Turbo M20K (231/252/Encore) Type Mooneys

While this section our Hangar Talk Forum is primarily intended for owners and enthusiasts of turbo M20K/231/252 type Mooneys such, it may contain select postings applicable to other similar vintage turbo models as well. Because many member/owner comments or contributions are of interest and valuable to most all Mooney owners, the moderators may place select contributions received from members in sections

Hangar Talk Turbo M20K/231/252/Encore; Members Postings, Comments, Queries, & Notices


Hangar Talk Member Notice/Posting:
Subject: 231 skip From: Marq Linden Hello I currently own a 1979 M20K, our engine has approximately 950 hours on it and recently have been having some odd occurrences . These occurrences has happened twice. When climbing through 13000 feet (once) and 10500 (second time) the engine suddenly skipped. Both times we were in the 2nd or 3rd step climb to a higher altitude. The skip happened so quick that no anomalous instrument or gage readings were possible. The skip feels as though something has momentarily turned the mags off and then on. In both circumstances we descended to a lower altitude and the "skip" did not reoccur. Once on the ground after the first incident we discovered a broken connector to the spark plug that may have been causing an arc, we have also replaced the wiring harness and plugs. I have spoken to various A/I 's and have received varying ides. One idea was that we were running to rich and it was causing some sort of induction problem donw the harness (huh?). I am suspect of this. The second person suggested water in the fuel. My limited guess would be the mags of the fuel controller. Any help in this matter would be appreciated. Marq Linden MarqLinden@csi.com
Marq,
Forum Moderators: Problems such as you noted are (of course) very difficult to firmly diagnose w/out more information. The first thing you have to determine is that is it one of 3; mechanical, electrical, or fuel related. That is; mechanical can be a stuck valve, intake leak, etc., and electrical is the obvious (wire/plug/mag etc.,) and fuel could be water or too rich etc. I suspect a temp stuck valve or something which could take out a whole cyl or two. Maybe electrical, but mostly electrical will be more predictable. Hard to say w/out having more information. This is one reason I strongly reccomend multi-probe eng. anylizers for both egt and cht. If you don't have one, I have some favorites to reccomend.
Call sometime, and we can discuss some other options. Coy


Hangar Talk Member Notice/Posting:
Subject: RE: 231 skip (again)
From: Marq Linden
To: Coy Jacob
Coy,
Hello again,
We think we have found the problem, our A&I took the mags apart and found a blown capacitor and evidence of charring on the mag. Firstly what does that capacitor do and what is the likelihood of that happening again? Secondly what would have caused that and does altitude exacerbate the problem? Thanx for your help
Forum Moderators: Marq, I am sorry to say, I haven't run into very many TSIO 360 "experts" at TCM who know M20K installs. Remember, these guys have to know many engines and many installations etc., so they can't be "up" on just the single M20K install. I am not exactly sure what function a capacitor serves except to enhance or store the current or some other necessary "electron moving stuff". Yes, altitude can and most likely does exacerbate the arcing problem as it is thinner and allows the spark or current to arc more than thicker air which is more dense and insulates better.
Heat may have also been known to deteriorate eng./mag electrical components as when Mooney certified the 231 they had temp. problems right off the bat. They had to "caulk" the cowl baffle's to get the temps down. Usually, when one cyl runs hot, there is a problem which is unique to that cyl. Single Mag problems usually don't cause a whole cyl. "skip" and then the problem not be repeatable again farly often. Most mag. problems cause a "roughness" of some sort that a pilot can sense and then by switching the mags, can attribute to the problem mag. Most Slick Mags are only good for 600-1000 hrs through. Most A&P's know how to test for pressure leaks on mags, it is simple, you apply shop pressure and check for air comming out. Even that shouldn't have caused the dramatic problem you describe as un-pressurized mags will work w/good plugs for a while especially up to the mid teens. I suggest fine wire plugs for all turbo Mooneys. Are yours fine wire or the more common and cheaper massive plugs?
I need to know more, but suggest it is "mechanical", not electrical. Maybe a "slug" of water in the fuel. How are your gas cap "O" rings and retainers? Feel free to call sometime.
For what it is worth, I fly/own a M20K/252 personally, and have had this problem over the "deep blue" Gulf of Mexico (of all places)! Mine was (apparently) several intermetantly "stuck" valves and solved by Marval Mystery Oil in the fuel and oil.
Good luck, & let me know how things go......Coy Jacob

The Hangar Talk Moderators welcome all members to post Q&A's as well as relate your flying, "care & feeding" Mooney related comments on M20K Mooneys in this section. Beginning Fall of 1998 in this section is filling with interesting notices which you should check back and refer to often.
Thank You.

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