Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: We have a Citabria 7ECA with a Lycoming O-235-C1 engine. We live in East Texas, where summers are very long and very hot. Even with an external oil filter with a blast air tube, the oil temps push 220°+ on normal altitude flights, even when babying the air speed and climb rate (which means that we need to climb to pattern altitude to get from cruise to landing configuration. Not really, but the old joke does illustrate the point.) We think we need an oil cooler.

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Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: I’ve been having trouble with my Lycoming O-360-AIA engine for some time. The oil temperature is running about 200° on a cool day. The head temperature is in med green.

I have completed the following to determine the problem: A few months ago a new temperature control oil cooler by-pass unit was installed; and I checked the oil temperature probe by placing it in boiling water. The instrument in the aircraft read about 200°.

The oil cooler is a Positech with six tubes. The air source is an outside air inlet. I believe that the air flow is enough to cool the oil. I have no way to check. I have asked around the airport for help but this has not been fruitful.

GARY QUESTA, via e-mail

A: Gary, after reading your e-mail, I could hardly get the smile off my face. I don’t quite know how to tell you this, but most Lycoming engine operators would really like to have that kind of oil temperature on their engine.

Let’s look at some of the important things about oil temperature. [Read more...]

Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: I recently saw your article about Narrow Deck vs. Wide Deck and believe you are just the person to ask this question. A fellow AMT has been field overhauling his Lycoming O-360A1A engine. It is a “first run engine” out of an early Mooney. It is a Narrow Deck engine. (Yes, I know it is way past the 12 year time frame).

Here is the issue: The engine has small “stepped” dowel pins in the case half main bearing saddles (where the main bearings are installed). The removed bearings (original from factory) have small holes to match the small dowel pins. The new bearings (except for the forward {long} bearing) have much larger holes for the dowel pins. [Read more...]

Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: I’ve seen this in Lycoming literature — “Keep in mind that all turbocharged Lycoming engines must be broken-in on ashless dispersant oil only” — but why is it true? My engine overhaul shop, Central Cylinder in Omaha, Neb., insists, in writing, that for its warranty to be valid, I must break my turbo’d IO-360 in on mineral oil.

PAUL MILLNER via e-mail

A: This requirement has caused some confusion for Paul and I bet he’s not alone. [Read more...]

Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: Hi, I am a Mexican looking for my first plane. I found a 1980 Cessna 172 with an H2AD engine that has just 100 hours since overhaul. The serial number ends in 76T; I had read about 76A. Is it OK? Is it the same as the 76A?

GERARDO ARRIOLA, via e-mail

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Paul McBride, an expert on engines, retired after almost 40 years with Lycoming.

Q: My engine, which now has 300 hours on it, is an O-290-D2B which had a new-limits field overhaul. It has settled-in as a nice smooth-running, economical and reliable powerplant with plenty of power. It gets about 7-8 hours per qt. (Aeroshell 100) at 6.5 gph. All EGTs and CHTs are normal and it always has a clean oil filter element (it is cut and checked at each oil change, 50 hours or six months), and has a healthy oil analysis report (no anomalies or unusual artifacts). However, I’ve noticed the compression going down at each annual on all cylinders and a recent pre-annual check-up has them in the low 60s (over 80) with a static compression test. It also takes a bit of “prop-rocking” to get it to settle in. I can hear some blow-by in the dip-stick tube. It seems uncanny that all cylinders would have this problem, so I’m a bit puzzled.

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Q: Could you please help my pretty blonde wife and myself with our spark plug problem? We are desperate! Our mechanic is going to put the new fine wire plugs we just bought into our 1976 Cessna Cardinal RG, but we have conflicting information on the proper plug.

We bought some SR83P plugs from a dealer at Sun ‘n Fun, who assured us that the plugs were the same as the Champion fine wire plugs that fit our Lycoming IO-360-A1B6 engine, and that they cross-referenced just fine.

JIMMY & SANDY HONEYCUTT

A: After doing some research of Lycoming Service Instruction 1042Y dated Sept. 1, 2009, which covers all “Approved Spark Plugs” for all Lycoming engines, I was afraid you may have a problem because there is no SR83P listed. I had a strange feeling about this, so I did some further checking with an old friend from the industry, Frank Gurko, who spent nearly a lifetime with Champion Spark Plug Co., then started his own company, PlugGuy.com, after retiring. He confirmed the SR83P spark plugs you bought are approved for your IO-360-A1B6 in your Cessna Cardinal RG and will work fine to replace your present REM38S plugs.

It would appear that there was an oversight by Lycoming during its last revision to SI 1042Y from earlier versions. As a matter of fact, the SR83P was shown as approved for your engine in SI 1042X, which I believe was dated in 2002. I discussed this with Lycoming and they will address this oversight when SI 1042 is next revised. So Jimmy, it looks like you’re good to go with the SR83P spark plugs for your engine.

I really appreciate you sending in your question because it reminded me of something I’ve been meaning to address. I’d like to make certain all readers understand that the outcome for Jimmy could have been much different had these spark plugs been the incorrect type for his engine. If incorrect plugs had been installed, there is the possibility that several nasty things could have happened and none you’d like very much. [Read more...]

Q: My Tri-Pacer has an O-320 with a narrow deck (A) engine. It has SL32000N-A1 Millennium cylinders, which are are installed with no plates and splined nuts. Can this be correct? I have no wide deck cylinders to compare them to.

BLAIR MOHR, via e-mail

A: Let me see if I understand what you’re telling me: You have an old Lycoming O-320 Narrow Deck engine that has Millennium cylinders installed using the spline type cylinder hold-down nuts? Yes, it could be possible that these cylinders would be installed without cylinder base hold-down plates, which was done on the early low compression engines.

The spline type nuts have been long gone but, as you mentioned, apparently still in use. Should you wish at some point to convert to the more recent Cylinder Base Allen Head Nuts, this may be accomplished by complying with Lycoming Service Bulletin 213A, dated way back in 1957, but I’m not certain I’d go through the work. I think what you’ve got should work just fine.

Paul McBride, an expert on engines, retired after almost 40 years with Lycoming. Send your questions to: AskPaul@GeneralAviationNews.com.

Q: I am about to change my Alfa Romeo boxer engine to a Lycoming O-360A1F1 on my experimental Glastar aircraft. I read your answer recently to a question if LASAR is really useful (Will my engine benefit from new technology? Jan. 12 issue). Its actual price is $2,500. Do you think that it is really worth this high sum?

My mechanic has doubts, saying he is not confident in electronics — that if the electronics don’t work, the engine will stop. He also says that standard magnetos usually always work.

G. FRANK, Italy

A: I appreciate the fact that you read my article on the LASAR system. One thing I overlooked when explaining the system is that any interruption of the three data sensors — manifold pressure, cylinder head temperature, or rpm — and the system automatically reverts to the fixed timing on the engine just like the LASAR system was not there. Therefore, the engine would not stop as a result of the LASAR system experiencing an electronic failure.

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A: I have a narrow deck configuration in my 1964 PA 30-270. The first entry in the aircraft logbook, made on Jan. 3, 1964, shows radio installation and LE serial #S or L 606-55 and the RE L 640-55. However the engine log books show LE L 938-55 and RE L 909-55 and the first oil change at 55 hours. Both are IO-320-BIA. I have not yet confirmed the numbers on the installed units — too many screws — and I don’t know the exact place of the info plate.Also, the N number was changed from N7373Y to N4009Y in 1966, but I have no idea why. Please help! I am baffled.

KARL ROESCH, Arlene, Montana

A: Karl, the difference in your logbooks is interesting and confusing, to say the least. The only thing I can think of is that the original engines were replaced at some point with the higher serial number engines. I am surprised, however, that this isn’t reflected in the aircraft log. [Read more...]