Bill_Pyles

Just to be clear, I am suggesting draining the oil, closing the drain valve, pouring a gallon of avgas in the oil filler pipe--(same place oil is added), let the avgas sit for 15 minutes, then drain the avgas/residual-oil until it stops dripping and then close the valve, install a new filter and pour 8 qts of new oil in. I can't imagine there would be enough avgas left in the sump to cause any issues. I also don't believe avgas will corrode bearings! If I do this, I will measure the gallon of avgas and measure how much gas/oil drains out after 15 minutes. I am just looking to get as much of the old oil out as possible. Guess I will call Lycoming as well.

I read somewhere that avgas can be used to flush the crankcase after the old oil is drained and prior to filling the crankcase with fresh oil. A gallon of avgas is allowed to sit for a few minutes in the crankcase in order to thin the residual oil and to keep it from contaminating the fresh oil. What is the general consensus about this practice? Are there any good reasons not to flush with avgas? Is there a better alternative fluid?

Thanks Mitch and Scott. Those sound like easy tests. Guess I need jacks...

What is the deal with replacing the landing gear donuts? Mine say 1998 and they look great, as in no cracks and they are smooth and black. I have read that they need to be replaced every 5 years and up to every 15 years. Has anyone tested the resilience of the old disks versus new disks? Has anyone checked them with adurometer? Are old discks harder or softer than new disks and what is the effect of the difference in terms of ride and handling characteristics? Does anyone know the science on these Lord disks, or is the replacement of them based partly on tribal tradition? I would really like to know.

I did the inspection myself. Do I HAVE to have an A&P do the inspection to comply with the intent of the SB? I know SBs are not mandatory. Can I make a log book entry myself? This is a pretty basic inspection.

Thanks Rob. I will look at my charger to determine if it has float-charging capability.

Do you need some sort of trick, aviation charger, or will an ordinary charger like you get at the auto parts store do the job? Also, what is a "battery minder?"

I read the Gill vs Concorde thread. A) it looks like I am due for a new battery and it aint gonna be a Gill just based on the overwhelming endorsement for the Concorde. Thanks!

I have a 1979 J model with a Gill G-35 12V battery. Best I can tell, this battery was installed in April of 2007, about 250 hrs ago. I have owned the plane since Sep 2011 and I live in AZ, but the battery hasn't seen a full, battery-life-shortening summer. I have flown the plane about 60 hrs and the battery has always started the engine---until today, when the battery gave up. How many years or hours can we expect our batteries to last? Thanks!

Get a pre-buy inspection by a mechanic who is very famliar with the make and model. Fix everything---within reason. Upgrades can be handled later if you have a limited budget, but make sure the airplane is rigged properly, the landing gear works properly, all the ADs are taken care of, log books complete etc.

I really like the old Richard Collins formula that says light piston airplane cost-of-ownership is about 3x cost of fuel, so if you pay $6/gallon for your Mooney, and burn 10 gallons/hour, then your total ownership cost will be $180/hour. Using this formula, if you have the discipline to toss $120/hr into the Mooney bank account everytime you fly an hour, you should be good to go. Obviouslly, if you live somewhere where your hanger cost is $600/month, this formula is probably on the low side, but if your hanger/tie-down costs between $100-200/month I bet the formula is still close. I spent about $25,000 my J making everything "right" at the annual last August when I bought my airplane, (including having the tanks sealed by WeepNoMore) so with a little luck, my annual will be a non-event this August. Of course, I could be one naive airplane owner too.

I appreciate the comments and photo by flyboy. I guess I will find something else to be concerned about ;-)

I know Mooney landing gear on the Mooney has positive camber, meaning the angle of the plane of rotation of the tire is such that the top of the tire leans outboard. Perhaps it is my imagination, but I think my J has a little more positive camber than other Mooneys I have looked at. Is there a spec on what this angle is supposed to be? Clearly, the landing gear was checked at the last annual and it works fine, but I still wonder why tires on some Mooneys appear to be more nearly vertical than mine. Thoughts?

Mineral oil is superior for break-in. Synthetic oil molecules are so slippery that they impede the seating of the rings and lead to the glazing or polishing. Rings need to abrade against the cylinder walls and take on their shape so as to ensure good sealing. The mineral oil lubricates and cools, but still allows the rings to acquire the shape of the cylinder at the micro level.

OK, I gotta check the gap with the cowl flaps closed and adjust them to be open a little...when closed. How in the heck do you evaluate the effectiveness of the baffles? You close the cowl and hope they do their thing? Now I am thinking I need to have the timing re-checked.

The Mooney POH says max CHT is 475 and max oil is 245. Why is it that 400 CHT is too hot? I would prefer to see 380, because the strength of aluminum noses over significantly with higher temps, but why would the manual allow the higher temps?

Yeah, I was running maybe 25 MP and 2500RPM and seeing 210 oil temp and 400 CHT on the hottest cylinder, but if I trailed the cowl flaps I would lose 10-15 degrees of oil temp and 10-20 degrees of CHT. I always run ROP. I need to do the speed test NSEW and see what I am dealing with performance-wise.

I had the timing set on my J the other day and now the oil temp and CHT appear to run approximately 10 degrees hotter, all being equal. Also, the engine does not like to idle as well. Overall performance seems the same although I haven't done a speed test. Is this temp increase likely because the timing was advanced slightly more than my earlier setting? How accurately should timing be set in terms of degree BTDC?

Thanks everyone, for the replies. Looks like the IO390 is basically "it."

What is the most powerful normally aspirated engine that can be installed in an M20J without modifying the airplane and by that I mean that the standard cowling is used and no reinforcements of the airframe. I can understand using a different motor mount if necessary. Who has put a higher HP engine than the IO360xxxx in a J?

So, basically 10% of the price of a new engine with two independent mags. Nice.

I have an IO360A3B6D like a lot of us. So what is the "best" upgrade path if I want to get away from the dual mag? Where would I get the new hardware and can any competant A&P install it or should I find a MSC to do it? I live in Phoenix.

Earlier this year, I bought my cosmetically pretty J from an airplane dealer who had taken the airplane in on trade. Supposedly the dealer had a pre-buy on the plane before he took it in on trade. However, I had the pre-buy done by Willmar and they found about $19,000 of things that were wrong with the airplane including the leaking fuel tanks. The avionics shop found another $6,000 worth of suff. The seller worked with me on the price, and I had every single item fixed including having Weep No More (Paul Beck) seal the tanks. Evidently, the guy who did the pre-buy for the dealer turned a blind eye to a lot of things. I could have elected to not have some of the work done, but I feel a lot more confidence in the airplane since so many discrepanicies were corrected and I haven't had a hiccup in 50 hrs of flying in the last 80 days. Maybe I am naive, but I hope to have a relatively painless annual next August.

Good for you! I agree, when I got my instrument rating, I thought I had never studied so hard for something. Now the trick is to stay current!