Help removing crank shaft sprocket

Hello all my name is: Angela from New Zealand. I have a 1992 GTO, N/A, manual.
I am in the process of installing an oil pump as the original sustained damage to the actual lip below the crank sprocket when a loose bolt got between the cam belt and oil pump cover (the rounded bit at the bottom).
crank sprocket
If you are able to view the photo you’ll see that there is literally nothing for the oil pan to seal to properly because of the area that’s chipped off. Funnily enough, there was not a lot of leaking, just enough for oil to splash under the lower timing belt cover and mess up that area under there and also onto the exhaust thus making it fail an inspection.
I need to remove the crank sprocket but it is not keen on moving. I did manage to remove one off a parts car with careful use of a pry bar but the lip is very easy to damage and sure enough, even though I was careful, the sprocket sustained chipping to the lip so I cannot risk damaging the one currently on the car. Is there a tool available that anyone knows of? A puller would be cool but there is little room between the sprocket and the block and my word it’s really difficult to get one to co- operate in such a tight space. I have banged it with a mallet to no avail and it will not pull off. Any suggestions? Otherwise I’ll just have to risk damage and look at a new sprocket if I can find one.
Yes I have checked the manual but cannot find anything about removing the sprocket.

These can be a real pain. They are machined surfaces and fit very snugly. Even the slightest piece of debris or rust will make removal seemingly impossible but once it is clean, it will slip off easily.
There are a couple of tips that I can give you and maybe other people on the forum may have others.

  1. Remove the bolt and then spray penetrating oil around the end of the shaft. Don’t be in a rush and repeat the process over a couple of hours or days if it is really seized on.
  2. Do not attempt to pry it off on one side only. Even pressure on 2 or more sides is the trick.
  3. Once the area has been well soaked in penetrating oil for a while. Screw the bolt back in about 3/4 of the way. Pack something tightly behind the sprocket in multiple points and gently tap the bolt with a small hammer. DO NOT HIT IT HARD.
    This should free it up and it should slide off easily as long as you work it from multiple sides at the same time. If it sticks part way. Just spray more oil and then tap the sprocket back on before trying to remove it again.

Thanks Joe. I’ll give it a try. The lip is very brittle and unfortunately it has been damaged and am not sure about reusing it once it’s finally off. I’d be a bit worried about the cam belt getting damaged it it should somehow work its way to the edge of the sprocket. Seems too that there is a difference between the Gen 1 and Gen 2 sprockets, the Gen 2s not having the lip on the rear edge. Funny things, these GTO’s.

1 Like