352 light engine knock
Thread Starter
|
Freshman User
Joined: Apr 2004
Posts: 27
Likes: 0
352 light engine knock
I have a `67 100 ranger with a 352. The engine runs strong and holds good oil pressure, but while I'm in neutral at higher rpm a rapid light knock occurs. I know this appears to be a rod knock. The thing is, when I run the engine at even higher rpm the knock appears to go away. Maybe if I have a bad rod bearing the oil pressure at high rpm holds the bearing together thus the knock is quiet. I have done the wooden dowel trick and the spark plug trick to locate the knocking rod and I didn't do to well because I did not locate the noise. I listened into the engine running at idle with a wooden dowel and I can hear the knock. The engine runs strong and fires right up every time too. Regarding the symtoms what could be the problem?
Last edited by Trail Master; Apr 9, 2004 at 11:19 PM.
Elder User
Joined: Sep 2003
Posts: 908
Likes: 4
The fuel pump can make a loud "plop plop" noise that sounds like a knock, but I've only heard this at idle. It sounds to me like it may be a wrist pin, which will make a light rapping noise that changes or goes away with accelerator pressure. The noise will be loudest when the motor is "floating" until it gets bad enough to knock under load.
Elder User
Joined: Feb 2002
Posts: 987
Likes: 2
From: East Bend, Carolina, U.S
There is an arm on the fuel pump that projects into the engine. This arm rides on an eccentric mounted to the end of the camshaft at the timing gear. When the arms pivot point wear out it gets fairly sloppy and will create a knock.
If you haven't ruled out the fuel pump you need to since it isn't a major undertaking.
Pull the fuel pump off and check it by lifting up and down on this arm. If it appears very lose just by lightly moving it then you have the fuel pump noise at least. What have you got to lose if it isn't the fuel pump since you should tear the engine down further to find and fix the problem?
If you haven't ruled out the fuel pump you need to since it isn't a major undertaking.
Pull the fuel pump off and check it by lifting up and down on this arm. If it appears very lose just by lightly moving it then you have the fuel pump noise at least. What have you got to lose if it isn't the fuel pump since you should tear the engine down further to find and fix the problem?
Thread
Thread Starter
Forum
Replies
Last Post
AbandonedBronco
Ford Inline Six, 200, 250, 4.9L / 300
20
Dec 30, 2010 11:07 AM
460
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
3
Feb 15, 2006 05:14 PM
