Why my Chevrolet Corvair decapitated its spark plugs (and what’s next)


My 1965 Chevrolet Corvair Corsa has been great to me. Yes, the expected headaches of an old car pop up here and there, but so far no situation has proved too much to handle. The Corvair’s latest mishap, however, was a reminder that parts for the car’s rear-mounted flat-six are old. And with old bits, anything can fail at any time.

This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2018/11/21/corvair-decapitated-spark-plugs


I’m looking forward to the “Rebuilding a Corvair Engine” time lapse video. At the end it will start up and drive out of the garage.


@drm101 - This engine doesn’t need a full rebuild just yet, as the compression is good and valvetrain intact. I do have a “spare” 140hp engine in the corner of the shop though that with any luck will be a slightly wilder engine for this car in the future. That “spare” has a dropped valve seat, or at least thats the story I was told when it was acquired.


LOL…been a victim of that “while I’m in there” snare myself…more than once. Sometimes it makes sense. Other times I wished I’d forgotten the password to my PayPal account.
Oh…and get some dirt under those nails before taking pictures. Like “Bulgarian supermodels”…it just doesn’t fit.


@Jim-R - You caught me. I do have clean hands as the vast majority of my hours are spent at a computer and not under the hood. Wish it was the other way. I took these photos days after the disassembly, but that’s hardly an excuse…

“While I’m in there” shouldn’t be too bad this time around. This marks the second time I have had the top shroud off this engine, so most of the big stuff has been done. Little things add up faster than I would care to admit though.


This issue has been the topic of an ongoing discussion on the CorvairCenter forum:


There appears to be an issue with corrosion (sometimes not obvious) leading to fatigue cracking and catastrophic failure of the magnesium fans. A known source of corrosion is sulfuric acid mist from the battery. That is why all Corvairs originally came from the factory with vented battery caps with rubber vent hoses leading out of the engine compartment. These were usually discarded long ago with a battery replacement. The originals a very scarce so the current solution is to use a sealed gel or AGM battery.

I notice your fan looks to have been painted. If it was sandblasted prior to painting, there may be embedded silica particles contributing to hidden corrosion. Our recommendation is to use soda, plastic media, or other inert soft material if a fan needs to be blast cleaned.

The original Corvair magnesium fans were not painted but were given a medium to dark gray chromate conversion coating.


@VairsUPnorth - Thanks for chiming in. I’m also a member on Corvair Center (Kyle_in_Mich over there) and have been having conversations about inspection and selection of a replacement fan. The spare I had in the corner of the shop I sent to a fellow forum member who blasted just one rib and found what he called three cracks. In the photo he sent the “cracks” didn’t appear to penetrate much at all and there was no corrosion present. He declared it garbage, I’m not going to argue.

I’m ordering one from out west in the hopes of finding a good one.


Wouldn’t Power coating help?


@rmpe739 - I assume you mean powder coating, and honestly I’m not sure. The science of powder coating (beyond the basics) is more science than I understand. I’ll do a little research and see if it might help. I’m sure my girlfriend would love me baking a powder coated fan in the oven at 350 on Saturday afternoon.


LMAO!!! Just get it done at your local power coater


My Mom owned two Corvairs. A 1964 Monza coupe, and a 1967 Monza coupe, both with the 110HP engines and PowerGlide.

Only problem we ever had was the bearing for the cooling fan got noisy on the '64. My sister’s boyfriend was an ace mechanic, and did it in an afternoon for us.


Never really studied it but I don’t see powder coating adding much strength to your suspect spare fan. And seems like you’d have to be careful with the balance.
Side-note…thinking back maybe 10 years I remember being surprised by an early Corvair in a local U-Pull-it yard while looking for some parts to keep my daughter’s college car on the road. It was wrecked and rusted beyond belief, but the engine was still there. Probably didn’t last long.