Update - 2003 Subaru timing belt replacement concerns

Some kind folks here had helped me sort out a couple issues related to replacement of the timing belt on our 2003 Subaru Outback.

We had the work done recently, including the replacement of the water pump, thermostat, and drive belts as recommended, and all seemed well.

However, two issues arose:

(1) While doing the job the mechanic checked on a smell we had noticed and found that the CV boot on the passenger front axle was torn and grease had leaked out - causing the smell. He replaced the axle with a NPA one, but immediately called and said that it didn’t seem right, so ordered a new one. That one went it, we drove 1,000 miles on a long trip, and about midway noticed a clicking sound up front (freaking out my wife). We just had it in and he said it was another poor axle, so he replaced again (I know he’s replacing them, he shows me, and I’d trust him with my dog). Does anyone have prior experience with these axles? The obvious response is "don’t use NPA axles", but he’s confident it was just a bad batch.

(2) After getting the timing belt changed, the car had a decidedly low idle when stopped in Drive. It made the steering wheel vibrate a good bit and was loud. We took it back and they said they had to adjust the Idle Stop back up? Is that routine with a timing belt change? I figured the computer controlled all that now.

Sure this recent clicking sound is the same axle? If it is, then it could be a lousy supplier rebuilding those axles.
Most parts rebuilding companies hire low wage, non-mechanically astute employees and many of them may not be able to recognize a worn out part no matter what. Couple that with high employee turn-over rates and it could be a problem on the customer end also. I’m also assuming here that a mistake was not made during the axle installation. Subaru axles have a few quirks and improper installation can cause problems.

You can run into defective reman axles no matter who you get them from. Lately I’m starting to think that a “rebuild” is nothing more than a trip through the solvent tank, new boots/grease, and call it good. I’ve installed a lot of reman axles over the years with no problems but have seen 3 reman failures in about the last 6 months.

The computer does control the idle through the Idle Air Valve. There is no way they should be tinkering with the throttle plate screw. If they are, then they’re just attempting to cover up a problem in the easiest manner possible.

Something is seriously wrong in (2). The computer controls the idle speed via the idle air control (IAC) valve. NO ONE is supposed to mess around with the throttle stop screw. The idle should not be any different after the timing belt replacement than it was before.

I’ve never had a problem with parts store axles, but I suppose it’s possible. Are they being replaced under some sort of guarantee? I would hope so.

Do not let them adjust the idle stop. That is not the cause of the low idle, in fact it can cause low idle because if it is set too high, the computer will never get the signal that it is supposed to take over the idle via the IAC.

I have never had any luck with a reman axle. Someone might get lucky because it appears that your mechanic turned in a good axle that only needed new boots, and when it gets rebooted, someone will get your good axle. The good news it that for about the same cost of a reman, there are brand new axles coming out of China. EMPI sells them and there is a good brand available at Advance Auto parts. Have your mechanic look into them. BTW, if a boot on one axle split, the boots on the other axle will soon follow although 4 years seems kinda quick for one to split. They are usually good for 6-7 years, but it is dependent on climate.

Well, you didn’t boost my confidence about this most recent axle, but we’ll see. :slight_smile: If we notice something starting up again, I’ll definitely ask him to take a new approach; perhaps the China axles keith mentioned.

As for (2), they did adjust the Idle Stop (I just asked). He said the idle should be at 650 rpm on this car according to Sub. There are two marks between 0 and 1 on the tach, whereas there are three between 1-2, 2-3, etc. The first between 0 and 1 is a heavy line like the middle (500) marks between 1-2, etc., so I assume that the marks between 0-1 are 500 and 750. At rest the car sits about at 750 (if I’m right), so that would mean they went too far - as you suggested, they shouldn’t have messed with it (which now seems obvious since it didn’t work). If we can get this figured out, I’ll ask him to reset the idle stop to where it was before.

My mechanic is genuinely interested in fixing this and seems a bit confused. He works on other Subarus fairly often and says that he’s seen noticeable vibration carried from the engine to the driver because of the mounts and the design of these H4 engines. He’s thinking we just have sagging motor mounts. Could that be it? What else would cause this vibration? For the record, it happens more and more as the car warms up (within 10 minutes of driving, it’s doing it all the time) and you only notice it when the car is in gear and stopped. Sounds fine when moving or when in Park.

Subaru has never had engine mount problems that I’m aware of and that diagnosis should be taken with a grain, or two, of salt.
If this problem did not exist just before the timing belt job and surfaced immediately afterwards then one wonders if the cam timing is off a tooth, etc. due to improper installation of the timing belt. This could cause an engine performance problem and your mechanic should know that adjusting the throttle stop screw is not the cure to solving the problem. That screw is to tampered with only under very narrow circumstances and this ain’t one of them.

Wished I could be of more help but without car in hand it’s difficult. My personal opinion is that the motor mounts are not the problem if I did have the car in hand rechecking the timing belt marks would be something I would consider as a first step.

Often the reason the passenger side axle boot fails is because of its proximity to the exhaust system. On some models the exhaust is located within inches of the boot and exhaust heat will cook the rubber over time.

My mechanic and I agreed that the surfacing of this problem after the timing belt change made us want to point to that. However, the car runs great and nothing is noticeable unless you’re stopped and in gear. We got excellent gas mileage on our recent 1,000 mile trip and have not noticed any performance issues. He said (and from what I’ve read he seems right) that if this car had a timing belt installation problem (off a tooth, etc.) the performance problems would be very obvious and harmful to the engine. He even put the car on the lift to watch the engine when it was doing this (so presumably someone was in it on the lift - uh, OK), and he could stop it by “putting a bar under the engine”. This was a short spur of the moment description, so I wouldn’t read too much into it, but it he can stop it that way, it lends some more credibility to the mount issue, no? Anyway, we don’t know what else to check… any ideas?

So maybe it needs new engine mounts?

That’s what I was hoping someone could tell me! I’m just not convinced that this is a serious thing (knock on wood) because of the good performance and rather mild nature of the shudder. I just don’t know what else to try.

I was just expressing my opinion on this issue because motor mounts have never been an issue with Subarus and have never seen or heard of a bad one even after working for a number of years at several different Subaru dealers. Not to say it could not happen but the odds are very, very slim.

The pry bar trick to stop vibration may or may not be infallible as a way of checking mounts. It could simply be masking a problem; much like readjusting that throttle plate screw that should not be tampered with.

The cam timing can be off a tooth and the car may still appear to run fine with a rough idle. Any problem would be most noticeable at idle and other than going back and rechecking the timing marks a vacuum gauge could be connected to the manifold to see if there is anything abnormal going on with the vacuum. If the cam timing was off a tooth and this is causing a rough idle then it should show up on the gauge reading.
A vacuum leak could also cause the same symptom and could also be verified with a vacuum gauge.

Just my 2 cents anyway.

Some other Subaru owners have noticed very similar problems with N*PA and other reman’ed axles, so I’m thinking the safest approach is to start with getting a better axle in there and see if that clears things up (and get the idle/throttle stop back to OMS). I checked EMPI’s site, but do you know how to get them - can any shop order from them? Also, what’s the Advance brand you refer to?

I think the timing belt is off-time ( a tooth off). Changing a Subaru timing belt is harder that other engines. The belt is much longer, and there are more pulley and cam sprockets to align properly. I think they missed. That can make the engine out of balance and shudder at idle.
The people who did the timing belt should be re-doing it… correctly.

So here’s the latest… I find it irritating when a thread ends without resolution, so I’ll try to finish this one off.

It turns out that remanufactured axles, and NAPA in particular, are becoming notorious for causing this idle-only shudder. It seems the shaft is slightly too short in most cases. It doesn’t make a ton of sense mechanically, but enough people have had this problem occur and fixed it by replacing with an OE axle that it’s pretty clear. So, don’t put NAPA axles in Subarus! I’ll post if the one I ordered fixes my problem (crossed fingers). MWE Axles (google it) is a good guy that sells them.

If the timing belt was off a tooth there would be serious problems on this car… at least that’s what the other 5 people I asked said, all Soob guys. I don’t personally know.

And, my mechanic noted to me that the throttle stop screw simply can’t be messed with much on these engines without causing problems (as everyone here has now noted). When he said he adjusted it, it was only a “few thousandths” if any, so he didn’t mean to have given the impression he adjusted that in any real way.

Just my four cents about Subaru engine mounts. It’s a good design, having the crankshaft going from front to rear and the drive axles going side to side. The torque of the engine and the drive axles aren’t working together to destroy the engine mounts. A bad engine mount won’t show up as bad as the regular arrangement with the usual sideways engine. It all works a lot smoother.

Unfortunately, your post is not the end of this problem.
Are you stating that your mechanic is claiming that a defective half-shaft can cause a roughness at idle - as in the vehicle stationary and not moving? Or is it meant by idle-only if you let off the throttle and coast? If it’s the former, then it’s time for the aluminum foil hats.

Still incorrect. The cam timing can be off a tooth and not cause serious problems other than a rough idle.

As to adjusting the throttle screw, a “few thousandths” is a few thousandths too much.
At this point, color me even more skeptical than I was.

I have bought axles from CVO in Fl. They have every brand and must have machines to rebuild them right. One Subaru, another Chryler both with good results and over a years use. Prices are reasonable and quick service. There is a parking lot test where you test by turning right and left about 10mph. I believe if it clicks turning right its that side etc. Maybe someone can correct me here. I know OE belts have marks to get timing right and sure makes it easier!! I’m not sure about this engine but older 1.8 L wouldn’t start being 1 tooth off. I’ve done several 2.2’s and never a problem because of factory timng marks on belt. Do you live in area were there aren’t many Subarus and mechanics aren’t that experienced?

My mechanic isn’t claiming this, but we’re trying it out. Spin over to ultimate subaru message board (USMB) and read the 100 or so threads about a vibration developing at idle after a half-shaft replacement with NAPA, etc. It could be a wild coincidence, but the evidence is against it. True, it doesn’t seem intuitive, but why would doing nothing but putting an OE axle back in fix it time and time again? If we replace with a Subaru half-shaft and it doesn’t fix the problem, I’ll be eating some crow.

Finally I get to post a conclusion to this mess!

We pulled the NAPA axle and replaced it with a reman’ed Subaru axle from MWE Axles in Colorado - vibration gone! Simple as that. No foil hats needed.

The connection between aftermarket axles and the idle vibration (in gear) on Subarus is indeed tough to explain. Apparently the mismatch, however slight, sets up a vibration that transmits back through the transmission and into the steering wheel/seats/floorboards somehow. This happens often, and no one has a good reason why it happens. E.g.,


But, experience indicates that the safe thing to do is always replace half-shafts on Soobs with Soob half-shafts. The MWE axles are much cheaper than a new full assembly from Subaru.

Sorry, but there is something incorrect in all of this. You are stating that a half-shaft is causing a vibration while the car is idling, in gear, and stationary.
That CANNOT happen; no way, no how. The half-shaft is at rest and nothing is moving. If the vehicle is moving then you have a point.

If posters on another board claim this then they’re delusional at best.

Yes, happens at rest in gear.

Follow the link and read. It’s happened to more than a handful of people. Since replacing with a Soob axle fixes it time and time again, you tell me what’s causing the vibration. I wouldn’t call people that own shops and work on Subarus for a living delusional.