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1991 Fleetwood 60 Special
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24 Posts
Discussion Starter #1
after sitting overnight or long enough in the winter to fully cool down, the engine knocks for a minute or so, length of time knocking is dependent on how cold it is outside and how long the car has been sitting.
If started after sitting out overnight at below 20 deg F it will knock for nearly 5 minutes before completely quieting down.
It sounds like piston to cylinder bore or wrist pin to piston?
Doesn't sound like a rod or a main and it has great oil pressure when cold.
Anyone have any experience with this type of knock?
It has been doing it for about 2 years now but it is steadily getting worse, knocking longer on start up.
I would like to get it fixed if possible??
thanks
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,494 Posts
Do some searching in this forum and Tech Tips. I believe the 4.9 is noted for a cold start #1 main bearing knock.
 

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70 Deville 77 Fleet 78 Seville 92 Deville 03 Deville
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3,310 Posts
I hope your oil isn't too thick. I used to run synthetic in the winter to make engines turn over easier. Now I run it year round.
 

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1991 Fleetwood 60 Special
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24 Posts
Discussion Starter #4
thanks will do

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I am using Pennzoil 10W-40, maybe will give mobil 1 a try on next change??
I have an oil pressure gage installed and it makes almost instant oil pressure (20 PSI) and builds quickly from there to about 70 PSI in under 10 seconds, so I am thinking it is getting plenty of oil such that it shouldn't knock for 5 minutes??
But at this point I am game to try anything.
thanks for the suggestion
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Synthetics flow better than conventional oils in EXTREMELY cold conditions. In normal winter conditions, the difference is negligible.
 

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70 Deville 77 Fleet 78 Seville 92 Deville 03 Deville
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3,310 Posts
20 below qualifies as extreme for most people. In my experience it is noticeable at 10 degrees f and lower.
 

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Registered
1991 Fleetwood 60 Special
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24 Posts
Discussion Starter #7
all; I did an oil change last weekend and went with Mobil 1 10W40, unfortunately it had no affect on the cold start knock?
bummer
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
cadillac_al said:
20 below qualifies as extreme for most people. In my experience it is noticeable at 10 degrees f and lower.
I missed the 20 below part.
 
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