Fuel injector hydrolock engine while running?

Posting for a friend that I've been helping. Technically a 3rd gen 4runner but it's the 5VZ and figured I would get more reads here.

1997 4runner that he bought about 2yrs ago. He has known the PO by working at her house and she finally decided to sell. Folder full of maintenance records including (2) head gasket jobs with the second time having a new set of heads put on. Late August/early September 2023 he blew another head gasket. With the new heads being done last time he figured maybe it was the block and decided to go with a replacement engine.

He was looking at getting a Yota1 engine and I found a company on eBay called Phoenix Engine Specialists. They offered a long block with no core, quick build time and about 2/3 the price. Motor showed up quickly and looked good. We installed over the course of a couple days with all OEM gaskets. Engine ran great after installing, with no leaks and no codes.

Fast forward to about 2 weeks ago and 800 miles on the PES engine. His 21y/o son is driving down the freeway when there is a catastrophic failure and has to be towed home. Tow truck driver finds pieces of the block on the road. I realize the son is young but I honestly do not think the engine was being driven hard.

They remove the engine and pull the oil pan. It looks like from front of engine to back it's bearing position 2 and 3 that have broken rod caps and position 4 has a bent rod. The guess is that there was a single rod failure that caused the rest of the damage by broken pieces flying around and jamming into tight spaces.

Friend calls the builder and is first told that the engine was either over revved or hydrolocked. After a couple more calls and going over pictures, the builder is now saying the engine was hydrolocked from a stuck injector and won't budge from that. They have offered to have him send their engine back along with his old short block and build him a motor for $1800.

Sorry for the novel but wanted to try and give the full story. I find it hard to believe that a stuck injector with a flow rate of 240cc/min can flow enough to hydrolock a cylinder at freeway speeds. I can of course see an injector doing that when the engine is not running. But I wanted to see what people thought on here and if they have seen similar happen. I came across another thread of a rod through a block that looked similar but there was never anything said as to what caused it.

Thanks in advance for any help.

 

what are these black pieces?

 

Pull the oil filter and carefully cut the plate end off and unroll the media. You are looking for fine metal bits of bearing etc. If there is nothing then it truly came apart fast. If it has bearing material then there was a build issue. Will they accept an internet motor diagnosis, who knows.

 

initially this is my thought

fuel 'typically' doesnt hydrolock an engine
IF this occurred.....the head would be damaged from incorrect timing from a the part that controls timing for the head and short block to be in-sync.....T-chain or gears or tensioner

other things i noticed...
-doesnt look like oil deprevation(no rainbow heat marks on bearing surfaces)
-there is a large amt of scoring on bearing surfaces(dry start when 'tested' by vendor?)
-that is a shit ton of RTV overlapping the pan/block surface

im trying to get a hold of my friend that builds engines
to see what he says
he loves crap like this

 

HA!
i got a hold of him

first of all and MOST IMPORTANTLY............
-was there signifigant amt of fuel in oil?
-did the oil smell strongly of fuel?

if not this is a excellent way to disprove vendor's 'fuel hydrolock' condition for failure.

secondly, he noticed a cracked rod but no bent rods
again, hydrolock condition would bend rods not crack rods
here is your pix of 'cracked' rod:

 

75% of our convo were about these 2 pix
we think this is the failure point
unknown exactly which side failed first, but friend makes some good pts

 

I believe those pieces are from the block and he pulled them and the bolt/nut from the skid plate.

 

see the dent on the oil pan
can be determined that the side of the rod cap with the missing bolt struck OP

the opo side of rod cap has bent connecting bolt.....and is sheered off
(pix quality too low to see if there are beach marks on sheered bolt to deter if metal fatigue)

we are guessing from your pix that the rod cap side with the bent bolt failed.
on down stroke the cap became loose, twisted and eventually failed and struck pan
then catastrophic to SB occurred.

 

Really appreciate you and your friend taking the time to look and talk this over. I don't think there was a strong smell of fuel but I will verify. Here's the latest pictures he sent me.

 

the other theory is that the twisted rod cap with missing bolt was never on the cap/never torqued
see the threads on the missing bolt side?
would think that those threads would be in much worse condition if bolt came off bc of forced impact with oil pan
this would also explain the bent connecting bolt on the opo side

this theory wouldnt hold if the vendor just dressed up engine and just used a used SB...friend said this possible from vendor

eager to see what others say!
friend wants me to update him on this too
GL

 

there is the cracked rod

 

hey
my friend just called me back
OldSilver is going to love this..............

he said another possibility
bc of the uneven wear on the crankshaft journal
bc that uneven wear is the furthest from the harmonic balancer
poss tht the crankshaft was unbalanced....causing that rod cap bolt to come loose then catastrophic engine dmg
worn/not torqued harmonic balancer

the only reason this might not be the case is only 800 miles driven
OldSilver has lots of experience/knowledge on this HB stuff

 

Here are the pictures from cutting the oil filter open. Break-in oil (royal purple) was used initially and oil change was done at 600 miles. I asked about metal in that oil but he doesn't recall. Might still have that first filter.

 

Wouldn't all this metal disprove the builders claim that the damage is from a fuel hydrolock? If it hydrolocked sure there would be metal from things flying around, but the engine isn't going to get many revolutions after locking. All this metal seems like it would have taken a bit longer of the engine running to accumulate. Friend says he is pretty sure there is metal in the heads also, which seems likely if the filter had that much.

Also, one of the broken parts looks to have broken the oil channel in the block between the oil filter and oil cooler. This seems like it would stop oil flow because of th ebig hole in the block.

Thanks again.

 

Seems like the rod bolts weren't torqued. The way the threads are gauged indicates its been loose for a while. Nut probably lost enough torque to side load the other bolt and break it whipping the rod and piston around. Checking the torque of the other rod bolts would prove this theory. I doubt the injector stuck open and I doubt that much fuel would cause a hydrolock. It would be easy enough to test but the engine builder shows clear signs he doesn't want to pay for a replacement anyways.

 

This right here says the nut was missing before it blew up. The nut was missing and threads here damaged. Every blown motor from over revs or hydralock the nuts were still on the bolts. The bolts would be broken or bent but nut would still be on there.

 

My thoughts exactly. If the motor started to eat itself slowly there would be metal in the filter and like you said not too many RPMS after the block got ventilated.

 

Oil/oil filter look fine
Assuming no fuel or fuel smell

not a stuck injector hydro lock 100%

from the evidence shown
2 possible causes now

1-something to do with those rod cap fasteners
2-HB

how did harmonic balancer look?
Was the crank shaft bolt super easy to take off?

 

Engine came without harmonic balancer so it was swapped from old engine and torqued with a new bolt.

Seems like we all agree that it is very unlikely this was caused by a stuck injector. Friend is going to send a link to this post to the builder but I'm not optimistic they will do the right thing. What is the point of a warranty if they will not stand behind their product? I understand in this day and age that some consumers will make claims that are false and try and take advantage of businesses, but this is not the case here and some simple questions and investigation would help determine what happened.

I hope I am wrong and that the builder will reevaluate. If they do, I will make sure to post that so that future engine shoppers can know who to buy from and who to avoid.

 

GL

hope everyone’s diagn/comments help your cause