The $9k annual (and counting) with not much to show...

tawood

tawood

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Display name:
Tim
I need to vent...

My plane has been at the mechanic's since the first week of April. I like my mechanic, but I'm considering looking for someone new...

When I took it in for annual, I was having a problem with a high EGT reading, and I also had requested they look into a interference problem with my Comm 1 KX155 caused by my JPI fuel flow meter. I had three additional requests: to change an old King 170 radio for a newer King kx125, to change an old Mitchell turn and bank for a new Turn Coordinator, and to IFR certify.

Well, its been in the shop for over two months, twice I've been told it's ready, and I've paid 3 invoices totaling $9k...yet both times I picked it up I still have a problem with a high EGT reading, and I still have a squelch problem with my Comm 1. Last night, the mechanic pretty much said he would keep trying to find the high EGT problem, but admitted he didn't know what else to do and would have to call for help.

So far, I've got new mags, and my induction system checked for leaks. Probes/meter swapped to eliminate that as the problem. Compressions are fine. High EGT problem is still there.

For the IFR cert: EVERY SINGLE pitot related part replaced: airspeed indicator, VSI, Alt, new tubing, new pitot. Finally passed.

For the radio interference problem: Virtually all antennas, wiring, ground, etc to both comms, JPI, and audio panel replaced. KX155 replaced with shop KX155 to eliminate radio as the problem. JPI 450 replaced with one from the shop to eliminate the fuel flow meter as the problem. Problem still there.
 
Our airplanes are old, and complicated problems like radio interference are complicated and can get expensive. Sorry about your expensive annual, I know it sucks. If it makes you feel any better, I just heard a guy talking about his first annual marching north of $20K (more than he paid for the aircraft). His strategy is to pickle the engine and fix it when he can save up the cash.
 
I had a 155 with what sounds like a *very* similar set of issues. The source turned out to be the antenna connector that interfaces with the radio tray. The shielding on that cable was deteriorated, and it was shorting the center conductor. Very hard to see.
 
I'm not sure I understand what "high EGT" means? Read the link below, maybe it'll help alleviate your stress and help you stop throwing money at an EGT issue that probably isn't real.

Let me excerpt a little piece from the conclusion:

"There is no such thing as a maximum EGT limit or red line, and trying to keep absolute EGTs below some particular value - or even worse, leaning to a particular absolute EGT value - is simply wrongheaded. Don't do it. "

http://www.gami.com/articles/egt_myths.pdf
 
Most CHT and all EGT probes degrade over time. Start with something simple, test the probe(s).

Tim
 
CC268 said:
Seriously...some of these guys will nickel and dime you to death if your not careful.
Click to expand...

More accurately, I think most mechanics are not trained to diagnose problems. Instead they throw parts at it, because that is what they have been taught. The parts they choose to through at the problem tend to be the ones which have previously solved the issue for them.

Tim
 
If our good ole boy Tom D was here he could have fixed it in a heart beat! RIP Tom.
 
bradg33 said:
I'm not sure I understand what "high EGT" means? Read the link below, maybe it'll help alleviate your stress and help you stop throwing money at an EGT issue that probably isn't real.

Let me excerpt a little piece from the conclusion:

"There is no such thing as a maximum EGT limit or red line, and trying to keep absolute EGTs below some particular value - or even worse, leaning to a particular absolute EGT value - is simply wrongheaded. Don't do it. "

http://www.gami.com/articles/egt_myths.pdf
Click to expand...


In a nut shell: number 3 cylinder EGT is up to 250 degrees hotter than the rest...any attempts to lean the engine immediately causes bad miss (presumably from number 3 cylinder). Altitude exacerbates the problem (which seems opposite to me). I don't have a cylinder head temp gauge, but oil temp stays normal.

tspear said:
Most CHT and all EGT probes degrade over time. Start with something simple, test the probe(s).

Tim
Click to expand...

Probes and gauge swapped and high EGT still present.
 
CC268 said:
If our good ole boy Tom D was here he could have fixed it in a heart beat! RIP Tom.
Click to expand...
More than likely he would, or at least take a good shot at it.

He's an experienced mechanic, but most folks on here like to discount it, and his abilities.
 
Your annual cost more than my airplane... :eek2:
 
tawood said:
In a nut shell: number 3 cylinder EGT is up to 250 degrees hotter than the rest...any attempts to lean the engine immediately causes bad miss (presumably from number 3 cylinder). Altitude exacerbates the problem (which seems opposite to me). I don't have a cylinder head temp gauge, but oil temp stays normal.

Probes and gauge swapped and high EGT still present.
Click to expand...

I am by no means an expert, but that behavior screams partial fuel blockage to number 3.

Tim
 
tawood said:
In a nut shell: number 3 cylinder EGT is up to 250 degrees hotter than the rest...any attempts to lean the engine immediately causes bad miss (presumably from number 3 cylinder). Altitude exacerbates the problem (which seems opposite to me). I don't have a cylinder head temp gauge, but oil temp stays normal.



Probes and gauge swapped and high EGT still present.
Click to expand...

This isn't an "EGT" problem, this is an engine problem. It sounds like the EGT may be reading correctly and is telling you that something isn't right, especially since you have issues when you start to lean. Chasing EGT probes is probably a waste of time and money, since it sounds like that isn't the real problem.
 
I'm sorry to hear of your tribulations. I had similar experience with my Grumman Tiger and an A&P that reminded me of Jerry Seinfields car mechanic. Since then I've vowed to stay with experimentals and am much happier.
 
Ryanb said:
More than likely he would, or at least take a good shot at it.

He's an experienced mechanic, but most folks on here like to discount it, and his abilities.
Click to expand...

I was actually being honest haha...Tom was a real dick sometimes but at least he knew what he was talking about most the time.
 
tspear said:
I am by no means an expert, but that behavior screams partial fuel blockage to number 3.

Tim
Click to expand...

Could also be an intake leak at that cylinder, right? Letting in too much air, causing it to run lean.
 
bradg33 said:
This isn't an "EGT" problem, this is an engine problem. It sounds like the EGT may be reading correctly and is telling you that something isn't right, especially since you have issues when you start to lean. Chasing EGT probes is probably a waste of time and money, since it sounds like that isn't the real problem.
Click to expand...
Yes, I agree completely...
 
Sorry, but I have more questions than answers:

Is this a carburetted engine or fuel injected?

Is this egt problem relatively new or has it been an issue for a long time? How long have you owned the plane? Maybe this is why the previous owner sold?

Are all the probes the same type?

Has your mechanic done a fuel flow test for each cylinder?
 
It it a carbed or fuel injected? The one time I had a very high cylinder turned out to be a clogged injector.
 
If there is a metal primer line going to it, remove it, cap the system and fly it. Other common leak areas is where the intake manifold tubes meet the oil sump.

If nothing works and already exhausted all other options either live with it and see what happens or pull the cylinder and drive it over to Central Cylinder.
 
Carbed o-320. New problem. All probes the same. Not sure about the primer.
 
tawood said:
Carbed o-320. New problem. All probes the same.
Click to expand...
first thing I'd do is swap an EGT probe with a neighboring cylinder....if it's still high check for either air or fuel issues.

I'm betting on a bad EGT probe....they do wear out.
 
tspear said:
More accurately, I think most mechanics are not trained to diagnose problems. Instead they throw parts at it
Click to expand...

That's been my experience. Most can change tires, batteries, etc. Finding the root problem is not in most of their skillsets. These airplanes are aging and the new generation often doesn't know what to do
 
tawood said:
Already done. Still shows high on 3.
Click to expand...
then it's either an air or fuel issue.....without knowing the actual temps it maybe "normal" to have a higher EGT on one vs. another cylinder. Carb'd engines are known for uneven fuel air distribution across cylinders.
 
Checkout_my_Six said:
explain the physics behind that?

pulling the lifters would be how to inspect....but I'd not get a high EGT on that.
Click to expand...

I'm hoping Ted might be able to.

Can't pull lifter on a 320 lycoming, only way to see anything is pulling cylinders.

(maybe you can on the O320H2AD or a newer one with roller lifters)
 
If your plane is safe for flight, package it up and ferry it to someone else. It is your aircraft and as the owner you control the maintenance.
Bitching about mechanics is just that. All mechanics aren't o320 experts or avionics experts. Would you trust a GP to perform a heart transplant?
 
If you suspect cam/lifter problems, simply pulling the rocker box covers and noting the approximate lift for each valve should show the valve train condition. There will be little or no visible lift on any bad valve/camshaft lobe. Even if the cam will lift a valve half open (for example) there will be little effect on power or EGT. The problem should be visually obvious on any bad cylinder. It isn't necessary to measure the opening heights.
 
bradg33 said:
This isn't an "EGT" problem, this is an engine problem. It sounds like the EGT may be reading correctly and is telling you that something isn't right, especially since you have issues when you start to lean. Chasing EGT probes is probably a waste of time and money, since it sounds like that isn't the real problem.
Click to expand...

Even then, how much of a problem is it really? My experience has been that cylinder #3 is typically the hottest cylinder in the little 4 cylinder carbureted Lycomings.

Chore #1 in this case is to determine if there is a real problem or a perceived one.
 
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