Worse case annual.

Tom-D

Tom-D

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Tom-D
Last summer I was referred by a friend to help an owner of a 172 to change an oil sump on a 1957 172. It was bought cheap, if you know what I mean.

This month the annual is due. So. I have him bring it up to my hangar and we start the annual.

The first discrepancy was the nose bowl of the cowling was cracked in several places and the cowling fasteners were loose in their anchors, easy fixes.but,

As I start the compression check #1 is barely 60/80 PSI #3 is 73/80 #5 60/80, # 6 60/80 #5 40/80 and #2 58/80

I inform the owner that I can't pass the engine with these readings. He then tells me he can't afford to do any thing with it.
I ask him if he would like me to continue the annual, and sign it off as unairworthy and give him a list of discrepancies, he says no. and wants the aircraft buttoned up and able to return to his home field.

and that is what happened, no sign off in any log.

and he went home.

his first annual with a new A&P-IA.
 
Isnt 40/80 without exhaust valve leakage a passing compression for a continental O-300A?

If it's not, its a recent change.
 
NotSure said:
Isnt 40/80 without exhaust valve leakage a passing compression for a continental O-300A?

If it's not, its a recent change.
Click to expand...

I don't care if it is legal or not, when I hear the air escaping thru the crank case like a hurricane thru florida it is not getting my signature.

My compressor couldn't keep up with it.
 
After reading the link, you must have questions.

the oil was pitch black, with 30 hours.

most of the leakage in the 60/80 were both rings and valves.

the cylinders were all chrome (orange bases) and have 512 hours and 18 years on them, all cylinder hold down studs are very corroded.

what Mike eludes to is the cylinder will run great on dynamic compression alone, and the compression rings can be worn and the oil usage can be OK with good oil control rings.
 
What were the compressions last year? Was there a prebuy inspection checking cmps? I think you probably right Tom, but I would fly it for an hour lean and check the comps again. Maybe, just maybe it will come up, but air leaking in the crank case is not aa good sign.

Could you rework just that cylinder? The others are border line.... kinda.:redface:

I am not an A&P, but I did sleep in my own bed last night. ;)
 
Geico266 said:
What were the compressions last year? Was there a prebuy inspection checking cmps? I think you probably right Tom, but I would fly it for an hour lean and check the comps again. Maybe, just maybe it will come up, but air leaking in the crank case is not aa good sign.

Could you rework just that cylinder? The others are border line.... kinda.:redface:

I am not an A&P, but I did sleep in my own bed last night. ;)
Click to expand...

When any engine is that low across the board in all cylinders, I don't advise getting one cylinder to develop high compression, It causes a rough running engine. 5 of them going putt, and one going bang.

as I mentioned these are chrome cylinders, with 512 hours on them, I suggested we pull all of them and see if they need rings, if the cylinders have good bores, we may try lapping the valves, and re-ring it. Its a cheap fix and MAY get him a couple hundred hours.
 
Chrome is good from the perspective of no rust in the cylinder bore but its a bit of a pain for seating rings....
I'd do the same thing you did. No way I'd sign it off and if he doesn't want to spend enough to make it legal I guess he doesn't get it signed off. I understand the pain in spending money on unexpected repairs but its part of the program at times. Getting the plane cheap should make it easier to spend a bit on bringing it up to snuff. Some things need to be done and others are optional. When more air is getting pumped into the case than into the exhaust pipes things need to be done. Hope you can make him understand its his butt in the seat.....along with the innocents he takes with him.

Frank
 
Tom-D said:
When any engine is that low across the board in all cylinders, I don't advise getting one cylinder to develop high compression, It causes a rough running engine. 5 of them going putt, and one going bang.

as I mentioned these are chrome cylinders, with 512 hours on them, I suggested we pull all of them and see if they need rings, if the cylinders have good bores, we may try lapping the valves, and re-ring it. Its a cheap fix and MAY get him a couple hundred hours.
Click to expand...


I'll give you another trick. Mix up Barkeepers Friend (Oxalic Acid Crystals) with a carrier (I often use GM X-66 Carbon Remover but have used water as well) into a slurry that still has crystals and run it through the engine. Mix up about a quarts worth, throttle up to about 1500 rpm and then introduce it to the airstream. With an up draft it's trickier so I take a hose and funnel securing one end of the hose under the carb inlet. Regulate throttle and flow to keep it running as you feed about 3/4 of the quart in and then with the last bit just open the throttle full and dump at the same time to kill the engine. If you can't kill it on the updraft, ICO it at that time and let it sit for about 20 minutes which is about the time it'll take to pull and clean the plugs. Once it's back together start it and run it like you would if you were seating up a fresh set of rings (with chrome cyls you usually have soft iron rings with now have a fresh magnetite face on them which seals readily against a chrome wall). If it worked, change the oil and he's good to go.

It's a 5minute $5 technique that has a better than 65% chance of fixing the ring seal problem if the rings aren't broken.
 
I have seen that trick actually work........:yesnod:

There is a real "backyard" trick too !!!! Warning, for lawnmower engines only !!!... Get a can of Bon Ami and let the carb ingest it as you pour it out of the container..... Then go mow the grass while running the motor wide open to work it hard.... It will reseat rings and wear out the motor all at once.:D:hairraise:
 
Yeah, problem with all those is they are silica based and leave sand in your bearings. There is no silica in B/F, it all dissolves away quickly. I used to fix the old Honda CVCC engines this way, I'd charge $500, no cure no pay. They would all start smoking around 80k, this had over a 90% cure rate on them.:yesnod:
 
Cool trick, will have to try it sometime. My jeep burns oil though I believe it is leaky valve guide seals that is causing my troubles. It has yet to get so bad that I feel the need to do something about it, but when that day comes I would not have trouble pouring some nasty stuff into that engine, it has over 200k anyway might as well go for broke.

I have used both products to clean boats and they've worked well for me there. Might as well pour them into my engine haha
 
dell30rb said:
Cool trick, will have to try it sometime. My jeep burns oil though I believe it is leaky valve guide seals that is causing my troubles. It has yet to get so bad that I feel the need to do something about it, but when that day comes I would not have trouble pouring some nasty stuff into that engine, it has over 200k anyway might as well go for broke.

I have used both products to clean boats and they've worked well for me there. Might as well pour them into my engine haha
Click to expand...


When does it smoke? Does it clear some when the engine warms up? Does it smoke at idle and go away if you floor it? If so it's likely the guides. You can get a set of valve guide umbrellas from a Chrysler 318 to help with that.
 
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There is no magic chemical that will put the metal back into a ring, when they are worn out, they are worn out.

Every chrome 0-300 / 50 cubic inch cylinder I have ever seen wears out a set of rings each 500 hours.

it's time.
 
Tom-D said:
There is no magic chemical that will put the metal back into a ring, when they are worn out, they are worn out.

Every chrome 0-300 / 50 cubic inch cylinder I have ever seen wears out a set of rings each 500 hours.

it's time.
Click to expand...

That's not necessarilly true. The problem could just be an edge hardening/surface tension issue which the oxalic acid slurry will both physically scratch with about a 320 grit effect, it will also chemically etch and change the surface condition. It costs $5 and 5 minutes to try and has a >65% success in the hundreds of times I did it growing up at a used car lot. Seriously, you have nothing to loose and it works.
 
Tom-D said:
There is no magic chemical that will put the metal back into a ring, when they are worn out, they are worn out.

Every chrome 0-300 / 50 cubic inch cylinder I have ever seen wears out a set of rings each 500 hours.

it's time.
Click to expand...

When someone gets the cylinders real hot and glazes the surface, and the rings still have spring tension left in them all it takes is a slight abrasive like what Henning is suggesting to "reseat" the rings... I have seen people remove glazed cylinders and hone them to create another 'cross hatch' and put it back together... What Henning does is make a batch of "liquid hone":idea: Altho in this case I would do just like you did,,, don't sign any log books and send him on his way.... :yesnod:
 
N801BH said:
When someone gets the cylinders real hot and glazes the surface, and the rings still have spring tension left in them all it takes is a slight abrasive like what Henning is suggesting to "reseat" the rings... I have seen people remove glazed cylinders and hone them to create another 'cross hatch' and put it back together... What Henning does is make a batch of "liquid hone":idea: Altho in this case I would do just like you did,,, don't sign any log books and send him on his way.... :yesnod:
Click to expand...


Exactly! I am doing a light in place chemical and physical (fully dissolving) hone to break the glaze. This is not a 'Miracle Cure' process, this is a simple physical application of known principles. With chrome cylinders you use soft iron rings and this combination is prone to glazing the rings. It doesn't take alot to break that glaze. The chrome surface is so slick that the chances the rings are worn out is low. The reason I use the X-66 is that typically there is a secondary issue of the rings being stuck in carbon, and as far as that goes, there isn't anything better than X-66 that I found and I haven't found a like product elsewhere on the market.
 
Henning said:
When does it smoke? Does it clear some when the engine warms up? Does it smoke at idle and go away if you floor it? If so it's likely the guides. You can get a set of valve guide umbrellas from a Chrysler 318 to help with that.
Click to expand...

Smokes the most when i'm crawling around in 4lo for extended periods of time usually under 1500rpm

Its the 4.7 liter. They also have an issue with dropping valves IIRC
 
N801BH said:
When someone gets the cylinders real hot and glazes the surface, and the rings still have spring tension left in them all it takes is a slight abrasive like what Henning is suggesting to "reseat" the rings... I have seen people remove glazed cylinders and hone them to create another 'cross hatch' and put it back together... What Henning does is make a batch of "liquid hone":idea: Altho in this case I would do just like you did,,, don't sign any log books and send him on his way.... :yesnod:
Click to expand...

I've also seen some pretty miraculous things happen when you pull heads, bottom the piston and run a ball hone up and down the cylinder
 
dell30rb said:
Smokes the most when i'm crawling around in 4lo for extended periods of time usually under 1500rpm

Its the 4.7 liter. They also have an issue with dropping valves IIRC
Click to expand...

No doubt, it is the guides... The umbrella seals on the intake valves will fix the smoking.... Try a VP-24, they are tall and narrow so they fit inside the springs better..... You can do that repair "inframe".. Just get a compression tester that fits an airchuck. pressurize the cylinder, tap the corner of the spring retainer to loosen the keepers, remove spring, install stem seal, rinse and repeat...
 
dell30rb said:
I've also seen some pretty miraculous things happen when you pull heads, bottom the piston and run a ball hone up and down the cylinder
Click to expand...

I agree... those "knobbies" cure a multitude of sins.:yesnod::yesnod:;)
 
I might have to give that a try. Tired of this thing burning oil
 
N801BH said:
No doubt, it is the guides... The umbrella seals on the intake valves will fix the smoking.... Try a VP-24, they are tall and narrow so they fit inside the springs better..... You can do that repair "inframe".. Just get a compression tester that fits an airchuck. pressurize the cylinder, tap the corner of the spring retainer to loosen the keepers, remove spring, install stem seal, rinse and repeat...
Click to expand...

What is a VP-24.. a tool?
 
dell30rb said:
I might have to give that a try. Tired of this thing burning oil
Click to expand...


Yeah, they work well. You might want to roll an o-ring on the stem on top as well, use Nitrile. The key indicator/differentiator between guides and rings is vacuum. When you are idling or let off the gas pedal you smoke, but it clears up at least pretty well under hard WFO acceleration. If the smoke multiplies under acceleration it's rings.

First I would check and make sure my crankcase breather and PCV systems were functioning properly and the hoses aren't rotted on the bottoms.
 
Tom-D said:
Last summer I was referred by a friend to help an owner of a 172 to change an oil sump on a 1957 172. It was bought cheap, if you know what I mean.

This month the annual is due. So. I have him bring it up to my hangar and we start the annual.

The first discrepancy was the nose bowl of the cowling was cracked in several places and the cowling fasteners were loose in their anchors, easy fixes.but,

As I start the compression check #1 is barely 60/80 PSI #3 is 73/80 #5 60/80, # 6 60/80 #5 40/80 and #2 58/80

I inform the owner that I can't pass the engine with these readings. He then tells me he can't afford to do any thing with it.
I ask him if he would like me to continue the annual, and sign it off as unairworthy and give him a list of discrepancies, he says no. and wants the aircraft buttoned up and able to return to his home field.

and that is what happened, no sign off in any log.

and he went home.

his first annual with a new A&P-IA.
Click to expand...
Why you didn't ground him?
:yikes:
 
WarriorPilot said:
Why you didn't ground him?
:yikes:
Click to expand...

I didn't want my name on it, besides I didn't want him stuck in my hangar.

As of tonight he has a hangar at BVS that we will use to pull the cylinders and see what is wrong.

He grounded himself. I had no need.
 
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WarriorPilot said:
Why you didn't ground him?
:yikes:
Click to expand...

OBTW an A&P-IA has no authority to tell an owner what they can do with their aircraft.

it was still in annual, and the pilot considered it safe to fly.
 
N801BH said:
I have seen that trick actually work........:yesnod:

There is a real "backyard" trick too !!!! Warning, for lawnmower engines only !!!... Get a can of Bon Ami and let the carb ingest it as you pour it out of the container..... Then go mow the grass while running the motor wide open to work it hard.... It will reseat rings and wear out the motor all at once.:D:hairraise:
Click to expand...


I'm going to give away my age on this one:

My Dad was in the garage business when I was a small kid. I hung around the shop alot and learned alot even as a small child. I was there when the "New Motoramic Chevrolet" (marketing buzz words for the '55 Chevy) hit the scene. The first year 265 small block Chevy had ring seating problems. It was actually factory recommended to use Bon Ami for ring seating.

I barely remember it, but my Dad did this to several nearly new cars with great success. He immediately changed the oil after the process. I'm sure that in the long run it did indeed decrease engine life.
 
MBDiagMan said:
I'm going to give away my age on this one:

My Dad was in the garage business when I was a small kid. I hung around the shop alot and learned alot even as a small child. I was there when the "New Motoramic Chevrolet" (marketing buzz words for the '55 Chevy) hit the scene. The first year 265 small block Chevy had ring seating problems. It was actually factory recommended to use Bon Ami for ring seating.

I barely remember it, but my Dad did this to several nearly new cars with great success. He immediately changed the oil after the process. I'm sure that in the long run it did indeed decrease engine life.
Click to expand...


It won't really decrease engine life, what it will do is ruin the crank so you can't use it for the next rebuild. That's why I use Bar Keepers Friend, doesn't have that issue.
 
MBDiagMan said:
I'm going to give away my age on this one:

My Dad was in the garage business when I was a small kid. I hung around the shop alot and learned alot even as a small child. I was there when the "New Motoramic Chevrolet" (marketing buzz words for the '55 Chevy) hit the scene. The first year 265 small block Chevy had ring seating problems. It was actually factory recommended to use Bon Ami for ring seating.

I barely remember it, but my Dad did this to several nearly new cars with great success. He immediately changed the oil after the process. I'm sure that in the long run it did indeed decrease engine life.
Click to expand...

I think what decreased engine life on those early 265s was the lack of an oil filter, or even a place to put one. 'course this was the first production V-8 by Chevy since the teens.
Even the pre-filter aircraft engines, had at least a fine mesh screen, which the '55 265 didn't have.
 
bluerooster said:
I think what decreased engine life on those early 265s was the lack of an oil filter, or even a place to put one. 'course this was the first production V-8 by Chevy since the teens.
Even the pre-filter aircraft engines, had at least a fine mesh screen, which the '55 265 didn't have.
Click to expand...


Most of the early 265's got aftermarket oil filters. They were much the same as was used on the Chevy sixes of the time with hoses up to them. They were not full flow however.

I remember seeing my Dad put several such filters on customers cars.

Given the road draft tube, the available engine oil of the day and the fact that most people didn't change oil often enough probably had more to do with shortened engine life than anything.

By the way if 56 the oil filter pad was cast into the block, but no oil filter there yet. I always thought that was strange.
 
bluerooster said:
I think what decreased engine life on those early 265s was the lack of an oil filter, or even a place to put one. 'course this was the first production V-8 by Chevy since the teens.
Even the pre-filter aircraft engines, had at least a fine mesh screen, which the '55 265 didn't have.
Click to expand...

Cheap V-8, then. My 1954 Buick Special (first year of V-8s in Buicks) had an oil filter. I remember replacing that every time I changed the oil in that tank. 7 quart capacity pan, too.
 
Ghery said:
Cheap V-8, then. My 1954 Buick Special (first year of V-8s in Buicks) had an oil filter. I remember replacing that every time I changed the oil in that tank. 7 quart capacity pan, too.
Click to expand...

Was the Buick a 'spin on' or a cannister with a element inside ?:dunno:
 
MBDiagMan said:
I'm going to give away my age on this one:

My Dad was in the garage business when I was a small kid. I hung around the shop alot and learned alot even as a small child. I was there when the "New Motoramic Chevrolet" (marketing buzz words for the '55 Chevy) hit the scene. The first year 265 small block Chevy had ring seating problems. It was actually factory recommended to use Bon Ami for ring seating.

I barely remember it, but my Dad did this to several nearly new cars with great success. He immediately changed the oil after the process. I'm sure that in the long run it did indeed decrease engine life.
Click to expand...

Used to sail for a guy in GM engineering management who told me about the Bon-Ami for ring seating. I don't recall what the application was though.

MBDiagMan said:
Most of the early 265's got aftermarket oil filters. They were much the same as was used on the Chevy sixes of the time with hoses up to them. They were not full flow however.

I remember seeing my Dad put several such filters on customers cars.

Given the road draft tube, the available engine oil of the day and the fact that most people didn't change oil often enough probably had more to do with shortened engine life than anything.

By the way if 56 the oil filter pad was cast into the block, but no oil filter there yet. I always thought that was strange.
Click to expand...

PCV made a big difference in engine life. The same engineer talked about how they thought PCV was going to cause problems - but turned out to do wonders for engine longevity.
 
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