180 hp (pre E model) Oil Cooler line routing & oil/engine temps

[mike20papa]

We all know the various engine temp.s we all see from A models thru C's.  Recently I've began to notice the various routing used to feed the oil cooler from the accessory case and think there may be some correlation to engine temps.  Seems as though some 180 hp Mooneys have no temp problems (unless we forget to open the cowling flaps!)  were some experience high engine temps regardless of efforts made to sealing baffles, etc. 

 

So, I'm a lucky dude as I have no issue with engine temps - sometimes even see less than 300F CHT's at low power setting cruise and 330 at 70% power.  I never see oil temps over 190F (and I live in TX) generally around 185F (good/new  Electronics Int. instrumentation)

 

My oil lines run down from the accessory case, then forward to the cooler at the bottom of the cowling.  I see lots of 180hp mooneys that run the lines thru the dog house on top of the cyl.s, then down to the cooler.  My dog house tin has patches to close off the old routing.  Don't know the history behind that, either.

 

So, anyone want to chime in?  Joe/N8335E

[bonal]

Cooler lines run down from behind the engine then to the front along the bottom of the cowling my temps are always under 400 and in a slightly reduced power cruise are at the bottom of the normal green arc. I have an original engine gauge cluster so the numbers don't mean much only that they are consistently where I expect if I see something abnormal then it's time to take action

[Jim Peace]

There is a SB on this on the Mooney site:  sbm20-110 oil cooler lines rerouting

 

I think for earlier serial numbers

[mike20papa]

Thanks for the SB reference.  I see that it is entirely about oil cooler cracking - nothing about oil temps.   Odd that Mooney doesn't list it under the earlier models, even though the SB reads that it does apply.  I've seen plenty of 180 hp Mooneys with the lines running up top.  Again, thanks.  Joe

[Wesley brown]

Thanks for bringing this up Joe! I'm certainly looking into moving my lines.

[Hector]

Mine run down behind the engine then forward but I would not call mine a cool running engine. During cruise my cylinder temps are 340 to 380 with the hottest cylinder around 380. During climb I have to be careful to maintain at least 120 to keep from going over 400. In the hot Florida summers sometimes I see 420 then I have to do 130 or so for a little while to get temps back down. My dog house is in pretty good shape. I have 1200 hours on a factory reman and she is running strong with about 1 qt every 9 hours consumption and better than 77 on all cylinders. I think I've made piece with myself on this issue and not worry excessively about my cyl temps. I'll do what I reasonably can to manage the temps but I have accepted that's just the way my M20C runs and it does not appears to be destroying my engine. I keep reading here to see if anyone finds a magic bullet, but I don't think the routing of the oil lines is my problem. Maybe Sabremechs new cowling may offer and improvement.

[Jim Peace]

Mine run down behind the engine then forward but I would not call mine a cool running engine. During cruise my cylinder temps are 340 to 380 with the hottest cylinder around 380. During climb I have to be careful to maintain at least 120 to keep from going over 400. In the hot Florida summers sometimes I see 420 then I have to do 130 or so for a little while to get temps back down. My dog house is in pretty good shape. I have 1200 hours on a factory reman and she is running strong with about 1 qt every 9 hours consumption and better than 77 on all cylinders. I think I've made piece with myself on this issue and not worry excessively about my cyl temps. I'll do what I reasonably can to manage the temps but I have accepted that's just the way my M20C runs and it does not appears to be destroying my engine. I keep reading here to see if anyone finds a magic bullet, but I don't think the routing of the oil lines is my problem. Maybe Sabremechs new cowling may offer and improvement.

Do you have any cowling mod on now?  LASAR etc....?  When I did mine my temps dropped about 40 to 50 degrees

[M204ever]

The dog house on my plane is original meaning with cracks and dents. It seals not very properly to the engine.

When I replaced the forward rubber seal between the dog house and the cowling I took care that the seal exactly finds the tracks of the curved cowling inlet.

It takes some iterations until the seal pressure against the upper cowling is right. Before that I replaced the rubber engine mounts and shimmed accordingly for proper spinner-cowling center alignment.

This made a big difference in cooling. No more over 400F in summer takeoffs. It feels much more comfortable now since you do not have to have always an eye on the CHT.

Can recommend to yanyone with high CHTs. Oil lines are above the engine, on the cool side of the plenum.

[Wesley brown]

Well I had the oil lines over the cylinders and a cooler that was mounted way to close to the exhaust literally blocking half of the coolers opening on the back. I was seeing 430 on one cylinder during climb out and it would barely level off at 398 and the other cylinders around 380-365. After talking with joe I decided to run the lines bellow the cylinders and move the oil cooler forward gaining more room from the exhaust. I haven't flown it yet but I sure hope it helps. This engine is new so it's still pretty tight tolerances. Hopefully after I see 80 hours temps will settle even lower. I also flushed my oil cooler and it had a lot of gum up and gunk built up in it. I sure that will help as well!

[Wesley brown]

Well I report good news! Today we completed the oil line reroute and minor change to the cooler mount and maintenance. Now I see 350-360 on all cylinder compared to the almost 400 degrees on head temps. My oil temp went down to 190 from 210-220. I still see 430 degrees on one cylinder on climb out and I have to bring the nose down to 120 mph to keep it there. As soon as I level off though temps drop dramatically! This mod is worth it for sure and I even think if I got a heat shield sleeve for the lines it will help even more.

One of the major factor is increasing airflow through the cylinders with the lines removed. Not that the lines are much cooler bellow. I had a temp gun and very little temp differences with it being next to the exhaust.

I did buy two 90 degree oil line fitting for better fitment rather than the 45 deg that it had.

Attached Thumbnails

[mike20papa]

Wesley, that's great work.  I think your oil cooler install is probably good as is, too.

[Wesley brown]

Wesley, that's great work.  I think your oil cooler install is probably good as is, too.

Thanks for the compliment! Most of the work is in the oil cooler mount. For everyone reading our earlier planes had two sizes of oil cooler mounts one which is aluminum and shallow in depth and another that is fiberglass which is deeper in depth. The deeper it is the closer it will be to the exhaust.

One thing about my engine temp monitors. I noticed when I turn on my lights that it changes the temps on my CHT and EGT gauges. I'm not sure how or why my lights and fuel pumps with would effect this? But it does..mi use my gauges as a reference but don't trust there accuracy 100%. This will be a future project on straightening this mess up. I noticed when I was landing I turned all the lights on and the temps were getting hot. I was getting concerned until I found out that the lights dropped temps 80 degree on cylinder #2 when turned off. Geeze

[mike20papa]

Yes, the wiring over the years gets modified and remodified and some A&P's think that AC wiring in the GA fleet is "generally appauling".  I lost a com radio one day before I decided to do my panel upgrade - which one thing leading to another..a complete rewiring of the AC.  Anyway my Com 1 was powered off the inst. panel lights, just twisted together - in the cabin roof area!  The wiring behind the panel looked like a rats nest and I had just spent a considerable amount of $$ getting a Garmin audio panel put in.  Not that the job was poorly done, it's just working on wiring behind the panel - with out removing the windshield - is like building a ship in a bottle.   Wesley, do you have the old mechanical master switch - cable actuated toggle - or did Doug install a master solenoid?  I see that Skytech is now selling PMA'd master & starter relays (solenoids).  Lamar was the only previous alternate source.  I think another source of concern/design is the lack of redundant ground connections.   The lighting effecting the engine temp readings could be not so much a lack of potential, but a lack of ground raising circuit resistance.  The ground wire sizing and integrety of connections (especially) Joe

[Wesley brown]

I think you are spot on! The plane definitely has a lack of ground wires and it makes since that the lights would change the resistance. It's ironies that my radio repair guys said the same thing today.

As for the power switch I still have the cable/ double toggle switch on the firewall. I didn't realize that is the power switch I thought the cable was for the landing gear warning sytem. Go figure . If I switch to the PMA silanoid what is the advantages for that?

[mike20papa]

Reliability, for one.  Plus the original toggle has a limited amperage rating compared to a battery master solenoid.  But!  I certainly wouldn't fret over it!  Again, though a battery master solenoid can turn itself off..if the solenoid looses it's ground.  And that's not unheard of.  Look for one (if you replace it) that has a separate (redundant to the housing) ground wire/terminal.  I know Lamar sells one.  I have a copy of the 337 I used to replace mine.  A lot of older aircraft had this large toggle switch for a battery master.  Ercoupes come to mind and there is a STC to replace them.  Also, the cable actuates another toggle switch - can't remember for sure - I'd have to look at the wiring diagram.  Perhaps the alt. field?  Do you still have the original charging system with regulator?  You need to know exactly how the airplane is currently wired before doing anything.  Make sure you know the existing systems and any modifications before hand and talk to your A&P/IA.  Right now, I'd just fly the airplane.  I need paint, but everytime I walk in the hangar N8335E always says "FLY ME" have yet to hear "PAINT ME"

[Hector]

Do you have any cowling mod on now? LASAR etc....? When I did mine my temps dropped about 40 to 50 degrees

I have the LASAR mod.