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John V · 07-13-2017, 07:45 AM

It doesn't *need* anything. If it runs okay with new coils and plugs, drive it. If you get sick of it, sell it.

The low compression is unlikely to be fixed with anything other than a rebuild. There's an off chance that their oil-soak could do something, but my guess is it won't.

Engine rebuild costs depend on what needs to be replaced. It's possible to do a tear-down, clean the carbon off of everything, throw new seals and springs at it and slap it back together for under a grand. Such an engine will run fine and likely give many years of service. A full rebuild will involve evaluating all of the housings and the rotors and determining what is good and what needs to be replaced. New rotor housings are upwards of $500 each for the RENESIS. Side housings usually can be reused, but they're on the same order of magnitude for cost if they need replacement. I don't remember how much RENESIS rotors go for these days but $500-$1000 each doesn't seem unlikely. So a "full" rebuild could easily cost $4k just in parts.

I do like rebuilding rotaries but I don't see myself wanting to take that on in the near future. I have a pretty full plate right now.

07-13-2017, 07:45 AM	#34
John V No more BMWs Join Date: Apr 2005 Carmudgeonly Ride: Ram, MS3, CX-5, RX-8 Location: Glenwood, MD Posts: 14,753	It doesn't need anything. If it runs okay with new coils and plugs, drive it. If you get sick of it, sell it. The low compression is unlikely to be fixed with anything other than a rebuild. There's an off chance that their oil-soak could do something, but my guess is it won't. Engine rebuild costs depend on what needs to be replaced. It's possible to do a tear-down, clean the carbon off of everything, throw new seals and springs at it and slap it back together for under a grand. Such an engine will run fine and likely give many years of service. A full rebuild will involve evaluating all of the housings and the rotors and determining what is good and what needs to be replaced. New rotor housings are upwards of $500 each for the RENESIS. Side housings usually can be reused, but they're on the same order of magnitude for cost if they need replacement. I don't remember how much RENESIS rotors go for these days but $500-$1000 each doesn't seem unlikely. So a "full" rebuild could easily cost $4k just in parts. I do like rebuilding rotaries but I don't see myself wanting to take that on in the near future. I have a pretty full plate right now.