Improving cylinder 6 cooling TSIO520

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    I am seeking any advice about how to optimise the cooling of cylinder 6. It is the limiting cylinder for LOP ops on my left engine, often running 20 degrees hotter than the others. It is not a rich outlier (it peaks in the middle of the pack) and the GAMI spread is within 0.5 GPH, so I’m fairly sure it’s a cooling issue rather than a ‘heating’ one. I have a similar issue with #2 on the right engine, but I have used Dick’s tip of the rolled up baffle seal behind the cylinder to address this – hopefully it will help. Cylinder 6 was always hot on my bonanza too, but GAMI make a modified ‘blast tube’ baffle arrangement that fixed it. I haven’t seen any baffle mods to keep #6 cool for the twin cessna engines (or any aftermarket baffling mods for that matter, we seem stuck with the factory crap), so do any of you have any experience and tips to obtain better cooling airflow over this cylinder?




      Martin, cylinder #6 should run the coolest. I even added a small piece of aluminum in front of the cylinder to warm mine up. I would check to make sure you have the correct GAMI injector in the #6. Also make sure the intake tube gasket is in place and that the big red intake tube connecting hoses are tight. You don’t want it running lean. Also make sure the innercylinder baffle between #6 and #4 is snug up against both cylinders bases. Pump some red high temp silicon around the innercylinder baffle to seal it up tight. Make sure the exhaust gasket is not blown and blowing hot air on the CHT probe. Swap some CHT probes around to see if the problem follows. Finally make sure the balance tube between the #5 and #6 is not cracked or the weld has broken loose at the center mounting bracket.


        With #6 up front you would expect it to be quite cool which is the case on both engines on my 340. #4 (followed by #3) run the hottest on both of my engines and I think this is what I have heard from others as well. Sorry, I know this doesn’t help you. If nothing obviously wrong with the baffling try swapping CHTs just to confirm.


        If things don’t make sense check the probe and wire connections. I had a enine monitor installed and they swapped the #4 and 6 probe wires. The monitor indicated #6 but it was actually #4.
        Just a thought


        I’d actually been wondering that. Nothing seems amiss around #6 and everything looks identical to the other engine, on which #6 is one of the coolest. I’ll look into that possibility…


        Maybe the guy who wired that side of your JPI is used to working on Lycomings where #6 is actually the outside rear cylinder, ie: same position as #2 on a Continental and THAT one (#2) is the hottest cylinder on my left engine.

        Disconnect your probes, one cylinder at a time, fire up your JPI and see what’s missing or what the JPI says is “open”. Go through each probe, verify everything first.


        the right engine in my T310P also has a cooling problem in the even cylinders. Sometimes (most times) #4 is the hottest sometimes #6.
        We checked the baffeling over and over again and could not find a reason.
        I would be interested in some pictures of the “Dick’s” modification.

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