Working out bugs w/ 65 Corsa / no Turbo boost

[firstgencamarojunkie]

Been driving my '65 Corsa and loving it. Just finished upgrading the headlights w/ H4 Halogens using relays - what a difference! Next - I need to figure out why my Turbo does not appear to boost. My boost gauge will show "zero" with the engine off - and - show vacuum during normal driving. When I try and kick it into boost - such as a freeway on-ramp - I can get the gauge to zero - but - never in the positive. Also, I don't feel anything other than the normal acceleration so it appears I'm not getting any boost. I've been told I should check for exhaust leaks, but, with the lower shrouds off it's next to impossible. I saw on that "other" web site I should stuff a rag into the exhaust - and - if the engine does not die I likely have an exhaust leak. Any advice would be appreciated.

Thanks - Andy.

[firstgencamarojunkie]

Quick follow-up comment / when I had the engine out, I did verify that the turbo spins and is not seized.

[SyntheticBlnkerFluid]

I would start by checking your exhaust system, make sure everything is copacetic, but would also check the hose between the compressor and intake pipe.

[firstgencamarojunkie]

Being Saturday, had time to get the Corvair up on jacks and check out the exhaust. Tightened all the bolts for the various pieces of the exhaust - and - most were snug but all required a little tightening. I then performed the "Wet rag in the tailpipe" test - and - the engine died within less than 15 seconds - so - it appears as if the exhaust system is pretty tight. Road tested - appears to actually run a little better - but - no matter what no boost. I'm going to check the boost gauge w/ an air supply just to be sure - but it's starting to look like a turbo rebuild. Trying to decide if this is a task I should/could take on myself - I have decent mechanical skills but the turbo rebuild videos i've see seem a little scary. What's the popular opinion? If I have it rebuild by a professional, what should I expect to pay? Anyone in the forum do this work? Thanks in advance - Andy.

[bbodie52]

One of our resident "experts" on the Corvair turbocharger is Nick Williams "miniman82". You might drop a PM (Private Message) to him using the link below and direct some of your questions to him. He produced the two turbo booklets attached.

memberlist.php?mode=viewprofile&u=275

[miniman82]

Could still be a weak mixture or incorrect timing, the pressure retard can in particular is notorious for not working correctly or at all. Also keep in mind these don't boost like a modern engine, the boost tends to build gradually and goes higher with RPM. On mine boost came on around 3500 RPM, depending on how it was driven and what gear I was in. Have you tried flogging it on the freeway yet? If it won't do anything in top gear with the pedal mashed at around 50 mph, there's a good chance the turbo is in fact bound up enough to keep it from working.

Just be ultra careful to listen for detonation, which sounds like a rattle can of paint. If that happens for too long under heavy load, very bad things can happen to the engine. Melted pistons, dropped valves, etc. It's very important that the fuel and ignition systems are up to snuff for the engine to work correctly, so double check those before blaming the turbo.

Also, the turbo engines are known to have issues with carbon buildup in the intake logs. You might have an intake restriction, but the only way to see it is with a borescope or by removing the heads and valves to have a look.

Good luck and if you can't figure it out, I'd be glad to have a look at your turbo.

[miniman82]

One last thing, make sure you have the correct carb. The 150 and 180 carbs look very similar, but if remember correctly they are in fact sized a little different. That means a 150 carb on a 180 engine might cause an intake restriction, leading to a no boost situation.