2.5L ('98-'01) Dead cylinder?

[Dirtman]

Ok follow me on this. Got a friend who brought me his 2000 rannger 2.5. Said the first motor blew a head gasket and cylinder 4 was dead. Coolant in the oil total milkshake so he scrapped it. So he buys a JY 2.5 and throws it in and shortly after cylinder 4 is dead. 50psi on compression test. Leakdown test is blowing air out of the crankcase not the intake or exhaust.

It did run and codes show 303 and 304 misfire. 8 plug engine, not connected by a single coil.

Put a borescope down and saw nothing catastrophic in #3 or #4. Intake is full of oil, pcv line is dripping oil though.

Before I go through with ripping the head off, any ideas?

What would you do here? I'm ready to pull the head... but seems fishy both died on cylinder 4.

 

[adsm08]

Turn the engine by hand with the scope in there. Make sure piston is moving.

 

[Dirtman]

Turn the engine by hand with the scope in there. Make sure piston is moving.

Did this. Had to move the piston down for better camera angle. Had it up and down. Absolutely moving by the crank. No disconnection i.e broken rod.

 

[adsm08]

Kill it with fire?

 

[Dirtman]

Kill it with fire?

I'm going to throw a pickle at you one of these days.... or make you babysit me one day. Jackass.

 

[RonD]

What were the compression numbers?

I understand leak down showed air in crank case, as it should on all cylinders in dry test, but was there a number on air pressure loss at TDC, like 50psi in and holds 45psi, so 10% loss, which is normal, or 20% loss which is high

Any 4cyl engine has a 1 in 4 chance of a failed cylinder so two 4 cylinder engines having same cylinder fail is not that long in odds
Yes, suspicious, but can't think of any reason for it, even if all parts except block and heads(long block) were swapped over

 

[Roert42]

My problem with a j/y engine is, why was the truck junked? Could have had 300,000 miles on it.

 

[Dirtman]

The junkyards here pick and catalog the engines with the title so unless they cheated the mileage at the DMV you get the true mileage when you buy a motor.

But besides the point.... found the issue.

So I don't know what happened exactly but someone drilled a spot in the top of the piston, they used probably a 3/4" drill bit so it didn't go through, just left a dimple. My thought is some idiot tried to "balance" the rotating assembly themselves with no clue what that meant.

The engine is bored .030 over so it was rebuilt...

Well that drill mark was in a very thin part of the piston and burnt through and made a pinhole. I'm assuming much more was going on, carbon, pinging, who knows but the start of the hole was clearly done by a drill which lead to the hole via some other issue.

We are now arguing with the JY for a refund. They have a 90 day warranty like most places but it's been longer than that. Doubt it'll go anywhere. Truck is gonna end up scrap.

 

[Roert42]

I'm sorry about the truck but that is hilarious.

 

[adsm08]

Any 4cyl engine has a 1 in 4 chance of a failed cylinder so two 4 cylinder engines having same cylinder fail is not that long in odds

The junkyards here pick and catalog the engines with the title so unless they cheated the mileage at the DMV you get the true mileage when you buy a motor.

But besides the point.... found the issue.

So I don't know what happened exactly but someone drilled a spot in the top of the piston, they used probably a 3/4" drill bit so it didn't go through, just left a dimple. My thought is some idiot tried to "balance" the rotating assembly themselves with no clue what that meant.

The engine is bored .030 over so it was rebuilt...

Well that drill mark was in a very thin part of the piston and burnt through and made a pinhole. I'm assuming much more was going on, carbon, pinging, who knows but the start of the hole was clearly done by a drill which lead to the hole via some other issue.

We are now arguing with the JY for a refund. They have a 90 day warranty like most places but it's been longer than that. Doubt it'll go anywhere. Truck is gonna end up scrap.

@RonD Care to calculate the odds of this happening?

 

[RonD]

@RonD Care to calculate the odds of this happening?

Well the first engine is always a known value, in this case #4 failed
So on the 2nd engine there would be a 1 in 4 chance of it matching the same failed cylinder


Unless there was a batch of "drilled pistons" used in #4 cylinders on 100,000 4cyl engines

 

[Roert42]

Well the first engine is already a known value, in this case #4 failed
So on the 2nd engine there would be a 1 in 4 chance of it matching the same cylinder

But what’s the odds someone drilled a whole in top of the #4 cylinder causing to fail. 1:42?

 

[RonD]

Stupid throws the laws of probability out the window

i.e. A "fool" will be born that can beat ANY "Fool proof system", it has always happened and always will happen, new fools come along every day, stupid has no boundaries or limits of any kind

I think Dirtman should take a picture of that hole and send it to ALL Piston makers DEMANDING they put a Warning on the top of all pistons saying DO NOT DRILL HERE
We need protecting....................

 

[Snoranger]

i.e. A "fool" will be born that can beat ANY "Fool proof system", it has always happened and always will happen, new fools come along every day, stupid had no boundaries or limits of any kind

First... Every since I started working for the government, I’ve stopped using the term “fool proof” and replaced it with the more correct term of “idiot resistant”. It just seems to be more accurate.

Second... We’ve already had a discussion here about chances. There’s always a 50/50 chance of anything. It’s either going to happen or not.

 

[Dirtman]

Anything is possible therefore anything has a 50/50 chance of happening. Ask me yesterday if I'd find someone drilled a hole in a piston and I'd say no, ask me today and I'd say yes. Thats 50/50....