Rotary Compression
10-10-17, 03:13 PM
#1
Junior Member
Thread Starter
Rotary Compression
Hey guys,
Been in the market for an FD for a while now and I've seen many for sale for 80K-100K+ miles.
Most shops say that they will require a rebuild since most that I've been looking at are OEM engines.
If a compression is done, what other factors such as abnormal smoke, cold start, hot start and boost psi should I be looking for?
I know it will require a rebuild in the future, but is it always a mystery?
Thanks
Been in the market for an FD for a while now and I've seen many for sale for 80K-100K+ miles.
Most shops say that they will require a rebuild since most that I've been looking at are OEM engines.
If a compression is done, what other factors such as abnormal smoke, cold start, hot start and boost psi should I be looking for?
I know it will require a rebuild in the future, but is it always a mystery?
Thanks
10-10-17, 08:43 PM
#2
A lot of people will claim "the motor was just rebuilt" when selling, ask for proof. If it was just rebuilt they should have receipts from the shop documenting mileage etc. Also look for the normal stuff leaky oil, grinding gears etc..
10-11-17, 12:10 AM
#3
Junior Member
Thread Starter
Congrats on the car!
10-11-17, 08:57 AM
#4
Rotary Freak
There are a few different ways it can manifest itself, and you already mentioned some of them. Smoke, particularly grey or black. Other things can cause it, but low compression will do that. Usually with low compression the car becomes hard to start after it is warmed up (so if you test drive one, get it to full operating temp and make sure it is completely warmed up. Then stop, wait a few minutes, and try to start it. If it takes awhile to start or it floods, it can be a sign of low compression).
Then there are other things that can force you to rebuild that aren't necessarily compression. A coolant seal leak will cause it to overheat and billow white steam from the exhaust while consuming coolant. An oil control ring failure will usually cause blue smoke (but turbos can do this too as they age and the seals wear.) Either of those problems requires an engine rebuild to fix (except for the turbos, of course).
Edit: Forgot to mention you can compression test it to be sure, but that might be a little bit involved (if I recall correctly, getting to the spark plug holes on an FD is tricky). There are write-ups available if you search for them.
Then there are other things that can force you to rebuild that aren't necessarily compression. A coolant seal leak will cause it to overheat and billow white steam from the exhaust while consuming coolant. An oil control ring failure will usually cause blue smoke (but turbos can do this too as they age and the seals wear.) Either of those problems requires an engine rebuild to fix (except for the turbos, of course).
Edit: Forgot to mention you can compression test it to be sure, but that might be a little bit involved (if I recall correctly, getting to the spark plug holes on an FD is tricky). There are write-ups available if you search for them.
10-13-17, 08:03 AM
#5
Getting a compression test done on a Rotary is a little difficult, but there are ways to do it. Whether you're doing it yourself or having someone else check the compression, this is a really great video with good knowledge to have!
-Austin
-Austin
