Ben123456789

I've just changed the power steering pump (the old one developed a loud whine last weekend) and whilst I was bleeding the pump, I was looking at the belts and I noticed that the crank pulley appears to be wobbling slightly.

This may not be a new problem; I have not paid much attention to the belts / pulleys before, so it might have been doing this for some time previously but I just haven't noticed until now.

Anyway, I'm pretty sure it shouldn't be doing this, but since I've only had the car for 4 1/2 months and I'm no expert on Scooby's, there may be an innocent explanation.

Does anybody know (a) if it is normal, and (b) if not, what could be the problem? Should I stop driving the car until I get it fixed?

I've taken a video and put it on youtube, it shows the wobble quite clearly.

YouTube - Subaru Impreza - Crank pulley wobble

petedotuk

It is a distinct wobble, have you checked the bolt is tight?

clark822

funny you sould post this been doing the timing belt and mine had this check the pulley bolt is tight mine was'nt and wrecked the crank cog & pulley.But i also had damage done to my timing belt so check it is right or could cause you big trouble

harvey

iTrader: (48)

As above. Check the bolt is tight and fully home. If it is keep an eye on the pulley from time to time. Chances are it will not get worse.

Splitpin

That's quite pronounced, and no, not normal. Provided the bolt is tight then on one hand the temptation may be to leave alone - although the net effect is going to be to stress out the power steering pump and alternator bearings as you'll need to effectively overtighten the belt to prevent it slipping on the "loose" part of the rotation. When it goes to the "tight" side, the bearings on the auxiliaries will start to complain a bit (might, at least in part, explain why you had to change the PAS pump originally).

If the bolt is tight, I'd be tempted to take the pulley off and investigate, see whether there's any way of rectifying it.

Incidentally - I know you haven't had the car long so you probably won't know much about its history, but, do you have any idea whether it has ever been involved in a front-end accident, or, have you checked the engine number to see whether it corresponds with the one on the VIN plate?

Alan Jeffery

Common reason is cam belt change, followed by failure to tighten the bolt properly. It usually chews up the crank keyway, and can be bad enough to require a new crank.
We have got away with it by using a lightweight pulley, RCM or similar, then tightening up the bolt really well. Use a new bolt! The standard pulley is a very heavy item, it's like that for a reason, but harmonic imbalance is a lesser problem than the pulley falling off!

Ben123456789

Thanks for the advice everyone. I have checked the bolt, and it is tight (over 150 ft pounds, the maximum setting on my wrench). The cam belt was changed long before I had the car, over 20k miles ago.

I'd like to sort it out, because it can't be a good thing in the long term.

I've done some reading on lightweight pulleys, and seen harmonic imbalance mentioned. Realistically, is this likey to cause big problems with the engine?

merlin24

iTrader: (1)

You need to remove the front pulley to see what is worn.
You might be lucky if its just the slot in the front pulley worn - replace the pulley.
If the slot in the snout of the crankshaft is worn and the woodruff key has rolled - then it may need a new crankshaft to sort the job out.
Or as mentioned above by Splitpin - a front end accident impact can also bend the snout of the crankshaft.

Mick

Alan Jeffery

We took the view that the slight issue with the use of a light pulley was going to be a smaller risk than having a pulley wandering around the engine bay at 5000 rpm! It was either that or replace the crank. We had a long chat with the customers involved, explained all the issues and went for it. We've had no cause to regret the decision we made.

Ben123456789

Alan, I'm assuming that the reason you decided to fit a lightweight pulley was because it is more likely to stay on when it is being held by the bolt only due to having no woodruff key in the crankshaft? Sorry if this is obvious, I just want to be sure this is a definite solution if I take the old one off and find the crank is damaged. Also, what torque did you tighten the bolt to? I'm guessing more than the recommended 127 Nm?

I've sourced a new pulley, and will be picking up a new bolt and woodruff key tomorrow from the local Subaru dealer. So long as I have time I'm going to attempt the replacement tomorrow evening, fingers crossed!

Ben123456789

Right, I've finally got around to removing the pulley, and it is not good news See photos below.


The keyway in the crank looks like it's been enlarged considerably (I assume it's not meant to be any wider than the keyway in the crankshaft sprocket). The woodruff key has been worn away considerably, as per the photos below. The key is actually slightly shorter than a brand new key (shown along side for reference), and has areas which have been abraded.


The keyway in the crank pulley looks slightly off-centre, but it is difficult to see from the photo.


On the positive side, the crankshaft sprocket keyway looks fine to me, no obvious signs of damage. In addition, the woodruff key sits firmly in the crankshaft keyway, pressing against the side of the sprockey keyway, holding it in place.


It also looks like the crankshaft seal is leaking, which I suspected anyway, and am planning on replacing when I have time.


My question is; if I fit a lightweight pulley, with a new woodruff key and bolt, doing the bolt up very tight (>150 ft/lbs), is this likely to be a satisfactory repair, or is it a ticking timebomb that will only last a few hundred miles? My only other option is a new engine, realistically


As ever, advice would be much appreciated.

merlin24

iTrader: (1)

The keyway slot on the snout of the crank looks well worn tbh - the woodruff key should be a "tap" in fit with a small hammer.

Mick

Brett_555_Sti

iTrader: (18)

As above. That is not 5 minutes worth of wear either. I bet that at times the performance has been poor.
Well its either a bodge, a full rebuild or replacement from here on.

Ben123456789

To be honest, the performance has been excellent since I bought the car. I think I'm going to just fit a lightweight pulley for now, as for £100 it's worth a try before going for a replacement engine.

Brett, I notice you're in Guildford (so am I). Do you know of any local reliable sources of secondhand engines, in case I do have to replace it? Also any local places who can be relied upon to do a good job of rebuilding?

harvey

iTrader: (48)

The O/E crank pulley is around 2.51 kg. Quite a big lump to be rotating at any revs never mind 7k rpm.
Under driven light weight item here is 400 grams/.4kg. So removing 2.1 kg rotating mass has to be a good thing. Bollocks to this harmonics business. About 9 years ago when I fitted my first light weight and under driven pulley I got all that crap from experts along with the flat battery brigade. Never had either problem on what must be close to 100 cars since.
Whether it is a long term cure or not, time will tell but for £75 plus postage for the crak pulley and alternator pulley, what have you got to loose. It is a small cost in comparison to finding a good engine.
Also consider the pros and cons of using 2 pack industrial super glue to hold the pulley in place once it is trial fitted and properly located.

Fuzz

Being as the timing belt sprocket is also held in position with that woodruff key I'd be VERY suspect about just bunging a lightweight front pulley on.
You can clearly see the cog is already out of alignment

Ben123456789

Having looked through the various bills that came with the car, I've just noticed that a new crank pulley, sprocket, woodruf key and timing belt were fitted around 25k miles ago, in 2006. I'd say there's a very good chance that these items were fitted because of a loose pulley at the time, which although isn't a good thing, it does imply that it's lasted this long in that condition! The bolt wasn't loose when I undid it; it needed a 3 foot steel pipe on a breaker bar to shift.

Harvey, I like the glue idea. I might use some 'fast metal' or similar heavy duty resin to fill in the keyway around the woodruff key, which may or may not reduce future wear.

I've made some enquiries about replacement engines, which I will do if I need to, but for the sake of fitting a pulley I'm going to try that first.

tjmatt

iTrader: (1)

Just for your interest...

This happened to mine, bolt came loose pulley flopping around. When I took it apart properly it had snapped the woodruff key and taken a chunk out of the pulley where it should be - it looks like this was a good thing though because it limited the damage to the crankshaft. The crankshaft sprocket was so rusted on it took a homemade puller to get it off. It was this probably stopped the crank sprocket wobbling and wearing out the key and crankshaft hole.

I used a new woodruff key, refaced the crank sprocket somewhat and did the bolt up to 110ft and its been ok since. I want to redo it with a new bolt at some point however.

I also considered using a lightweight pulley but found a second hand oem one for a tenner and it seems to be ok.

Julio Jordio

I dont think that crank looks too bad?

I had the same happen with mine last month, and it was a complete ******* to get the crank pulley off. I was panicking it was new engine time, but I was assured the crank was fine, fitted the two new pulleys, and bolt and key and did the cambelt too. Its been absolutely fine since. It isnt always bad news

Ben123456789

Right, I meant to update this thread a few weeks back, but have been busy with work and other things! I have carried out a successful repair

For anybody else who finds themselves in this position, you may find this write up (with photos) useful. I did the following:

• Removed the timing belt with the woodruff keyway in the 12 o clock position (I used some G-clamps and some old bits of cut up timing belt from another car to lock the camshaft pulleys together to stop them turning, although this may not have been necessary; it certainly wasn't with the nearside pulleys).

• Removed the crankshaft sprocket, and cleaned up the crank keyway with a small wire brush on the Dremel. Welded the left hand side (i.e. the side with the wear) of the keyway, using about 4 or 5 very short (< 1 second) bursts with a MIG welder, set on around 125 amps, wire speed 6. This deposited enough metal to work with, and the current seemed to be about right.

• I then used a Dremel and various small grinding stones to carefully take away the excess weld metal, and get a good profile on the keyway. When finished, the new woodruff key was a nice tight fit, and needed a gentle tap with a hammer to sit in place with the sprocket fitted OK, it isn't quite as good as new, but it doesn't wobble around anymore, the sprocket stays put.

• At the same time I replaced the oil pump with a modified one from API, as the car has done 127k+ on the original pump. There was an oil leak around the old pump, I'm still not sure whether it was the crankshaft seal or the pump itself, but the seal didn't look too bad and there was very little gasket on the sealing faces when I removed the old pump, so it could have been a poor seal. Either way, there is no more leak now with the new pump.

• I put the old timing belt back on again, because I hadn't bought a new one. This was for two reasons: firstly to check the condition of the idler pulleys and tensioner to see if I needed to buy a complete kit or not, and also to check for play in the crankshaft (a possible cause of a leaky oil seal). I decided if there was play, that there would be no point spending any more money! Luckily, there was no detectable play, but two of the idlers had slightly noisy bearings and noticeable play.

• I fitted a lightweight pulley from Scoobyworld, and torqued it up to 150 ft/lbs. I didn't use any thread lock or other adhesives.

Anyway, this was over 3 weeks and 1000 miles ago, and it has proved to be a successful repair so far I got around to replacing the timing belt and idlers / tensioner yesterday, and the weld has held firm, no noticeable additional wear! Also, the fuel ecomony seems to have improved slightly (about 1mpg), and I could swear the performance has improved, although it may be psychological. Anyway, I guess the timing was in fact sligthly out at times due to the wear.

Finally, thanks to everyone who has offered me advice, especially Brett 555 Also thanks to API and Scoobyworld for supplying the oil pump and pulley quickly.

Photos of the repair below:




The crankshaft cleaned up and ready to begin welding.




Weld metal deposited on crankshaft keyway, ready to be ground to shape.




Ground to give a good tight fit, new woodruff key in place.




Old oil pump removed, gasket face cleaned, and Three Bond grey gasket sealer applied.




New oil pump fitted, sprocket back in place.




Timing belt back in place, all done up, and nice shiny new pulley installed!