kimberlyanne546
Final Approach
If you PM me your email address, I can send you the manual I have, though my trainer 152 was a 1978 model year.
Hard starting 0-235
- Thread starter dell30rb
- Start date
If you PM me your email address, I can send you the manual I have, though my trainer 152 was a 1978 model year.
dell30rb
Final Approach
Thanks, but I did manage to get the manual online.
I did some inspecting and found that the primer system has likely not been touched for some time. The left side looks alright but the right side has had one nozzle removed and the cylinder capped. The remaining primer nozzle and line are showing some good corrosion.
I did some inspecting and found that the primer system has likely not been touched for some time. The left side looks alright but the right side has had one nozzle removed and the cylinder capped. The remaining primer nozzle and line are showing some good corrosion.
It is not unusual to see that, IIRC they came from the factory like that. I have seen them in various states of one, three, and four cylinders with nozzles on the O-235..
Kiloalphadriver
Pre-takeoff checklist
Why is the thinking limited to a fuel problem??
Have the impulse couplers checked on the mags.
Have the impulse couplers checked on the mags.
The description of the failure/start process for the most part.
Kiloalphadriver
Pre-takeoff checklist
If the impulse couplers are worn and not engaging, or if the lag angle is out, it will be very hard to start.
dell30rb
Final Approach
Hot starting is easy for the most part. The priming system is there mostly to help with cold starts and that is when the plane is at its worst.
Also, cleaning and inspecting the primer system is easy. If this does not fix it, next up will be the impulse coupling..
Yes, but it will be kicking back and stalling the prop and then will suddenly 'spring to life' not 'stumble along'. The impulse couplers are a possibility, but lack of priming is the simpler solution and easiest/free to confirm/eliminate.
Kiloalphadriver
Pre-takeoff checklist
As with ALL trouble-shooting, start with the simple things first. But, understanding that a hard starting engine can be more than just fuel is just as important.
Tom-D
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Remember we are talking about a 0-235....... with out the impulse it won't start at all.
How would the lag angle change in service?
Kiloalphadriver
Pre-takeoff checklist
Are you suggesting it can't??
My point was don't assume a starting problem is limited to fuel. That type of reasoning can become very expensive..
I have many stories where a problem turned out to be something other than what you normally would think it would be.
Dan Thomas
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Lag angle is the amount the mag is retarded as the impulse coupling winds up and then releases. It's a fixed value, built into the magneto. If the mag-to-engine timing was retarded, that's something different and you'd pick up on that by seeing a power loss, especially noticeable at full throttle. It would have to be really badly retarded before the engine would refuse to start at all.
The O-235 has a reputation for stubbornness in starting. Fooling with ignition timing won't improve it. The OP might have weak spark, but it would also likely show up in the runup.
Dan
Tom-D
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yes..
The only thing that changes in service is what wears, the cam follower on the points. as it wears the points will open late, and close early, changing the dwell and weakening the spark.
Lag angle has two methods of retarding the spark, an impulse coupling as on the common bendix and slick mags, that a steel pin embed in the housing trips the spring at a set point on the mag and the centrifugal fly weight design of the early bendix VMN7DF-A style. that actually advances the rotating magnet, and cam assembly.
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Kiloalphadriver
Pre-takeoff checklist
Okay. You win. It's impossible for the mags to cause hard starting and it would be a complete waste of time and money to check them.
http://www.sacskyranch.com/eng16.htm
Tom-D
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That is not was stated, you used "Lag Angle" as a cause. that will not cause the problem, other things can.
as your article stated lag angle is designed into the mag. it does not change in service.
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Kiloalphadriver
Pre-takeoff checklist
If this is an affected engine and this hasn't been complied with, then it certainly CAN be the problem. I originally said check out the mags and one of the things to check is the lag angle.
I'm done!!
Lycoming Service Instruction 1362 changed the lag angle of the impulse coupling from 15 degrees to 5 degrees to compensate for the fast turning starter and greatly improve starting on this engine.
Ray, it's understood that a mag can cause hard starting, just in this case because of the way it is hard starting (fuel issues act differently than ignition issues, "hard" is not very definitive) that most likely it is a fuel issue. The key clue is the stumbling rough running after it starts.
Kiloalphadriver
Pre-takeoff checklist
henning:
Just because it's running rough after start doesn't necessarily mean there's something wrong with the fuel system. It could be "pilot induced". How many times have you seen a perfectly good engine run rough and belch smoke simply because of poor starting technique? Does that mean there's something wrong with the engine?? Arfter all of the priming, throttling, and mixture play, the engine comes to life simply because the ignition decides to play along.
Of course it's going to run rough with all of the fuel pumped into it.
What's the first thing most people do when a 152 won't start?? Prime it some more!! Because this is one of the couple of things they can actually do..
Aviation is a world of "cause and effect"..
My WHOLE point to all this not to assume anything one thing is the culprit. Look at everything.
I have seen engines and airplanes torn a part looking for a problem when it turned out to be something very simple and unrelated to what they were looking for!
Tom-D
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Operator technique doesn't give an engine type a bad reputation for hard starting.
poor primer system design does.
I never said there was anything wrong with the fuel system, I said it was a fuel issue. If you look at the beginning of the thread I told him to give it a couple more shots of prime exactly because hard starting 99% of the time is caused by the operator not priming the engine sufficiently.
Kiloalphadriver
Pre-takeoff checklist
Are you saying that if a 152 is hard to start, it has to be the primer system?
Of course not, which has been my point all along..
It could be anything..
There are many holes in the ground because of assumptions based on past experiences..
I'm really, really done this time...lol
Good luck!!
Oh BTW.. our flight club had a dozen or more 152's which I spent a lot of time in. A lot of times having to stop because of the "8 in 24".
I never remember one being hard to start...
Hmmmm
Tom-D
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Really???
all that does is place more fuel in one intake pipe, which with out proper preheat will to drain into the cowl and create a fire hazard.
If you want the 0-235 to start easy, preheat it even when you think it shouldn't need it.
It depends, I've seen 1,3, & 4 primer nozzles on an O-235, and I've seen people who have trouble starting them when it's 70+ outside.
dell30rb
Final Approach
Great, we've gone from hard starting to me killing myself.
I mentioned in an earlier post that our club has 4 152's. This one is significantly more difficult to start than any of them. But once running, it runs smooth and mag checks are even and smooth on both mags.
Sure it could be the impulse coupling. Both the impulse coupling and the priming system need to be in good order for an easy start. The primer is easiest to check, and the symptoms agree with a fouled priming system, so that's what i'm looking at first.
I got my sign off for the instrument checkride this morning. Cleaning the primer system is on hold depending on when I can get that checkride scheduled!
Kiloalphadriver
Pre-takeoff checklist
Great, we've gone from hard starting to me killing myself.
I mentioned in an earlier post that our club has 4 152's. This one is significantly more difficult to start than any of them. But once running, it runs smooth and mag checks are even and smooth on both mags.
Sure it could be the impulse coupling. Both the impulse coupling and the priming system need to be in good order for an easy start. The primer is easiest to check, and the symptoms agree with a fouled priming system, so that's what i'm looking at first.
I got my sign off for the instrument checkride this morning. Cleaning the primer system is on hold depending on when I can get that checkride scheduled!
LOL!!
Just trying to point out that aviation is full of myths and falsehoods passed along from generation to generation.
Dan Thomas
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And some of us who have experience with the recalcitrant O-235 are just trying to point out that it's a hard engine to start at the best of times, and that in many cases the starting can be improved by cleaning or replacing the primer nozzles since they do actually get clogged and coked up with fuel. After the engine starts, there's still fuel in the nozzles, and the terrific heat cooks it off and leaves the residues, which accumulate over time and plug them up. Since the O-235 is more prime-sensitive than their bigger brothers (320 and 360) it's natural to ask about the primer nozzles.
Dan
David
Pre-takeoff checklist
I'm the one that suggested checking the primer nozzles because I went through the same thing several years ago with my O-235 - mags, plugs, wires, etc. It was simply the primer nozzles. I suggested the same solution to someone on the AOPA board with the same problem and it worked for him. I think you need to understand how the primer system works to understand why it could be the primer nozzles.
Kiloalphadriver
Pre-takeoff checklist
Since the problem sits unresolved until after the ride, anyone want to place any wagers?
Kiloalphadriver
Pre-takeoff checklist
I'm not saying it isn't the primer system. How the heck would I know?? No more than you are 100% sure it is. I'm just saying if your mind is made up that it just one thing, it could get very, very expensive looking for something that you're just sure has to be there.
I guess 20+ years of taking care of very expensive airplanes has taught me not to assume anything.
I had a signed agreement with our primary maintenance facility that if they R and R'd a component and it doesn't fix the problem, the airplane will be returned to the condition it was in when I brought it in and the bill will be zeroed before they start again.
I have seen many, many times when it was assumed that the squawk just had to have this one fix, only to find out it wasn't it after tying up the airplane all day.
Trouble-shooting with an open mind is the best way to approach it.
And it doesn't stop there. You have to ask "why did the problem occur in the first place??"
I guess we approach this with two different philosophies.
I hope it is the primer system and the fix is quick and cheap. Just be prepared for if it isn't. Stay involved and stay ahead of it.
Which is the point I've been VERY unsuccessful at trying to make..lol
I guess 20+ years of taking care of very expensive airplanes has taught me not to assume anything.
I had a signed agreement with our primary maintenance facility that if they R and R'd a component and it doesn't fix the problem, the airplane will be returned to the condition it was in when I brought it in and the bill will be zeroed before they start again.
I have seen many, many times when it was assumed that the squawk just had to have this one fix, only to find out it wasn't it after tying up the airplane all day.
Trouble-shooting with an open mind is the best way to approach it.
And it doesn't stop there. You have to ask "why did the problem occur in the first place??"
I guess we approach this with two different philosophies.
I hope it is the primer system and the fix is quick and cheap. Just be prepared for if it isn't. Stay involved and stay ahead of it.
Which is the point I've been VERY unsuccessful at trying to make..lol
dell30rb
Final Approach
Tom-D
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You sure took the long road to do it.
If this 0-235 taxied up to my shop and told me it was difficult to start, this is what I would do.
make the aircraft safe to work on.
remove the cowl.
place a timing disk on the prop spinner
rotate the engine up to TDC compression stroke #1
set timing disk to Zero.
rotate the engine backwards 180 degrees.
slowly rotate the engine forward to TCD noting where the impulse coupling snaps. if at 5 degrees, your SB has been complied with.
Remove #1 spark plug lead for the impulse mag.
Rotate the engine 180 degrees before TDC for #1.
hold the plug lead 3/8" from a known good ground, and bring the engine up thru the impulse snap, and note the color of the spark, (if you got one) If it is nice and blue and jumped the gap. I would eliminate the ignition as the problem.
then replace all disassembled parts.
then I would inspect the primer system. to see why the engine isn't getting fuel. it may be as easy as the primer pump has a stuck check valve, and isn't delivering fuel.
dell30rb
Final Approach
You sure took the long road to do it.
If this 0-235 taxied up to my shop and told me it was difficult to start, this is what I would do.
make the aircraft safe to work on.
remove the cowl.
place a timing disk on the prop spinner
rotate the engine up to TDC compression stroke #1
set timing disk to Zero.
rotate the engine backwards 180 degrees.
slowly rotate the engine forward to TCD noting where the impulse coupling snaps. if at 5 degrees, your SB has been complied with.
Remove #1 spark plug lead for the impulse mag.
Rotate the engine 180 degrees before TDC for #1.
hold the plug lead 3/8" from a known good ground, and bring the engine up thru the impulse snap, and note the color of the spark, (if you got one) If it is nice and blue and jumped the gap. I would eliminate the ignition as the problem.
then replace all disassembled parts.
then I would inspect the primer system. to see why the engine isn't getting fuel. it may be as easy as the primer pump has a stuck check valve, and isn't delivering fuel.
If its that simple I may have the maintenance guys do that test before working on the priming system. Would it be worth pulling the plug wire myself and just checking for a nice blue spark?
In the past when i've had weak spark issues on motors (not airplane ones, but simple carbureated motorcycles with mags) the motor would show some symptom while running. It would either not idle and/or it would run rough and not do well at high rpm. This 0-235 exhibits none of these symptoms and runs like a champ. Also, pulling the prop through by hand, I can hear the impulse couplings clicking solidly.
The primer seems to operate normally. Pull it out, hear it fill for 3-5 seconds and then push it in. It makes the same noises and feels the same as the other 152's I have flown.
Previously it would get firm and difficult to push in about halfway through the second stroke. The plane sat for 2 months during annual. I figured it was cranky from sitting... maybe there was some restriction in the system
Oh, and when did the SB come out for the 5 degrees? This motor was rebuilt - IIRC in 2000-2001 by one of the big overhaul shops. I'm guessing they complied with it...
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Tom-D
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From what I read from that, your engine typical 0-235, it starts hard like all the rest of them..
don't forget the turn the mag on to get a spark, and handle the hand propping accordingly.
Have you tried to use the throttle as the primer system?
some will some won't.
to know if it will, pump the throttle a few times and watch for fuel dripping out of the carb air box. if none, no accelerator pump, and it won't work.
David
Pre-takeoff checklist
My O-235 was never hard to start after the primer nozzles were cleaned. In fact, even before they were cleaned, once the engine was warmed up, it would restart in a blade or two every time. The O-235's in the little grummans I used to rent were never hard to start either hot or cold. The mechanic that maintained them is the one that told my mechanic about the primer nozzles. It seems to me that's it's probably a good idea to clean them periodically.
Tom-D
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It depends upon which 0-235 you have. some only prime 2 cylinders. and which installation it is in.
I had a customer with a Beech skipper and 1 with a Tomahawk both started easy, and 1 with a clipper and it will not start below 70 degrees with out preheat.
I had a customer with a Beech skipper and 1 with a Tomahawk both started easy, and 1 with a clipper and it will not start below 70 degrees with out preheat.
David
Pre-takeoff checklist
I'm not sure which it was Tom. It was in a 7ECA Citabria.
Kiloalphadriver
Pre-takeoff checklist
You sure took the long road to do it.
If this 0-235 taxied up to my shop and told me it was difficult to start, this is what I would do.
make the aircraft safe to work on.
remove the cowl.
place a timing disk on the prop spinner
rotate the engine up to TDC compression stroke #1
set timing disk to Zero.
rotate the engine backwards 180 degrees.
slowly rotate the engine forward to TCD noting where the impulse coupling snaps. if at 5 degrees, your SB has been complied with.
Remove #1 spark plug lead for the impulse mag.
Rotate the engine 180 degrees before TDC for #1.
hold the plug lead 3/8" from a known good ground, and bring the engine up thru the impulse snap, and note the color of the spark, (if you got one) If it is nice and blue and jumped the gap. I would eliminate the ignition as the problem.
then replace all disassembled parts.
then I would inspect the primer system. to see why the engine isn't getting fuel. it may be as easy as the primer pump has a stuck check valve, and isn't delivering fuel.
You sure took the long road to do it.
Whew!! I was beginning to wonder if they had stopped putting ignition systems on 152's!!
It's nice to see a shop approach a problem without the assumption it can ONLY be one thing.
slowly rotate the engine forward to TCD noting where the impulse coupling snaps. if at 5 degrees, your SB has been complied with.
Did you actually check to make sure the lag angle (a question in my first post on this thread) was correct?? Noooo...you can't do that!! lol
Nice post...thanks!!
dell30rb
Final Approach
Yup.. as i described in an earlier post pumping the throttle usually does the trick
Yep, just make sure you're cranking when you pump.