Cylander ove haul symptoms?

[anthonydesmet]

Morning Mooney people,

i have a possible cylander overhaul question.  Here is what I have ran into the last 6 months.  After my annual in July in which I had no issues, normal compression, etc. on two separate occasions I have had an engine run up where my #2 cylander temp dropped to zero on my right mag check.  Mags overhauled last January.  On both occasions, lower plug was pulled found fouled and failed bench test. After cleaning, plug passed test, installed and good mag check and follow on normal flight.  During flights on JPI, #1 and #2 temps are within each other by about 10 to 15 deg EGT and 20 deg CHT.  my oil consumption has not risen any either.  And it does not appear to be o be isolated to aircraft sitting for a week or after a flight 2 days prior.  My mech says though he has found oil in the plug which is causing it to fail.  Any thought?  Time for cylander overhaul? Ha had no issues with the upper plug, only lower.

[carusoam]

Smut,

a few or more questions that might help the conversation get started....

1) Fine wire plugs or the standard type?

2) When the plugs were fouled was there a lot of ash caused by burning oil, or were they wet with oil?

3) How much time since the cylinders were overhauled last?

4) How many hours go buy before you need to add oil?

5) Does your mechanic have a camera he can send down into the cylinder to look at the hatched patterns on the wall?

6) Can you swap out the lower plugs for new ones to take the plugs out of the equation?

I would be expecting a higher oil usage to go with higher time on the cylinders. The oil starts to show up on the lower spark plugs.  Wear and smoothing of the cylinder walls may visible using a camera.  You also can get a good look at the exhaust valves while you are in there...

How does that sound?

I am only a PP, not a mechanic.

Best regards,

-a-

[Marauder]

Morning Mooney people,

i have a possible cylander overhaul question.  Here is what I have ran into the last 6 months.  After my annual in July in which I had no issues, normal compression, etc. on two separate occasions I have had an engine run up where my #2 cylander temp dropped to zero on my right mag check.  Mags overhauled last January.  On both occasions, lower plug was pulled found fouled and failed bench test. After cleaning, plug passed test, installed and good mag check and follow on normal flight.  During flights on JPI, #1 and #2 temps are within each other by about 10 to 15 deg EGT and 20 deg CHT.  my oil consumption has not risen any either.  And it does not appear to be o be isolated to aircraft sitting for a week or after a flight 2 days prior.  My mech says though he has found oil in the plug which is causing it to fail.  Any thought?  Time for cylander overhaul? Ha had no issues with the upper plug, only lower.

How much time are on the cylinders? The fact you are not seeing an increase in oil consumption suggests that you are not burning any more than before.

When you said they were found "fouled", were they fouled by oil or by lead? Do you lean on the ground? If your compressions are good, oil consumption is reasonable and there no indications of problems, I would be leery of changing out cylinders.

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[anthonydesmet]

Sorry Gents, I didn't give you enough info. Engine is TSIO-360MB. 800 hours from zero time factory overhaul in 2009. Mech said it was "most likely" oil. I do lean pretty aggressive on ground after start. Little more background, my job takes me way out of the country for 3 to 4 weeks at a time so airplane will sit until I get home for a month then i fly at least once a week and usually Florida to Virginia once or twice in that month

Also, when I am not doing a mag check and running in both mags on the ground #2 will be about 50-70 deg hotter than all others when this happens so I usually know when it's going to happen

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[jackn]

Anthony,

I have a TSIO-360SB which is very similar to the MB. First, if you're using Champion Plugs change over to Tempest. I use Tempest Massives, they work fine. I heard Champion updated their plugs but I had many problems with them.

Second, Is the oil very dirty after 5 - 7 hours? If so you might have a bad ring.

Third, have a MX do a borescope of the #2 cylinder. This will tell you a lot.

Good Luck

[cliffy]

Don't change the cylinder until you do some more investigation.

Do you swap the plugs top to bottom when you pull them to clean? Or do you put the same plug in the same hole each time?

Have you checked the spark plug lead for problems and high voltage leaks with a lead tester?

If Champions have you measured the internal resistor for correct ohms? They are known to fail there. 

As was mentioned was the plug wet with oil? Or did it have lead fouling?

Have you done a compression check yet? 

I would certainly eliminate all of the above way before I pulled the cylinder. 

My guess is you'll find the problem in the plug or lead being as it happens to the same plug all the time. 

[Guest]

Along with cylinder compression have you checked your crankcase pressure?

Here is the link, http://www.tcmlink.com/pdf2/M89-9.pdf

Clarence

[anthonydesmet]

Gents,

thanks for all the great info. I just wanted to clarify that I am in no way near going down the overhaul road yet nor is my mechanic pushing it.  We've outlined an investigation process and you guys have offered some great info to add to our plan and I will definitely post updates.  Here is how I did over the weekend after the plug cleaning:

- flew 6.5 hours this weekend without losing any oil.

- oil is about 2.5 months old and 17 hours old.  Not new looking but still doesn't appear to be "over dirty". You can still make out dipstick markings through the oil.

- out of the 17 hours flown I have lost about 1/2 a quart.  For some reason my engine likes 6.5 quarts on the dipstick.  After oil change and putting in 8, it will go to 6.5 and stay there.  After my June annual it went to 6.5 and I added 1/2 quart To keep it at 6.5 until my last 50 hour change in October.

- compression check happening this week, probably wednseday

- JPI over the weekend showed #2 EGT within 10-20 deg of all other 5 cylinders. However it did always have the highest CHT, by about 20 degrees.

- climb, cruise, fuel flow numbers all seem normal

 

here is my plan so far:

1.  Compression check - if compression still normal and I get another episodes then when I go back to Thailand in January - replace plugs with tempest when I'm gone

2. Obviously if compression check is bad then bore scope and see what I have.

 

ill keep you posted.

[anthonydesmet]

Sorry, one more thing to answer Cliffy's question.....we did check the plug resistor during the cleaning and it was fine.  Checking the plug leads when we have the cowl off for th compression check on Wednesday.

[anthonydesmet]

Update:

i was a little to eager with my last answer, so I was not able to get out to the airport today but I had someone check my oil level because I had to run off in Sunday and couldn't wait 30 to 45 minutes for the level after shut down.  Turns out I burnt a little over half a quart in about 7 hours flying which is a little high for me.  Just curious to how often you guys have to add oil/hour.

 

comoression check tomorrow.....

[ArtVandelay]

I lose oil thru the breather, as my oil accumulate hours, I lose at a faster rate.

[anthonydesmet]

Update:

we did a compression check on Wednesday and all normal.  In fact #2 was one of the strongest at 72.  Also did a bore scope and everything looked normal.  Next step is to continue to monitor oil consumption and possibly due a crankcase pressure check but for now after three flights, all appear to be normal from last plug cleaning.  

At my 50 hour oil change in March I also think I am changing to tempest plugs

I also think I am similar to you teejay in that my oil consumption goes up at about 30 hours into my 50 hour oil.  Hi how is where I am now.

 

more to come.....

[Guest]

I would suggest more frequent oil changes for your engine, oil changes are cheap, engines less so.

Clarence

[anthonydesmet]

Update:

went out on Wednesday to get airborne and had another bad mag check on right with #2 rolling back as described in original post.  Pulled cowl off that afternoon, swapped plugs with #4 and still had same issue with #2 ahhahhh....mech isolated it to my right mag block after we did a little digging in the logbook at what was replaced during the mag overhaul last January.  Mech team pulled right mag yesterday and found one pole gummed up.  Not sure with what and what all was done to the block but I will let you all know all details when I see my logbook today.  But in any case, engine is running nice now.  

 

Still had had a little oil on #2 plug I will have to track. But as I mentioned before I have to add a a quart about every 14 hours and maybe a little more frequently the more I get above 30 hours.  Oil still looks nice though and not dirty.

Next steps:

- thanks to some great advice here I am bumping my oil changes up to 30'hours

- next oil change this January I am probably going to swap out current champion plugs with tempest after all my reading.