Camshaft Key-way Damaged

[Skokie]

Outback 2000 - 2.5L

Problems started after doing the HGs. Engine ran properly for a couple of days then occasionally rough and some rattling from what sounded like the driver’s side. The performance and sound became progressively worse to the point where the engine would stop then eventually would not run.

Suspecting something went wrong when I did the HGs I proceeded to remove the heads. When it came time to remove the camshaft sprocket on the driver’s side I found the sprocket was seated slightly loose. After removing the sprocket I found the key-way to the camshaft was damaged. It appears the key worked on the key-way in the camshaft to the point where the key-way has been flared. The key is fine and the key-way in the sprocket is okay.

Any thoughts on repairing the camshaft key-way or is it something that needs to be replaced.

TIA
David

[grossgary]

if you can get it properly lined up, just bolt it down really tight and it won't go anywhere. the cam shaft bolt is threaded into iron (the cam) and not aluminum so it won't easily strip and you can get some serious foot pounds on it.

can you post a photo, this is a tough call to make without seeing it in person?

[canubaru]

if you have any doubt, replace the cam shaft if you can do it in the car? maybe not. you can get a replacement head for about 100$, camshaft included. or just the shaft for about 45$.

the danger here is how far off was the timing?
are the valves damaged?

so try lining it up and torquing the crap out of it to see how it runs.

[Skokie]

Here are pics of the cam and sprocket.

There does not appear to be any damage to the valves or piston heads so the timing did not go out that much.

I will begin my search today for replacement parts... sadly here in Canada the prices for the parts are higher (sometimes 2x to 3x higher).

I understand the camshaft is tempered steel... drilling a larger key way is not an option?

Thanks,
David

[canubaru]

this is the first time i have heard of this for a cam shaft, but it is not uncommon for the crank shaft. especially for a first timer on a timing belt and using the wrong torque on the crank bolt.

get a replacement sprocket that is good condition and bolt it on. i'm not sure how you will hold it to tighten it. but with the crank pulley / shaft they are only boogered in one direction, counter clockwise. so you can set it in the correct position and it will not move when torquing it clockwise. i'm not sure if yours is the same , hard to see .

when my 93 crank pulley gave up, the mechanic applied some kind of thread lock ''that never comes loose'' and lined up the sprocket and pulley. snugged it up let it sit over night and then torqued it the next day. it ran great until i wrecked the car. this is not an ideal solution, but it might do untill you have to replace the valves, gasket or shaft.

Car-Part.com--Used Auto Parts Market for used parts.

[grossgary]

i would just install the sprocket as is without doing anything to the camshaft. tighten it down with some non-permanent lock-tite (replace that cam seal
while you're at it).

here's the easiest fix: replace the key with a dowel pin. drill a hole in the camshaft (the face of it) and sprocket and use a dowel pin. make sure the hole and dowel are properly sized together and the sprocket is properly positioned. subaru has used them before on crank pulleys and they're used on camshafts too. some simple googling will probably help you if you don't know what i mean.

[CNY_Dave]

I think the key here (groan, sorry) is if there is enough meat left to accurately position the sprocket. I have to guess if it's a little off it won't be tragic, after all it ran without bending anything so far.

If so, go with the loc-tite suggestion and crank it down good.



Dave

[wallyblackburn]

+1 on the LocTite. Use the green stuff, or even red, and treat this as a "lifetime" fix. In other words, once this needs to come off - in like 100K miles - that was the lifetime of that camshaft...

Good luck,
Wally

[Glennda5id]

You mention in the post that there is no damage to the sprocket, but the picture seems to disagree.

I have successfully repaired a crank keyway on a Subaru using Quiksteel. I would recommend replacing the cam gear. Use the quicksteel to fill in the gaps in the camshaft around the key. I also applied extra of the quiksteel. I then placed the gear on the shaft which will smooth out, compress and push out excess of the compound. Let it dry overnight or whatever the cure time is. After you are done you should be able to pull the gear back on and off without problem.

As most people stated, the key does not keep the gear from spinning, it is the force of the gear against the shaft once bolted down. The key is only for alignment. I also no not see a reason to use a lot of locktite, but maybe a little if you are paranoid. The main thing is to torque the bolt to the proper spec once the timing belt is on.

If you do not fill in the excess play in the camshaft journal, when you go to tighten the bolt the key way may move and then the gear will be out of alignment. This is also why I recommend replacing the gear to get rid of the play from that angle.

[John E Davies]

If it were my car I would just replace the buggered parts. Why take the risk of a shade tree repair going bad and then trashing the engine? Who knows where you might be, if and when that happened... if you were in the middle of nowhere you will be faced with an expensive tow bill at the very least. Maybe a cold night along some forest road.

I've fixed broken parts with JB Weld with great success - but they were not critical, highly loaded parts that would take out the engine if the repair failed.

Let's use some common sense here!

John Davies
Spokane WA USA