Running Mercruiser without rotor on it?

[Dave WJ]

I just replaced the cam seals on my 170 HP Mercruiser 470. After replacing the cover, I have thought about running it on muffs and bringing it up to temp without the rotor on it to check things out. Reason being, if I find some problem with the job I just did, or possibly another problem I don't know about yet, I wouldn't have to pull the rotor again (no stator - switched alternator). Barely enough room to do it and a real PITA.

Only reason I could see not to may be the flywheel effect the rotor has on the running engine. Would the lack of the rotor being a flywheel have an adverse effect on running the engine? I suspect it may, but like to hear from someone that knows for sure. Thanks.

 

[stonyloam]

I don't think that would be wise, doesn't the oil seal on the timing chain cover seal on the rotor? I think you would dump all of your oil into the bilge.

 

[Dave WJ]

The oil seal in the front timing chain cover seals on the crankshaft. The whole cover with the new crank seal and new cam seals has to go on before the rotor can be put back on. That's the reason for pulling the rotor - to be able to remove the cover to change the seals. The only issue I can see would be the flywheel effect of the rotor. Does this make sense?

 

[stonyloam]

I don' t think so. The rotor fits onto the crankshaft, and slips through the oil seal when you put it back on. If you look you should see where the seal rides on the machined surface of the rotor. I may be mistaken, but if you still have the old oil seal, test fit it on the rotor.

 

[Dave WJ]

Thanks again stony. As usual, I think you are right. After what you said I went out and took a quick look at the crank. And on it were the keys in the keyways for the rotor. I realized then no way a seal would work there and what I had been thinking had to be wrong. It was dark and didn't see my rotor right away, so will look tomorrow, although I'm sure you're right. Thanks again, and I've been reading your replies for months on the 470's, so I hope you keep checking my questions for me!

 

[Dave WJ]

Also, I do have the old seal, and just looking at it now I can see that hole part of the seal is way bigger than the crank diameter. Thanks again.

 

[Dave WJ]

Just to close this thread out, of course stonyloam was correct. Got the rotor back on this afternoon but didn't have time run it. Only problem I encountered was I lost the nut I had to put on the threaded rod to pull the rotor back on. After a few trips from the boat to my shop, and anywhere else I could think to look, I finally found it after about 30 minutes. It was in my pocket.

 

[SDSeville]

After a few trips from the boat to my shop, and anywhere else I could think to look, I finally found it after about 30 minutes. It was in my pocket.

Haha. I have done that.