Rear engine cooling

[Ron Ball]

Having cooling problems on my 1973 P-337-G, rear engine. New engine put in Jan 2002. CB engine with Riley air-condtioning and inter coolers added[ Riley] Ran mineral oil for 20 hours, oil burn good so went to 50 weight, at 20 hours. Always had high Cht on Right side, # 2, 4, 6, Now at 35 hours and out side air temps higher can not keep CHT below 400 on 2, 4, 6. At crise #2=400 f # 4 414 f and #6 450 f. I climb at 155 to keep # 6 below 450, but recently 455-460 on climb. Open or close cowl flaps no change, maybe 1-2 degrees. Oil temp running 210 degrees. at cruise. Run fuel high for cooling 30 " M.P. 2400 RPM and 14 GPH Left side #1 = 325 ,#3= 350 # 5 = 380. I asked Riley to make sure baffling was perfect. My mechanic says looks O.K. Back baffling curling forward, almost in half, Mechanic says probably is forced back, inflight. Looks to me like could be forced down and open up gap. When decending # 6 goes from 450 to 420 in about 5 minutes. When power pulled back and decending # 6 goes below 400. Any thoughts? By the way my air-conditioning not working, no manuals or trouble shooting guides from Riley, anyone know who can work on Air in Northern Calif.???

[rick bell]

make sure all the internal baffles are in place (or haven't come loose) between the cyl. some times the baffeling around the inlet to the intercooler does not seat here it comes through the rear shield. you also with old baffeling get a lot of leaks on the front of the engine. if it is old baffeling change it and go with the silcone type, last a lot longer and is thicker, more plyable. i'm supprised you are not vapor locking with thoes temperatures, mine did. i changed totally changed the baffeling plus insulated all the fuel lines as i was overheating plus vapor locking almost every trip usally in curse. now thats all gone.

[Mark Hislop]

Ron: If opening and closing your cowl flaps makes no change, I would really suspect bffling problems. Lots of little leaks can equal a big one. I also have a P337 (73) with a factory reman on the rear. My CHT temps, with cowl flaps closed, cruise power (65%), 21-22 GPH, are 375 at the most. Let us know what you find out.

Mark

[Bob Cook]

Ron

Agree with others. I might hit 200 on the oil during climb. CHT's not even close to 400. Use silicon baffling ie. blue or orange. Make sure tight around oil coolers.

Maybe someone can take dig photos and send them to you for comparison.

I think it is about time to discuss with the installer.

Bob

[Kevin McDole]

Originally posted by Ron Ball By the way my air-conditioning not working, no manuals or trouble shooting guides from Riley, anyone know who can work on Air in Northern Calif.???

Sterling Aviation in Concord knows A/C systems. They installed A/C in my 210 and have maintained A/C systems for me in 3 different aircraft. I'm sure they can help you out. Call up Mike Bruno at (925) 676-2100. But be forewarned, they do get pretty booked up so they may not be able to get you in right away.

[Bob Cook]

Ron

I know the system inside out. If your mechanic calls me i can give him directions.
I am sure you have a freon leak /r 134a. Guage ports are on back wall. any AC person can do the test. there is a low pressure cutout also high pressure cut out as well. The leak is probably the U joint on the high side at the compressor or a lose bulkhead connector between the evaporator and the rear AC bulkhead.

The wiring is really simple and elec troubleshooting is simple as well. I have the wiring diagrams.

I had to get system going myself. Once fixed it will hold.. Basically it is an automobile system.

Re baffling, you do need to try and sort out the leaks.

Bob

[Ron Ball]

We sealed off areas where leaks were apparent. Found a silicon baffle on # 6 was too long and covering up some cooling fins and not leting air through. Taped up other areas to seal ,for leaks. Will fly tomorrow. We found a broken fitting on the alum. tube fitting on upper compressor port. No freon, obviously. Tule River contacted me this morning and offered to help ,in anyway possible. Will follow-up monday with results.

[Bob Cook]

Ron

You will need to replace this fitting (90 degree soft bend). This is caused from vibration and poor support of hose where it passes thru the baffle.

You will need to pull a vacuum and test the system before charging. Also add a few ounces of refrigeration oil when charging as I am sure you will have lost some during the blow-out. There is a sight glass on top of the dryer (left rear inside firewall). this is a tall black "can". Use a mirror to look in the window. If there is bubbles when the AC is running then there is not enough refrigeration.

You can go to a local auto store and get a tire guage type of freon system checker. put it in the aircraft and if you have problem in future you can quickly isolate if the freon is gone or low.

good luck on sorting out the cooling problems. Sounds like you have a handle on it.

regards

Bob

[Ron Ball]

After taping up back baffles, long new baffle material curling forward and opening up. Oil temp went down 10 degress and cht 25 to 35 degrees. still over 420 degress.. Need to re do all baffling. 1,3,5 cht ate 350 t0 390 range. 2,4,6 402, 411 ,420 respectively.This is at 45 to 50 degrees ambient and 100 degrees rich of peak.

[rick bell]

definalely redo the baffeling; also check to make sure the metal baffeling between the cyl has not come out and they are in the correct order. when i replaced the engs the metal baffeling was installed incorrectly

[Ron Ball]

Thanks, Rick. Does the manual show the baffle between the cylinders. ? HOw do you know the correct order?

[GMAs]

look in the cessna parts manaual... it will give you the number... but, it doesn't give the dimensions of the slots in the bottom... however all boxes are the same... its just where they are placed... best to look at another one the same year that hasn't been taken appart... cessna used to tell you how wide the slot was for each part no... they have since quit... sorry.. gmas