Rate my baffle seals

[redbaron1982]

I'm working on improving the cooling of my M20J. Engine is running between 380F and 400F on the hottest cyl (#3) and this is even with cowl flaps trailing.

So now I removed all the seals I had and I'm installing CowlSaver from McFarlane. I finished the upper half of it, tomorrow I expect to finish the remaining seals (the ones that are in the front, under the air inlets.

From the pictures I'm sharing can you guys give me your feedback? I'm working with an AP but extra eyes is always good to make sure we are not missing anything.

I do have to do a few cuts in the seals on the back of the engine to make it stay flat agains the cowling.

My main doubt is on the front of the engine, the seal is not getting all the way to the front of the cowling. This was the case with the seals I removed, and now it's the same. Is that normal? I'm refering to this specific picture:

[MikeOH]

Is the 380-400 in cruise or on climb out? If climb out, I wouldn’t worry. If a hot day the numbers aren’t awful, but are higher than what I see in cruise (330).

Fix the gap in the middle (I think you said you were taking care of that)

I’m not sure what I’m looking at in the first picture? Just keep in mind any “leak” that drops pressure in the upper plenum is going reduce cooling.

[MikeOH]

Oh, and what is the blue tape covering? Hope it’s not the oil COOLER!

[redbaron1982]

380/400 is in cruise on a hot Texas day, at 6000 ft / 25C OAT.

The blue tape is covering the air intake filter, I didn´t want to get any debries there while working. Of course in my list of things to do when the job is finished. I did the same for the oil cooler when I was removing the old rivets, but that one is already removed.

Edited August 3, 2023 by redbaron1982

[MikeOH]

If that’s your hottest cylinder on a hot day, I wouldn’t lose sleep over it while you work to lower it.

 I had problems in climb on a hot day and I tried everything except fuel flow! That fixed my issue but that was full power climb, not cruise. So, likely not your issue.

[redbaron1982]

I need to go either way too rich or very lean to keep temps < 400F in cruise with cowl flaps trailing.

Anyway, the baffling was not in the best condition, so my idea is to get that in the best shape possible, so if temps are still high I will look somewhere else.

[Fly Boomer]

1 minute ago, redbaron1982 said:

I need to go either way too rich or very lean to keep temps < 400F in cruise with cowl flaps trailing.

Anyway, the baffling was not in the best condition, so my idea is to get that in the best shape possible, so if temps are still high I will look somewhere else.

I haven’t had to fight this yet but, from what I read around here, even sealing up a bunch of tiny holes between the upper and lower deck can make a big difference.

[EricJ]

In your first pic the idea is that the incoming air pressure will push the gasket against the cowl and seal it.

In your pic with the cowl on, that little hump that makes a leak can be cured by making a cut in the baffle right at that hump so that it folds over a little on itself.

Otherwise it's looking pretty good.

[N201MKTurbo]

You are missing a baffle plate on your #1 cylinder. You can see the witness marks where it used to be. I  think the RTV on the baffle to cylinder fins is doing more harm than good.

[redbaron1982]

5 minutes ago, N201MKTurbo said:

You are missing a baffle plate on your #1 cylinder. You can see the witness marks where it used to be. I  think the RTV on the baffle to cylinder fins is doing more harm than good.

Regarding the baffle missing, do you mean near the intake for the hot cabin air, next to the induction filter? I haven't completed that part yet, but what was there was a baffle seal, and is something that I will complete tomorrow. The part you say is missing is this or is an actual baffle (aluminum sheet) that is missing?

[A64Pilot]

Never said if your ROP or not, Cyl head temps follow power and power say 100 ROP is quite a bit higher than say -25 LOP. I can’t keep my cyl head temps down at higher power cruise with trailing flaps in Summer either, if I want high power they stay fully open.

My 2c if temps creep toward 400 with flaps trailing, open them fully. Do whatever you need to with the flaps to keep cyl head temp cool.

On a hot day I have to climb at 130 indicated full rich, cowl flaps full open to keep it in the middle of the green, Winter time I can hang it on the prop at Vy.

Don’t put too much into what you read on the internet, not saying others aren’t running cool with trailing flaps, but they may not be in Tx, or may be running lower power settings or maybe their engine is older and more worn and just doesn’t run as hot a newer tighter engine.

Depending on where in Tx and time of day, it’s awfully hot there, many have never experienced that level of heat.

Edited July 20, 2023 by A64Pilot

[N201MKTurbo]

3 minutes ago, redbaron1982 said:

Regarding the baffle missing, do you mean near the intake for the hot cabin air, next to the induction filter? I haven't completed that part yet, but what was there was a baffle seal, and is something that I will complete tomorrow. The part you say is missing is this or is an actual baffle (aluminum sheet) that is missing?

It is an aluminum plate that attaches where the three screws are and covers about half of the fins. 600370-007

[MikeOH]

As a reference point:

I see 330 CHTs in cruise running LOP at 65% with cowl flaps closed. 

[redbaron1982]

3 minutes ago, MikeOH said:

As a reference point:

I see 330 CHTs in cruise running LOP at 65% with cowl flaps closed. 

At what altitude/OAT? My last flights, at 6000FT or 8000FT here in Houston I was seeing 27C to 23C OAT. Not even close to ISA.

[redbaron1982]

6 minutes ago, N201MKTurbo said:

It is an aluminum plate that attaches where the three screws are and covers about half of the fins. 600370-007

Thanks! Now I see, and sorry for getting mixed Cyl #2 with Cyl #1. I was looking at the wrong picture.

What I will do tomorrow is go and check every single part of the baffle to make sure they are there, and order whatever is missing.

[MikeOH]

25 minutes ago, redbaron1982 said:

At what altitude/OAT? My last flights, at 6000FT or 8000FT here in Houston I was seeing 27C to 23C OAT. Not even close to ISA.

5500, OAT 21

I’m flying this afternoon and it’s been HOT (>35C) so I‘ll see what OAT I get at 5000 today.

[OR75]

59 minutes ago, redbaron1982 said:

Thanks! Now I see, and sorry for getting mixed Cyl #2 with Cyl #1. I was looking at the wrong picture.

What I will do tomorrow is go and check every single part of the baffle to make sure they are there, and order whatever is missing.

there was a discussion on this exact topic a few months ago. Some Js have that part installed and some don't. Mine does not.

[redbaron1982]

4 minutes ago, OR75 said:

there was a discussion on this exact topic a few months ago. Some Js have that part installed and some don't. Mine does not.

I'm going to give this a try, first is in the IPC, so it is supposed to be there. Second, it's cheap (McFarlane has this for 20usd I think). Third, the issue I'm having is with Cyl #3, and my flow dynamics master (just kidding) tells me that this part missing allows air to escape to the lower side through the front of Cyl #1, preventing this air from reaching Cyl #3. Cyl #1 and #3 are consistently 20F hotter than 2 and 4 in my case.

If it makes things worse, I can always take it out.

[redbaron1982]

3 hours ago, M20Doc said:

Good cooling depends on a pressure differential, higher pressure above the cylinder and lower pressure below the cylinders.  Sealing holes and gaps improves the differential.  I’d seal gaps at the oil governor line at the front right, around the starter nose case, the hole where the ram air door was, make a rubber diaphragm at the alternator, (don’t block the holes in the actual alternator).

Any puckers in the new sealing tapes can be corrected with a small slit with a razor blade.

What would you use to seal the gaps between the oil governor line? RTV? I have a few gaps in the front of the engine between the baffle and the engine itself. 

This how it looks now around the starter and alternator. I can see sealing the gap between the baffle and the starter, but with the alternator I'm not sure, there doesn´t seem to be a huge gap between the baffle and the alternator, and any attempt to reduce that gap it seems that is going to reduce air around the alternator.

[MikeOH]

Ok, I was overcome by events last Thursday and didn't get to fly

So, today, with ground temp right at 100 F, I went for a flight. WOT, 2650 rpm, full rich on climb, hottest CHT was 386 F during climb.

Leveled off at 5500 (5400 PA), WOT, 2500 rpm, leaned to about 30 LOP, 75% power, OAT 90 F, cowl flaps open.  Here are the CHTs: 318, 350, 349, 324.  Temps were about 10 F higher with cowl flaps closed, 3-4 mph increase in IAS.

[redbaron1982]

On 7/24/2023 at 11:55 PM, MikeOH said:

Ok, I was overcome by events last Thursday and didn't get to fly

So, today, with ground temp right at 100 F, I went for a flight. WOT, 2650 rpm, full rich on climb, hottest CHT was 386 F during climb.

Leveled off at 5500 (5400 PA), WOT, 2500 rpm, leaned to about 30 LOP, 75% power, OAT 90 F, cowl flaps open.  Here are the CHTs: 318, 350, 349, 324.  Temps were about 10 F higher with cowl flaps closed, 3-4 mph increase in IAS.

I would love to have those temps in my J.

Yesterday I went flying (KSGR <-> KHYI). During the climb, I was seeing 420F CHT in Cyl #1.

This flight was after adding the missing piece of baffle in front of Cyl #1, now Cyl #3 improved, but Cyl #1 got much worse.

This is the data from my flight: https://apps.savvyaviation.com/flights/shared/flight/7210566/ba7a9b2d-3f3e-448f-84f7-33046b1a7e5c

First leg (KSGR -> KHYI) was flying at 8k (DA 10.5k), the way back was at 5k ft (DA 7.5k).

[OR75]

43 minutes ago, redbaron1982 said:

I would love to have those temps in my J.

Yesterday I went flying (KSGR <-> KHYI). During the climb, I was seeing 420F CHT in Cyl #1.

This flight was after adding the missing piece of baffle in front of Cyl #1, now Cyl #3 improved, but Cyl #1 got much worse.

This is the data from my flight: https://apps.savvyaviation.com/flights/shared/flight/7210566/ba7a9b2d-3f3e-448f-84f7-33046b1a7e5c

First leg (KSGR -> KHYI) was flying at 8k (DA 10.5k), the way back was at 5k ft (DA 7.5k).

worse enough to remove the baffle ?

[MikeOH]

@redbaron1982

I fought high CHTs for years; my #2 would see 420 in climb on a hot day. New baffles helped, as did a lower cowl mod (a factory SB … I’ll have to look it up). Things that didn’t help: overhauled oil cooler and new hoses, new Vernatherm.

What solved it was complying with an AD on the fuel servo (yeah, multiple shops and I missed this over several years!) that substantially increased fuel flow at WOT. There should be a “G” stamped on the servo plug if complied with. Yeah, if you read the AD it should NOT have anything to do with fuel flow…all I know is that after compliance my fuel flow was higher and I no longer had a CHT issue. I ran around 15 gph before, and 17 gph now at WOT

[redbaron1982]

9 minutes ago, OR75 said:

worse enough to remove the baffle ?

Without the baffle #1 is < 400F and #3 is around 410F. With the baffle #1 is around 420F and #3 is <400F. So I think it's worse with the baffle.

I could cut the baffle so I get something in between... but doesn't look like something "legal" to do... 

[OR75]

22 minutes ago, redbaron1982 said:

Without the baffle #1 is < 400F and #3 is around 410F. With the baffle #1 is around 420F and #3 is <400F. So I think it's worse with the baffle.

I could cut the baffle so I get something in between... but doesn't look like something "legal" to do... 

it is expected that #3 is the hottest (that's why the CHT probe is on that cylinder when there is only one)