Reply from SOA about interference engine.....
 

The following is the reply I received from SOA about whether or not the svx is an interference engine or not...

Dear Derek:

Thank you for visiting the Subaru Web site and for your inquiry. The
EG-33 engine that is used in our SVX models is an interference engine.

Thanks for the opportunity to be of assistance. If you need any future
assistance, please feel free to contact us again.

Best wishes,

John J. Mergen
Subaru of America, Inc.

Re: Reply from SOA about interference engine.....
 

And this is John's first day at Subaru?????

Considering my 2nd SVX snapped a timing belt on the freeway at 80MPH without any damage other than the belt and a wound up idler, I beg to differ with John.

Doug

I agree with Doug
 

I'll have to check my Subaru shop manual when I get home but at this point I'm 95+% sure that it is a non interference engine.

Jay

thats what i thought and heard from everyone on here and also in the dayco belt guide of interference engines the svx is not listed..Nor for that matter is any subaru....kinda odd

other subarus
 

I'm not sure about the newest engines or the turbo ones but as far as I know all Subaru engines are non interference. Of course if I were to work on one I'd check the book first but like I said, as far as I'm aware, they are all non interference.

Jay

Re: Re: Reply from SOA about interference engine.....
 

John has been there for quite some time. I've gotten emails from him before. Maybe 5 years?:D

Re: Re: Re: Reply from SOA about interference engine.....
 

Yeah, I've gotten emails from John before.

I wonder if there's not something weird going on here - like maybe some of Subaru's engines (like the EG33)are non-interference, but for some reason they now have a policy to treat them as interference designs.

A number of factors come into play here, most notably CYA. An engine's pistons can have valve reliefs to allow clearance but over time can collect carbon and become an interference engine. Advanced bearing wear coupled with high rpm could also allow collision in some circumstances. Head gaskets having been replaced and having the head machined adds to the brew. Subie wouldn't be the first to adapt a new stance on the subject, there are other OEs doing the same.

They are considered a interferance engine because IF the gears that drive the upper cams break a tooth the intake and exhaust valves can come in contact with each other(ala warped valves) but not contact to the pistons.
I don't think you'll have to worry about the gears stripping...but it is possable.

The newer DOHC engines have a belt that drives all 4 cam pulleys, so if they break a belt they will warp the valves, so they atre an interfeance engine also.

All the SOHC Subaru motors are non-interferance (and I consider the SVX motor non-interferance, as the chance of stripping the gears is VERYYYYY slim)

I would think that something pretty catastrophic would have to happen for the cam gears to strip. Your heads would likely be wrecked, so who cares if you crash the valves into the pistons?

Maybe you should ask him more directly about the problem like( if my timming belt broke would the piston hit the valves?)


I do remember that the 2.5's were originally not considered interference engines, but then when unmaintained ones were snaping belts and smashing the valves together they called them interference motors. Usually interference means the piston comes in contact with the valve, but as new modern head designs are made so are the rules. I'm still sure the 3.3 is non-interference because i'v never hear other wise. Anybody want to pull of there T-belt and crank the motor over.

Already done it, when the Water pump siezed on mine and shreaded the t-belt...it being a 5-speed the momentem through the drivetrain kept the crank and pistons turning, till the car stopped, once I replaced the belt(and water pump and idler pulleys) she fired right back up, no damage what-so-ever to the valvetrain or pistons, and mine has 155k worth of built up carbon on the pistons.:eek:

An there ya go. Proof.