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Finished!
Finally had time to get everything put back together – now it runs properly & has everything properly bolted on. I ended up buying a proper cam pulley wrench, it wasn’t worth risking damaging the pulley teeth to avoid adding another special tool to the collection 😉 I’m impressed with how nicely made & robust the tool is:
http://www.company23.com/subaru/507
Roy
Finished!
Finally had time to get everything put back together – now it runs properly & has everything properly bolted on. I ended up buying a proper cam pulley wrench, it wasn’t worth risking damaging the pulley teeth to avoid adding another special tool to the collection 😉 I’m impressed with how nicely made & robust the tool is:
http://www.company23.com/subaru/507
Roy
It turns out, I’d used a bottoming tap last time. The real problem is that the bolt is a couple of mm longer than the original – just enough to let it bottom out without clamping the pulleys against the crankshaft shoulder. While I’m redoing things, I figure it’s time to replace the idlers, water pump & cam/crank oil seals.
Is there a work-around for the special tool to hold the cam sprockets while the bolt is being tightened/loosened? My first thought is chain Vise-Grips with a piece of old timing belt to protect the sprocket teeth.
http://www.irwin.com/tools/locking-tools/the-original-locking-chain-clamp
Roy
It turns out, I’d used a bottoming tap last time. The real problem is that the bolt is a couple of mm longer than the original – just enough to let it bottom out without clamping the pulleys against the crankshaft shoulder. While I’m redoing things, I figure it’s time to replace the idlers, water pump & cam/crank oil seals.
Is there a work-around for the special tool to hold the cam sprockets while the bolt is being tightened/loosened? My first thought is chain Vise-Grips with a piece of old timing belt to protect the sprocket teeth.
http://www.irwin.com/tools/locking-tools/the-original-locking-chain-clamp
Roy
Getting back to the original topic, I started taking the timing stuff apart today. When I went to unscrew the bolt holding the pulleys to the crankshaft, I found it was only finger tight! The basic problem was the pulleys weren’t tight, allowing them to flop around, allowing the key to munch out enough of them to make accurate timing impossible.
Evidently, when I repaired the original stripped crankshaft threads by tapping to M14x1.5, I didn’t tap deeply enough. At the time, the only tap I could get locally was a plug tap – when I tightened things during assembly, the bolt was bottoming in the incomplete threads, rather than actually clamping things together. With new parts, things fit closely enough that I couldn’t tell that the pulleys weren’t firmly clamped to the crankshaft. Now that I have a bottoming tap & know what to look for, I expect to be able to make a lasting repair.
Roy
Getting back to the original topic, I started taking the timing stuff apart today. When I went to unscrew the bolt holding the pulleys to the crankshaft, I found it was only finger tight! The basic problem was the pulleys weren’t tight, allowing them to flop around, allowing the key to munch out enough of them to make accurate timing impossible.
Evidently, when I repaired the original stripped crankshaft threads by tapping to M14x1.5, I didn’t tap deeply enough. At the time, the only tap I could get locally was a plug tap – when I tightened things during assembly, the bolt was bottoming in the incomplete threads, rather than actually clamping things together. With new parts, things fit closely enough that I couldn’t tell that the pulleys weren’t firmly clamped to the crankshaft. Now that I have a bottoming tap & know what to look for, I expect to be able to make a lasting repair.
Roy
Actually, I usually get very good tool life – I still have the beam style torque wrench I bought in HS – that was in about 1966! The newer torque wrenches only come out of their cases when something has a torque specified. The problem with the sick one is that the part of the handle containing the window displaying the setting has come unbonded from the body, letting it slide around. Because of that, there’s no way to be sure what it’s actually set at.
Roy
Actually, I usually get very good tool life – I still have the beam style torque wrench I bought in HS – that was in about 1966! The newer torque wrenches only come out of their cases when something has a torque specified. The problem with the sick one is that the part of the handle containing the window displaying the setting has come unbonded from the body, letting it slide around. Because of that, there’s no way to be sure what it’s actually set at.
Roy
After a few delays, replaced the lifters – no change in symptoms. Since I still have no power below about 2200 RPM + occasional “coughing” thru the intake at low rpm, I suspect the basic cam timing is off. About a year ago, I had to re-tap the crank after the pulley retaining bolt hole threads stripped out. With the bolt loose, the key sheared & chewed up both the cam & accessory drive pulleys – I replaced both of them & tapped the crank to M14x1.5 as a repair to the stripped M13x1.5 original opening.
Anybody got any thoughts that might save me from going down another dead end route?
One of the things that slowed the lifter replacement was breaking one of the rocker shaft retaining bolts when my (cheap) torque wrench didn’t indicate it was anywhere near properly tight. Murphy being in control, the bolt that broke was the lower left rear one – the one where there isn’t room for an angle drill to fit between the fender & the engine. By adding a piece of hex stock to a drill bit, I was able to use an angle screwdriver to drill the broken bolt deeply enough to get it out with an extractor. The torque wrench was replaced under warranty, at the same time, I picked up a really nifty “torque adapter” – actually, a digital read out torque indicator.
http://www.harborfreight.com/digital-torue-adapter-68283.html
I’m impressed with it! Despite what the specs say, it actually reads much lower torque values with no problem. It’s kind of blorky to actually use when tightening something; it’s great for setting a torque wrench that’s of questionable accuracy before using it. I’m apparently death to torque wrenches – half of my Craftsman ones have failed after the warranty expired, with repair costs exceeding the price of new ones! This is for things I consider precision tools – they’re kept in their cases & only taken out for specific uses.
Roy
After a few delays, replaced the lifters – no change in symptoms. Since I still have no power below about 2200 RPM + occasional “coughing” thru the intake at low rpm, I suspect the basic cam timing is off. About a year ago, I had to re-tap the crank after the pulley retaining bolt hole threads stripped out. With the bolt loose, the key sheared & chewed up both the cam & accessory drive pulleys – I replaced both of them & tapped the crank to M14x1.5 as a repair to the stripped M13x1.5 original opening.
Anybody got any thoughts that might save me from going down another dead end route?
One of the things that slowed the lifter replacement was breaking one of the rocker shaft retaining bolts when my (cheap) torque wrench didn’t indicate it was anywhere near properly tight. Murphy being in control, the bolt that broke was the lower left rear one – the one where there isn’t room for an angle drill to fit between the fender & the engine. By adding a piece of hex stock to a drill bit, I was able to use an angle screwdriver to drill the broken bolt deeply enough to get it out with an extractor. The torque wrench was replaced under warranty, at the same time, I picked up a really nifty “torque adapter” – actually, a digital read out torque indicator.
http://www.harborfreight.com/digital-torue-adapter-68283.html
I’m impressed with it! Despite what the specs say, it actually reads much lower torque values with no problem. It’s kind of blorky to actually use when tightening something; it’s great for setting a torque wrench that’s of questionable accuracy before using it. I’m apparently death to torque wrenches – half of my Craftsman ones have failed after the warranty expired, with repair costs exceeding the price of new ones! This is for things I consider precision tools – they’re kept in their cases & only taken out for specific uses.
Roy
After checking everything in the engine control electronics & finding no problems, I think what’s really wrong is leaking valve lifters. The engine is OK when it’s cold, has problems once the oil is warm. That fits with the check valves inside the lifters leaking; it also fits with them working less poorly at higher RPM. Before I replace them, I’m giving some snake oil a try – I replaced 1 qt of oil with Marvel Mystery Oil to see if that’ll fool the lifters into working properly. I suspect what I’m really doing is delaying replacing them by a few days.
RoyL
After checking everything in the engine control electronics & finding no problems, I think what’s really wrong is leaking valve lifters. The engine is OK when it’s cold, has problems once the oil is warm. That fits with the check valves inside the lifters leaking; it also fits with them working less poorly at higher RPM. Before I replace them, I’m giving some snake oil a try – I replaced 1 qt of oil with Marvel Mystery Oil to see if that’ll fool the lifters into working properly. I suspect what I’m really doing is delaying replacing them by a few days.
RoyL
I spent a fair amount of time rechecking the engine (& manual) – there is no knock sensor on it. That fits with most of the US parts suppliers not listing one; it’s not on US spec cars. Now that it’s been checked multiple times, let’s acknowledge that this engine doesn’t have a knock sensor.
The basic problem persists – when the engine is at normal operating temp, the timing is severely retarded at idle. Because of the retarded timing, the car is pretty much undriveable. If engine RPM can be coaxed over 2K, the car behaves almost normally. I’ve tried different cam & crank position sensors, coils, ignition modules & ECUs with no change. I’ve also cleaned & groomed all the relevant electrical connectors, verified that fuel pressure is normal & that there are no vacuum leaks.
Still looking for other possible causes of the problem.
RoyL
I spent a fair amount of time rechecking the engine (& manual) – there is no knock sensor on it. That fits with most of the US parts suppliers not listing one; it’s not on US spec cars. Now that it’s been checked multiple times, let’s acknowledge that this engine doesn’t have a knock sensor.
The basic problem persists – when the engine is at normal operating temp, the timing is severely retarded at idle. Because of the retarded timing, the car is pretty much undriveable. If engine RPM can be coaxed over 2K, the car behaves almost normally. I’ve tried different cam & crank position sensors, coils, ignition modules & ECUs with no change. I’ve also cleaned & groomed all the relevant electrical connectors, verified that fuel pressure is normal & that there are no vacuum leaks.
Still looking for other possible causes of the problem.
RoyL
From what I can find, the US version of the ’93 Impreza doesn’t have a knock sensor, versions sold in other countries apparently do have one. Checking common parts suppliers (Auto Zone, Advance Auto Parts, Pep Boys & NAPA) show that there isn’t one; oddly, O’Reilly Auto Parts claims there is one! Like I mentioned, I’ve got the genuine, official Subaru service manual for the car; it confirms that there’s no knock sensor.
Where would the knock sensor be if there was one? It’s entirely possible that the manual I’ve got has an uncorrected error. The only reason I’m inclined to believe it is the lack of a knock sensor on major auto parts sites. I usually use Auto Zone & Advance, mostly because they’re the closest to my house – I’ve never run into an accuracy issue with Auto Zone, I’ve had some problems with Advance’s accuracy. I haven’t used NAPA or Pep Boys enough to have a feel for their accuracy; O’Reilly just opened, I haven’t even been in the store yet.
The car’s behavior fits with a knock sensor issue. If there was one, I think the dealer would have caught it when I took the car in to have the pre-OBDII codes read. Once it’s warmed up, the timing is severely retarded, which makes it undriveable.
RoyL