C-145 (O-300A?) Heavy Leak/Drip & Tach Question

[c170b53]

Communication is definitely harder on the Internet. So until further clarification is provided by the poster ie. a picture, all of us are just speculating as to the severity of the problem.
I won't disagree with a thing written in the last few posts, I think the views and opinions in the last few posts and for that matter in any post are all given with the best of intentions.
Those responding to posts and offering solutions likely have asked themselves if their advice is appropriate for the recipient or the situation. Obviously the merrit of the information provided requires due diligence on the part of the person contiplating acting on the information offered.
Back to the problem; At first I thought the issue described was a fuel oil mix coming out the throat of the carb. In the last post I thought by the description that possibly, the fluid was just oil and by the colour, not new oil (clear), not old oil(black) but low time oil(green/blue) running on the outside of the carb. Now I'd like to see a picture because who knows what is leaking and where the fluid is coming from and how much because, nowhere in this thread has consumption come up.
Pilots are interesting because some may be mechanically inclined and some may never have seen a screwdriver. We've had a pilot concerned about a piece of 8x11 paper in the bypass of a 60k thrust engine. We've had one find a 8" crack in the spinner of a 30k thrust engine during his walkaround and ask if it was a problem.
Anything is possible and eventually you'll come across the impossible in aviation (retirement with enough money ).
This could be a problem or it may not. An IA has been involved in the past, is he a real IA? Or is this a real leak missed by fake or incompetent IA? Or is this an IA who might learn something from an IA in these forums?
More data please!

[voorheesh]

This is an interesting discussion and, for me has brought out memories from my aviation career dating back many years. As a 170 owner, the information/advice (both certificated and non certificated sources) found on these forums is invaluable and I appreciate it. For the original poster of this thread, I sincerely hope you don't feel bad about asking the questions even though my previous comments admonished you to get direct help. In aviation, the only dumb question is the one not asked. The airline pilot who wondered about a crack may seem a bit out of touch, but thank goodness he asked. Like pilots, aviation maintenance technicians represent a wide variety of competencies, but speaking as a pilot: God Bless Them!

[c170b53]

As stated earlier I agree with the positions previously posted and I also recommend a conservative approach when dealing with an issue that has unknown variables. Keeping the plane on the ground until there's further investigation is certainly an easy option if the owner has reservations as to whether the airplane is fit for flight.

[ptporebski]

Hello Everyone,

It has been a while since I posted about this problem. So here is an update. But first some background - I am a mechanical engineer. I make my living keeping old industrial machinery operating at a large power plant (500 MW power boiler, steam turbine, large rotating equipment, etc...) I have over 30 years of experience as an engineer in shipyards, chemical plants, and power plants. Although I have designed machinery, I am not a trained machinist or A&P but have worked with these type of people all my career. I have a better than average understanding of machinery and most importantly know my limits. I relate this because there was some discussion in peoples replies to my post about not knowing the original poster's (i.e. me) background. Some pilots have a lot of mechanical background, some don't.

Having said that, what started this thread was that my experience told me the IA who has maintained this plane for five years was wrong when he kept telling me that this oil drip was normal. I live in a residential airpark of over 100 homes and know most of the pilots in the neighborhood. The general consensus was that I am too fussy and that airplanes normally leak oil. Still my experience told me something was not right with this plane that I have flown all over the country since I bought it in 2009.

I respect the folks in TIC170A and the safety culture that is typically found here. So I posted this original question about the oil leak. After reading the replies to my post I decided to ground the aircraft until I was satisfied that I found the cause of the drip/leak.

I changed the oil, took the cowling off the plane, degreased, and washed the engine. Then I ground ran the plane hard enough to get the engine really warm. After that I put the plane in the hanger with paper under it and let it sit for a week while checking on it daily. I found that the plane developed a puddle of oil on the ground that continued to grow daily. This lead me to the source of the drip which appeared to be the front 5/8" plug and it's crush washer. So I pulled the front lower baffling. What I found was an un-airworthy patch on the bottom of the oil sump in front of the carburetor. The patch appears to be some type of epoxy with a fabric embedded in it. See the pictures below:

Overall view of patch

Closer view of patch

Red arrow points to crack that is source of oil leak/drip

It is apparent that when the engine was overhauled before I bought the plane (according to the logs in 2004) the mechanic attempted to repair a bad sump by applying this epoxy patch. As I originally said, the plane has always dripped oil since I had it. But the drip appeared to be getting worse. It is my opinion that the patch was progressively failing, and eventually I suspect would have lead to an in-flight total oil loss and forced landing. I am not happy to find this development. However, that is balanced against being satisfied with myself for following my instinct. Most importantly, I am glad I didn't continue to fly and have an in-flight failure.

I want to thank everyone here - your posts helped convince me not to ignore this matter and keep flying the aircraft. Bruce, George, Voorheesh, C170b53, hilltop170, sfarringer and all the others - THANK YOU for taking the time to read my post and reply. I wanted to let you know the result of your replies.

Now, I am going to pull the sump and either replace it or repair it. There is another experienced IA in the neighborhood who rebuilds engines - he came by to look and is searching for a serviceable sump. In the meantime if anyone knows of a serviceable sump or a repair service, I would appreciate them letting me know. I am still trying to get this bird back in service so I can complete the instrument ticket before my 3/31/15 deadline.

Regards,
Pete P.

[SteveF]

Pete,

if you are not already aware there are two different sumps that look alike.
Suggest you read in the forums about three and five hole sumps. If you are going to be looking
for a replacement sump then you need to be looking for one with the correct number of holes.

SteveF

[johneeb]

Pete,
A picture is worth a thousand words (I hope you are successful finding a sump), what I notice in your photos is the safety wire on the sump drain is backwards and could contribute to loosening of the plug.

[hilltop170]

Pete-
You are welcome, I'm just glad you found the problem before it fell apart. Take your time fixing the engine and get it done right. You can always rent a C-150 to finish your instrument rating. Don't give up on that accomplishment. Good luck.

[Bruce Fenstermacher]

Darn Pete. I hate to see this. I always wondered if a patch like this would work. To bad you found out.

It probably won't make you feel better but I doubt there would have been a catastrophic loss of oil. Likely you will find nothing but pin holes in the original magnesium. Like you, I still couldn't operate it in it's condition.

[c170b53]

Safe to say we all hate to see this as it's not an easy repair. Too bad it wasn't repaired properly at the O/H but seeing it was a " field overhaul" (and in this case, er sump, I'm seeing the back 40 with a large herd on it) it just shows to go ya that the quality of such O/H's can very significantly.
Pete anyone that can keep old machinery going in a commercial environment certainly will quickly come up to speed on our machines. Please keep us posted on your progress.

[ptporebski]

Hello Again,

Since I am now in the "looking for a sump business", I have been reading the Continental Engine Overhaul Manual (available online at the TCM website). I also searched our forum for sump repairs. BTW - I have counted holes and appear to have the 5 hole sump.

1. Sump material - all the posts I have seen seem to indicate the sump is magnesium. However, the TCM Manual describes it as an aluminum casting. Does anyone know what it is? I suppose it does not really matter. If I repair my existing sump any shop that I use will know. I just thought I would ask.

2. I searched the forum for sump repair. I came up an old post that indicated dissatisfaction with a shop named Drake repair and another shop that escapes me just now. What is the current consensus as to the best place to get one of these repaired?

Regards,
Pete P.

[c170b53]

Pete, I read the same thing you're read from the manual!
I'd be curious to know the specific magnesium alloys used, guess we would have to ask Continental for that info. I always thought both components were made out of the same material or at least they appeared to me to be the same when I took my 0-300B apart. My sump had the same issue that I believe you have. I believe I've posted this before but again, when first looking at the inside of my sump it appeared to be in good condition. But as I cleaned away the oil goop inside lower surface with a cotton cloth, the sump internal surface material simply turned into the consistency of sand. I literally with no effort, wiped away the inside surface material around the drain plug and the built up area of the carb stud attachment bosses.
So sorry I'm not really helping you here with your question because it's just speculation on my part as to what the material is.
I'd just like to comment that it would also be speculative to suggest you sump would have a catastrophic failure. I would think your oil leak would just increase in its rate as the sealant repair lost its grip. But having said that as the failure mode going forward is somewhat unknown, I would trend towards the conservative approach in this instance and repair asap.

[c170b53]

Arash, whilst I was poking away at my IPad, you made a new post . I recently had some 3D Boroscope training at work and I think with our 4mm or 6 mm scopes it would be difficult to get in there, that being the area ahead of the carb. That area is affected ( my belief) because of the slope of the sump would allow water to accumulate at the low point between the forward plug's aft side and the forward base of the carb attach boss. Even if you were to do some disassembly to gain access, I'm suggesting a visual may not be sufficient to assess whether there's an issue.

[170C]

There is a firm located in Kelowna, BC , which we visited at the 2006 C170 convention, that has a process for repairing our sumps. They line the entire sump with a material that prevents future corrosion. I don't remember the details, but it seems they won't preform the process if the sump has had prior attempts at repair (inside) and I am not sure if they do so if the sump is already leaking. Some of our members will probably recall more details and have the name of the firm available.

[ptporebski]

Hello everyone,

I asked an old IA in my neighborhood whether he had a useable sump and as to repair options. He didn't have a sump. He thought he had one but apparently sold it earlier - said he is either getting old-timers disease or has too much stuff around the hanger. Here is what he told me regarding repair options. BTW - this guy is an old-timer (approx 70 yr-old) in our neighborhood. For last couple decades has been doing field overhauls of engines. Has an excellent reputation in our airpark, FA40. Doesn't do annuals anymore and is semi-retired. I have always respected that he knows GA aircraft engines. So here is what he told me after he researched the matter:

1. Remove sump and send it to some place in Utah that was recommended to him. He has not used the Utah shop before but his network of repair contacts says that they are reputable. Cost about $500 - IF the sump can be repaired.

2. Remove sump and send to Divco for repair. (Note - in earlier post I said a forum search listed dissatisfaction with Divco repair. I was incorrect and edited that post. Shop's name was Drake). The IA uses Divco and says they are reputable. I asked him whether they offer a warranty on their repair; he didn't know but will ask. Cost about $500 - $800.

3. Try to find a serviceable old sump. However, from what I am reading about these old sumps I would be suspicious of re-using one without hot de-greasing and some sort of NDE test for porosity. As is apparent, these are 50+ yr-old parts. Since my sump is still on the plane, I don't know if mine is even repairable. One of our members has kindly offered to sell me a spare he has. I will take him up on that. Hopefully, with two candidates, one will be repairable.

The IA also recommends if we remove sump (which he does recommend), we should get a new gasket and take accessory case off instead of fussing about and trying to re-use the old gasket. I agree with him on this. I don't want to fix one leak and cause another - but more $$$.

Looks as though this is going to be an expensive repair. Which is why the past field overhauler cut corners and tried the epoxy patch that didn't hold up. But at this point I want it done right. Just one of those aspects of owning a vintage airplane I suppose. Sigh...

Regards,
Pete

[hilltop170]

The other option, the repair shop in Kelowna, BC has epoxy repaired many sumps with success and is an approved process. When I talked to them in 2006, they told me some they had repaired had gone thru a couple of TBOs and were still servicable without further repair.

They WILL NOT touch a sump that has had any type of weld repair due to potentail cracking although I would think your bootleg epoxy repair would not be included in that policy. You would have to check on that. You would also have to check on if they will repair a sump with an actual hole as opposed to porosity. But those things could be handled with one phone call.

One thing about their epoxy repair is that it covers the entire sump and eliminates any further corrosion problems due to trapped water or other contaminates because the repair completely coats the interior of the sump.

Mine is going on 8 years since repair and there is no evidence of failure although to be fair, chunks of epoxy would have to be falling out for me to be able to detect it. There are no chunks so far.

There are many of these sumps out there but no more are being made so repairing the ones we have left makes a lot of sense to me as opposed to junking and replacing with servicable parts.