Triple-locked LX470 blew plug out of cylinder 7 at 270k. New engine advice?

[ikellymo]

What is usually the root cause for this event?

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

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[kevgentile]

What is usually the root cause for this event?

I'd be curious too. I'm fairly new to the platform so my experience is limited, but my guess is that since it's not pulling the threads out with it that it's a torque issue.

The Ford Tritons have a casting depth fault so it pulls everything out with the plug.

 

[ikellymo]

Change all coil packs to OEM/Denso

@Bomar id presume they are OE, although I’ve only had truck for 50k miles. I bought a Denso spare from Amazon several years ago… you think there’s an issue with these?

Denso 6731303 Ignition Coil , Gray https://a.co/d/beUG8Bv

 

[vipergrhd]

I don't see anything bad in your borescope pics very minor nicks on top of the piston and I have seen worse case just go with an insert and call it good save the money for other things like others have said if the current shop don't want to do it find some one that will and install OE parts or Denso coils. Thanks for sharing that borescope I think I will buy one for myself.

 

[ikellymo]

I don't see anything bad in your borescope pics very minor nicks on top of the piston and I have seen worse case just go with an insert and call it good save the money for other things like others have said if the current shop don't want to do it find some one that will and install OE parts or Denso coils. Thanks for sharing that borescope I think I will buy one for myself.

Starting to wonder if I even need an insert.

But at the same time, concerned something is just rattling around in the head and will fall back through the valves causing more damage.

 

[excessive]

just buy a used engine off ebay (one with a warranty) and call it a day. its surprisingly easy to pull the motor in the 100 ( i did it in my garage with no help from anyone whatsoever)

 

[choyota]

That’s extremely low. Used long block? When was this? New coils alone are 1k.

Well, he just re-used my new coils packs and plugs I had just installed weeks prior. He had a LC engine with all new components installed. New rod bearings, piston rings, new head gasket, new valves, seals, o rings, list goes on. New WP/TB as well. This was like 2 months ago.

 

[ikellymo]

Thats great. Wish it was local for me. I don't have a go-to mechanic yet in the Portland Area.

 

[newbielx470]

Well, he just re-used my new coils packs and plugs I had just installed weeks prior. He had a LC engine with all new components installed. New rod bearings, piston rings, new head gasket, new valves, seals, o rings, list goes on. New WP/TB as well. This was like 2 months ago.

Would you mind sharing the name of the shop? And is the engine VVTI or non-VVTI? Thanks!

 

[MountaineerLC]

Based on the bore scope, it I'd stick a new plug in and run it. Just keep and eye on it to see if it's staying tight for a while.

 

[ikellymo]

If I could actually screw a plug in and drive it, How to address the issue of the electrode that is somewhere above the valves? Bore scope images clearly show that something (missing electrode on plug) was in there and left a few marks, although I got lucky.

Is there a way to look inside the head?

 

[MongooseGA]

FYI, new OE coils can be had from Rock Auto for pretty cheap, IIRC. I think I paid a few hundred bucks for a full set.

 

[awesomeissquid]

If I could actually screw a plug in and drive it, How to address the issue of the electrode that is somewhere above the valves? Bore scope images clearly show that something (missing electrode on plug) was in there and left a few marks, although I got lucky.

Is there a way to look inside the head?

From the borescope images I agree that something was in the cylinder. From the views, it does not appear to me that it is still within the combustion chamber. It is likely that it either was ejected out the spark plug tube and is imbedded in the coil pack or was pushed out the exhaust valves. I would re-inspect the coil pack to confirm if the missing piece(s) are found. If not, the pieces could be within the exhaust system, possibly stuck at the cat.

Based on the image of the threads, I would be cautious to assume you have enough threads remaining to work appropriately without some type of thread insert. I did some research in the past because I was in a similar situation and I think it was around 5 full thread rotations to feel safe. In my case I had about 7 of 12 thread rotations remaining so I ran it. It’s a bit hard to tell from the view if your threads remain or are broken off lower down. The second important part is insuring the spark plug compression washer has sufficient surface to seal against. You can get a feel for this by doing a leak down test and seeing how much air escapes out the spark plug tube. In my case I had some air escape, but I decided to see how the spark plug itself would seal (it ended up sealing okay).

If I was in your shoes, I would have a timesert installed with them using a thick grease on the tap. The grease helps hold any debris onto the tap so it does not fall into the chamber. Next, I would have the shop use a tube to vacuum out the cylinder and to also blow it out with compressed air. The goal is to make extremely sure that no foreign objects remain once it is closed up. Then I would have a leak down test run on that cylinder to verify it is not more compromised more than it looks. If all comes back good then I would run it.

 

[choyota]

Would you mind sharing the name of the shop? And is the engine VVTI or non-VVTI? Thanks!

Tommy @ TJ Auto in Garden Grove. I have an '02, so non-VVTI.

He's my official go-to for everything now for my LX. Very fair pricing and trustworthy work.

 

[newbielx470]

Tommy @ TJ Auto in Garden Grove. I have an '02, so non-VVTI.

He's my official go-to for everything now for my LX. Very fair pricing and trustworthy work.

Thanks a lot! I may need to get a swap done at some point

 

[abuck99]

IF you're worried I would see if you can get a better look at the exhaust valve before pulling the head. To do time-sert right and ensure you dont get any debris into the cylinder when cutting the new threads, removing the head is good practice- but not necessary- you have to be super diligent to get any shavings out of the top of the cylinder. I'd prob install a time-sert, do a compression test and drive it ( I wouldn't trust the threads after this event).

The blown spark plugs dont happen all of a sudden, they have a warning period- but you have to pay attention, listen and be familiar with your engine sounds to know the difference in the ticking sounds of injector noise, fuel pulsation damper and a leaking spark plug. Re-checking plug torque at 30k intervals is good preventive practice.

!! Read the Spark Plugs Alert thread linked above to know more about this, its a fairly common issue as our trucks rise in mileage. I think we're seeing a new post on this about once a month.

 

[ikellymo]

IF you're worried I would see if you can get a better look at the exhaust valve before pulling the head. To do time-sert right and ensure you dont get any debris into the cylinder when cutting the new threads, removing the head is good practice- but not necessary- you have to be super diligent to get any shavings out of the top of the cylinder. I'd prob install a time-sert, do a compression test and drive it ( I wouldn't trust the threads after this event).

The blown spark plugs dont happen all of a sudden, they have a warning period- but you have to pay attention, listen and be familiar with your engine sounds to know the difference in the ticking sounds of injector noise, fuel pulsation damper and a leaking spark plug. Re-checking plug torque at 30k intervals is good preventive practice.

!! Read the Spark Plugs Alert thread linked above to know more about this, its a fairly common issue as our trucks rise in mileage. I think we're seeing a new post on this about once a month.

Yeah I guess I noticed the sound but thought it was the manifold leak getting worse. Thanks a bunch. I’m talking with a few local shops now.

 

[Rednexus]

I'm going to check the torque on my plugs!

Honesty, you'll be surprised the kind of abuse an engine can take and keep on running, especially one as tough as a UZ. I had a Subaru EJ25 break a timing belt and bend all 16 valves when the hit the pistons - many would have abandoned the motor but I put 16 new valves and a new timing set in it and that motor is still running nearly 4 years later. EJs are tough little motors, but they aren't a UZ.

I'll echo what others said - if it was my rig, I'd put a thread insert in it and run it. You can do a compression test after the fact to verify that things are or are OK, if you did have low compression you could then do a leakdown test to determine if you may have damaged a valve or a valve seat. Even if you did, the head can be removed, the valve can be replaced, and the seats can be re-ground by a competent machine shop for a few hundred dollars (plus R&R labor, of course).

Given the cost of a new engine and the exquisite cross-hatching remaining on your UZ, I'd only replace your engine as a last resort.

 

[Trollhole]

Having dealt with quite a few plugs that have come out and tryinging to reform the threads doesn't work which it looks like it would for you then we use timeserts. You are crazy to think about replacing that motor or even yanking the head. It can all be done with the motor in the vehicle; even the back plugs.

 

[2001LC]

That cylinder is nice looking. It is such a shame to see this happen. I'd bet, you and your shops heard the tick. Thinking exhaust manifold leak/crack.

I beat this drum day in a day out. There is no reason for this. The sign are loud and clear. Not trying to make you feel bad. But a lesson for those that hear the tick. Check your spark if tick heard on cold start. Do not drive until, if tick heard after warm up.

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

forum.ih8mud.com

Sorry for that!

Hope this is helpful to OP.

You have about as good looking cylinder as one could hope for. I wish all I scoped looked pictures you posted.

It looks like threads are damage, unless picture poor/blur. You likely have other picture to confirm bad. I'd still run in a thread chase and see if a new spark plug will torque to 18ft-lbf. It's worth a shot.

For sure metal bounced around in cylinder. Clues of hit marks on piston and head are clear

Question, is there metal fragment between cylinder and piston on top ring. This line looks fresh, and is not a good sign:
60% chance metal still in there.

So what's best, course of action: Option 1, 2 or 3!

1) Cheapest, fast and will work: Time-sert with heads on.
90% you'll get metal in cylinder, doing this way. If some metal already (still) there, it will not matter much you add to. Compression is likely going to if not already be compromised anyway. But this will likely only result in, uneven idle and may be ~2% MPG loss. I doubt you'll notice. Worst case you replace a CAT and engine (or rebuild) at later date. CAT because bad compression, could foul one if allowed to run to may miles with a shot cylinder.

2) Remove only damaged head, repair threads. Best if head bolt replace too, helps keep compression even BK1 vs BK2. But still 60% chance some compression loss, due to metal still in cylinder.

3) Both heads pulled and machined or new, is a great option. But I'd not recommend, until at least 20K miles after head with blown plug repaired. If that cylinder is compromised. Than no need to throw extra cash at this engine now.

A trick you could try:
Move piston down. Inspect wall for metal, remove any.
Move piston up than back down. Inspect wall for metal, remove any.
Move piston up, and oil to cylinder. Move piston down. Inspect wall for metal, remove any.
Move piston up than back down. Inspect wall for metal, remove any.

If I got any metal out, before any repair. I would be inclined to roll the dice, pulling the one head to repair it..