One cylinder low on compression

[Geico266]

Originally Posted by Darren S

...... tell me what you do to help prevent lead deposits, or is it inevitable?

Darren

Stop using 100LL. At bear minimum cut it in 1/2 with mogas.

[Darren S]

I just ordered some TCP from Decalin chemicals and will start using it as soon as it arrives.

If I fly 25* LOP, will that help clear out any existing carbon build up in my engine? Or is it stuck there once it forms ?

I know there are a bunch of opinions on LOP vs. ROP and I have read the articles by Deakin. I did try LOP flying for a bit but was staring at the darn EFIS so much and not out the windshield, I was afraid I was going to fly into something

I have learned that at 65% power, which is where I fly mostly, there is very little I can do, as far as leaning, that will hurt the engine. So I am willing to lean out things a bit more if it will cut down on carbon build up

opinions ?

Darren

[Ironflight]

Originally Posted by Darren S

I have learned that at 65% power, which is where I fly mostly, there is very little I can do, as far as leaning, that will hurt the engine. So I am willing to lean out things a bit more if it will cut down on carbon build up

opinions ?

Darren

When I'm running at those kind of power settings, I don't stare at the EFIS, I just keep pulling back on the mixture until she gets rougher than I care to fly, push it a micro-nidge back in, and fly along knowing it is as lean as it will go. I THEN look at the EFIS, and am usually nicely LOP....

Paul

[jbDC9]

Originally Posted by tcrv7

Started Avblend and MMO [Marvel Mystery Oil], yes I know its mineral spirits and wintergreen, but 249 hrs later the rope hasn't been back in that cyl or any other YMMV.

It sounds crazy, but MMO seems to be working for me as well. A year (or 2) ago I had a stuck exhaust valve on #2 and had an engine shop bust it loose. As it turns out, the valve seat/stem has juuuust enough play in it to allow gunk to build on the stem and caused it to gum up and stick. The mechanic that fixed it advised the use of MMO in the fuel, said the solvent/oil in it should help keep it clean. Like tcrv7 said, I know it's mineral spirits, light oil, animal fat and mint scent, but it seems to be working... it's a coupla hundred hours later and no more issues with that valve.

Regarding lead deposits and build ups, other than that one stuck valve and last month's little piece of crud, my engine seems pretty clean. I'm running dual Pmags, NGK auto plugs and occasional mogas mixed into the 100LL. Not a lot, 10 gallons here and there, 700 or so gallons over 750 hours... my plugs are always clean and never had any lead fouling issues during a run-up. Is this a side benefit of using electronic ignitions? I dunno, but I like it!

[Bevan]

Can someone describe the procedure and tools required to do a compression test?

Bevan

[DanBaier]

Even though brand C, there's a lot of good info here. http://www.sacskyranch.com/SB03-3.pdf

Personally, I'd look into putting in a borescope and looking at the valve seat. (With the valve open, there should be a shiny spot all around the seat. If there's an area that's dull, the valve is leaking - something (ie., carbon deposit) has built up. That could be the source of your problem and it's not terrible to fix.

Your hours are low for it to be a problem - well before the recommended Lycoming wobble test. But that might be worth doing as well.

Dan

[sierrakilo99]

You need a differential compression tester and an air compressor, as well as an adapter to fit into your sparkplug hole to connect all the plumbing. I have a similar setup as this one:

http://www.aircraft-tool.com/shop/de...product_id=2EM

Comes with instructions, but basically you bring the cylinder up to TDC, connect up the tester with the valve closed, then slowly bring the valve open and apply pressure up to 80psi. The gauge tells you the amount in the cylinder, which is the 'difference' between the pressure in, and the pressure at the cylinder.
sk

[RV10inOz]

Darren

You asked a question about running LOP and cleaning the cylinders up. 60-65% power LOP will not clean them up.

Now listen carefully, and all you freaky stressed folk sit on your hands for a minute before jumping on the keyboards.

Take your machine out and do a full power low level run and lean it a bit enough to get a very mild amount of detonation going. You will see this by leaning a litlle and the CHT's shooting up. DO NOT bore along for hours on end with CHT's over 400, that would be bad, but a short run doing some mild detonation will help clean the heads up.

Now go check your leak down. If there is a valve problem best to fix it sooner than later.

As for running LOP, do it this way, level out....wait a minute or two, pull RPM back to where you are happy, and once you know where the 65% 20F LOP is by fuel flow numbers just rip the mixture back and set a fuel flow. Simple!

As for climbing, this is where you could be helped. Target the EGT number on say Cylinder 1 as you go through 500' AMSL (or close to it) and remember that EGT number. then every 2000' in the climb pull back the mixture to get that number. Simple

Read and read and read Deakins stuff a lot more so you understand it like he does. Can't learn from a once or twice read.

Cheers

DB

[aerhed]

enough to get a very mild amount of detonation going.

Boy, another funny one. How do you determine "mild detonation"?

[MauiLvrs]

Originally Posted by Darren S

I just ordered some TCP from Decalin chemicals and will start using it as soon as it arrives.
Darren

If you ordered it from Decalin chemicals, you must have ordered Decalin "RunUp Fuel Additive". Cheaper that "TCP" and works better...