I’ve been chasing this squeaking noise at the front of the Subaru for a while now. Well, not exactly chasing - more like ignoring in the hope that it would go away. Really, I was afraid that it was the timing belt tensioner (something you really shouldn’t ignore) which is a fairly big and (more importantly) expensive job. It turned out to be an easy fix.
I used my mechanic’s stethoscope to listen to a few different points on the front of the engine, but didn’t find a definitive squeak. Just for giggles, I tried removing the air conditioning belt, and lo and behold the squeaking stopped. Either it was the tensioner, or the AC pump clutch bearing. Because the sound didn’t change when I turned the AC on and off, I knew it wasn’t the AC clutch. It must be the tensioner.
Luckily this isn’t a critical repair. The absolute worst thing that can happen (if the AC is driven by its own belt, such as on most cars) is that the tensioner will seize, the belt will shreik then snap, and you won’t have air conditioning.
The AC tensioner pulley is a bit tight against the radiator fans, but with a few useful tools it isn’t difficult. To start with, the AC belt cover is removed to expose the AC pump and clutch:
That was easy! One nut, one bolt, and lots of room. Next up, the tensioner arm can be removed. Two bolts with moderate tool clearance - my offset wrench worked well here.
With the tensioner arm off, it can be disassembled.
I was actually prepared to buy an entire tensioner arm assembly, or perhaps just a tensioner pulley, but it turned out to be much cheaper than that. The pulley has a normal, pressed-in bearing that can be removed and replaced. This can be done with a hammer, as in the recent Metro drum brake replacement article, but if you have recently bought a gigantic vise you can use that instead!
It is normally preferable to press bearings in and out by the outer race (or inner race if it is being pressed on a shaft) so as not to damage the balls (that sounds… painful), but there’s no access to the outer race here and this bearing is toast anyway. I used an impact socket to press on the inner bearing, and a couple scrap chunks of steel to make room for the bearing to fall out.
Old bearing, new bearing (including new bearing Napa part number):
The new bearing goes in the same way, but pressed by the outer race with a big socket. A little grease helps it slide in.
And there you have it - a tensioner pulley with a new bearing. I’d love to say that reassembly is the reverse of disassembly, but it gets a little more complicated because you have to tension the belt.
I try not to reuse pictures, but what the heck - here’s the arm assembly again:
The pulley can be reattached to the tensioner arm, but not fully tightened down yet. Now is a good time to loosen the jamb nuts on the threaded rod that runs down the length of the arm, and loosen the rod itself by a few turns. Note that it is reverse threaded, sorighty-loosy, lefty-tightyapplies. Leave it loose for the moment.
With the tensioner arm back on the car and the belt back on the pulley, we can tension it. The threaded rod can be turned easily from above to tension the belt. A good rule of thumb is that belts should be tight enough that you can barely twist the belt sideways 90deg on its longest unsupported side.
This is where access gets tight. With the belt tightened, those jamb nuts need to be secured. I used a stubby wrench but could still only get a few degrees of turn at a time.
All that’s left is to reinstall the AC pump belt cover. Starting the engine should prove that everything is indeed squeak free. A proper Subaru should sound like an angry bear, not a frightened mouse.
Cost:
$6 - replacement bearing (Napa)
I used my mechanic’s stethoscope to listen to a few different points on the front of the engine, but didn’t find a definitive squeak. Just for giggles, I tried removing the air conditioning belt, and lo and behold the squeaking stopped. Either it was the tensioner, or the AC pump clutch bearing. Because the sound didn’t change when I turned the AC on and off, I knew it wasn’t the AC clutch. It must be the tensioner.
Luckily this isn’t a critical repair. The absolute worst thing that can happen (if the AC is driven by its own belt, such as on most cars) is that the tensioner will seize, the belt will shreik then snap, and you won’t have air conditioning.
The AC tensioner pulley is a bit tight against the radiator fans, but with a few useful tools it isn’t difficult. To start with, the AC belt cover is removed to expose the AC pump and clutch:
That was easy! One nut, one bolt, and lots of room. Next up, the tensioner arm can be removed. Two bolts with moderate tool clearance - my offset wrench worked well here.
With the tensioner arm off, it can be disassembled.
I was actually prepared to buy an entire tensioner arm assembly, or perhaps just a tensioner pulley, but it turned out to be much cheaper than that. The pulley has a normal, pressed-in bearing that can be removed and replaced. This can be done with a hammer, as in the recent Metro drum brake replacement article, but if you have recently bought a gigantic vise you can use that instead!
It is normally preferable to press bearings in and out by the outer race (or inner race if it is being pressed on a shaft) so as not to damage the balls (that sounds… painful), but there’s no access to the outer race here and this bearing is toast anyway. I used an impact socket to press on the inner bearing, and a couple scrap chunks of steel to make room for the bearing to fall out.
Old bearing, new bearing (including new bearing Napa part number):
The new bearing goes in the same way, but pressed by the outer race with a big socket. A little grease helps it slide in.
And there you have it - a tensioner pulley with a new bearing. I’d love to say that reassembly is the reverse of disassembly, but it gets a little more complicated because you have to tension the belt.
I try not to reuse pictures, but what the heck - here’s the arm assembly again:
The pulley can be reattached to the tensioner arm, but not fully tightened down yet. Now is a good time to loosen the jamb nuts on the threaded rod that runs down the length of the arm, and loosen the rod itself by a few turns. Note that it is reverse threaded, sorighty-loosy, lefty-tightyapplies. Leave it loose for the moment.
With the tensioner arm back on the car and the belt back on the pulley, we can tension it. The threaded rod can be turned easily from above to tension the belt. A good rule of thumb is that belts should be tight enough that you can barely twist the belt sideways 90deg on its longest unsupported side.
This is where access gets tight. With the belt tightened, those jamb nuts need to be secured. I used a stubby wrench but could still only get a few degrees of turn at a time.
All that’s left is to reinstall the AC pump belt cover. Starting the engine should prove that everything is indeed squeak free. A proper Subaru should sound like an angry bear, not a frightened mouse.
Cost:
$6 - replacement bearing (Napa)
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