Great Air Cooled story
04-30-2004, 04:49 PM
#1
Three Wheelin'
Thread Starter
Great Air Cooled story
This was posted on the Maverick Region PCA Yahoo list by a long time Porsche tech.
J
.........It is truly amazing how much heat an air cooled engine can put up with. I'll give ya an example of the worst I've seen to date:
Had a person call and say they could not shut off their 993 engine. Turned
the key to off position and it just kept running. Owner was in a business
complex parking lot and due to be in an important meeting in just minutes.
Gave us a call and explained situation. Said tow company was at least 2
hours from arrival. The car was 45 minutes from us. I drove over there (took
me about an hour to get free) and arrived just as tow truck did. Car was
sitting there locked and running. All the instrument warning lights were
illuminated. Owner came out and gave me the keys. The temp gauge was pegged
and the engine was pinging like nothing I'd ever heard. Out of curiosity
before shutting off (figuring damage was already done) I gave it light
throttle application and it couldn't develop enough power to even raise the
revs off idle. It was too bad the owner didn't think to simply dump the
clutch and kill it (what I did immediately). When we got the call she
quickly explained the situation; announced she had to go right now and
"bye".
Turned out that the oil cooler fan relay had a bent tab inside of it and
the tab was feeding +30 (straight battery power) to +15 (key in run position
power) . This provided the DME system the power to stay powered up when key
was turned off ( a back feed if you will). Unfortunately there was no power
to close the fan relay because key was shut off and the oil cooler fan never
came on. After engine totally cooled and problem resolved we drained the oil
and took a sample (checked ok). Engine started and ran fine. No smoke, no
knocking noises, nothing. 2 years later this car is still driven daily and
you would never know this had happened to it. Any water cooled engine would
have seized up long before we got there. Air movement over top end helped
keep cylinders, heads, below melting point and enough heat was wicked out of
bottom end to save it. Obviously air cooling and synthetic oil was the key
to it's survival.
Cliff
J
.........It is truly amazing how much heat an air cooled engine can put up with. I'll give ya an example of the worst I've seen to date:
Had a person call and say they could not shut off their 993 engine. Turned
the key to off position and it just kept running. Owner was in a business
complex parking lot and due to be in an important meeting in just minutes.
Gave us a call and explained situation. Said tow company was at least 2
hours from arrival. The car was 45 minutes from us. I drove over there (took
me about an hour to get free) and arrived just as tow truck did. Car was
sitting there locked and running. All the instrument warning lights were
illuminated. Owner came out and gave me the keys. The temp gauge was pegged
and the engine was pinging like nothing I'd ever heard. Out of curiosity
before shutting off (figuring damage was already done) I gave it light
throttle application and it couldn't develop enough power to even raise the
revs off idle. It was too bad the owner didn't think to simply dump the
clutch and kill it (what I did immediately). When we got the call she
quickly explained the situation; announced she had to go right now and
"bye".
Turned out that the oil cooler fan relay had a bent tab inside of it and
the tab was feeding +30 (straight battery power) to +15 (key in run position
power) . This provided the DME system the power to stay powered up when key
was turned off ( a back feed if you will). Unfortunately there was no power
to close the fan relay because key was shut off and the oil cooler fan never
came on. After engine totally cooled and problem resolved we drained the oil
and took a sample (checked ok). Engine started and ran fine. No smoke, no
knocking noises, nothing. 2 years later this car is still driven daily and
you would never know this had happened to it. Any water cooled engine would
have seized up long before we got there. Air movement over top end helped
keep cylinders, heads, below melting point and enough heat was wicked out of
bottom end to save it. Obviously air cooling and synthetic oil was the key
to it's survival.
Cliff
05-01-2004, 07:17 PM
#2
Racer
Join Date: Mar 2004
Location: Cheshire, England
Posts: 308
Likes: 0
Received 0 Likes
on
0 Posts
Err, sorry but I don't understand why a water cooled engine would die - all my water cooled cars would idle indefinatly with no overheating at all due to the thermostatic fan cooling systems built in to modern cars!!!!
Don't geddit!!! Sorry!
Don't geddit!!! Sorry!
05-01-2004, 08:37 PM
#3
Three Wheelin'
Thread Starter
Unfortunately there was no power to close the fan relay because key was shut off and oil cooler fan never came on.
