4.9L Knock on Startup?
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Junior User
Joined: Mar 2003
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4.9L Knock on Startup?
I bought a used 95 2wd f150 with a 300 six and 5 speed tranny. The truck is in great condition overall but has a knock on start up. No smoke, and runs great after just a few seconds on the initial start up. Also limited history to help out with the problem. I just purchased the truck two days ago.
The knock is a MOST of the time thing, but not all the time. It even comes and goes when warmed up.
I am going to change the oil this week. I always use motorcraft oil filters, but the truck currently has some other brand on it. I am a big fan of 10-30 penz but I have no idea what is in the truck currently.
I have heard good things about lucas and marvel oil additives. I have never tried either as an engine oil additive. I have had luck with the lucas tranny additive in my mustang.
The truck has 144k on the clock but runs like a top outside of the diesel sound on start up. Anyone else experience this? Should I be worried, or is this an easy fix? This is my first 300 six and I am a little concerned, but I am hoping to use it as a fishing, hunting, and around the house work truck. I do some traveling to hunt so I am hoping it can go another 100k.
Thanks,
Rod
The knock is a MOST of the time thing, but not all the time. It even comes and goes when warmed up.
I am going to change the oil this week. I always use motorcraft oil filters, but the truck currently has some other brand on it. I am a big fan of 10-30 penz but I have no idea what is in the truck currently.
I have heard good things about lucas and marvel oil additives. I have never tried either as an engine oil additive. I have had luck with the lucas tranny additive in my mustang.
The truck has 144k on the clock but runs like a top outside of the diesel sound on start up. Anyone else experience this? Should I be worried, or is this an easy fix? This is my first 300 six and I am a little concerned, but I am hoping to use it as a fishing, hunting, and around the house work truck. I do some traveling to hunt so I am hoping it can go another 100k.
Thanks,
Rod
Elder User
Joined: Feb 2007
Posts: 829
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From: Goose Creek SC
Ok......I'm confused......you said a knock on start-up........then you said diesel sound.
Knock makes me think inside the motor....rod bearings....worn and causing a rod knock. The diesel sound could be something completely different......like the octane knock you get from the truck being out of time perhaps.
If you have a rod knock....no additive is going to fix it. It'll go away when you replace the bearings.
If it's an octane knock then you might need a good tune-up and timing....maybe a knock sensor if that truck has one. Does it do the knocking under acceleration sometimes?
Good Luck and let us know more about it.......someone here can give you a better answer I'm sure.
Knock makes me think inside the motor....rod bearings....worn and causing a rod knock. The diesel sound could be something completely different......like the octane knock you get from the truck being out of time perhaps.
If you have a rod knock....no additive is going to fix it. It'll go away when you replace the bearings.
If it's an octane knock then you might need a good tune-up and timing....maybe a knock sensor if that truck has one. Does it do the knocking under acceleration sometimes?
Good Luck and let us know more about it.......someone here can give you a better answer I'm sure.
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Junior User
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It's not an octane problem. There is no diesel effect under load. The term "diesel" was used as a sound discription of the noise only.
I agree on the oil pressure check with a quality gauge. It doesn't seem to lose any pressure as it heats up, but then again with the on/off style gauge there is no real way to tell what kind of pressure it is really pushing.
I had done a little searching and heard of filter problems draining on the 300, but with this being my first 300 six I was unsure if it was common.
I have also been told there are some pickup screen issues. This is where the additives come in to play. I have heard of people running the above additives for more of a cleaning purpose I guess. Like I said, I have never tried an oil additive. I was looking for anyone who may have tried one in the past with or without success of some kind.
Thanks for the responses. The truck SEEMS to run way to smooth with no power loss and the sound quickly dissappears with NO sign of rod or bearing noise after initial start up. This is the somewhat baffeling part.
Thanks again,
Rod
I agree on the oil pressure check with a quality gauge. It doesn't seem to lose any pressure as it heats up, but then again with the on/off style gauge there is no real way to tell what kind of pressure it is really pushing.
I had done a little searching and heard of filter problems draining on the 300, but with this being my first 300 six I was unsure if it was common.
I have also been told there are some pickup screen issues. This is where the additives come in to play. I have heard of people running the above additives for more of a cleaning purpose I guess. Like I said, I have never tried an oil additive. I was looking for anyone who may have tried one in the past with or without success of some kind.
Thanks for the responses. The truck SEEMS to run way to smooth with no power loss and the sound quickly dissappears with NO sign of rod or bearing noise after initial start up. This is the somewhat baffeling part.
Thanks again,
Rod
Posting Guru
Joined: Jun 1999
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To smooth the initial start up knock.......use ONLY genuine motorcraft or WIX filters. I have tried EVERY brand out there......these are the only two that help...beleive it or not ...the WIX does way better on my truck. I have 190K now.....had 113k when I got it....hasn,t gotten any worse ......only when testing different filters. I use Mobil 10w30 conventional in all my automobiles.
Phillip
Phillip
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Joined: Mar 2005
Posts: 4,698
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From: Mexico, Missouri
May also be piston slap. I have the same sound on mine when it starts up. Sounds like a lifter or valve. I may be wrong here. But when mine starts up, it's sounds like it's a lifter that is dry. Took it to the shop to get expert advice. The mechanic who has been working on these ol' straight 6's says it's piston slop and I said I run her till she died on me. No smoke, doesn't use any oil, and putts away fine from point A to point B.
There is a lot of info concerning piston slap and valve ticking on here. I have heard some went to 10w-40 and had better results, but remember to use a GOOD Motorcraft filter (FL-1A) or buy an upgrade for the oil filter mount to angle it downward. Using a filter without an anti-drainback valve can have you tearing into the engine for a rebuild later down the road.
There is a lot of info concerning piston slap and valve ticking on here. I have heard some went to 10w-40 and had better results, but remember to use a GOOD Motorcraft filter (FL-1A) or buy an upgrade for the oil filter mount to angle it downward. Using a filter without an anti-drainback valve can have you tearing into the engine for a rebuild later down the road.
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Elder User
Joined: Nov 2006
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From: Pensacola, FL
i agree with the others change the oil and filter and hook up a mechanical gauge. my mechanical gauge will go from 50psi cold to 20psi hot at idle and the factory gauge constantly reads at the "M" in normal . next thing you might want to consider would be dropping the pan and replacing the pickup screen $15 at parts store. and pump also, only $40 i think i paid for mine.
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Joined: Aug 2006
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From: northeast
I have a similar problem with mine on startup, only when it is cold and the out side temperature is below like 35 degrees. It seemed that every time I changed the oil there was no oil in the filter. Me and my old man have always used Fram filters but since I've been having the drain back problem I bought a filter adapter by ford racing that angles is straight down so it can't drain back. Before I got the adapter it always knocked on start-up. Since I have to replace the pan I figured I would get a new pump anyway.
Junior User
Joined: Sep 2003
Posts: 65
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Its no big problem mine used to do that on start up, it sounded like the engines crack was falling off. Do a search on this site for offers a attachment to prevent oil draining out of oil filter. Some oil filter also have a built in thing to prevent it.
I use Canadian Tire white oil filters and it has not done the knock thing in years.
I use Canadian Tire white oil filters and it has not done the knock thing in years.
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Ryan0214
1987 - 1996 F150 & Larger F-Series Trucks
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