5vz hole in #6 piston

[djskorch]

Just curious if anyone else has heard of this issue. My dad recently bought a 2002 Tacoma prerunner with the 5vz. 170,xxx miles. Ran great for about 10,000 miles after they bought it. On his last trip towing our 800ish lb small trailer with an engine and transmission in it, it started running really rough like it was completely misfiring on one or more cylinders.

After getting to a place they could stop and checking everything they could think of, he ended up buying a replacement engine and having a shop do the swap (he was in California and our shop is in Idaho so getting back was not an option)

Upon swapping things over to the new long block including the oil pan, the shop informed him that they could see a hole in the number 6 piston.

We haven't pulled the heads off yet but the only 2 things we can think of are that a valve retainer broke and dropped the valve into the piston or that the injector was failing and that it ran lean enough in that cylinder to get hot and burn a hole in the piston.

The shop that did the swap had an ASE Toyota mechanic working there who said he had never seen that on a 5vz.

Just curious if anyone else has heard of this happening.

 

[LittleCaesar]

A rod through the block a couple of times yes. But never a hole in the #6 piston, or any piston for that matter.

Got any pics?

 

[gamefreakgc]

Never heard of it. I would think if it ran that lean then it would throw a lean code because of all the unburnt oxygen heading downstream. Plus you can all but neglect these engines and never have a problem.

Probably a foreign object in my opinion. Sorry to hear about your ordeal though, never like to hear such bad stories when on a road trip.

 

[djskorch]

I will try to tear into it this weekend and get some pics. The only code he received was a misfire on number 3, then a misfire on number 4, then a random misfire code. Cant remember the code numbers exactly.

Right before he stopped, (had to drive about 100 miles after it started running rough as they were in the middle of no where) the oil pressure light was starting to flicker at stops. Turns out all the oil was getting pumped up into the intake. When he pulled the intake tube off, he said it was just soaked with oil.

Very odd indeed. Cant wait to tear into it and see what happened. I wouldn't think that if a spark plug came apart that it would cause a hole since these are non interference engines and should have a bit of clearance between the top of the combustion chamber and piston and im not sure what other foreign object could have made it in but who knows.

 

[JayRolla]

This is normal in the tuner world. Yes running lean will cause that, lots of detonation from too much boost, timing, compression, ect. Then usually the valve burns first. I would really think of a failing injector.

 

[djskorch]

This is normal in the tuner world. Yes running lean will cause that, lots of detonation from too much boost, timing, compression, ect. Then usually the valve burns first. I would really think of a failing injector.

The Tacoma is all stock. No boost, fairly recent timing belt change etc so unless the timing belt jumped a tooth or 2 and fouled up the timing, it must be a fouled injector if that is the case and not a dropped valve.

 

[02SE]

I've seen lots of blown engines from cars, motorcycles, racing vehicles, etc. with holes in pistons, blocks, demolished rods, etc. I have quite the collection of damaged engine parts from destroyed engines.

As to why this happened to a stock 5VZ-FE, is all just a guess without inspecting all of the pertinent parts.

 

[19963.4lsr5]

I would speculate that cylinder was running lean from a dirty low flowing injector in that cylinder. Ran hot and melted the hole. Leaner is always meaner when tuning for HP but it comes at a price.

 

[JayRolla]

I would speculate that cylinder was running lean from a dirty low flowing injector in that cylinder. Ran hot and melted the hole. Leaner is always meaner when tuning for HP but it comes at a price.

Hell yea, on pump gas we would run super rich. Say 10.5:1-10.9:1. But on e85 12.5-13 (gas equivalent) depending how ballsy you are. LOL