Interference Engine

S

sandp500index

New member
When I asked my Toyota dealer about the timing belt and if it should be changed....he said I should change it. (45,000 miles on the vehicle...it is 2004) So I was prepared to fork over about $650.

I am not sure where I read this on-line....but I remember seeing that the 4Runner is an interference engine. I have been trying to find a more official source (something from Toyota would be great) telling me if my 2004 V8 4Runner has an interference engine or not.

I couldn't find anything official on-line. So I called a different local Toyota dealership. I talked to a woman in service. She said I have a NON-interference engine....so no reason to change it yet....unless I want to go by the Toyota recommendation of 90,000 miles OR 6 years.

I asked about my 2003 Sienna (100k miles) as well....she said NON-interference also.


Can anyone with certain knowledge confirm both cars are NON-interference. Any help is much appreciated.
 
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Interference

The V8 4Runner engine is an interference engine with a timing belt change interval of 90,000 miles.

Don't get too caught up in the interference/non-interference though... The main difference there is if/when the belt would fail wether or not the valves could contact the piston and cause some real $$$ problems.

(see images on this page) Gates Timing Belts

Interference, non-interference ... doesnt really matter unless you want to get stranded somewhere with a truck that wont run, either one requires replacing the timing belt (if so equipped) at its proper change interval.
 
If the belt or chain fails on an interference engine, the pistons and the valves try to occupy the same space at the same time. Replacing valvetrain parts is very expensive.
 
sandp500index said:
I couldn't find anything official on-line. So I called a different local Toyota dealership. I talked to a woman in service. She said I have a NON-interference engine....so no reason to change it yet....unless I want to go by the Toyota recommendation of 90,000 miles OR 6 years.
Click to expand...

You've got me intrigued on the "6 years" portion of the above. According to the PDF on the owners website for my '06, it says the below (copied and pasted from the PDF below). 108 monts = 9 years. I am only at 34k on my '06 and was going to wait another 4 years or so. Should I change it sooner then? Does the '04 have a shorter interval?


2006 4Runner 90,000 Miles - 108 Months

q Replace engine oil and oil filter1
q Rotate tires
q Lubricate propeller shaft (4WD)
q Replace spark plugs6
q Replace timing belt7
q Re-torque propeller shaft bolt
q Replace engine air filter
q Replace cabin air filter (if equipped)
q Inspect the following:
__ Automatic transmission fluid
__ Ball joints and dust covers
__ Brake lines and hoses
__ Brake linings/drums and brake pads/discs8
__ Drive belts
__ Drive shaft boots (4WD)
__ Engine coolant9
__ Exhaust pipes and mountings
__ Front differential oil (4WD)
__ Fuel lines and connections, fuel tank band and fuel tank vapor vent system hoses
__ Fuel tank cap gasket
__ Radiator core and condenser
__ Rear differential oil
__ Steering gear box
__ Steering linkage and boots
__ Transfer case oil (4WD)
Additional Maintenance Items for Special Operating Conditions:
Driving While Towing
q Replace front differential oil (4WD)
q Replace rear differential oil, including limited-slip
q Replace transfer case oil (4WD)
q Tighten nuts and bolts on chassis
Driving in Desert or On Dirt Roads
q Tighten nuts and bolts on chassis
Applicable Footnotes:
1) Reset the oil replacement reminder (“MAINT REQD”) light after replacing engine oil, if vehicle is equipped with this light.
6) Applies to 4Runner with 1GR-FE. Required under the terms of the Emission Control Warranty.
7) Applies to 4Runner with 2UZ-FE.
8) Inspect thickness measurement and disc runout.
9) See Maintenance Definitions (Engine Coolant) for details.
 
Ducman said:
Don't get too caught up in the interference/non-interference though...
Click to expand...

I disagree.

If you lose a timing belt on a non-interference engine, you have to get towed to get your timing belt replaced.

If you lose a timing belt on an interference engine, you have to get towed to get your timing belt, valves, and pistons (and prolly much more) replaced.
 
Barefoot said:
I disagree.

If you lose a timing belt on a non-interference engine, you have to get towed to get your timing belt replaced.

If you lose a timing belt on an interference engine, you have to get towed to get your timing belt, valves, and pistons (and prolly much more) replaced.
Click to expand...

If you read my entire post my point was don't get too caught up when trying to determine WHEN to change the belt. Interference or not, change it at its recommended interval.
 
Ducman said:
If you read my entire post my point was don't get too caught up when trying to determine WHEN to change the belt. Interference or not, change it at its recommended interval.
Click to expand...
With a noninterference engine, you can risk having the timing belt break -- the only added expense is the tow.

With an interference engine, you really can't risk the timing belt breaking - the added cost for repair is freaking huge
 
Or

M1911 said:
With a noninterference engine, you can risk having the timing belt break -- the only added expense is the tow.

With an interference engine, you really can't risk the timing belt breaking - the added cost for repair is freaking huge
Click to expand...

Or the potential loss of life if you just happened to be crossing multiple lanes of traffic when the belt breaks.

I understand what you are saying.. yes having a belt fail on an interference engine is bad and expensive, I mentioned that as well... Going beyond the recommended interval is taking unnecessary risk is all I'm saying.
 
stanleybb50 said:
You've got me intrigued on the "6 years" portion of the above. According to the PDF on the owners website for my '06, it says the below (copied and pasted from the PDF below). 108 monts = 9 years. I am only at 34k on my '06 and was going to wait another 4 years or so. Should I change it sooner then? Does the '04 have a shorter interval?


2006 4Runner 90,000 Miles - 108 Months

q Replace engine oil and oil filter1
q Rotate tires
q Lubricate propeller shaft (4WD)
q Replace spark plugs6
q Replace timing belt7
q Re-torque propeller shaft bolt
q Replace engine air filter
q Replace cabin air filter (if equipped)
q Inspect the following:
__ Automatic transmission fluid
__ Ball joints and dust covers
__ Brake lines and hoses
__ Brake linings/drums and brake pads/discs8
__ Drive belts
__ Drive shaft boots (4WD)
__ Engine coolant9
__ Exhaust pipes and mountings
__ Front differential oil (4WD)
__ Fuel lines and connections, fuel tank band and fuel tank vapor vent system hoses
__ Fuel tank cap gasket
__ Radiator core and condenser
__ Rear differential oil
__ Steering gear box
__ Steering linkage and boots
__ Transfer case oil (4WD)
Additional Maintenance Items for Special Operating Conditions:
Driving While Towing
q Replace front differential oil (4WD)
q Replace rear differential oil, including limited-slip
q Replace transfer case oil (4WD)
q Tighten nuts and bolts on chassis
Driving in Desert or On Dirt Roads
q Tighten nuts and bolts on chassis
Applicable Footnotes:
1) Reset the oil replacement reminder (“MAINT REQD”) light after replacing engine oil, if vehicle is equipped with this light.
6) Applies to 4Runner with 1GR-FE. Required under the terms of the Emission Control Warranty.
7) Applies to 4Runner with 2UZ-FE.
8) Inspect thickness measurement and disc runout.
9) See Maintenance Definitions (Engine Coolant) for details.
Click to expand...

My 2003 was supposed to be changed at 6 years. Sometime in 05 or 06 it got changed to 9 years. There is a newer part number on the Toyota timing belts so maybe they changed the belt design or realized it could go 9 years and not need changed at 6 years. I replaced mine with the newer part number and will go 9 years on it.
 
I would change it due to age Alone ....If it Breaks and your Somewhere Good Your gonna be hatin it ! I Had one break on a non Toyota and its a real pain to get it towed get a ride a service loaner, wait for repair, pick up vehicle etc. . But this should be done for reliability and peace of mind as well.
 
teampwr2 said:
I would change it due to age Alone ....If it Breaks and your Somewhere Good Your gonna be hatin it ! I Had one break on a non Toyota and its a real pain to get it towed get a ride a service loaner, wait for repair, pick up vehicle etc. . But this should be done for reliability and peace of mind as well.
Click to expand...


I rarely drive my car more than 1 hour away from home. I am more than willing to take the risk of a breakdown. My concern is only about taking a chance on major $$$ for repairs if it is an interference engine. I don't have $650 bucks to spend "just in case."

I just wrote a $3,000 check for braces on my kid and I still have 3 other kids that need braces.
 
Usually when a timing belt goes, you're looking at more than a broken belt regardless of engine type. Water pumps seizing are the most common way that those belts get torn up.

Every engine had the potential to be an interference engine. Especially these modern high comparison engines. The valves often barely clear the piston as is on a non interference engine. Add in wear and tear and so on and you're looking at bent valves anyways. Just because an engine is designated non inference does not mean it can't grenade like an interference engine, its just less likely under those conditions.
 
Last edited:
BlackWorksInc said:
Usually when a timing belt goes, you're looking at more than a broken belt regardless of engine type. Water pumps seizing are the most common way that those belts get torn up.

Every engine had the potential to be an interference engine. Especially these modern high comparison engines. The valves often barely clear the piston as is on a non interference engine. Add in wear and tear and so on and you're looking at bent valves anyways. Just because an engine is designated non emergence does not mean it can't grenade like an interference engine, its just less likely under those conditions.
Click to expand...

I have been glad since you joined. You have great info to share, and its been very helpful. Especially since people get these ideas in their head and think theyre right without checking facts. I love the internet and hate it at the same time. Its full of information, you just have to be smart about looking.
 
BlackWorksInc said:
Usually when a timing belt goes, you're looking at more than a broken belt regardless of engine type. Water pumps seizing are the most common way that those belts get torn up.

Every engine had the potential to be an interference engine. Especially these modern high comparison engines. The valves often barely clear the piston as is on a non interference engine. Add in wear and tear and so on and you're looking at bent valves anyways. Just because an engine is designated non inference does not mean it can't grenade like an interference engine, its just less likely under those conditions.
Click to expand...

Thanks for the help....this makes sense to me. Looks like I will be replacing the timing belt very soon.
 
sandp500index said:
Thanks for the help....this makes sense to me. Looks like I will be replacing the timing belt very soon.
Click to expand...

Sorry I didn't get back to you sooner, been busy with personal stuff and didn't get the chance to check TIS for what they say officially. But personally, modern engines are built far more compact than the old school 5.0's we grew up with. The tolerances are tighter and the combustion chambers are smaller and tighter. Most of the so called non interference engines use small relief cuts that barely clear the piston and valves, 3MZFE is an example.

Stick with the factory recommended interval and you should be good!
 
FYI:

2UZ-FE broken timing belt - Google Search

I'm having a hard time finding a first hand account of a broken timing belt at all. So it is that much more difficult to find someone who has had their engine destroyed as a result thereof.

The 4.7 IS an interference engine, everything I've read says it is. I know it is on the internet, but I'll trust it.
 
I live in the desert and I have always been told 90k or 6 years, whichever is first due to the dry climate and the risk of the belt breaking sooner. Can anyone else support this? 9 yrs seems like a stretch to me.
 
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