Engine knock

[wslusser]

Got a good one here....had a knockin noise coming from my 4.0 at idle and it would get louder as the engine was rev'd up. Knockin went away after about 15 minutes of running. When it went away the check engine light came on and the engine starting missing. Got the code read out and it said one of the cylinders was missing. I pulled the spark plug and it was destroyed. Change the plug and had no problems for about a week then the same thing happened again but this time the electrode on the plug was bent over the center. Change spark plug again and the knockin wouldn't go away and it got louder. I pulled the head to see if anything was maybe inside the motor but nothing was. I did find that the top of the piston was compressed (couldn't pull the rings out). Anyway I pulled the motor and installed a "used" motor and its doing the same thing. When I installed the used motor I installed all the sensors that came with it. Anyone have any ideas with what might be bad..... The only thing I can think of is the computer or maybe the O2 sensors.

 

[manaen]

the computer cannot cause a mechanical problem like you described. Did you use the same plug wires from the other engine? bad wires tend to click when they are going, almost sounds like a valve tap. Oh one other thing I just thought of, this happened on my SOHC, the Oil dipstick tube was slightly bent which caused the dipstick to come into contact with the crank as it rotated. It drove me crazy until I realized when I touched the dipstick I could feel the tap. All I did was push the tube toward the engine to slightly bend the bracket back, and that solved it.

anyway just a shot in the dark.

 

[wslusser]

Spark plug wires are new along with everything else. There is a whole different set of sensors that came on the new/used motor I switched with the original motor. We didn't touch the dipstick on the new engine. When I pulled the old engine apart the #6 cyclinder had all kinds of metal shavings. I think what was happening is the cyclinder was firing when the piston was on the up stroke. Now the new motor is doing the same. I just want to exhaust all options before I spend $130 on a rebuilt computer.

 

[manaen]

Did you go over the wires to make sure you have the timing set properly? if one of the wires is switched it can tear an engine apart.

 

[wslusser]

Which wires are you talking about? I've done point to point resistance checks between the computer, fuel injectors and the coil packs. All wires read good. I've also used 2 different "distributors", coil packs, and spark plug wires.

 

[bluesman2333]

By doing the same thing, so you mean the plugs are receiving mechanical damage like the old motor, or it just has a knock? Did you pull the oil pan off the old motor to see if the bearings were spun, or check the piston to see if it is broke? I don't know what the normal plug to piston clearance is so the thickness of a bearing may not be enough to cause the problem. Are you sure the knock is coming from the same cylinder?

 

[manaen]

Which wires are you talking about? I've done point to point resistance checks between the computer, fuel injectors and the coil packs. All wires read good. I've also used 2 different "distributors", coil packs, and spark plug wires.

the plug wires, make sure you have the correct timing order. That can cause sever detonation which will blow plugs and pistons to peices

 

[wslusser]

I've checked and rechecked all wires....when the spark plugs go bad it's pretty easy to tell.....the ground is bent past the center electrode. This has happened on #1, 3, 4 but mostly on #6. I'm thinking the timing is all messed up but can only be set by the computer and it's sensors. All the sensors are new or have been replaced.

 

[Turdle]

I susoect lean fuel mixture-either from the camshaft position sensor being bad-out of time, or a bad-plugged injector-
How is the fuel pressure?

 

[manaen]

the ground is bent past the center electrode.

it's actually bent? something is not right, lean, rich or otherwise will not cause the electrod to bend. Lean will burn them off. You need to check your clearances, make sure those pistons are not slapping the plugs.

Are you sure you have the correct plug for your engine, if the plug is too long it could impact the piston. That is the only way that the electrodes can be bent, unless they were bent on assembly :scratch:

without more information, I am at a loss on this one.

 

[wslusser]

When this problem first started, I had the same spark plugs in the original engine for 4 years without any problems. The initial sound the engine was making sounded like something was inside the engine bouncing around. Now the "new" motor I've installed is doing the same. The ground is actually bent all the way to the center electrode. They end up looking like someone beat them with a hammer. I'm pretty sure my clearances are good. Before installing this motor I removed the pan and plastic gaged all bearings. All were within tolerance. I keep leaning towards the PCM but I don't want to take a chance on that and be mistaken....$160 mistake. I can't even find one in the junkyards around here....I have the California model which makes it hard to find where I live. All the injectors and position sensor came with the new engine. Fuel pressure?

 

[bluesman2333]

I'm still having a mental block. Alls I can imagine is mechanical damage causing those plugs to fail that way. Detonation or anything else would cause simple erosion, right? The only other thing I can think of is hard carbon deposits that broke loose from something, if it was metal bits you would have noticed them.

 

[manaen]

I'm still having a mental block. Alls I can imagine is mechanical damage causing those plugs to fail that way. Detonation or anything else would cause simple erosion, right? The only other thing I can think of is hard carbon deposits that broke loose from something, if it was metal bits you would have noticed them.

yeah, detonation would cause the electrodes to get burnt off, not bent down. The carbon issue is sort of eliminated since he is working with a new engine.

This "NEW" engine was it a long block or did you use parts from your old engine (heads etc..). The PCM can in no way cause the spark plugs to be bent. If you are sure that you have the right spark plug, then I too am at a loss on this one. I guess I would start by measuring the clearance at TDC on the cylinders that are having issues.

Again the only thing that can cause the ground to be bent is mechanical contact with something in the cylinder. I would guess that it was an assembly problem from the factory(wrong rods etc..), however if it is doing it with the "NEW" engine then that eliminates those issues.

can you elaborate more on the process of the engine replacement, and what plugs are you using? (Make/Part#)

 

[bluesman2333]

A picture of the affected parts would be nice too, including the piston and stuff from the original engine.

 

[bluesman2333]

I've been thinking about this off and on for the last few hours. Since the plugs were in the engine when the problem started, we'll assume that the plugs are the right ones for the engine. We'll also assume that the original engine and the new engine has proper bearing clearance and all is well with the lower end. That leaves the piston damage and plug damage in the original engine due to foreign matter in the combustion chamber.

The only way that foreign matter can get into the combustion chambers is through the intake. This means either some component came apart, like screws off the throttle plate or who knows what, or someone maliciously placed foreign matter in the intake somewhere for it to eventually work its way into the engine.

Since the problem was still present after the engine swap, some part that was reused is at fault or some debris was left in the intake system to get sucked into the engine.

At least that's what I'm thinking right now.

 

[manaen]

It just doesn't make sense :scratch:

 

[wslusser]

Something in the motor is what I first thought of also. That's why I took the first motor apart. I pulled the heads then discovered all the damage in the cylinders. The motor I put in had everything on it....heads, intake, distributor and sensors. No parts were used from the old motor. Sorry I don't have pictures of the damaged spark plugs, we ended up throwing them away awhile ago. On a side note though when I pulled the #6 piston, I couldn't and still can't remove the rings. The piston is actually compressed on the top and jamming the ring in place. I ran through everything again today; wire harness, spark plugs and firing order. It is still knockin. It starts up good and runs kind of smooth but sounds like a bunch of bad rod bearings. It's pretty loud. I don't want to run the new motor like this cause it will end up destroying itself like the last. I'll try to post a picture of the #6 piston tomorrow.

 

[MetallicaRedneck]

I've been reading around, and i know i've posted before manaen. I'm aware of my timing chain issues on my '99 SOHC. But at the moment, i'm worried about the clicking and tapping at idle. Someone listened to it in person and said it sounded like valves tapping/clicking. I've got a video of the sound...

http://youtube.com/watch?v=XIQY8OzStCM

Comments on this? I've been told a new motor or a rebuild is a good idea at my current mileage. But straight from Ford, a crate SOHC. Runs alittle over $3100, i don't have that kinda money.

 

[manaen]

I've been reading around, and i know i've posted before manaen. I'm aware of my timing chain issues on my '99 SOHC. But at the moment, i'm worried about the clicking and tapping at idle. Someone listened to it in person and said it sounded like valves tapping/clicking. I've got a video of the sound...

http://youtube.com/watch?v=XIQY8OzStCM

Comments on this? I've been told a new motor or a rebuild is a good idea at my current mileage. But straight from Ford, a crate SOHC. Runs alittle over $3100, i don't have that kinda money.

You should really start a new thread on your problem it will get more responses. That noise is pretty severe as tapping goes, it could even be traced to the bearings. Did it happen all at once? was there an event that lead up to this sound ? or was it a gradual effect over time?

You could do what I did and start calling around the local yards for low mileage replacement, I was able to find one for $1200 with 32k miles on the clock. If you do find one, you may want to look toward the newer engine 2002 and up since most of the timing guide issues were supposedly resolved after mid 2001. Going with a newer engine may require you to replace the fuel rail and injectors from your vehicle.

Anyway you should start a new thread for this problem. I hate to say it, but that sounds a lot like my engine did when it spun a bearing

 

[MetallicaRedneck]

You should really start a new thread on your problem it will get more responses. That noise is pretty severe as tapping goes, it could even be traced to the bearings. Did it happen all at once? was there an event that lead up to this sound ? or was it a gradual effect over time?

You could do what I did and start calling around the local yards for low mileage replacement, I was able to find one for $1200 with 32k miles on the clock. If you do find one, you may want to look toward the newer engine 2002 and up since most of the timing guide issues were supposedly resolved after mid 2001. Going with a newer engine may require you to replace the fuel rail and injectors from your vehicle.

Anyway you should start a new thread for this problem. I hate to say it, but that sounds a lot like my engine did when it spun a bearing

2 people in my family have owned it before me, my father purchased it from an auction a few years ago. From what i was told, it was like that after they got it. So the problems have been driven with for awhile, seems like the noise is worse somedays then others. Finding one isn't a problem, just finding someone who'd swap the engine out for the right price is. But would a 2002 engine bolt up to mine? It looks alot different, can't find any examples of an '01 engine or if it would be interchangeable.