Ripping the 5.0 tonight

[AdamDude04]

Well I've unfortantly got a loud knock of some sort. In lames terms, it sounds like a rock bouncing around inside the motor. HOWEVER, here's the kicker.. it's not constant.

If you run the motor for lets say 20 minutes, you'll get a good 15 minutes of smooth quite operation. THe knocking noise however, is very random, loud as I can hear it with windows up and music on, and not constant by any means.

In search of this noise, I opend the hood and let it ilde at a normal 700rpm and heard the noise. It sounds like it's comming from the alternator/EGR valve area, however I'm not fully positive its location. I do know for a fact, it's on the passanger side of the motor.

If I give it a little gas while still standing infront of the motor, and it starts to knock around again, it'll knock as fast as the RPMS, so it is driven by the motor.

Like I said, it sounds like a rock bouncing around in the motor, and random: knock, knock.....knock knock knock knock....(4 minutes), knock knock knock knock knock knock knock knock knock knock knock knock...(7 minutes)... knock......knock knock

Anyone have any ideas??

Moving to Seattle soon (1800 miles) and gotta figure something out as this may be towing the girlfriends car..

5.0 with A/C, new plugs/wires/cap/rotor

 

[Justshootme84]

It could be lots of things like a bad idler pulley, alternator bearing, the fan hitting, or internal. For isolating engine noises, I like to use a 3-4 foot long piece of garden hose, and use it like a stethoscope. Place one end on various places of the motor while running, and the other end to your ear. OF course, be real careful of any moving parts like the fan or belt. The noise will be much louder when you put the hose on or near the part or area that's bad. If the alternator bearing is going out, you will hear it quite loud when you put the hose on top of the alt. If it's a valve knock, you'll hear it loudest thru the valve cover. JSM84

 

[andre]

here some thing to try remove fan belt see if noise still there

if no thend external not engine

what year and type is it

some have air pump for anti polution on passeger side can case that noise too

 

[AdamDude04]

Oh yeah..I forgot about the garden hose trick. I'll swing by harbor fright tomorrow and pick up a cheap hose for just that reason.

I have an 89 with a 302. IIRC, there is an "air pump"..though no idea what it is.

Thanks for the help guys..I'll keep ya'll informed. I was hoping someone had the same issue..but hard to tell especially when I don't have a sound clip. I may take some sound/video clips tomorrow and post em up

 

[Justshootme84]

Yeah, with the older engines with 3 belts, you could remove one at a time. But with one serpentine belt, not so. You can look at the fan while the motor is off, and check that it's not hitting the radiator, shroud or something on the motor. I had a bolt back out a tad on the alternator bracket, jsut enough to hit the fan. MAde heck of a racket. I found the bent connecting rod that was hitting the crank by listening to the bottom-rear of the oil pan and tranny bellhousing area. hopefully your's is just a bad pulley.

 

[AdamDude04]

I'm hoping it's a bad alternator.. EASY fix and not as costly/time consuming as anything else.

Didn't make it to harbor freight today to buy a hose. Will hit it up tomorrow when out shopping and stopping by the bank. Then spend the rest of the day working on the Bronco. Tuesday/Wednesday a test run with a u-haul tow dolly to see how well that situtaion works for our move!

 

[AdamDude04]

Well I can't find the source. I tried the hose thing.. all I could hear was the sound, but muffled by the air rushing by. I could hear it better and clear with just my ear.

I narrowed it down more though.. it sounds like it's right below the throttle body, but again, unsure if it's an accessory or internal. Sprayed the pulley system with WD40 and noise was still there.. so unfortantly, I think it's time for a new motor.

I may do an oil burner swap.. or a regular fordmotorsports 5.0 performance motor

 

[Justshootme84]

Did you try the hose on the valve covers? A stuck/ burnt valve will cause alot of noise, may be time for the next step. Compression test.

 

[AdamDude04]

Did you try the hose on the valve covers? A stuck/ burnt valve will cause alot of noise, may be time for the next step. Compression test.

Yeah I put the hose everywhere.. pain though, because I had to wait for the noise to come to me. Hose didn't help out very well as like I said, lots of air rushing by and disrupting the sound.

After talking to the girly.. I think a new crate 302 motor with a supercharger is in the mix for this summer. Total cost should be no more than 9k for everything needed that I had planned.

I did however, find an 89 Bronco with a 5.0 with a broken transfer case. $800 for the whole truck, with 9k miles on a rebuilt motor, so I may buy that, and slap that into my Bronco so I can still take it camping this year while the new motor gets set up

 

[AdamDude04]

Well I have a random knock in the motor. Not constant, but when it starts to knock, it'll last a few seconds to a few minutes. It really sounds like it's comming from inside the passnager valve cover.

SO when I take the valve covers off, what exactly should I look for as far as "loose" parts?

Anything common on the upper portion of the motor I can get to, that is common to fail, or cause such random knocking?

I got wifi out in the garage, so inbetween workin on the motor, I'll check back online here!

5.0 V8 with 315k miles

 

[50joe]

I would start by inspecting all the valve springs. Make sure none are broken, or dislodged. Also comparing each valve with the others will give you a sign if something is wrong usually. Sometimes takes a real close eye to catch it. If nothing can be seen, pull the fuel pump relay and the plug on the coil. Then have someone crank over the engine with the cover off. May find a valve hanging up intermittantly. Good luck and keep us posted!

 

[AdamDude04]

I'll try cranking it per your instructions tomorrow.

However, I did find something while inspecting the springs.. The third one back (from front)is sitting slightly lower than the rest. All of them appear to be equal in height and position, except the one. Spring looks fine, and whole assembly is solid. Could this be a problem? The rods all check out strong and proper

 

[AdamDude04]

How about this one guys.. the Alternator? The knock is very random, and sounds like its right near the Alternator/EGR/Valve cover (closest to motor).. I know the alternator was having an overcharge problem a couple months ago, then went away..

Could a internal in alternator or bearing be going??

 

[andre]

take fan belt off and run motor sound still there not alt thend

cauld also be a dischange or stuck lifter when valve couver off try to press rocker on push rod side if it go down easy bad lifter

bent push rod

and yes some lifter will be high depend where cam lift is at

check whit a long screwdiver or piece of hose good to pinpoit noise

be carefull no to get in mouving parts

knocking can be any thing from bad rocker to piston rease pin wear

hope this help you

 

[50joe]

I'll try cranking it per your instructions tomorrow.

However, I did find something while inspecting the springs.. The third one back (from front)is sitting slightly lower than the rest. All of them appear to be equal in height and position, except the one. Spring looks fine, and whole assembly is solid. Could this be a problem? The rods all check out strong and proper

Is this with the rockers still on? If so, like Andre said, thats to be expected depending on where the cam is. If the rockers are off, and it is still sitting low, then you have bad valve or spring. Running it with the belt off will eliminate all the belt driven accesories, and yes, I have seen alternators, air pumps, and even water pumps make noises that sound internal. A faulty lifter could cause this as well, but if the push rods are still tight, wouldn't suspect that just yet.

 

[AdamDude04]

Yeah everything under the cover seems to be in place. I tried hitting all of them with a rubber hammer to see if I could notice anything abnormal, but everything sounded fine.

I'll be putting it back together in an hour or so..

But here's the problem.. the knocking noise is VERY random. You don't hear it upon startup.. usually takes a couple minutes until it starts. But like I said, problem is, it's very random. Sometimes it'll go 20-30 minutes without knocking (knocking only lasts 3-50 seconds) or sometimes it'll knock every 2 minutes.

So how long can I run the motor without the belt?

Also, I assume if the knocking is comming from lets say the alternator pulley.. with the belt off, if it was going out, would there be any grinding or resistance when turning the pulley by hand?

 

[50joe]

I wouldn't run it for more than a few minutes without the belt on. You dont want to overheat it without the water pump running. Maybe warm it up then remove the belt? You might get a lil resistance in the alt pulley, but its unlikely unless its a constant noise. A long thin screwdriver works really well as a stethascope, better than a hose does in my opinion. Plus it transfers vibration too. Also you can try watching the belt tensioner while its knocking. If one of the accesories is binding, the tensioner will tend to "jump" when it happens.

 

[AdamDude04]

Hmmm okay yeah I'll try the screwdriver effect. I bought a hose..didn't work at all. Too much air rushing through drowning out the noise. But like I said, Ill put it back together and try that.. I may just continue to drive it at night to my buds house (for beer drinkin times) and hope that it's an accessory, and that it either gets worse (constant) so I can find the source, or it just flat out fails (got free tow servies via insurance company) then I'll know what the issue is..

 

[50joe]

Yeah, that'll narrow it down pretty quick...LOL