Oil Cooler Baffle

[Skybrd]

I noticed on a friends M20A Mooney that there is a baffle plate on the rear of the oil cooler to redirect the exhaust air closer to the side of the cowling instead of it's normal rearward flow.  Will this help the number 2 cylinder to run cooler. My EGT shows the hottest temps on #2. I would rather try this, than do the mod to relocate the cooler to the back of the air box. Have any of you tried installing a baffle plate to redirect the air closer to the cowl?

[takair]

Quote: Skybrd

I noticed on a friends M20A Mooney that there is a baffle plate on the rear of the oil cooler to redirect the exhaust air closer to the side of the cowling instead of it's normal rearward flow.  Will this help the number 2 cylinder to run cooler. My EGT shows the hottest temps on #2. I would rather try this, than do the mod to relocate the cooler to the back of the air box. Have any of you tried installing a baffle plate to redirect the air closer to the cowl?

[Skybrd]

Quote: takair

 I had high oil temps on my 64E model earlier this year.  It does not have the baffle, but I spent a bunch of time trying to figure out if it should.  In the end, the E model does not, but what I learned is that it was originally fitted because of cracking of the #2 exhaust stack.  Apparently to cool air and rain were thought to cause cracking.  There are some SBs that talk about it.  I don't think it would help CHTs or EGTs.  Based on my research I would say that it is actually keeping your #2 exhaust stack cooler.  Basically, even though the air is warmed by the oil cooler it is still over 1000 deg cooler than yourEGTs.  If you need the SBs, they are on the Mooney site or I can dig up the reference for you.

Thanks for replying. I think this baffle might help cool the number 2 cylinder since the exhaust of the oil cooler would cause a change in the needed low pressure area under the cylinder. It would seem to raise the pressure to a higher value than the other cylinders. A few minutes ago, I was checking out Mooneys in the BarnStormers advertisments and saw a 1967 Mooney M20C with the cowl off and it had the baffle I described on it. Another thought concerning this is the change in EGT would cause us to richen the mixture to overcome the higher reading of the #2 cylinder.

[takair]

http://www.mooney.com/images/pdfs/sb-pdf/sbm20-93.pdf

http://www.mooney.com/images/pdfs/sb-pdf/sbm20-99.pdf

Depending on what model you have, these are the bulletins that install the plates.  The kit is not made for fuel injected versions. 

If number 2 is running much higher than the others, I would be suspicious of a leak in the intake tube.  The Orings going into the lower plennum/oil pan often wear and you will get a lean running cylinder.  Alternately, if you are an e/f you could have a patially blocked injector.  What is the EGT running at?  Are you a c or and e model?