95.5-2004 Tacomas & 96-2002 4Runners 4th gen pickups and 3rd gen 4Runners

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Old Apr 24, 2008 | 08:02 AM
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98crazyrunnerJE's Avatar
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From: P.A.
engine question

I was just wondering if the 3.4 liter V6 engines are a interfierance or a non interfierance engine.
any help would be great thanks guys
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Old Apr 24, 2008 | 08:32 AM
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From: 5th Gen San Diegan, California
I'm assuming you're asking if its a direct timing gear or not?

The 3.4 timing belt, oh and I see what your asking...

No, it won't blow up if it breaks...

I think many people tend to wait until the belt breaks before changing it out actually.

Last edited by BajaRunner; Apr 24, 2008 at 08:34 AM.
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Old Apr 24, 2008 | 09:16 AM
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From: P.A.
Ok thanks that put me at ease a little becasue it needs doing, I just dont have enough money to get it done yet
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Old Apr 24, 2008 | 09:43 AM
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From: DFW TEXAS BABY!
Along these line, one thing i have always woundered is since the 3.4l is a non interfierance engine, can it be over reved?

Yes i know it CAN be i am talking other than just reving so high it it blows up.

Example, once i reved mine to over 6k (or 1k over redline, what ever that is) by mistake expecting the rev limiter to kick in (i guess it doesn't have one) but it never did. have always woundered if that hurt soemthing/if it could.
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Old Apr 24, 2008 | 10:52 AM
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The 3.4 is an interferance motor
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Old Apr 24, 2008 | 11:11 AM
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Everything I have read says it is NOT an interference motor...
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Old Apr 24, 2008 | 11:21 AM
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Originally Posted by fillsrunner4
The 3.4 is an interferance motor
Check your facts bud...its a non-interference engine. Like SC said, it won't harm anything if the timing belt breaks.

Originally Posted by Texas_Ace
Along these line, one thing i have always woundered is since the 3.4l is a non interfierance engine, can it be over reved?

Yes i know it CAN be i am talking other than just reving so high it it blows up.

Example, once i reved mine to over 6k (or 1k over redline, what ever that is) by mistake expecting the rev limiter to kick in (i guess it doesn't have one) but it never did. have always woundered if that hurt soemthing/if it could.
I mean, I don't know for a fact that it could harm something but I sure would imagine if done enough times it could. Heat build up and such. Personally, I wouldn't worry about it...because...well...these are work horses and off-road machines...not race cars. I'm not sure I understand how you ACCIDENTLY revved the engine to 6-7k rpms. Generally, if I do that by mistake...I realize I'm not in gear by 3k rpms at the highest...so if you have your foot on there too long to the point of redlining it...well honestly...then you might deserve a little bit of engine trouble.

Sorry man but its true...back on topic though....like I said above..non-interference...
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Old Apr 24, 2008 | 11:21 AM
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From: DFW TEXAS BABY!
Originally Posted by mjwalfredo
Everything I have read says it is NOT an interference motor...
Ditto.
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Old Apr 24, 2008 | 11:26 AM
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From: DFW TEXAS BABY!
Originally Posted by Skrillah
Check your facts bud...its a non-interference engine. Like SC said, it won't harm anything if the timing belt breaks.



I mean, I don't know for a fact that it could harm something but I sure would imagine if done enough times it could. Heat build up and such. Personally, I wouldn't worry about it...because...well...these are work horses and off-road machines...not race cars. I'm not sure I understand how you ACCIDENTLY revved the engine to 6-7k rpms. Generally, if I do that by mistake...I realize I'm not in gear by 3k rpms at the highest...so if you have your foot on there too long to the point of redlining it...well honestly...then you might deserve a little bit of engine trouble.

Sorry man but its true...back on topic though....like I said above..non-interference...
LOL, it was an acident because it happend on a rainy day when the roads were slick. So i decided to have some fun fishtailing on an emplty parking lot. Well i got a good slide going and kept the gas to the floor thinking the rev limiter would kick in. But it never did and I looked down to see it 1k over redline.

I got thinking and i know tha tthe biggest danger to an engine over reving is the valves getting bent. Then the bottom end flying apart.
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Old Apr 24, 2008 | 11:30 AM
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From: Bloomington,Indiana
Originally Posted by Texas_Ace
LOL, it was an acident because it happend on a rainy day when the roads were slick. So i decided to have some fun fishtailing on an emplty parking lot. Well i got a good slide going and kept the gas to the floor thinking the rev limiter would kick in. But it never did and I looked down to see it 1k over redline.

I got thinking and i know tha tthe biggest danger to an engine over reving is the valves getting bent. Then the bottom end flying apart.
Yeah...that sounds about right....
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Old Apr 24, 2008 | 12:19 PM
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From: DFW TEXAS BABY!
Originally Posted by Skrillah
Yeah...that sounds about right....
Your a lot of help...lol
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Old Apr 24, 2008 | 02:16 PM
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There is a rev limiter and it kicks in at 6k, you were probably still under that and just felt like it was close to 7k.
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Old Apr 24, 2008 | 03:33 PM
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From: DFW TEXAS BABY!
Originally Posted by pat161
There is a rev limiter and it kicks in at 6k, you were probably still under that and just felt like it was close to 7k.
What ever the red line is, it was right at 1k over that. I know because i looked down I freaked out that it was not only in the red line but WAY in the red line.

I will need to look at the Tach when i am out there and see what RPM that is again.
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Old Apr 25, 2008 | 07:15 PM
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Originally Posted by Skrillah
Check your facts bud...its a non-interference engine. Like SC said, it won't harm anything if the timing belt breaks.
Ive triple checked my facts and they prove that at least my year for some reason is. Now that doesn't necessarily mean if you break or jump timing you interfere but its possible at a point you can. Not likely but possible
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Old Apr 25, 2008 | 07:24 PM
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From: DFW TEXAS BABY!
Originally Posted by fillsrunner4
Ive triple checked my facts and they prove that at least my year for some reason is. Now that doesn't necessarily mean if you break or jump timing you interfere but its possible at a point you can. Not likely but possible
Got any links please? I would like to see this info.
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Old Apr 25, 2008 | 07:40 PM
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From: Woodinville, wa
Originally Posted by Texas_Ace
Got any links please? I would like to see this info.
Its a transmission shop's service manual online. They are ASE certified, and one of the best Trans shops around.

Its just the facts ive seen on dealing with at least my 3.4 v6. I had head problems recently and found that my motor is an interference motor and i did have bent valves.

I cant say 100% that it is, but I have seen the facts that state that it is an inference motor and it comes from factory provided websites.
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Old Apr 25, 2008 | 07:44 PM
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From: DFW TEXAS BABY!
Originally Posted by fillsrunner4
Its a transmission shop's service manual online. They are ASE certified, and one of the best Trans shops around.

Its just the facts ive seen on dealing with at least my 3.4 v6. I had head problems recently and found that my motor is an interference motor and i did have bent valves.

I cant say 100% that it is, but I have seen the facts that state that it is an inference motor and it comes from factory provided websites.
Not saying you are wrong, would just like to see it for myself as up until now everything i have heard is that these are non-interference.

I really am curious myself.
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Old Apr 25, 2008 | 08:09 PM
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Yes, me too, I have always heard the 3.4 is non-interference. The 22r(e), on the other hand, is an interference motor.
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Old Apr 25, 2008 | 09:35 PM
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Ill try to get more info on the matter monday when I have a chance to visit the shop again. Im not 100% either
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Old Apr 25, 2008 | 09:38 PM
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To set things straight:

The 3.4 V6 is not an interference engine by design (pistons can touch valves).

I just finished rebuilding my 3.4 engine from the ground up and turning the crank without the timing belt on does not result in pistons touching valves, period. Not even close.

If you you are spinning past redline and manage to have valve float (worn or broken springs) then sure, it is a possibilty.

For the record, when I started the rebuild I did bump the engine around during the struggle to get the cam pulleys loose, and after I removed the belt and turned the crank it did indeed seem like the piston was now touching something in the number 1 cylinder on the compression stroke. Once I removed the heads I literally found a handful of loose carbon in most of the cylinders, enough to get lightly squeezed by the pistons. I obviously knocked it all off and onto the pistons.

http://i259.photobucket.com/albums/h...tsofcarbon.jpg
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