Left engine High CHT

[Ken Bagwell]

I have been flying my 81 P58 since last August and put on 60 hours but can't seem to get the #2 and #4 cylinders to an acceptable temperature on climb out or in cruise.  When I bought the airplane, the fuel flow was set to low and the prebuy inspection showed that cylinders 2-5 needed to be overhauled.  When I accepted delivery, I had my mechanic send the fuel system to B&S to have the flow dividers matched and calibrated.  The problem is at  takeoff power, I still only get 30gph which B&S says is the maximum that Continental allows. It is very difficult to keep #2 and #4 below 400 on climb out (2500 rpm 35inches) and above 12,000 feet, both climb above 400 to 415.  

In addition, at cruise I have to keep the left engine cowl flap open to keep both of these cylinder down.  Here's what my Insight monitor read:

#1  1417   347

#2  1502   404

#3  1449   354

#4  1455   403

#5  1402   368

#6  1425   377

TIT 1523

These temperates are at 15,000ft 40 degrees OAT, cowl flap open, 17.2 gph, IAS 145 knots, 2300 rpm, 30 inches.  If I close the cowl flap, #2 and #4 would go above 425 quickly.



To compare, my right engine reads with cowl flap closed:

#1  1423   331

#2  1502   360

#3  1428   354

#4  1462   365

#5  1394   359

#6  1400   342

We have checked baffling and though both sides are old, they look good.   I have replaced both the #2 and #4 CHT probes.  Considering the EGT readings of #2(1502) and #4 (1455) are slightly higher, I think I have a fuel related problem.  I had my mechanic clean the injectors but this didn't help.

Anyone got ideas or suggestions?  

[Don Lawrenz]

Ken

My takeoff fuel flows range from 33 - 36 GPH depending on temperature (primarily). Unfortunately I believe the only way to adjust yours upward is to remove and send to someone with a flow bench. If you want to do that I can look through my documents and given you a contact for the people who overhauled my Bendix system. Let me know.

#2 is hard to cool. Look carefully for obstruction to airflow to this area caused by a big bundle of ignition wires near the oil fill cap. This could also affect #4. Rearrange the wires to present the least area to rearward flow.

I've also found that placing a double button of baffle material between the #2 cylinder and the adjacent (rear) baffle increases the air flow and cooling for #2 significantly. I'll send you a picture showing a method of doing this if you supply me with your email address. Apparently you can't attach pictures with the new board setup or at least I don't know how to do it. IIRC Ron Koyich gave me this info. Note that I did not use as large a piece of material as shown. I used a hole punch to make a button, then glued 2 pieces together to get enough spacing. It does help.

[Ken Bagwell]

Don,

I will check the ignition wires.  They were replaced last December.  My email is N153b@aol.com.  I would like to see the picture of the baffle as this sounds like a good idea.

BTW, I was told maximun FF at takeout should be 32 gph.  I would like to get the 36 you are getting. I have already sent my servos off for adjustment and this did not help on takeoff.  I think these engines need at least 36 gph to keep everything cool.  32 gph is not enough.

 

Ken

[Larry Hirsh]

I'm not so sure this is abnormal, though 425 is high.  I have two cylinders on my left side that typically run a little warmer than normal but @ 30" and 2,300 RPM I push about 18 GPH per side through, however at around a 1,550 +/- TIT.  Maybe you just need to burn more fuel or maybe your fuel flow gage is off???  Good luck.  It can be confusing and frustrating and I inquired abut this a bunch of times since I've had mine (2003).

Larry Hirsh

N58LG

[Ryland Davis]

Don Lorenz could you email me the illustration regarding the "button" and where it is installed? I have a 36TC that has a hot cyclinder and we have checked everything we could. I am hoping this might work.Thx, Skip Davis. Email rylanddavis@msn.com

[Don Lawrenz]

Done