neither of my guys has ever used it.
Anyway he took the cylinder off and says he sees a crack. There is a very thin line near the intake valve and going into the fins on the outside, it looks like maybe a trail of oil. I an not fully convinced, it is so small and he admits that he has not seen cracks on the cool side, intake, before. It did not leak when compressed air was added to the cylinder.
But there doesn't seem to be a source of oil anywhere else. So he will replace the cylinder with a rebuilt one.
Both valves in the old cylinder look good by the way.

I have been leaning toward getting an overhaul, and it looks like Ram in Waco is the best choice. Anyone here have an experience with them or with O H on these type engines, the TSIO 520?

I had one redone at Signature, a few years back, still running strong.

You may have heard of this one but I've used deodorant to find leaks, for years. Clean the area, spray on one of those womens deodorants that turn to power, Arid might be one, start the engine and within a few minutes, the leak will stick out like a sore thumb. And your engine will smell better too.