There's something in there...

I just don't think the spark plugs are that close to the piston. The valves would be touching before the piston came close to the plug

 

Right. Unless you had massively long spark plugs for some reason and then the issue would be in all cylinders. Instead, we are looking at two cylinders with marks from something bouncing around inside, one spark plug that has been damaged, and another that is actually missing its electrode. Impressively confusing

 

It looks like One spark plug that is missing the ground strap and electrode.

 

It was the spark plug of cylinder 4 missing the strap and electrode. When I bore scoped and found nothing the first time, I put new plugs in and the one in cylinder 4 was damaged again.

 

I passed judgement on my truck yesterday, and carried out the sentence today: OFF WITH IT’S HEAD.

Cylinder 4:

more beat up than before.

Cylinder 3:

about the same as before.

Cylinder 1:

Wait, that was clean before, no marks at all..

What? I skipped Cylinder 2!?

Yeah. Notice the matching mark on piston 2:

left side.

I’m 100% sure that was not present on the head or pistons last time I put it back together.

It also went through all 4 cylinders this time.. at least 1, 2, and 4. Piston 4 looks like it’s been sandblasted now.

Hopefully, in a week or two when I can put it back together .. it should be done with this crap.

I’m done for the night, I’ll scope the cat and see if the electrode is in there. Pretty sure this guy is the strap.



Is there an emoji for pulling one’s hair out?

 

Looks like moderate to severe detonation to me. If it had progressed to pre-ignition, there would be far more extensive damage. Most common cause is ignition too advanced for conditions. Excessive heat with a failure of the knock sensors could also do it.

this causes chunks to break off the piston crown and then bounced around causing what you see on the heads.

larry

 

any update on this?

 

Maybe mice ate through the air filter and packed a load of crap in there. That could be intermittently sucked in and do some damage.

 

Hi Larry,
I hadn’t replaced the plugs in a while and one of them had lost the electrode and the grounding strap. I found the strap the second time I pulled the head off.

 

Air filter was perfect, pulled it to clean and re-oil the first time I put it back together (K&N). From the piece I found in cylinder 2 the second time, I’m positive it’s from the spark plug failing.

 

Sorry, I went out of town for work for a week. Should get the new head gasket, head bolts, and the rest of the small parts I need here and there tomorrow and I’ll put it back together. This minute, all of the oily parts are wrapped in plastic wrap or in ziploc bags in the cab, and the engine itself is wrapped in plastic wrap. Nothing has changed since my last post except onesy-twosy small parts arriving in the mail and sitting on my table, but thanks for checking in.

 

Sixty years doing my own shade-tree work on engines, including 50's to 70's all kinds including high-compression and changed a lot of plugs: I have never seen anything like this failure. Plugs with insulator cracks, center electrode worn down to almost nothing, ground strap almost down to a nub? Yes: but never this. I think there is a piece doing a tour around the intake and exhaust and raising h*ll in there.

Keep us posted.

 

no worries! Just glad to hear you’re moving forward with it.

 

Well.. I put it back together. Again.

I'm still getting a misfire, although in cylinder 1 this time. Some intermittent rattle too.
I'm going to pull apart another of the NGK spark plugs to see what the electrode looks like. I found some pieces in the catalytic converter when I used the bore scope before putting this back together the 2nd time, I had assumed the electrode was there. I'm tired of throwing in $12 spark plugs, so when I put it back together I used the same ones I had used last time. After getting the misfire, I pulled the #1 plug again and it had some small impact marks .. so I'm not sure if something is still in the cylinder or not, although I'm not sure where it would be from or what it would be, the head was clean, all of the ports were clean, and there was nothing in the intake when I put it back together.

I know what I have to do. Going to go buy more spark plugs (again...) to see if there's any material in the cylinder somehow, and play musical chairs with the injectors and coils, to see if the misfire follows any one component.

I'm on a shoestring budget at this point, so telling me to go replace all four coils and injectors isn't going to help

.. Am I the only one that wishes the air box didn't go over the top of the valve cover so one could access the plugs easier? Although I must admit, I'm getting to be quite good at pulling that part (not sure of the actual name for it) off and putting it back on.

 

Before you go throwing more money at this, pull your #1 coil and take a good look at the boot. You may have a small tear in the boot causing your misfire issue which you can easily test by swapping the coil pack to another cylinder. If the trouble follows the pack then you know where the problem lies.

-J

 

Agreed, this is what I meant by "play musical chairs with the injectors and coils", it'll be my first step.

 

Ok, we have electrodes melting or breaking off, melted aluminum chunks stuck to cyl head, misfires and now rattling. How much more evidence do you need that this is detonation? Seems pretty classic detonation symptoms to me. Realize that this is not seen so much by the younger folks, due to electronically controlled fuel and ignition, but that doesn’t mean it is a thing of the past.

suggest the op research this

larry

 

i have seen it several times, usually due to detonation from a combo of low octane fuel, high CR and excessive advance.

 

^^^This^^^ FWIW: "Detonation" is an old vague term, but it's one of the worst conditions (I'll call it "failures" here) that can happen in an engine. It's ignition before the piston reaches it's optimal upward compression position and the explosion occurs too soon while the piston is on the way way up, causing a collision between compression and ignition. When it happens, it can break a ton of stuff and destroy the engine. Cheap no-name gas is a main contributor.

 

Hard to tell with all the gouges of debris now in the cylinders, but the pictures look like detonation to me. Everything looks sandblasted.
Excess heat and cylinder pressure breaking plugs.