whats a "knock" ?????
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Senior User
Joined: Dec 2001
Posts: 461
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From: b.c. canada
whats a "knock" ?????
In my 85 300 i6 when i first start it up i hear a "noise" and when i shut it down i also here a "noise"
could this be a "knock"???
After 3 seconds of it running it runs smooth and nice, but i hear a clunk clunk as soon as i shut it off...... I cant tell if it comes from the engine or if its just normal old age noises......
will a knock be pressent all the time???????
-gbm-
could this be a "knock"???
After 3 seconds of it running it runs smooth and nice, but i hear a clunk clunk as soon as i shut it off...... I cant tell if it comes from the engine or if its just normal old age noises......
will a knock be pressent all the time???????
-gbm-
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
whats a "knock" ?????
Usually, "knock" means preignition/dieseling/run-on/pinging/detonation/valve tap, which can be caused by several things including a lean mix, low octane, hot spots in the combustion chamber, or high compression. It damages the engine because the pressure & temperature it generates are too high, and can actually burn holes thru the pistons.
"Rod knock" is different, and is caused by the crank bearings being worn out, or from the rod caps being stretched, or just from low oil pressure. Since oil pressure is low at startup, I assume this is what you're hearing immediately after cranking. A cheap mechanical oil pressure gauge will identify this.
I don't know what the "clunk" is at shutdown.
"Rod knock" is different, and is caused by the crank bearings being worn out, or from the rod caps being stretched, or just from low oil pressure. Since oil pressure is low at startup, I assume this is what you're hearing immediately after cranking. A cheap mechanical oil pressure gauge will identify this.
I don't know what the "clunk" is at shutdown.
Senior User
Joined: Jan 2003
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whats a "knock" ?????
According to the Haynes manual, the 300 I6 should have between 40 and 60 psi at 2000 rpm at normal operating temp.
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From: b.c. canada
whats a "knock" ?????
Originally posted by steve83
20psi at idle (hot or not) sounds pretty low to me. You might get some more life out of it by going to a heavier oil, like 20W50. It's all I ever run.
20psi at idle (hot or not) sounds pretty low to me. You might get some more life out of it by going to a heavier oil, like 20W50. It's all I ever run.
20 psi at hot idel is considered to be very addiquite...
-gbm-
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Senior User
Joined: Dec 2001
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From: b.c. canada
whats a "knock" ?????
Originally posted by steve83
If you consider it adequate, great.
If you consider it adequate, great.
-gbm-
Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
whats a "knock" ?????
you only need 6psi of oil pressure to keep things from knocking..... I know I had an 82 1 ton van that held NO oil pressure at idle, but had 35 pounds at running speed. I had bad bearings......... reallllllllllly bad bearing. Dura Lube got me and extra 9 months of use out of it.
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From: b.c. canada
whats a "knock" ?????
Originally posted by pfogle
you only need 6psi of oil pressure to keep things from knocking..... I know I had an 82 1 ton van that held NO oil pressure at idle, but had 35 pounds at running speed. I had bad bearings......... reallllllllllly bad bearing. Dura Lube got me and extra 9 months of use out of it.
you only need 6psi of oil pressure to keep things from knocking..... I know I had an 82 1 ton van that held NO oil pressure at idle, but had 35 pounds at running speed. I had bad bearings......... reallllllllllly bad bearing. Dura Lube got me and extra 9 months of use out of it.
On a update note i think my shutdown noise is just a exhaust bracket rateling around as the motor gives that last kick before it stops turning.......
-gbm-