My experience with V-type engines has always been that one bank or head will fail before the other. Having said that, I will further state that I don't know if any of these Briggs V engines have a tendency for one particular bank to fail before, or more often than, the opposite bank. I do know that there are a number of things that can lead to head gasket failure, but "pin-pointing" a cause on these engines is hard to do and usually it is just better to make sure you perform the repairs carefully and correctly than to fret over what might have caused the initial failure. The one thing I would definitely check would be to remove the sheet metal shrouding (aka "fan ductwork) and clean out any accumulation of cutting debris or mouse nests. Other than that, proper torquing of the head bolts is about the most critical detail in the repair. Try to clean the old gasket "footprints" from the head and block using carburetor cleaner and a very fine, hand held "scotch brite" pad. Make your cleaning strokes (with the pad) follow the "long side" of the gasket outline. This means: Scuff/clean so all the micro scratches made by the scuff pad "run with" the gasket outline instead of "across" it. The benefit of doing this is: The scuff cleaning creates very tiny scratches in the metal surfaces of the head and block. If you scuff ACROSS the outline of the gasket, it has the "effect" of "digging a drainage ditch" or "plowing an escape route" for combustion gasses to travel through. If you scuff clean keeping your strokes in the same long direction of the gasket shape, you realize a benefit (instead of creating a potential problem). With the micro-scratches running "with the gasket", you create a multitude of "teeth" in the metal surfaces that "bite into" the "clear coat sealer" on the new gasket. This helps to secure the gasket better than having it just pressed against the head and block. If the gasket is "held better", it is not as likely to leak. Clean the surfaces with spray carb cleaner after scuff cleaning and blow dry with compressed air or simply let it dry "naturally". DO NOT clean the new gasket using carb cleaner or any other powerful solvent. Doing so could remove or damage the thin, "shellac like" coating that is on the new gasket. Whether you want to replace both gaskets at this time is a decision for you to make. If you decide to only replace the gasket you find to be leaking, you should at least check the torque of the head bolts on the other cylinder. DO NOT be tempted to "over-torque" the bolts. Too much torque on fasteners will distort both the head and the crankcase which will mean the gasket IS NOT "clamped down" evenly and will fail again soon. You will need to check and adjust the valves on each cylinder that you replace the head gasket on. Possibly Walt Conner or some of the other bona fide Briggs pros will offer comments about the failure rates of these engines and whether it is common to "go after both banks" at the same time or simply address the issue upon failure. In the automotive field, we usually replace head gaskets in pairs on V type engines, except in cases of failure while still under factory warranty. In warranty cases, the OEM dictates what you do. Sometimes they say "only the head gasket that failed". Other times they say "replace both".

Well they checked the fittings last time - so either tight enough or too tight. If too tight I assume they have to be replaced? How do you tell except by trial & error? any interesting tricks to that?

I'm not a big fan of oversizing the coil to increase SEER (that's why they do it) as it actually impairs dehumidification. It's not necessarily done to increase SEER, but to reach the rating that AHRI matches the equipment to. Ironically, this rating is just a number that if you use a certain set of equipment parts and pieces you 'should' hit the SEER number. It doesn't mean you 'will' hit the number, because proper installation is always the elusive variant. No matter how much or how little you want to realize this fact. A nice pretty install picture doesn't mean the system was 'installed properly'. But people, God bless them, don't look at things this way. They say 'company A' uses xyz brand and 'company B' uses xyz brand so it's the same brand so the outcome will be the same as in a 'properly installed HVAC system'. However, it doesn't work this way in the real world. You're not buying a toaster. Having a larger coil does not necessarily hurt dehumidification either. The whole purpose of dehumidification is removal of water from the air. A larger coil has more surface area in which to ring moisture from the air. BUT, the difference is proper to improper. As if there are condensate draining problems with the said coil, it can reintroduce the condensate (humidity) from the air that was removed back into the air from whence it came. So if this thread is good for anything, it's to show that what I mention repeatedly about 'proper' versus 'improper' goes much farther than most people understand. ---------------------------------------------- Deb, hopefully this time you get what you paid for. Good luck.

Thanks for pointing out the charged-line systems. That would make things even simpler for the DYI installation. My primary concern or point of research would become the reliability of a compression-fit refrigerant line. That's standard in auto AC units but I wonder if the pressure may be higher in home units...would this apply to mini-splits? I have done some copper line flange fits for water lines and that works fairly well. Are the DYI units washer-less fits? I would have to think a pre-flanged, or washer-based fitting would be a no-brainer feature if manufacturers are pre-charging lines to help the DYI application. All of the home units I have had installed were sweated in so I assume that is the most reliable connection. Of course, my full-sized professionally installed unit failed with a leak in the cooling coils so go figure :>)