<VV> Car running lean - advice appreciated (Was 828 miles)

[Guus de Haan]

Op 8 okt 2009, om 22:35 heeft FrankCB het volgende geschreven:

> Guus,
>      Glad to learn that you were able to run the turbo Corvair on  
> the autobahn.  I've driven on the autobahn but never in a turbo  
> Vair.  Do you have any idea just how much boost you were getting?   
> 16 to 20 inches of mercury (in.Hg.) could be expected at full output.

Hello Frank,

It was nowhere near full as I was a little cautious as not to let the  
engine knock too much. Also couldn't (and did nog want to) go further  
as my son was with me in the car and the indicated 152 km/h (94 mph)  
was fast enough for him in this 44 year old car with all its noise!  
But it was a lot better then I noticed on the short runs locally. I  
guess the engine being fully warmed up on the autobahn did help.

> Did you see what the CHT gauge (cylinder head temp) was reading when  
> the warning light and buzzer came on?

It was just over the 400 mark, not even close to 500.

>   When that does happen, the best way of cooling off the engine is  
> simply to slow to a moderate speed, like 50 mph (about 80 kmph) and  
> watch the CHT drop.  Whatever you do, make sure you do NOT shut off  
> the engine since doing so STOPS the flow of cooling oil through the  
> overheated turbo where it can "cook" and decompose forming deposits  
> which will eventually block the flow of oil through the turbo  
> bearing which means the end of that turbocharger.

I did just that. Since I new the fan belt was still on I drove it to  
the next exit with a moderate speed and let it idle to check the belt  
and feel the heat in the engine bay. It wasn't very hot compared to  
normal. I just wanted to shut down the engine for a few seconds to get  
the light out and the buzzer off. The we went back to the autobahn to  
continue our trip on more moderate speeds and stopped on the next gas  
station to get ourselves a sandwich and let the car cool down some  
more.  Everything was fine after that.

Thanks to all others that responded. Like a said the engine was  
suddenly running lean (16) on the indicator on the way back. Someone  
suggested that a vacuum-leak has developed somewhere. I'll recheck  
what is indicated on the temperature gauge the next time I'll take the  
car out and see if I can find any leaks.

Also want to experiment with the boost a bit more but before I do that  
I want to upgrade the fuel quality. If the car needs to perform it  
deserves the best octane I can get.

Regards,

Guus de Haan
The Netherlands
'65 Corsa Turbo-Charged Cvt