ClubWRX Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1 (Edited)
SHORT VERSION - My 2.0 EJ20 developed a mechanical knock/rattle sound (not pinging/detonation) and doesn't want to idle. Anything I can do/check before tearing down the motor?

FULL VERSION - I was out in my Subaru turbo dune buggie today and was not running hard, when I had a problem with the engine. When I ran up the RPM's I heard a medium loud noise (or rattle) that I thought sounded a lot like a rod or bearing knock. I heard the noise a couple of times and pulled to over to check it out. When I came to a stop the engine would not idle and stalled. When I tried to restart it cranked a little hard and fired, but would not idle unless I applied some throttle. I proceeded to limp home for a couple of miles trying to keep the rpm's under 2000. The engine did not miss on the way home, but if I raised the rpms I started to hear the knocking sound (which sounded like a rattle on deceleration). When I came to a stop the engine would stall.

Here is all that is known about my motor (I was not the owner during the build)

* 2.0 EJ20 long block (exact year & model unknown, assume late 90's JDM)
* Subaru factory turbo
* Outback intake and exhaust
* no intecooler
* tuned for 8 psi low boost, 12 psi high boost on 111 octane leaded
* 2 years since installation
* Super low mileage since install - 85% road, 10% hardpack, 5% sand
* Have heard detonation once or twice in the past, even when running 111
* I usually run with the dial-a-boost down, keeping boost below 10 psi
* I occassionaly run 91 octane when cruising around town, and turn the boost down to 5-6 psi max.

When I got home I determined the following:

*coolant level was normal
* drained some coolant and it looked fine
* oil level looked high
* drained some oil and it appeared to be thinner than normal (maybe just hot?)
* I could not detect any metal in the 10 oz (or so) of oil I drained.
* oil did not appear to have water in it.
* pulled all 4 spark plugs and they looked dry and burning properly
* no sign of external leaks on abnormalities on the engine
* restated the engine when cooler, and still did not want to idle without extra throttle
* didn't rev the engine much on restart and didn't hear the noise
* couldn't check the compression yet, need to get gauge tomorrow


Last time I used the car was in the dunes. Thinking back I remember that I accidentally buried the tach running up a large hill. Never did that before, but the car ran fine the rest of the day after the red-lining.

I know it hard to diagnose a motor without tearing it down, let alone over the internet, but hear are my questions.

1) Are there any other useful diagnostic steps I can take before tearing down the engine? i.e. Oil pressure? Drop the oil pan and look for metal? Oil analysis? (I'm going to do a compression tomorrow).

2) Is there anything else to check other than engine internals? i.e. If my timing suddenly went off, could I hear a mechanical knock/rattle? (not a pinging sound, more mechanical)

3) If I was running too much boost or timing, what is the typical failure mode for these engines? i.e rod bearing, main bearing, broken ring etc?

4) If I overeved the engine what is the typical failure mode? i.e spun main bearing, rod bearing etc?

5) From what I've heard it's cheaper to get a new short block or used JDM long block than trying to rebuild the bottom end. Does that sound correct?

6) What do I need to check to see if I can bolt my 2.0 heads, manifolds, etc onto a 2.5 short block? Will I need bigger injectors or turbo if I am shooting for 300HP (or less) on 91 octane?

Thanks to anyone can assist.

Sorry this got so long but I'm taking my frustrations out by pounding on this keyboard:mad:
 

·
Premium Member
Joined
·
11,095 Posts
I assume a compression test will tell you that one cylinder is probaly really low.

What are you using for engine managment? What are you using to raise/lower boost? Just a MBC?

Can you actually get some kind of engine code off of the motor?


And it's usually cheaper to get a shortblock and go from there. You can get a Subaru shortblock (2.5 liter) for around 1600-1800. The 2.0 should be close to that price.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #3
I assume a compression test will tell you that one cylinder is probaly really low.

What are you using for engine managment? What are you using to raise/lower boost? Just a MBC?

Can you actually get some kind of engine code off of the motor?


And it's usually cheaper to get a shortblock and go from there. You can get a Subaru shortblock (2.5 liter) for around 1600-1800. The 2.0 should be close to that price.
Thanks for the reply.

I just pulled my valve cover and found that the left side exhaust cam sprocket has jumped a tooth on the belt.

I looking online now for timing belt alignment instructions for the best way to re-align the sprocket.

After I get the sprocket re-aligned, I going to check compression for any damage to the valves.

FWIW - I'm running a Micotech ECU with a custom (dyno-tuned) map. The boost is variable via a rheostat controlled the waste gate.

Thanks again!
 
1 - 3 of 3 Posts
Top