HIGH CHT after run up???? Any Idears?

[Brian Scranton]

Mooniacs,

Flying my M20F with an IO360a1a, turbo normalized (ray jay)...went for a little scenic cruise yesterday and here's what happened:

1) Oil was just above 6qts, so I figured I'd add another qt before the next flight

2) Leaned for taxi, rolled to the threshold, and did my run up. First click on the mags and the engine loses 200 rpm, runs rough. Ok on the other mag. Ok on both. So I rev up to 2200 rpm, lean for best power, hang for 30 seconds and check the mag again. Still rough. I repeat the leaning/fouling rectification procedure and this time it works, everything is fine and dandy. However, I notice cyl #2 has crept up to 405. I pull the power back, but since its hot as hell 90degrees, high DA 8500ft, and not a lot of cooling, I don't see much of a drop. I think to myself, let's roll and see what happens.

3) So I line up and go WOT and #2 goes up to 420. I abort. Head the FBO. Drink an iced tea. Add a qt of oil. Wait 20 mins.

4) I try again. No fouled mag check. Temps all stay low (350-370). I go WOT no turbo (24inches, 2600 rpm, but the rpm takes 5 seconds to spool, kinda hangs at 2400 for a bit then get to 2600 on the roll), I hit 410 on climb out on #2 but that comes down quickly after I nose over and speed up to 115 for cruise climb (full rich, no turbo, 24/25). At 8000 feet, I add the turbo just to see how it affects the temps, all good. I lean. All good. So, what happened? EGTs were all fine around 1290-1360. Could I have stressed the cylinder that much during the plug foul operation to make that one cylinder that hot? If #2 had the fouled plug, I would expect the CHT to be lower...#1 340, #2 420, #3 380, #4 340...

I don't have the GEM computer to download any data so you'll just have to go with the above. Mind you, my #2 is always the hottest by about 20 degrees compared with #3 and by 30-40 degrees compared to #1 and #4. Interesting that 1 and 2 are both in front, and that 1 has more baffle around it and it looks like #2 is intentionally missing a few inches baffling (#1's go straight across the entire length of the cylinder and #2 has a 3 inch gap between baffle pieces). Also, #2 is about 70 hours new, I so I get that the higher temps could be a break in thing. About 20 hours ago I replaced the mineral oil with 100Wplus.

Thanks for your thoughts! 

B

[Brian Scranton]

So I've had high CHT readings (400 was easy to reach at 24/25 in the climb with laaaame climb rates) all summer on #2. It has baffled me. Turns out...the baffling. Had a few baffle flaps folded in the wrong direction from playing with the cowling a bunch! And, cleaned and gapped all the plugs...holy crap what a difference!!!!

I can use my turbo now! 

[carusoam]

Ahhhh.... The power of MS.  

Best regards,

-a-

 

[Brian Scranton]

3 hours ago, carusoam said:

Ahhhh.... The power of MS.  

Best regards,

-a-

 

I was surprised that no one responded to my original post--but I blame some air show that's going on. I even said that my #2 is always the hottest..heh heh...and no one took the bait. So, the real hero on this one isn't MS but my trusty, old, cynical, gun-toting, helluvanamerica, and fine fellow...A&P. 

[Shadrach]

Verifying that baffle seal is correctly oriented is part of my preflight (I am not the only one who flies the plane). The first few times my partner changed the oil, he missed this detail. The nice thing about the guppy mouth is that you can stick an arm in there and roll into place by hand. I am surprised #2 is/was your hottest; #3 is typically the most challenging to keep cool.

How abysmal are your climb rates without the turbo? At a DA of 8500 you ought to be making 700FPM if under 2300lbs. The attached screen shot is from my trip to NY this past Tuesday. I cruise climb at 120MIAS until I get to abou 8000' and then climb at 105-110MIAS. Add 2500' to the altitude read-out to account for DA. This data is actually pessimistic compared to what I saw in the plane. We departed at just over 2400lbs. GPS altitude was 12000'.

Dont bust my balls over the expired plate, I had current paper in the cabin!

 

[Brian Scranton]

At 2700lbs, DA of 10,000, 90F...23'' and 2600rpm, I was seeing 200-300 fpm at 110mph IAS.  High, heavy and HOT. I was not really that surprised. 

The baffle check is now part of my preflight! I guess I never realized how much it matters. And #3 is always 5-10 degrees cooler that #2--strange but true! #2 is 80 hours new...maybe that makes a difference. 

[Shadrach]

Why 2600? You're climb rate increase a bit by going to 2700 and but more importantly, you'll probably run a tad cooler on the CHTs.

[M20F]

12 hours ago, Brian Scranton said:

At 2700lbs, DA of 10,000, 90F...23'' and 2600rpm, I was seeing 200-300 fpm at 110mph IAS.  High, heavy and HOT. I was not really that surprised.  

Lower the nose you need barely a dot on the attitude indicator to get 500-1000 FPM at 120.  It climbs worse the more you put the nose up. 

[Brian Scranton]

On July 29, 2016 at 9:22 AM, Shadrach said:

Why 2600? You're climb rate increase a bit by going to 2700 and but more importantly, you'll probably run a tad cooler on the CHTs.

2600 is all she does! I don't get redline on my tach--I'll have my A&P look at that. 

And maybe that's my problem Mike--I climb at 100-110 and it's 400fpm...I'll nose over tomorrow and see what 120 gets me. 

[Shadrach]

1 hour ago, Brian Scranton said:

2600 is all she does! I don't get redline on my tach--I'll have my A&P look at that. 

And maybe that's my problem Mike--I climb at 100-110 and it's 400fpm...I'll nose over tomorrow and see what 120 gets me. 

I look forward to reading you results. 110 is about what I'd be using at that altitude. The POH says best climb at SL is 113MIAS and it drops by about 1mph for every 1000' feet you climb.  So 105MIAS at 8000' and 100MIAS at 12,000'. 

[Guest]

1 hour ago, Brian Scranton said:

2600 is all she does! I don't get redline on my tach--I'll have my A&P look at that. 

And maybe that's my problem Mike--I climb at 100-110 and it's 400fpm...I'll nose over tomorrow and see what 120 gets me. 

Don't just have the governor changed to 2700 without determining that the tachometer is accurate.  Tachometer accuracy check is part a Canadian annual inspection.

Clarence

[Brian Scranton]

 

18 hours ago, Shadrach said:

I look forward to reading you results. 110 is about what I'd be using at that altitude. The POH says best climb at SL is 113MIAS and it drops by about 1mph for every 1000' feet you climb.  So 105MIAS at 8000' and 100MIAS at 12,000'. 

Flew this morning--DA at 7500ft on takeoff. I was basically climbing between 8000-15,000 based on DA. Anyway, 120mph was essentially level flight and only getting me 200fpm, while 105mph was giving me a solid 500fpm. I was at 27MAP and 2600 rpm. 

[Brian Scranton]

On July 29, 2016 at 6:09 AM, Shadrach said:

Verifying that baffle seal is correctly oriented is part of my preflight (I am not the only one who flies the plane). The first few times my partner changed the oil, he missed this detail. The nice thing about the guppy mouth is that you can stick an arm in there and roll into place by hand. I am surprised #2 is/was your hottest; #3 is typically the most challenging to keep cool.

How abysmal are your climb rates without the turbo? At a DA of 8500 you ought to be making 700FPM if under 2300lbs. The attached screen shot is from my trip to NY this past Tuesday. I cruise climb at 120MIAS until I get to abou 8000' and then climb at 105-110MIAS. Add 2500' to the altitude read-out to account for DA. This data is actually pessimistic compared to what I saw in the plane. We departed at just over 2400lbs. GPS altitude was 12000'.

Dont bust my balls over the expired plate, I had current paper in the cabin!

 

Also, after the baffle fix, #3 is now my hottest (2 and 3 are very close). So, you were right!!!