I have been a member for a little over a year and have spent countless hours looking at the posts. Thank you all for the great information you provide.
This is my first post so here it goes!
I purchased N2850C about a year ago from two friends (both A&P's) that spent three years of their lives restoring her as she had been sitting for 30+ years. We were in the process of installing real gasket pushrod tubes and discovered two lifter bodies cracked on different cylinders. Since it is the bodies and not the internals I know that we have to split the case. We have started the process to remove the engine from the airframe and should have the engine on the work stand this Thursday. Some background on the engine. The engine has less than 500 SMOH but it was done in the mid 70's. From my understanding this would make it a candidate for a major overhaul. This is my question: Do we split the case and send out all the parts to be inspected and do a field overhaul? (My A&P friends are willing to help me) or should I start looking for a shop to rebuild the engine? (possibly western skyways in Montrose CO) Since I just bought the airplane I'm a bit tight on cash but would rather let the airplane sit a year or so and do the job right then just try to get buy and have to do the job properly in the future. I live in Colorado and my aircraft is based at KLMO so I'm looking forward to meeting you all and helping as much as possible (we just had a baby so time is tight ) with the convention.
Thad
Thad. This is a touchy subject but it regards piece of mind. If you are carrying family or friends I would tear it down. If it was you only, then you are your own insurance policy. I am not trying to generate work, but you have no idea who had their hands on your motor before. Going through an old motor will allow you to sleep at night if you know what I mean. Many field overhauls were good back in the day but the kind of leaks you speak of speak volumes and reviewed. I dont mean to speak in riddle but it is purely an integrity and facing the unknown that makes me wonder everytime I fly someone elses airplane. It goes with the teritory. Best of luck. D
There is certainly nothing wrong with a properly done field overhaul as long as you have confidence in the overhauler. With the proper tools, proper supervision, and a proper place to work, I would personally elect to do a field overhaul to save money and learn.
blueldr wrote:There is certainly nothing wrong with a properly done field overhaul as long as you have confidence in the overhauler. With the proper tools, proper supervision, and a proper place to work, I would personally elect to do a field overhaul to save money and learn.
Sorry to hear your bad news, hopefully you'll get it sorted out quickly. I'm sure everyone has a different opinion and I'm no different. The way I look at it is; you've bought an aircraft with an unknown and now you know a little bit more. I wouldn't fly an unknown over the rocks so although your discovery was unpleasant, now you going to discover what you really bought and in the end you'll have the peace of mind that all is well as it can be up front.
So first if you disassemble everything your going to know exactly what will be required to make it right. That's if you have the experience, tools, time and patience. If you lacking in one of these commodities, it's possible that you might incur increased costs by accidental damage so that's one consideration. Then the inspection and analysis of your engines state, again will require tools (albeit basic measuring devices), likely some NDT work and regardless of condition some refurbishment of components. Sure you can clean the bottom of the oil sump and hope the bottom doesn't dissolve away but I'm guessing you're going to have to farm the speciality work out. The bulk of your money is going to be spent on the parts so really by doing it yourself you'll be mostly saving money on the labor. Its not a question about what's your time worth but rather what an approved shop's time is worth. In my mind it comes down to this;
If you do it all, only you'll know how good it is and how much you put into it. Which means if further down the road you were to sell you'd have to have convince the new owner on everything. If an approved shop does it, you'll have the paperwork, warranty and recourse if things go awry. Doesn't mean you can't do it but you don't have the shingle that carries the same weight.
Its really up to you and only you know what's best for your personnel situation but don't cheap out along the way. As an example the only way you'll know if your crank is any good is with a complete inspection including NDT. That's what your really doing here, in the end (if done right either by yourself or by the shop) you'll be removing all doubt on exactly what you really have.
Thanks for all the replies. We had flown up to Leadville a couple weeks ago and she ran fine, again a testament to how good these engines are. I have also had her up to 14500 many times last year crossing the mountains. Either way we go (sending the engine out to a shop or doing the work ourselves) we will not be cutting any corners and the engine will be put back together with new tolerances not just serviceable tollerances. I agree that when I do sell the aircraft (hopefully not for a long time) that it does look better to the potential buyer that a reputable shop did the work instead of me and my buddies in my hangar. I'm just wondering how much will I really save by the time I send out all the major parts to be yellow tagged and putting it back together vs sending the whole engine out. The time factor is another elliment that I need to consider. Does any one know of a good engine shop In Colorado? I have left a message for a quote at Western Skyways in Montrose CO. Does any one have anything to report on this shop? If we do the work ourselves I was considering seding the parts to Aircraft Specialties Service in Tulsa OK, has anyone used this shop?
Side note: I bought the pushrod tubes last year from aircraft spruce and they have the black springs. Is there something I should know about the springs?
My personal choice was doing it myself and that is the way I'd do it if or when I need to again. I used Aircraft Specialties Services and have nothing but good things to say about those folks.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
I think a field overhaul on a 170 engine is fine, provided you do it right. Make teardown measurements, send parts out for NDT, cert, grinding, etc., replace all parts as recommended by Continental, and rebuild to new limits. Several of the guys here on the forum are good examples of how to do it.
IMO the resale value of a name shop overhaul is less of a factor on a 170 than it might be on, say, a 210. And the educational value of doing it yourself under experienced supervision is tremendous. How often in our aviation lives do we get to do that? I recently got quotes for a major overhaul and was surprised at the long lead times, so it may not take as much longer to do it yourself as you think.
Thanks Bruce, I almost feel like I know you. I have read many of your posts since buying my 170 and have learned a lot!
How long did it take you to rebuild your engine and ( I don't mean to pry just bracing myself) how much did it end up costing you? The guys I have talked to locally also recommended Aircraft Specialties Services so you being on board with that makes me feel good about them.
Hi Dave, my airplane is located at KLMO but I live in Fort Collins.
I read a post about one of our member writing an article for the quarterly publication in 2006 about rebuilding his motor. I have searched the forum for the article but cannot find. Does anyone have a copy? It had something to do with if you build your engine like the overhaul Manual states it will leak. I don't want a leaky engine.
she ran fine, again a testament to how good these engines are
Absolutely these engines can be very forgiving but that can all change in an instant. Then again it could be just a steady continuation of a slow degradation in performance, only time will tell. You could do just the bare minimums and get by or go all out and have problems with new components but in my mind the more you know the better off you'll be. So another question I'd ask the backyard builder, were the cases reconditioned say at Divco or was spray can liquid penetrant good enough. I'm just putting this out there and I understand there are very knowledgeable people who can do work better than the shops. But... even though these engines are forgiving...time is still marching on and along with that time are the unknowns that are likely to increase due to aging.
That's interesting about the Real Gasket tubes. I bought them from spruce a little less than a year ago and they came with all the paper work. I talked with Chris before the install and he seems like a good guy. We will make sure the proper springs are used. Thanks for the heads up.
It's been a few years since I did my engines. It took a few weeks to ship have the parts inspected and shipped back. I ordered the parts while waiting. Once I had everything it took a day or two to assemble. Whether you do it or you have someone else do it, the time will likely be the same. Most shops aren't going to do their own parts inspections sending them out instead, maybe even to the same place you will.
It may have been my engine you heard leaked after rebuild. It did. I inspected and overhauled as necessary the cylinders I had. The pushrod tubes eventually leaked (didn't take long) despite my efforts to reswage them. I never really did anything about it until it leaked a lot of oil. The engine did not leak otherwise because I followed the overhaul manual to a T.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce,
Thanks for the info on you engine. I talked to Western Skyways about rebuilding my engine and was told it would be aproxemetly $22000.00 to do. The gentleman that I talked to seemed very knowledgable and friendly but the airplane would have to go into hibernation for two years for me to come up with that amount of cash. I also talked to aircraft specialties services today. I talked to a gentleman that again seemed very knowledgable and friendly. His qote to do all the machining and parts would be aproxemetly $4000 to $5000. The case would have to be sent to another shop and would be aproxemetly $650. I talked it over with my AI and he thinks we should go for the field overhaul. I think as long as everything is sent out and looked at we can asemble the engine ourselves.
I think the article was written by cessna170bdriver. (I think in 2006) I will try to pm him.
Thanks again to everyone! I promise to keep you updated as we progress through this.
twlareau wrote:I read a post about one of our member writing an article for the quarterly publication in 2006 about rebuilding his motor. I have searched the forum for the article but cannot find. Does anyone have a copy? It had something to do with if you build your engine like the overhaul Manual states it will leak. I don't want a leaky engine.
The 170 News is available online in the Members Only section. Look on the bottom of the first column on page 15 of the second quarter 2006 issue.
We have started the process to remove the engine from the airframe and should have the engine on the work stand this Thursday. Some background on the engine. The engine has less than 500 SMOH but it was done in the mid 70's. From my understanding this would make it a candidate for a major overhaul. This is my question: Do we split the case and send out all the parts to be inspected and do a field overhaul? (My A&P friends are willing to help me) or should I start looking for a shop to rebuild the engine? (possibly western skyways in Montrose CO) Since I just bought the airplane I'm a bit tight on cash but would rather let the airplane sit a year or so and do the job right then just try to get buy and have to do the job properly in the future. I live in Colorado and my aircraft is based at KLMO so I'm looking forward to meeting you all and helping as much as possible (we just had a baby so time is tight 
) with the convention. 
