Knocking sound...
Laughing Gas
Joined: Jul 2001
Posts: 850
Likes: 14
From: Fayetteville, NC
Knocking sound...
I just got done replacing the oil pump and rear main seal on my truck tonight. I got everything back together and added a new filter and new 20w 50 oil. Well...I pushed it out of the garage and started her up. Bingo...we have oil pressure. Problem is the engine ticks or knocks real loud now. It's not a light tick either...it's a rather hard knock. Could this just be from the new oil being run throught it, or could the valves be sticking now? It was run for about a minute once the oil pump went out. Once I noticed it I shut it down and had it towed it home.
I'm kinda at a loss on this one here.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
I'm kinda at a loss on this one here.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
Knocking sound...
How much oil pressure? Let it warm up real good and with an aftermarket oil pressure guage, see what pressure you have. If it's down around 5lbs or less, or pulsating with the knock, your bearings are probably shot.
Laughing Gas
Joined: Jul 2001
Posts: 850
Likes: 14
From: Fayetteville, NC
Knocking sound...
The oil pressure was normal. It went up to 79 psi.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Knocking sound...
It almost sounds as if when the oil pump went out it may have taken a rod bearing with it. Might be worth it to pull the pan and look at some bearings...
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
Laughing Gas
Joined: Jul 2001
Posts: 850
Likes: 14
From: Fayetteville, NC
Knocking sound...
[font size="1" color="#FF0000"]LAST EDITED ON 30-Sep-01 AT 01:09 PM (EST)[/font][p]I was just thinking...I know the timing is off and needs to be adjusted badly. I know by having off timing it will cause the valves to tap some. Could the combination of this and the new oil be doing this also?
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Knocking sound...
Is the knocking at engine speed, or twice engine speed? If it's at engine speed, your problem is in the bottom of the motor. If the knocking is twice engine speed, your problem is in the top end. To help determine how fast the knock is occuring, hook a timing light up and compare the strobe to the knocking. The strobe operates at engine speed.
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
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Laughing Gas
Joined: Jul 2001
Posts: 850
Likes: 14
From: Fayetteville, NC
Knocking sound...
Well just out of curiosity I pulled the rocker covers off and checked the valve springs and all. Hmm...I have no valve stem seals! Most of them have disinigrated! There are pieces of them laying in the bottom of the springs. (that explains the smoking it's been doing). Now how hard is it to replace the valve stem seals and set the valve lash on the 351M's? I'm not going to run the engine until I get them replaced. I can't afford to screw up the new oil pump or anything else. I do have a Chiltons and Haynes repair manual that describes how to do it. One of the books also said that they won't need adjusting because the hydraulic lifters takes care of the lash. Is that true?
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Robert
1978 F-150 4x4 Stepside 351M
Please don't pull out in front of me! The last thing I want to do is play identify the pieces with you or your car.
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
Knocking sound...
If you are curious, while the engine is knocking, pull each sparkplug wire off individually and see if the knock lessens for a certain cylinder. At least you will know where to look. Keep reading those manuals. They will give good info that you need and yes, they are right about the rocker arm bolts.
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