Interference or Non-Interference?

[LouDawg]

How can a person know whether his car is an interference or non-interference engine? I have an '07 Honda Accord EX-L with the 3.0 V6 and I've read through the manual at least twice as well as lots of online stuff. I don't recall seeing that, but I may have just missed it.

After reading the recent Hyundai post, it got me to thinking...

TIA!

 

[psudaytona]

Check here, they discuss alot of the tech aspects of the honda engines.
http://www.honda-tech.com/zeromain

 

[brianl703]

The Gates Rubber timing belt application catalog lists this information for engines with timing belts.

http://www.gates.com/brochure.cfm?brochure=2256&location_id=3487

 

[LouDawg]

Well, I did a search on honda-tech, but didn't find anything. The Gates web site, however, tells me that I do indeed have an interference engine. Guess I'm going to have to make sure I keep an eye on this timing belt. Thanks for the info, guys.

So why would a company even make an interference engine? There must be some advantage, right?

 

[The Critic]

Have fun with your 105k service. It's around $1k, last that I checked.

 

[Auto-Union]

Definately interference. Most cars are. Probally, anything over 9:1 compression is. Also, if you install high-lift cams in a non-interference engine it can interfere. I am currently grappling with a popped belt on MiL's V6 12v A6. Only got 70k out of the belt and the WP leaks too. Current situation is tht parts made from 2001-2004 are pretty junky and don't even last as long as the old original oems. Case in point, the TB/WP/Rad/Clutch are all original on my 1987 Audi Coupe 2.2 (I-5) 240k miles.

 

[Cutehumor]

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Case in point, the TB/WP/Rad/Clutch are all original on my 1987 Audi Coupe 2.2 (I-5) 240k miles.

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[Shannow]

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So why would a company even make an interference engine? There must be some advantage, right?

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There's only so much acreage inside a combustion chamber to get valves and stuff in. So the valves tend to be as big (or as many) as they can get in.

To get adequate compression, and efficiency, the "pancake" shape of the chamber has to be as shallow as possible (overly simplified, as shape means a lot).

This brings the valves close to the pistons, and oft ends up with the two occupying the same space, but at different times in the stroke.

 

[LouDawg]

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Have fun with your 105k service. It's around $1k, last that I checked.

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Yep...I heard $1200-1300 most recently. Ughhh.

 

[LouDawg]

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So why would a company even make an interference engine? There must be some advantage, right?

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There's only so much acreage inside a combustion chamber to get valves and stuff in. So the valves tend to be as big (or as many) as they can get in.

To get adequate compression, and efficiency, the "pancake" shape of the chamber has to be as shallow as possible (overly simplified, as shape means a lot).

This brings the valves close to the pistons, and oft ends up with the two occupying the same space, but at different times in the stroke.

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Yes, now that I think about Auto-Union's comments about compression and what you said, it all makes sense now. This engine has a 10:1 compression ratio.

 

[Auto-Union]

Oversquare engines with a longer stroke would tend to be another exception.

 

[Axe Man]

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The Gates Rubber timing belt application catalog lists this information for engines with timing belts.

http://www.gates.com/brochure.cfm?brochure=2256&location_id=3487

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And not 100% accurate. It lists a Kia Sportage with the Mazda DOHC FE engine as an interference design. It is not. You can break a timing belt on this engine and no damage will occur. That's been confirmed numerous times from unlucky owners who broke a belt.

 

[Drew99GT]

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Oversquare engines with a longer stroke would tend to be another exception.

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http://en.wikipedia.org/wiki/Oversquare

 

[Rand]

Well hyundai 1.6L's sure are interference. my gf's 01 accent just busted a belt at 98k miles.. cost 870$ bent number 2 cyl. valves
Dont have it back yet so that might not be the final bill.

 

[Mokanic]

Your Honda will run easily to 105K on the original belt. I don't know what dealers are getting to do this belt. My shop gets about 600$ total for a V-6 Accord. That includes genuine Honda t-belt,water pump,hyd.tensioner,and new accessory drive belts as well as coolant. It's not a particularly difficult engine to do and is tough as nails with normal maintenance. Honda has had interference engines for ages and they give little trouble except for those that refuse to service them.

 

[The Critic]

No way, how do you survive? $600 only?

My sources tell me that labor alone for a Honda V6 (Timing Belt and Water Pump) is 5 hours at $100/hr (most shops).

You do a valve adjustment at 105k as well, right?

 

[Mokanic]

I live in rural N.C. It is quite a bit different from Cali as far as the cost of living goes. Most dealers here are on the 60-75$/hr. range but will lowball the snot out of a customer to get them in the shop.

 

[gedcruise]

Locally, the stealer wants $680.00 for the V-6, and $610.00 for the 4 cyl Accord. You can do it yourself, of course, but certain engines require certain seal replacements, which, say, a Haynes or Chilton probably won't mention, so be forewarned.
You can also find indies who will do it cheaper. This is not a bargain unless they use OEM parts, and can actually do the work well enough that your new T-belt lasts another 105K.

 

[gedcruise]

Mokanic,
You seem pretty savvy, so I'll ask you.
I've owned Hondas for ages, and am well aware that you don't even want to think about a broken T-belt.
However, I have heard here and there that, while both are interference engines, with a Civic, a failed belt will result in bent valves at the least, while with an Accord 4cyl, you may simply experience the sudden death of engine output, but no mechanical damage.
Now, this is not a theory I have tested, or intend to test, but have you heard any such thing?