98 Forester interference engine?

[SoCal LS-L]

Last night one of my boss' friends towed in their 98 forester, when its started the engine makes a loud clanking sound, almost like rod knock. He verified that the timing was slightly off........ so is this engine interference type? Its the 2.5 liter on a 98 Forester.... thanks guys.

[Manarius]

Originally Posted by SoCal LS-L

Last night one of my boss' friends towed in their 98 forester, when its started the engine makes a loud clanking sound, almost like rod knock. He verified that the timing was slightly off........ so is this engine interference type? Its the 2.5 liter on a 98 Forester.... thanks guys.

Yup. He's got pistons running into valves.

[svxcess]

.

Through 1996, all SOHC EJ251 engines were non-interference engines. They were run by a single timing belt driving both cams on both sides of the engine, and the water pump.

Because they were non-interference engines, if the timing belt failed, these engines would not be destroyed. The oil pump was driven directly from the crankshaft and the water pump by the timing belt.

Beginning in 1997, all DOHC and SOHC EJ engines are interference engines. If the timing belt fails, the engine will likely be destroyed or the valves and pistons will be heavily damaged.




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[Green1995SVX]

Those are the worst engines subaru ever made.

[svxcess]

We were so happy with the 3.0 flat-six engine on our Outbacks. They had timing chains which never needed replacing and were non-interference.


Looks like our new 2010 Outback 2.5 will need watching again in this area. At over 50,000 miles a year, the recommended replacement interval will be here before I know it.

.

[SoCal LS-L]

Apparently according to the tech that redid the head gaskets, the timing is on, the belt didnt slip..... however the engine sounds horrible when started, similar to rod knock.... and apparently hes also claiming that the oil is ok and full.

What could possibly cause so much internal engine damage if the timing is correct and the oil level is ok?

[Thursday23]

A leak-down test should let you know if you have at minimum bent valves.

Oil level/condition not being the same as oil pressure, you could still have some oil starvation up top in valve train.

Of course, very possible to 'float' a valve on a missed shift as well.

Depending on how recent the head gasket work was, might be worth verifying timing isn't off. Technicians can be reluctant to admit mistakes at times. Lining the cams up to the wrong mark(s) when reinstalling the timing belt after head work is not impossible.

And add to that, if the head work did require re-surfacing/decking the head, the clearance between the valves and pistons is reduced, a very small amount for sure, but reduced all the same. Add to that either an over-rev or a timing error, plus valve spring which could be a little fatigued, very possible you start bending valves.

But, to answer your question, if a valve did bend due to over-rev you could possibly get a misfire code p03xx, if you have the ability to also check the freezedata when it set, you might see elevated engine speed. Typically the misifre wouldn't trigger at the first misfire detection, but you might still see a 7000+ rpm with a vehicle speed of 50-60mph (the typical missed 5-4 shift speed) through a few subsequent triggers.

Since it sounds like you have a horse in the race on this one, if your leak down test confirms a bent valve, and you've confirmed timing is still on, I'd explore a possible overrev.

[Manarius]

Originally Posted by svxcess

.Through 1996, all SOHC EJ251 engines were non-interference engines. They were run by a single timing belt driving both cams on both sides of the engine, and the water pump.

All the EJ25's are interference. You won't find any that aren't.

[svxcess]

You are correct.

I was thinking of the earlier EJ22 2.2 L Phase I engines. The little 4-bangers had 137 hp, and had dual exhaust ports, which made them non-interference.

Later in production, 1995-1996, the late Phase I EJ22 was reconfigured for a single exhaust port, making it an interference engine.

This continued into the EG22 Phase II engines, until replaced with the EJ25.

.

[Manarius]

Originally Posted by svxcess

You are correct.

I was thinking of the earlier EJ22 2.2 L Phase I engines. The little 4-bangers had 137 hp, and had dual exhaust ports, which made them non-interference.

Later in production, 1995-1996, the late Phase I EJ22 was reconfigured for a single exhaust port, making it an interference engine.

This continued into the EG22 Phase II engines, until replaced with the EJ25.

.

Actually, the original phase 1 EJ22's had 130hp/137ft-lb torque. SOHC non-interference. Mid 1996-beginning 1997 MY, the EJ22 was refitted with reshaped piston crowns, slightly raising the compression ratio. Raising the HP to 137hp/142-143ft-lb torque. With this reshaping came the interference design. Along with this came the single port exhaust. However, some phase 1's in mid 1996 have been known to have come with the single port exhaust, so that's not a good signifier of interference or not.

[svxpert]

and the SOHC 2.5 wasnt out till 1999

[svxpert]

Originally Posted by Manarius

All the EJ25's are interference. You won't find any that aren't.

Originally Posted by svxcess

We were so happy with the 3.0 flat-six engine on our Outbacks. They had timing chains which never needed replacing and were non-interference.


Looks like our new 2010 Outback 2.5 will need watching again in this area. At over 50,000 miles a year, the recommended replacement interval will be here before I know it.

.

How come you didnt go with the 3.6 liter? I have one in my Tribecca, runs strong on regular fuel too!

[Manarius]

Originally Posted by svxpert

and the SOHC 2.5 wasnt out till 1999

True. This is the EJ25 that does NOT have the typical HG problems of the early EJ25's.

[SoCal LS-L]

Can someone explain to me why having a single exhaust port would make an engine more likely to be interference?

I get the concept of interference and non-interference..... the piston having a stroke that allows it to contact fully open valves.... but what are some of the other factors?

( I like to sound like I know what im talking about at work )

[Hocrest]

The exhaust ports have nothing to do with interference, other than the coincidental change at about the same time as the non-int/int change