04 4runner V8 Sport 2uz-fe timing belt failure, aftermath and the repair

Streetfighter

Streetfighter

New member
Timing belt exploded,
Only 79k after replacement (200k total) on the belt but there was a small leak of coolant that I ignored for years that finally caught up. It made the belt explode and the timing jumped tremendously (almost 180 degrees on the driver side cams).

Before finding out that it was the timing belt, the symptoms includes;
1. Complete lost of power, car was towed home
2. Multiple misfire, random, clear code and the misfires change cylinders
3. Smell of fuel from exhaust
4. Spark plug fouling
5. Starts but runs on a few cylinders
6. No check engine light unless misfire but vsc trac and other lights would Flash fast

Changed spark plugs, same symptoms.
Changed all 8 coils (EBAY), same symptoms.
Cleaned MAF
Checked for Vacuum leak

Finally dived in and took apart the covers and looked at the disaster that awaits. I thought the engine was gone. Looks like, from the investigation process, and constant starts and revs after replacing parts, it made the timing jump worse and worse. I read this was an INTERFERENCE motor. YIKES.

I said who cares and ordered a timing rebuild kit with new AISIN water pump, etc. Cleaned the engine well because there were belt shavings everywhere!
Also, this time I waited a full day after applying gray rtv sealant so it fully cures on all gaskets.

Crossed my fingers and started the truck. RAN ROUGH meaning choking and bogging, and 15 seconds later…she PURRRRRRRR’D. I guess it had to get the rest of the build up out.

Checked plugs and it’s burning perfectly (golden brown).

No new engine ticks, no metal in the oil, no major issues. (except p0430, probably caused by flooding engine) please help if you can with this HERE.

SO, the 2uz-fe is bulletproof, and if it truly is an interference motor, it will barely interfere.

Just wanted to post this so hopefully, it will help someone in the future.
one last thing, in my opinion the 2uz-fe is NOT an interference motor.

PICS: the DAMAGE






pics: AFTER


keywords: noninterference p0420 failure failed check engine light 2uzfe
 
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The belt is pretty messed up but still intact, had it come apart your engine would be toast.
 
OP, you mentioned a coolant leak led up to this. Can you elaborate? Where was the leak and could it have been a coincidence? Thanks!
 
46runner said:
OP, you mentioned a coolant leak led up to this. Can you elaborate? Where was the leak and could it have been a coincidence? Thanks!
Click to expand...

Yes, the coolant leak came from 2 places on the main gasket of the pump, the 2 left and right lower points of the pump gasket.
also the thermostat housing attaching to the pump, this dripped more...it dripped on top of the belt possibly.
I used GRAY rtv on both sides of the metal gasket this time and waited 24 hours. no leaks after 100 miles.
 
Streetfighter said:
if you read carefully the timing on the driver side cam did a 180, thats catastrophic for a interference motor, this proves it wrong.
Click to expand...

there seems to be conflicting info out there. ive read it several times over the years.

one place says ALL 4.7/2UZFE are interference engines.
another place says only post VVT-I engines are. meaning pre-05 are not.


then there is this site, that flat out says its a NON-interference engine.

2UZFE: Everything You Want to Know


just an FYI, my timing belt repair manual lists ALL iterations of the 4.7/2UZFE as interference.



I hope to personally never find out.
 
Last edited:
Streetfighter said:
if you read carefully the timing on the driver side cam did a 180, thats catastrophic for a interference motor, this proves it wrong.
Click to expand...

it absolutely does not prove it wrong. If the belt was still intact the valves weren't able to stay open and be damaged by the piston. The belt was definitely messed up but please go try and cut the belt completely and tell me your engine is fine.
 
TORCH said:
it absolutely does not prove it wrong. If the belt was still intact the valves weren't able to stay open and be damaged by the piston. The belt was definitely messed up but please go try and cut the belt completely and tell me your engine is fine.
Click to expand...

the motor didnt shut down after the timing jumped, i ran it hard thinking it was a spark plug issue. LOL
 
Let it Begin

Streetfighter said:
the motor didnt shut down after the timing jumped, i ran it hard thinking it was a spark plug issue. LOL
Click to expand...

I tend to agree with the OP. I have an engine that because of an extreme carbon build up (long story) from the original owner not changing oil, the driver’s side cam seized in the head. The car was going down the highway at 70 mph. When the cam seized, the bolt holding the timing pulley broke. I have taken the motor apart and found no damage to the pistons, valves, rods. I did measure the distance from the head surface to the valves and actually found a clearance when the valves are open. I don't have the exact number with me at the moment, but the engine doesn’t have any internal damage.
 
Streetfighter said:
Timing belt exploded,
Only 79k after replacement (200k total) on the belt but there was a small leak of coolant that I ignored for years that finally caught up. It made the belt explode and the timing jumped tremendously (almost 180 degrees on the driver side cams).

Before finding out that it was the timing belt, the symptoms includes;
1. Complete lost of power, car was towed home
2. Multiple misfire, random, clear code and the misfires change cylinders
3. Smell of fuel from exhaust
4. Spark plug fouling
5. Starts but runs on a few cylinders
6. No check engine light unless misfire but vsc trac and other lights would Flash fast

Changed spark plugs, same symptoms.
Changed all 8 coils (EBAY), same symptoms.
Cleaned MAF
Checked for Vacuum leak

Finally dived in and took apart the covers and looked at the disaster that awaits. I thought the engine was gone. Looks like, from the investigation process, and constant starts and revs after replacing parts, it made the timing jump worse and worse. I read this was an INTERFERENCE motor. YIKES.

I said who cares and ordered a timing rebuild kit with new AISIN water pump, etc. Cleaned the engine well because there were belt shavings everywhere!
Also, this time I waited a full day after applying gray rtv sealant so it fully cures on all gaskets.

Crossed my fingers and started the truck. RAN ROUGH meaning choking and bogging, and 15 seconds later…she PURRRRRRRR’D. I guess it had to get the rest of the build up out.

Checked plugs and it’s burning perfectly (golden brown).

No new engine ticks, no metal in the oil, no major issues. (except p0430, probably caused by flooding engine) please help if you can with this HERE.

SO, the 2uz-fe is bulletproof, and if it truly is an interference motor, it will barely interfere.

Just wanted to post this so hopefully, it will help someone in the future.
one last thing, in my opinion the 2uz-fe is NOT an interference motor.

PICS: the DAMAGE






pics: AFTER


keywords: noninterference p0420 failure failed check engine light 2uzfe
Click to expand...

Do you know if the belt that went bad was an OEM belt or an aftermarket belt??

Since I have a 2004 V8, your post make me feel better if mine timing belt was to ever break.

nevada said:
there sees to be conflicting info out there. ive read it several times over the years.

one place says ALL 4.7/2UZFE are interference engines.
another place says only post VVT-I engines are. meaning pre-05 are not.


then there is this site, that flat out says its a NON-interference engine.

2UZFE: Everything You Want to Know


just an FYI, my timing belt repair manual lists ALL iterations of the 4.7/2UZFE as interference.



I hope to personally never find out.
Click to expand...

I also hope to never find out if my 2004 is or isn't an interference engine, but this topic does make me feel a little more at ease about possible timing belt failure.
 
nevada said:
there sees to be conflicting info out there. ive read it several times over the years.

one place says ALL 4.7/2UZFE are interference engines.
another place says only post VVT-I engines are. meaning pre-05 are not.


then there is this site, that flat out says its a NON-interference engine.

2UZFE: Everything You Want to Know


just an FYI, my timing belt repair manual lists ALL iterations of the 4.7/2UZFE as interference.



I hope to personally never find out.
Click to expand...

Well, 2uzfe from 03-04 has physically different pistons than the 2005, and the 06+ have physically different pistons from the previous models. I have an 05 and have accidentally put the cam wheels on the wrong sides and started the truck with both 180 out of phase and not destroyed the engine. Actually, I switched the cams to the correct sides on the same day and started the truck, it still has no problems and is running fine. I have also heard that it is interference, but never had an issue when I rebuilt mine.
 
All the belts replaced was with the oem Mitsubishi belt. 2nd and 3rd change
Aisin water pumps come with a metal gasket with a thin Brown silicon edge, please don't trust this and use gray silicone.

The timing belt that exploded was wet and brittle. Felt like rubber drenched in oil.

This is after 4 to 5 years of knowing the leak.

No matter what this engine is amazing.
 
Last edited:
I'm glad your engine is ok. This is good tech info but I have some questions since it's hard to go out on a limb and say there is no interference when so much data suggests that it is an interfering eng. You had to physically rotate the drivers cam to line everything up? A true 180*? Maybe I'm blind but I see belt teeth throughout the whole belt. But something made it run like poop, so it jumped teeth? If it jumped teeth, this would immediately retard valve timing. This increases the piston to valve clearance for the intake valves and decreases the clearance for the exaust. Intake valves are always larger than exhaust valves so they are at the most risk. Say you jumped 180 on the driver cam, this will retard the cam, and cause all your symptoms, but since the cam is retarded, there is more intake valve clearance. This only works out in your favor if the cam didn't spin 360 or more. And you may have kissed valve to piston anyways. Hot steel valves vs hot aluminum can put a good mark in the piston but still leave the valves and piston relatively ok, it all depends on how much interference there is. You can check by scoping through the spark plug hole. Some people get lucky when a belt snaps in half because all the valves stop and aren't at max lift. Let's fully diagnose this before we call this 2uz-fe interference engine a myth.
 
Oh man, this does make sense. But to be honest the passenger side was off by 30 degrees too when lining up the crank from what i recall and you can see the pic, the driver side is more like 270 degrees. Either way, with me troubleshooting for days by running it like a dog before finding out it was the timing kind of proves its barely interfering



Phils4th said:
I'm glad your engine is ok. This is good tech info but I have some questions since it's hard to go out on a limb and say there is no interference when so much data suggests that it is an interfering eng. You had to physically rotate the drivers cam to line everything up? A true 180*? Maybe I'm blind but I see belt teeth throughout the whole belt. But something made it run like poop, so it jumped teeth? If it jumped teeth, this would immediately retard valve timing. This increases the piston to valve clearance for the intake valves and decreases the clearance for the exaust. Intake valves are always larger than exhaust valves so they are at the most risk. Say you jumped 180 on the driver cam, this will retard the cam, and cause all your symptoms, but since the cam is retarded, there is more intake valve clearance. This only works out in your favor if the cam didn't spin 360 or more. And you may have kissed valve to piston anyways. Hot steel valves vs hot aluminum can put a good mark in the piston but still leave the valves and piston relatively ok, it all depends on how much interference there is. You can check by scoping through the spark plug hole. Some people get lucky when a belt snaps in half because all the valves stop and aren't at max lift. Let's fully diagnose this before we call this 2uz-fe interference engine a myth.
Click to expand...


Oh man, this does make sense. But to be honest the passenger side was off by 80-90 degrees too when lining up the crank.
 
Wow! I've been looking high and low for a 4th gen V8 because the price/performance on a 5th gen left me very unimpressed but this right here has me scared of buying a 4th gen V8.
I've even heard of a bad pulley causing a V8 to become trash.
I'm sure the chances of this happening are probably 1 in a 1000 but in my head that 1 will happen to me.
What was Toyota even thinking making this an interference engine?

Sent from my XT1650 using Tapatalk
 
The point of this post is NOT to scare you but to make you feel better about owning a v8.

this was the owners fault for bad maintenance. but even after the disaster, the engine RUNS GREAT. so you should buy a v8 without question.

sr5owner? said:
Wow! I've been looking high and low for a 4th gen V8 because the price/performance on a 5th gen left me very unimpressed but this right here has me scared of buying a 4th gen V8.
I've even heard of a bad pulley causing a V8 to become trash.
I'm sure the chances of this happening are probably 1 in a 1000 but in my head that 1 will happen to me.
What was Toyota even thinking making this an interference engine?

Sent from my XT1650 using Tapatalk
Click to expand...
 
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