okay guys..i'm sure you've all probably heard this one already but here it goes. I have a 1995 f150 with 111,000 and ever since i have bought it it has had a knocking sound at low idle and goes away with rpm. And i am definately sure it is not lifters or anything of that nature. It sounds like it is coming from the lower end. The sound gets better when the engine warms up but never goes away fully. I've heard everything from an exhaust leak(i highly doubt that) to a rod...(hopefully not that) to the torque converter shucking. i use full synthetic oil and it doesn't use any oil. Any suggestions would be welcomed. thanks.

 

With that kind of miles it sounds like a rod or main bearing. Put some 15w-40 in it and drive it another 100k miles! Oh and save for a long block.

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99 F250 LD 4x4 S/C 5.4 3.73LS
K&N, Custom 2.75" dual exhuast.

 

Not sure what it is. If it goes away as it warms up I'm thinking it has something to do with the exhaust. Had a 86 pontiac 1000. This was when I still lived at home. Got this sound that sounded like an exhaust leak. It was coming from around the exhaust manifold so I figured it was that. My step dad thought otherwise. Found a small crack on the pipe connecting to the manifold. Got that replaced and the sound was still there. there was the aluminum sheild wrapped around the manifold so I decided to take that off and look for cracks. Sure enough the exhaust manifold cracked. Found that after me and my step dad looked at all kinds of other stuff. I told him that's what is was right away but he didn't believe me.

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1997 XLT Teal 4.6L Flareside 4x4 ORP. Automatic, Reg. cab, 3.55LS, tinted windows, bug deflector, Dual exhaust, K&N Generation 2 air filter, BullDog keyless entry/remote start, Modern 16" wheels, bedliner, Covercraft tonneau cover, White faced gauges, electronic shift on the fly, Clarion ADX5655z Double Din Cassette & CD, 4 Pioneer TS-A6865 speakers and superchip.

Future mods: Supercharger, headers, NOS, tranny upgrade(heavy duty gears, clutch packs, etc.), performance torque converter, composite driveshaft, bore cylinders 30 over, new pistons, crank, and rods, get performance heads or port the ones I have, gauges for the a-pillar, new L if they still make them and I like the way it looks, and a Z06 Vette or BMW Z3.




Click here to see more pictures

 

[QUOTE]Originally posted by unclebeldin:
[B]With that kind of miles it sounds like a rod or main bearing. Put some 15w-40 in it and drive it another 100k miles! Oh and save for a long block.

okay..i like your optimism and i will try tht...i can use synthetic 15w-40 and be okay. and i guess maybe i'm stupid but i'm lost on the whole save for a long block thing...explain please!

 

[QUOTE]Originally posted by King James:
[B]Not sure what it is. If it goes away as it warms up I'm thinking it has something to do with the exhaust. Had a 86 pontiac 1000. This was when I still lived at home. Got this sound that sounded like an exhaust leak. It was coming from around the exhaust manifold so I figured it was that. My step dad thought otherwise. Found a small crack on the pipe connecting to the manifold. Got that replaced and the sound was still there. there was the aluminum sheild wrapped around the manifold so I decided to take that off and look for cracks. Sure enough the exhaust manifold cracked. Found that after me and my step dad looked at all kinds of other stuff. I told him that's what is was right away but he didn't believe me.

thanks..i appreciate the info and i will check that out. once again really appreciate it

 

alright kev...i appreciate the info..but when i press the accelerator the knock goes away the faster the rpms are..i'm only hearing it at low rpm or at idle..so does that mean it's not the bearing..hate to replace thme and not have that be it!..let me know..oh yeah the engine is a 302!

 

Hey Spiritofthewild5, I have a 1990 F150 with a 5.0L 302ci as well. I am having the exact same problem, with a few exceptions. Mine has progressively gotten louder over the past few months. Now it is to the point where it scares me to take it on long trips because it gets so loud. After replacing the hydraulic lifters, push rods, and rockers the noise didn’t get any quieter and we determined that was not the problem. I have taken it in to several mechanics and have gotten two different answers from all of them: main bearings are loose or shot, and a piston slap of wrist pin coming loose. Well I doubt that it is the pistons, though they may be making some noise, making all of that noise under my hood. In my case the noise is fairly loud and kinda like it is a clacking noise at idle and then when I rev up the engine it goes away but upon deacceleration it is the loudest. I haven’t lost any power at all with my truck, have you?

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 90’ F150
 K&N Generation II
 PowerAid throttle body spacer
 Flowmaster Dual cat back exhaust
 Rhino Bed Lining
To Come:
 Thorley Tri-Y Headers
 4 inch Rancho Suspension Lift
 35 inch TSL Thornbirds

 

Oh I am in total agreement about finding out for sure if it is a bearing before tearing down the engine. You may want to take it to a local garage and have a couple of the mechanics listen to it. If you are absolutely positive it is not in the valve train, then it could be a rod or main bearing or exhaust leak. Also remember the injectors make a ticking noise when firing but it would be at the top of the engine.

Also I have pulled off an oilpan on a 302 F150 while the engine was still in the truck. It only took a couple minutes. I removed the engine mount bolts, jacked up the engine as far as I could without putting any stress or kinks in the lines etc and I was able to just unbolt and remove the pan. With the pan off, you can unbolt your rod caps and verify there are no bad bearings. Just torque them afterwords and don't mix the caps up, just do them one at a time.

Good luck
kev

 

[QUOTE]Originally posted by badhabit:
[B]Hey Spiritofthewild5, I have a 1990 F150 with a 5.0L 302ci as well. I am having the exact same problem, with a few exceptions. Mine has progressively gotten louder over the past few months. Now it is to the point where it scares me to take it on long trips because it gets so loud. After replacing the hydraulic lifters, push rods, and rockers the noise didn’t get any quieter and we determined that was not the problem. I have taken it in to several mechanics and have gotten two different answers from all of them: main bearings are loose or shot, and a piston slap of wrist pin coming loose. Well I doubt that it is the pistons, though they may be making some noise, making all of that noise under my hood. In my case the noise is fairly loud and kinda like it is a clacking noise at idle and then when I rev up the engine it goes away but upon deacceleration it is the loudest. I haven’t lost any power at all with my truck, have you?

hey i appreciate the reply..and no i haven't lost any power at all...engine seems to run good despite the noise....thanks for responding though....who knows what we've got here!

 

Usually if a rod bearing is bad you won't necessarily hear it at idle but when you rev the gas you will hear it clearly. Same thing, if you depress the throttle slowly and hold it at a higher rpm you won't hear the knock as much. Try standing at the engine compartment with the truck running and rev the throttle at the intake. When it revs you should hear the knock the loudest and at idle or constant rpm it should be less noticeable.

Oh and if it is a rod bearing you may be able to keep driving it for awhile or it might seize up and blow your rod in half and out the side of the block! My suggestion is to pull the engine out and replace the bearings and have a machinist look at the crank and make sure it isn't scarred. You may be able to fix the block for $30-$60 and one weekend of work if you go this route. Or you can wait until it blows then tow back the truck and drop $1000+ into a new engine.

Is the engine a 302?

Hope this helps
kev

 

My dad has a 92 F-150 with the 5.0. His had a similar problem and when it finally went, it appeared that there was an oil starvation problem in the # 8 cylinder. Ford replaced with one of their FQR engines and it went again in less than 10K. Same problem was diagnosed in the #8. Since that FQR was still under warranty, the Ford dealer called fred Jones and spoke to the manager there. Apparently, according to this person, some engines made it out of fred Jones that were not assembled???? correctly. They ( the Fred Jones people) had fixed the problem and all of their engines now have corrected the problem. I'll beleive it when I see it. Right now my dad has about 3K on this last block, so I guess time will tell????

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2000 F150 Lariat Supercab, Oxford White/parchment,157"WB, 5.4, 4R70W,single fact. CD premium sound, remote keyless entry, full leather, 3.55 LS,SRW, Class 3


Mobil 1 5w30 oil with Motorcraft FL-820s
K&N Filtercharger
Penda Bedliner
Solo Radar Detector

 

well everyone..i have an update on this whole issue..especially to the gentlemen that has the 90 ford with the same problem. I took the truck to the local ford dealership today and after a technician listened to the truck and put a stethascope to it he decided that the noise is actually coming from around the torque converter-transmission area. He told that I needed to change the fluid in the tranny and the torque converter and replace it because sometimes sludge can build up on the fins in the torque converter causing this noise. that is also the reason why the noise would get better as it got warmer. So i'm going to do that this weekend. and just so everyone knows i am feeling much better now that they have ruled out any type of bearing. just thought i'd update everyone..thanks for all the replies!

 

Hey Spiritofthewild5 please keep me updated and let me know if it works. So you must have and automatic transmission, now I may not be really mechanically inclined but I have a 5spd manual tranny and I don’t think I have a torque converter do I? But, it does sound like the noise is coming from that area around the tranny.

 

Hey if anyone else has any insight on this please help. And, could Spirit's diagnosis be right on my application even though I have a 5spd manual and I think he has an automatic tranny?

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 1990 Ford F150 XLT Lariat
 K&N Generation II FIPK
 Power Aid throttle body spacer
 Flowmaster Dual Cat-Back
 Rhino Bed Lining
 Rhino Undercoating
 Tint
 Loudest Regular cab stereo in the state of Utah with 3 12's behind the seat
To Come:
 Doug Thorley Tri-Y Headers
 4 inch Ranch Suspension Lift

 

hey bad habit....well for starters you are right..you do not have a torque converter on your truck being a 5 spd. Um i personally think the tranny is still a spot to check or perhaps the bolts that hold you're clutch and flywheel in could be loose. another option the mechanic gave me i forgot about! hopefully i will be digging into this soon.and update you.