#6 Piston Damage w/Pics (1 Viewer)

[medikateme]

Out of town for the next few days but will post more pics when I get back. Do not know the heat range on the plug at the moment. New to these vehicles. Truck has 164,000 miles. Impulse EBAY buy in VA and drove it back to New England. Drove fine. 16mpg hwy doing the speed limit. Idle at start up was strong. Once warm idled at 400rpm. Didn't sound the smoothest but never stalled out. Radiator had been replaced May 2017. Neglected to ask about this . Significant moisture out tailpipe. Did carbon test of coolant steam. Yellow in about 3 minutes. Pulled the head. Moisture in #1 and #6 cylinders.

 

[FJ40Jim]

My question is how were all of those gouges created in such an isolated area of the cylinder? Could they have been caused by the spark plug insulation breaking off, falling in, and being crushed a couple of times before they flew out the exhaust?

Yes, the plug insulator fell off then bounced around in the reciprocating cylinder. Sometimes when the piston came to TDC the foreign objects were in the piston dish, sometimes they were in the quench area where there is only .020-.030" of clearance.

Is the aluminum that soft that ceramic insulation could cause that kind of gauging? Strange if you ask me.

Yes, AL is soft compared to hella hard ceramic. So the ceramic readily dinged the soft AL, but the super hard (brittle) ceramic was crushed into sand eventually. Once the pieces were small & light enough they were carried out the exhaust port by pumping airflow.

FJJim: What is it about those valve seats that catches your attention? First rodeo for me here.

Here's a crappy picture edit. The valve seat area is the silver ring inside the red highlight. It should be bright silver and perfectly smooth, almost a mirror. These exh seats are all pockmarked and dinged up. The valve will also look the same. Plus the valves are a little bent from landing on the seat, with a piece of garbage in one spot so the valve head is subjected to a bending load.

 

[nukegoat]

I'd consider it a freebie shot peening. The aluminum is likely stronger now.

 

[medikateme]

I'd consider it a freebie shot peening. The aluminum is likely stronger now.

FJJim I apprecciate your explanation. Thank you. Is it an absolute that those valves need to be replaced or is there a chance they are within spec? I plan on filing down the high points on the piston crown today. Ill post pics f the valves as well once they are cleaned up.

 

[FJ40Jim]

Considering the damage a dropped valve can incur, I would replace those 4 without a thought.

If you like, I can recommend a positive non-destructive test method.

It's called the "drop test". Drop each valve in a bucket of water. If it floatss, it is good for re-use.

One dropped exh valve leads to an entire new engine:

 

[Tools R Us]

Considering the damage a dropped valve can incur, I would replace those 4 without a thought.

If you like, I can recommend a positive non-destructive test method.

It's called the "drop test". Drop each valve in a bucket of water. If it floatss, it is good for re-use.

One dropped exh valve leads to an entire new engine:

Nice carnage, been there on older motors. In the new to emissions years, there was lots of scramble to make stuff live, sodium filled stems and other silliness. Those problems are decades behind us, stuff is much more reliable now.

Got pictures of that type of carnage on a 1FZ, I have never experienced anything close to that, in fact would rate them in the rock solid category. Most that we have had off, don't even get a valve job, just cleanup and seals, even with ~300K miles. My guess, from the pictures, could do a valve job and it's good to go for another ~300K.

 

[FJ40Jim]

My concern is that the valves have munched garbage at speed, which puts a bending load on the valve head, possibly repeated many times, leading to microcracks in the valve that propagate to failure.

Or not.

 

[BILT4ME]

My concern is that the valves have munched garbage at speed, which puts a bending load on the valve head, possibly repeated many times, leading to microcracks in the valve that propagate to failure.

Or not.

i agree. I would also replace the guide because of this. Do it once, do it right.

 

[LCHardriver_02]

My FZJ is in the shop now having just been rebuilt. I ended up replacing the pistons, injectors, fuel pump, and oil cooler. Similar, I had damage on 1 cylindar, so we ended up having the cylinders bored out. I am expecting to get the truck back soon.

FYI on the oil cooler... I was not expecting to have to replace this, but small internal separations was allowing oil and coolant to mix. You may want to pull yours and check it. Expect a ton of cleaning to be needed just to be able to inspect the internals.

 

[slow95z]

if you want to just replace the head with a known good unit i have one. it would still need to be worked but its on a running engine.

 

[medikateme]

Thanks for the replies and the offer of the cylinder head. Pics below.

 

[OGBeno]

Yuck.

 

[FJ40Jim]

Skip the drop test. Those valves will clearly not float, and therefore should be replaced ASAP.

 

[medikateme]

Pics of high spots on piston removed. Have we gone far enough?

 

[danthman114]

my ocd would make me rebuild the whole thing... but that's just me...

 

[OGBeno]

Agreed. That just looks like s***.

 

[danthman114]

would be a good time to head over to navy fed, get a loan and get a crate b4t cummins...
then throw that whole engine in the landfill...

 

[danthman114]

makes me wonder if you would find something in your #1 cat...

 

[Trollhole]

What did the head gasket look like on #6?

 

[medikateme]

Gasket block-side at #6.