A trip to the doghouse. Woof.

[DXB]

As  an inexperienced C model owner, I thought Sabremech's cowl mod looked cool but didn't initially get why people were SO excited about it.  

I think I get it now.  

For the first time on my own, I opened the top of my 48 year old doghouse, wanting to change my top plugs and RTV caulk some gaps that I'm tired of looking at.  It seemed like a simple enough job for an owner with boundless enthusiasm but limited experience and tools.  Well, years ago someone riveted shut the small side access panels for the plugs (huh?), so you now have to pull the whole cover. Tons of screws, many damaged screw holes jury-rigged with various screw types - painful to keep straight and reinstall.  Then I had to run out and buy an extension for my torque wrench, since  the spark plug access is still tricky with the cover off.  The lower front rubber baffle strips, which are now hidden by the cowl closure mod, were dry rotting and had multiple holes that I did my best to caulk shut.  I learned all kinds of Houdini tricks to get to numerous gaps all over the baffle, some intrinsic to the original design . Then there was a large ragged gap at the bottom of the alternator that was too large for caulk - looks like someone had cut away a piece of the doghouse here at some point. Why??  Maybe they had trouble getting the old generator out?  There  was another large, unfillable gap at the top left of the starter. I probably will need to convince a mechanic to design and rivet in place some custom baffle strips for these two areas.  Yet my doghouse has numerous cracks (all stop-drilled now) and looks like the whole thing will disintegrate into a pile of dust at any moment, so I don't want to put any more resources into it than absolutely necessary.  And I can't imagine deciding to remove and re-install that crappy thing if I have to overhaul engine at any point. 

So David needs to get his cowl mod to market soon, and tell me where to send a deposit.  

[Hank]

Welcome to the club . . . I've done restoration work on my doghouse the last two annuals. My annual,starts on Friday, maybe I won't need to do anything this time?

[DXB]

Yeah I'd given my shop carte blanche to improve the baffling however they could at annual last month, But they didn't seem to do much except replace a missing horizontal tie rod on one side with a long piece of safety wire.  I think I understand their lack of enthusiasm to work on it now.  

[Yetti]

I replaced the safety wire with a rod.  If you look there is no way to get the Safety wire tight enough and it will start to rub on things like the oil return line alum tubes.  If it rubs long enough it will cause another oil leak. It will also cut through the alum tabs on the baffles, then you have to repair them.   Sloppy lazy work by the shop.  It is a pain to get the rods on properly. I would not let them get away with it. 

[DXB]

33 minutes ago, Yetti said:

I replaced the safety wire with a rod.  If you look there is no way to get the Safety wire tight enough and it will start to rub on things like the oil return line alum tubes.  If it rubs long enough it will cause another oil leak. It will also cut through the alum tabs on the baffles, then you have to repair them.   Sloppy lazy work by the shop.  It is a pain to get the rods on properly. I would not let them get away with it. 

Yeah fair point. I'll see if I can find a rod.  

[Yetti]

It is possible that homer dan would have some steel rod down at the end of the fastener isle. You can cut the rod with a 4.5" grinder, or hacksaw or bench grinder. A little quality time with a die and some stainless nyloc with some stainless washers will get you going.

[Ned Gravel]

I am a little different than the rest of you here.  Clarence rebuilt my doghouse when I did the engine overhaul in 2009.  He powder coated it shiny black and it has absolutely zero leaks in it.  Before this was done, there were times when I would see my JPI top 390 for one or two of the CHTs.  After it was done, the hottest I would see on a hot summer day was around 365.  Mostly my CHTs are between 320 and 350.  Nice and cool.

I like the idea and look of Sabremech's new cowl and I certainly want one too, but I am a little scared of giving away the great cooling of my current doghouse.  He promised me (at Oshkosh last year) that his new cowl will provide just as good cooling air as my doghouse. 

I remain hopeful.

[DXB]

31 minutes ago, Ned Gravel said:

I am a little different than the rest of you here.  Clarence rebuilt my doghouse when I did the engine overhaul in 2009.  He powder coated it shiny black and it has absolutely zero leaks in it.  Before this was done, there were times when I would see my JPI top 390 for one or two of the CHTs.  After it was done, the hottest I would see on a hot summer day was around 365.  Mostly my CHTs are between 320 and 350.  Nice and cool.

I like the idea and look of Sabremech's new cowl and I certainly want one too, but I am a little scared of giving away the great cooling of my current doghouse.  He promised me (at Oshkosh last year) that his new cowl will provide just as good cooling air as my doghouse. 

I remain hopeful.

Man. Until messing around with my baffle yesterday, I would have had no clue how nice yours is. That looks REALLY nice.  And actual functioning side access panels.   I would kill for my hottest temp in climb to be 390, though I have no issues in cruise. I covet the shiny new exhaust also.   I think mine is original.  

I notice yours lacks the two ducts off the back of the top cover that shoot air onto the mags.  Does that mean these two are vents are unnecessary?  If so plugging them might help.   

[Ned Gravel]

DXB:

Don't know about vents warming the mags.  Clarence would know.  I am in Myanmar right now and I can't open up the cowl to look.

Here is what it looked like during my pre-purchase inspection.  Can you guess who did that too?

 

[DXB]

1 hour ago, Ned Gravel said:

DXB:

Don't know about vents warming the mags.  Clarence would know.  I am in Myanmar right now and I can't open up the cowl to look.

Here is what it looked like during my pre-purchase inspection.  Can you guess who did that too?

 

Wow that old baffle looks like a disaster- I dare say much worse than mine.   Thanks I'll wait for Clarence to weigh in.  

[Guest]

The mag cooling blast tubes are still in place on Ned's engine.  Making the baffles work is not really difficult, it's a willing owner and a willing maintainer.

Clarence

Edited January 18, 2016 by M20Doc

[Hank]

12 minutes ago, M20Doc said:

The mag cooling blast tubes are still in place on Ned's engine.  Making the baffles work is not really difficult, it's a willing owner and a willing maintainer.

Clarence

Wish the same could be said for the doghouse! I'll post a picture of my resurrected one to compare to your recreation. I'm impressed! Do you offer long distance rebuilds? Or do you need some time away from the snow and ice? It was 62°F (17C) here yesterday.  

 

[DXB]

14 minutes ago, Hank said:

Wish the same could be said for the doghouse! I'll post a picture of my resurrected one to compare to your recreation. I'm impressed! Do you offer long distance rebuilds? Or do you need some time away from the snow and ice? It was 62°F (17C) here yesterday.  

 

If you decide to go down and see Hank please stop in Philly as well!   

[Andy95W]

1 hour ago, M20Doc said:

The mag cooling blast tubes are still in place on Ned's engine.  Making the baffles work is not really difficult, it's a willing owner and a willing maintainer.

Clarence

Definitely wisdom from a knowledgeable craftsman.

Dev (the OP) said that he had given his shop carte blanche to fix his baffling.  Part of the problem was probably a lack of knowledge. The other part was that they were thinking that it would take a tech 10+ hours to fix your baffling, and they didn't want to hand you a bill for that much shop time for what sounds like simple work.  When I was working on other people's airplanes, I always had to balance how long a job would take against how much the customer would be willing to pay.

Dev's shop probably wasn't aware that he was actually willing to pay for the time and materials required to do the job.  My suggestion is that at the next annual, you take a look at your doghouse with the cowling off alongside the mechanic doing the work.  Together you can discuss all the areas that need to be addressed and a fair number of hours that you would be willing to pay for the work.  That way you can get a better doghouse, and the shop owner knows you won't complain.

[Guest]

19 hours ago, Hank said:

Wish the same could be said for the doghouse! I'll post a picture of my resurrected one to compare to your recreation. I'm impressed! Do you offer long distance rebuilds? Or do you need some time away from the snow and ice? It was 62°F (17C) here yesterday.  

 

The cost of a cooked engine far out ways the cost of fixing the baffles.  As much as the thought of a road trip sounds appealing, I've got plenty to do here.

Clarence

[DXB]

It's interesting to me that doghouse baffle components seem hard to come by on the parts market.  A search on ebay yields all the mooney cowl pieces you could ever want, but no baffle stuff.  I'd like to build up some components so I can incrementally improve the thing.   Particularly I'd like to replace the top piece on mine so I can get spark plug access back.

[Shadrach]

1 hour ago, DXB said:

It's interesting to me that doghouse baffle components seem hard to come by on the parts market.  A search on ebay yields all the mooney cowl pieces you could ever want, but no baffle stuff.  I'd like to build up some components so I can incrementally improve the thing.   Particularly I'd like to replace the top piece on mine so I can get spark plug access back.

Do all of the carbureted birds have a Plenum (doghouse)?  I thought it was a mid 60's thing. My 67 Exec does not have one.

Is this the suff you're looking for Dev?

 http://www.ebay.com/itm/Lycoming-0-360-Mooney-Pressure-Cowl-Baffling-/151934974431?hash=item236007b9df:g:r9UAAOSwv0tVLw4a&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-Mooney-Pressure-Cowl-Baffling-Right-Rear-/161934457777?hash=item25b40bbbb1:g:hq4AAOSwv0tVaaTh&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-O-360-Mooney-Pressure-Cowl-Baffling-Left-Rear-Baffle-/161934458275?hash=item25b40bbda3:g:0I4AAOSwl8NVaaJH&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-O-360-Mooney-Pressure-Cowl-Baffling-Right-Rear-Baffle-/161934457594?hash=item25b40bbafa:g:e3cAAOSwstxVaaLf&vxp=mtr

[DXB]

6 minutes ago, Shadrach said:

Do all of the carbureted birds have a Plenum (doghouse)?  I thought it was a mid 60's thing. My 67 Exec does not have one.

Is this the suff you're looking for Dev?

 http://www.ebay.com/itm/Lycoming-0-360-Mooney-Pressure-Cowl-Baffling-/151934974431?hash=item236007b9df:g:r9UAAOSwv0tVLw4a&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-Mooney-Pressure-Cowl-Baffling-Right-Rear-/161934457777?hash=item25b40bbbb1:g:hq4AAOSwv0tVaaTh&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-O-360-Mooney-Pressure-Cowl-Baffling-Left-Rear-Baffle-/161934458275?hash=item25b40bbda3:g:0I4AAOSwl8NVaaJH&vxp=mtr

http://www.ebay.com/itm/Lycoming-0-360-O-360-Mooney-Pressure-Cowl-Baffling-Right-Rear-Baffle-/161934457594?hash=item25b40bbafa:g:e3cAAOSwstxVaaLf&vxp=mtr

I bow to your superior internet skillz.

[Shadrach]

20 minutes ago, DXB said:

I bow to your superior internet skillz.

I've never heard it called a pressure cowl. I just happened to see these the other day when doing a parts search.

[pinerunner]

I'm gonna rebuild my doghouse too. Then I'm gonna start calling it a pressure cowl or plenum. That really looks good. Mine isn't the worst but it's got some badly worn area's, some that are kinda sharp (you can get cut on). Great post and discussion.

[DXB]

On January 16, 2016 at 0:18 PM, DXB said:

Yeah I'd given my shop carte blanche to improve the baffling however they could at annual last month, But they didn't seem to do much except replace a missing horizontal tie rod on one side with a long piece of safety wire.  I think I understand their lack of enthusiasm to work on it now.  

Update- I got the shop to work on it a bit more but they still didn't close one of two big gaps that I'd wanted something riveted over - a large ragged hole on the front of the doghouse under the alternator created when someone ripped out the generator at some point. So I'm gonna cut a piece of rubber baffle and slap it on the front of the hole, holding it in place with RTV silicone applied from the back, with care not to obstruct or get slicone on the vents in the alternator.  Hopefully the FAA does not frown on my creativity.  

That's the last of the gaps I can see.  If my climb temps are still high in the summer heat, next may be increasing the opening in my cowl flaps slightly (which are fixed position in my 68C).  But I hate to add drag since I have no temp problems in cruise.  I'm told there's an adjustable cowl flap mod for my plane?  This is getting ridiculous - how far along is Sabermech's cowl mod again?

[Mooneymite]

The real doghouse:

Beware of the Doghouse!

[Sabremech]

HI DXB,

I'm still a ways from getting the modification certified. An option that I may have is to install the mod on an airplane as a field approval in support of the STC. If this is an option for you, we can talk about it after I submit the project to ACO. That's the one way you can get the mod sooner if you'd like it.

Thank you,

David

[carusoam]

Dev,

Old observation that has been released from my memory...

the generator had a piece of thick felt stapled to the dog house that 'sealed' (sort of) against the generator.  That was a standard back in the '60's.  They invented silicone rubber after that time...

On my C, the felt got old and stiff, folded, and didn't fit very well after some of the staples wore and disappeared. (Things that make you go hmmmmm....)

Best regards,

-a-

[mooniac15u]

Airforms sells PMA'd replacement baffle parts for some models including the M20C. 

https://www.airforms.biz/index.php?route=product/manufacturer/info&manufacturer_id=14