Without attempting to write an entire book on this page, we have compiled
what are some of the more common Corvair engine problems.
BAD BLOWBY - BUT NO SMOKE OUT OF THE TAILPIPE - if you see a lot of smoke coming out of your road draft tube (60-62) or pcv tube (63-69) when disconnected, then you probably have excess crankcase pressure, caused by, in order of probability -
A BAD PISTON- usually burnt or otherwise disintegrated. If the disintegration is towards the top of the piston you can get bad blowby but an insignificant amount of smoke out of the tailpipe. The best way to check is to remove the oil cap with the engine running - a rhythmic puffing MAY be a sign of a hole in a piston or....
A DROPPED VALVE SEAT - normally accompanied by a knocking noise - but not always. Do a compression check - a complete lack of compression is a good clue.
BROKEN RINGS - will usually cause smoke out of the tailpipe. The same with bad guides. While it is possible that a blocked vent system can cause excessive pressure, this is easy to rule out by cleaning out the draft tube or pcv tube. Nearly all cases of excessive internal pressure will require at least removing the head of the offending side - remember that if you have a disintegrated piston it would be wise to replace all six because the others are likely to be weak also.
THE ENGINE MAKES A HORRIBLE RATTLING NOISE - yes, I realize
that you think you have rod bearings going out but this is rarely the case.
First, remove the fan belt and run for a short period of time. If the rattle
goes away you can be pretty sure that the blower bearing is bad. That not
being the case the next thing to suspect is a bad flywheel. A positive test
is to let the engine idle in neutral and slightly depress the clutch pedal
- if the rattle goes away or changes then you have bad rivets in your flywheel
and it must be replaced with a new bolted unit Sometimes there is no rattling
but a lot of vibration.
THE ENGINE RUNS ROUGH AND NO POWER - actually I wish you hadn't asked me that one, for where shall I begin? Well, we probably know about the obvious things - but here are a few not-so obvious. THE POINTS - simple, yes? Not always with Corvairs. Points gap is important. Any Corvair that suddenly starts running poorly should have the points gap checked because sometimes the points can slip. Also the POINTS PLATE can get worn and cause problems. Replace (U-1639) if in doubt. THE CARBURETORS - if your Corvair has sat around for a long time then the carbs will need a thorough cleaning and rebuilding because the internal rubber parts have probably gotten brittle. THE COIL - some Corvairs still have the original! Coil problems can look like electrical OR carburetion problems.
Many times you may experience a very large loss of power - this will usually be the result of one of the two primary carbs quitting. This trouble may be temporary (a piece of dirt plugging something) or may be the symptom of age. For smaller losses of power suspect a breakdown in one of the spark plug cables.
If the spark plug cables are more than 2 or 3 years old then it's a good idea to replace them. Corvairs are hard on them. ELECTRONIC IGNITIONS? - These are great - once you've tried one you'll never want to go back BUT.....you shouldn't install an electronic ignition to 'solve" a mysterious problem. This is because if the problem isn't electrical, the new ignition may only confuse matters. Install our PN U-651 electronic ignition ONLY after the engine is running perfectly!
CARBURETORS? - We've already mentioned them, but should also add that oftentimes poor running can be fuel (carbs), OR electrical. We sell many rebuilt carbs to folks only to find out that the carbs 'didn't do any good". Do your best to diagnose any problems ahead of time. That way you'll avoid unnecessary delays and expenses.