EJ25D Engine Noise (98 Legacy GT)

[eternalphoenix64]

So this thing has been a mystery recently....

 

Engine started to make a knocking noise that instigated a rebuild of the engine. COULD NOT FIND CAUSE.

 

Went away when we put it back together.

 

Got timing wrong by a LITTLE bit (like, one tooth on one cam) and caused a CEL. Got it fixed in a jiffy. Could have sworn we were dead on when we put it in though. Seemed like the driver's side was off by a half tooth between the two cams though. Couldn't be fixed....

 

Now the same knocking (it's not a BANG-BANG knock more of a TICK-TICK knock) noise is back. When I replaced the timing belt my dad (former flat rate mechanic with ~99% success rate) said that the tensioner was good and didn't need replacing. Could the original knock, CEL, and this knew "knock" all have actually been caused by a worn out tensioner allowing for just enough jump in timing that didn't damage the engine but caused a noise?

 

The two knocks BOTH came on when I was in the processes of decelerating for a continuous turn (both on freeway interchanges at different speeds).

[pginter96]

Does it knock on idle? Make any difference on cold starts?

Edited December 24, 2014 by pginter96

[pginter96]

Could just be a worn lifter. ticking-type knocks usually mean valvetrain, while harsher, louder, knocking means rods/crank/wrist pins.

Ive driven with lifter knock for over a year, no adverse effects. You could drive with piston slap as well. Of course its not recommended, but it wont severely damage anything. failed lifters simply wont open valves, and might beat up rocker shafts but if its to that point I would replace those anyways. Piston slap is... well, piston slap. not much can be done about it apart from a major overhaul.

 

How many miles?

[eternalphoenix64]

almost 275000 miles, just rebuilt the engine including checking the valves (they were good, no leaks). Does it at all engine speeds, engine temp makes no difference.

 

Is there a way to test whether or not the tensioner has gone bad?

[pginter96]

What condition were lifters/rockers/rest of the valvetrain? Because that's a lot of miles... especially on an EJ25D. They can make it there, but parts get worn and s**t breaks.

 

As you've stated before, if the timing belt jumped due to a bad tensioner, it would most likely throw a CEL.

best way to check a tensioner is to remove it and put it in a vice to re-compress it. It should take at least three minutes to compress, as long as you don't force it. If it compresses too fast/easily, its bad. personally, I would replace the tensioner and idlers whenever I do the timing belt, as they are the most common failure points. I can try to find the service info on it. I just glanced at it because I simply replaced my tensioner, however I know theres a procedure.

 

Have you checked engine oil pressure with a gauge?

 

EDIT: FORGET WHAT I SAID ABOUT THE 3 MINUTE THING, I FOUND SERVICE INFO

Edited December 24, 2014 by pginter96

[pginter96]

Here, straight from Subaru service info. This is for a 97 EJ25D, Tensioners SHOULD be the same, but Im not 100% positive. Procedure should still work.

 

[Gloyale]

Could just be a worn lifter. ticking-type knocks usually mean valvetrain, while harsher, louder, knocking means rods/crank/wrist pins.

Ive driven with lifter knock for over a year, no adverse effects.

 

Shim on bucket.  No lifters or rockers.  Solid no hydro.

 

So I doubt it's valvetrain nice.

[idosubaru]

yes tensioners can go bad and sound like rod knock.  remove the covers and start the engine.

the tensioner will be visibly bouncing around if it's bad enough to be "knocking".

or stethoscope it first and see if it's in that general area.

those tensioners are best replaced as maintenance, they fail often enough to warrant it for some people.

 

96 Ej25D's had HLA's right?  so if the engine was ever swapped in it's life...fairly common for EJ25's...it could have a low but reasonble chance of having HLA's?

if so - they can take awhile to shut up - how many miles since rebuild?

that sound should be notably one side if it's just one though.

[Fairtax4me]

Id agree with the bad tensioner theory. The tensioner on that engine is finicky and fails fairly often.

[Jack3m]

I am the Dad in this mess.  I am clueless at this point.  It is not valve train, DOHC and solids.  If we have any professionals here, I am in need big time,  Something very strange is causing this problem.  I am going to throw out all sorts of information here, possibly not in order.  I had 10 years front line in dealerships, knew my stuff, did it all, and was the problem child fixer.  I worked on Nissans, but 1980 was my last year in the profession.

 

Initial sound was exactly like a rod knock.  Sounded like RF cyl.  Engine running well, no missing, no other unusual sounds.  No signs of head gasket leak.  Oil pressure after rebuild 100 psi by gauge at the sending unit port.

 

Engine rebuild consisted of crank kit and pistons and rings....pistons had new Jesus clips. 

 

This went fine for a little after the rebuild then it had a ticking noise that turned out to be the timing had slipped on one side.  From one of the posts I am now certain the tensioner is weak, it is pretty easy to push and can do quickly.  BUT now with new noise that sounds similar to a rod knock ,but not if you know what I mean and running, the noise is behind the tensioner, either oil pump (new) or something at rods.

 

Now, on teardown, it needed bearings really, really badly, one of the worst I have even seen.  There were signs of the nuts on the con rods hitting the inside of the case in all cyls.  Not really bad, just noticed and thought the new bearings and crank would cure the issue. 

 

Con rods at torque were 0.00015,  Mains at just tightened, no torque was 0.0001~0.000125.

 

Also on initial tear down it looked like one cylinder had (at least at one time) had a lockwasher go through it.  We did not find anything that could have caused that.  The auto had not been recently worked on.

 

OF NOTE  Both times this car started making this noise was on a deceleration to make a turn.

 

Interestingly with all this, the valves have apparently not been hit as they are still okay and the engine runs fine. 

 

Oh ya, today when he first started it today, until the oil pressure built up, the knocking was not there.  Oil pressure made it show and very, very loud.

 

NOTE EDIT:  I don't know what you mean with HLA.  I am sure I will slap my forehead, but right now it is already pretty sore.

Edited December 24, 2014 by Jack3m

[Fairtax4me]

Hydraulic Lash Adjuster

 

Pull the timing cover and visually check the tensioner with the engine running. If it's making the noise it will be bouncing up and down like crazy.

[Jack3m]

Nope did not move at all, the noise is definitely down in deep.  I am wondering if a con rod is hitting the case again....but why?

[Gloyale]

Did you make sure to orient the pistons with the correct sides "up" and forward?  They are all marked but it's easy to get them mixed up.

 

These engine have offset wristpin pistons(1mm).  All pistons must offset to the same side of the rotation direction of the crank.  This is to prevent piston slap being so prevelant.

 

IF you got a piston in upside down it could cause some funkyness.  Slapping or perhaps even hitting the case.....the ends of these rods do run VERY close to the case(that's why the small 48mm rod bearings).  One of the things they changed in the Phase II blocks was opening that up so that 52mm rods could be used

[eternalphoenix64]

We put new pistons in. I was pretty sure the orientation was correct, but just in case we need to get into it that deep as we tear it apart, how can we verify that?

[Jack3m]

The new pistons came with only dots on one side all were oriented to the front of the engine on assembly.  But we got at least 50 miles before any sound like this and the point of deceleration starting the noise is just bugging the heck out of me. 

 

Very frustrated, no idea what to do even by tearing it down without a known issue to look for, I expect to see the nuts on the con rods have been hitting again, but will be hard to tell if new or old as I didn't do anything to the marks before re-assembly.

Edited December 26, 2014 by Jack3m

[Gloyale]

If all the dots were forward then the pistons should be correct.

 

Any chance you used non OE bolts for the torque converter to flexplate?  The OE ones are half height heads, for clearance in the belhousing.  If so a bolt head could be hitting sometimes and that would fit with the change in rotational force from on/off throttle.