Interference Motors?

SUBYDAZZ · Post by **SUBYDAZZ** » Sat Sep 18, 2010 2:01 pm

Just wanted some info on what Subaru engine are interference types. ie; when the timing belt breaks the valves will hit the pistons.

I know the EA82 isn't.

I'd specifically like to know which EJ25s are, for example, whichever one comes in a 2002 RX Liberty...

Pootcrum · Post by **Pootcrum** » Sat Sep 18, 2010 2:36 pm

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

From there:

The SOHC EJ Subaru boxer engines were non-interference engines through 1996, run by a single timing belt driving both cams (both sides of the engine) and the water pump.

I was curious about this a couple weeks ago myself and couldn't find more information than that when I did research.

Gannon · Post by **Gannon** » Sat Sep 18, 2010 2:41 pm

As far as i know...

EJ20/EJ25 DOHC engines are interference
EJ20/EJ22/EJ25 SOHC made after 1997 are interference

EJ18/EJ20/EJ22 SOCH made before 1997 are non-interference

So if the timing belt on your SOHC EJ25 will cause your pistons a lot of pain if it breaks

RSR 555 · Post by **RSR 555** » Sat Sep 18, 2010 11:15 pm

From my experiance with EJ engines.. all are non-interference with pistons. It's valves that hit valves that causes damage. This will only happen on a DOHC EJ engine if a Timing Belt breaks. SOHC EJ's only have 1 camshaft so unless the camshaft snaps in 2 then valves will never touch. I've not played with any Gen 5 EJs so I can not comment on those

YouTube · Post by **El_Freddo** » Sun Sep 19, 2010 4:42 pm

RSR 555 wrote:From my experiance with EJ engines.. all are non-interference with pistons. It's valves that hit valves that causes damage. This will only happen on a DOHC EJ engine if a Timing Belt breaks.

This is what I've heard as well...

Cheers

Bennie

SUBYDAZZ · Post by **SUBYDAZZ** » Tue Sep 21, 2010 2:35 pm

I rang Subaru and am told that my SOHC model is an interference motor, that they initially thought that they were non interference, but they've had 2 come in that proved not to be. Ouch. Based on that they say they have to assume that they are an interference motor.

SUBYDAZZ · Post by **SUBYDAZZ** » Tue Sep 21, 2010 2:36 pm

I wasn't too sure about the wiki article on the EJ motors, just seems very US-centric. I'm pretty sure that at some stages and models we were getting different motors etc. in Aus delivered vehicles.

spike · Post by **spike** » Tue Sep 21, 2010 5:00 pm

interference motors usually are based on the piston and the valves, in which case there not interference motors.

but when the timing belt lets go the valve touch and thats all she wrote.
just remember if you ever have a broken timing belt to check everything adn redo timing when you put a new one on.
i know rally driver who build subaru who are happy to just put a new belt on adn keep going, not bother with the timing

SUBYDAZZ · Post by **SUBYDAZZ** » Fri Sep 24, 2010 12:44 pm

So if it's a SOHC how can the valves hit each other if a timing belt breaks?

Gannon · Post by **Gannon** » Fri Sep 24, 2010 6:11 pm

Its SOHC and has 4 valves per cylinder, but they are all driven by the same camshaft, so no, they cant touch each other.
But they can still hit the piston.

Im sure that it was only the pre 97 EJ22's that were non interference. All others will be damaged by timing belt failures

Either way,.. change the belt at the specified intervals and you wont have any worries