HP500 valve spring life
02-08-2003, 06:13 PM
#11
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REPLACE the valve springs on ALL 500HP and lower Merc motors at NO MORE than 200 hrs, problems or not! You can fill the cyls with air (piston @TDC) such as doing a leakdown test, and change the springs without removing the heads. I have replaced the springs on at least 50 motors, and seen broken springs from 35 hrs to others lasting well over 400 hrs. ALSO, replace the keeper wedges that hold the spring retainers on the valve without fail !!! Those are the 2 weakest links in Merc motors, and consistently cause the most problems.... and if you lose a keeper @ speed, I assure you, you won't even have a useable core left. There are several tools for valve spring replacement that are not expensive, but depending on the room you have, may require more than 1 tool to make things easy. Don't wait, get after it!
02-09-2003, 09:53 AM
#12
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Location: Prospect, Ky
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Originally posted by Tom McCann
If your in doubt about the springs change them. If a spring breaks, and you wont even know it especially a inner spring , You will keep running the boat as you do this that broken spring over time will wear into the head. Then when its time for a rebuild you will have a junk head. Allso if a spring breaks it could cause the valve to let go and smash the top of your piston. So for the little trouble it is to change the springs I would do that. The heads can be removed with out even removing the motor from the boat. Remove the heads and take them to your machine shop.
If your in doubt about the springs change them. If a spring breaks, and you wont even know it especially a inner spring , You will keep running the boat as you do this that broken spring over time will wear into the head. Then when its time for a rebuild you will have a junk head. Allso if a spring breaks it could cause the valve to let go and smash the top of your piston. So for the little trouble it is to change the springs I would do that. The heads can be removed with out even removing the motor from the boat. Remove the heads and take them to your machine shop.
02-09-2003, 11:05 AM
#13
Charter Member #1171
Charter Member
Originally posted by FindMe
REPLACE the valve springs on ALL 500HP and lower Merc motors at NO MORE than 200 hrs, problems or not! You can fill the cyls with air (piston @TDC) such as doing a leakdown test, and change the springs without removing the heads. I have replaced the springs on at least 50 motors, and seen broken springs from 35 hrs to others lasting well over 400 hrs. ALSO, replace the keeper wedges that hold the spring retainers on the valve without fail !!! Those are the 2 weakest links in Merc motors, and consistently cause the most problems.... and if you lose a keeper @ speed, I assure you, you won't even have a useable core left. There are several tools for valve spring replacement that are not expensive, but depending on the room you have, may require more than 1 tool to make things easy. Don't wait, get after it!
REPLACE the valve springs on ALL 500HP and lower Merc motors at NO MORE than 200 hrs, problems or not! You can fill the cyls with air (piston @TDC) such as doing a leakdown test, and change the springs without removing the heads. I have replaced the springs on at least 50 motors, and seen broken springs from 35 hrs to others lasting well over 400 hrs. ALSO, replace the keeper wedges that hold the spring retainers on the valve without fail !!! Those are the 2 weakest links in Merc motors, and consistently cause the most problems.... and if you lose a keeper @ speed, I assure you, you won't even have a useable core left. There are several tools for valve spring replacement that are not expensive, but depending on the room you have, may require more than 1 tool to make things easy. Don't wait, get after it!
I got REALLY lucky,,, I bought a 502 with only 90 LBS of compression in #6 last spring,,, figured Id throw it in, run it all summer and rebuild in the off season if it held all summer,,, well,, it did,,, yanked the valve cover to start teardown,,, and there it was ,,, one of the keeper wedges came out just enough to ride the rocker arm and not let the valve close fully !!!!!!!!!
NO DAMAGE !!!!!!!! not even to the rocker arm !!!!!!!!
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02-09-2003, 04:46 PM
#14
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Scott,
The Gills can be removed without removing one of the motors. There are several ways of doing this. One way is you can take all the nuts off the studs, then slide the manifold all the way towards the other manifold. Take a pair of needle nose visegrips and from the bottom lock them on the stud between the head and the manifold and work the stud loose. Another way it can be done is loosen a nut on the stud, then take another nut and thread it on, tighten the nuts together and try turning the stud out with the inner nut. Then another way that you could remove them is with a stud remover, thats if there is enough room. There are probley other ways to remove them, you have to be imaginative. Those are ways I have removed them in the past. They can be removed with out taking a motor out. I have other ways too. Hope that I helped you out. If you have any questions feel free to e mail me. Have fun
The Gills can be removed without removing one of the motors. There are several ways of doing this. One way is you can take all the nuts off the studs, then slide the manifold all the way towards the other manifold. Take a pair of needle nose visegrips and from the bottom lock them on the stud between the head and the manifold and work the stud loose. Another way it can be done is loosen a nut on the stud, then take another nut and thread it on, tighten the nuts together and try turning the stud out with the inner nut. Then another way that you could remove them is with a stud remover, thats if there is enough room. There are probley other ways to remove them, you have to be imaginative. Those are ways I have removed them in the past. They can be removed with out taking a motor out. I have other ways too. Hope that I helped you out. If you have any questions feel free to e mail me. Have fun
02-09-2003, 05:24 PM
#16
Ginger or Mary Ann?
Charter MemberThread Starter
Great info guys. But just to clarify, I do not have a boat at the moment. I was considering one with twin 500's and looking for what to expect. Thanks!!!
Also, as far as filling cylinders with air to hold the valves closed, while it sounds all good, (and have done it this way before myself)
I myself just prefer to have piston at TDC with no air and just use a spring compressor that has the fingers to compress the spring. Reason being, compressed air has a way of rotating a motor over if not positively blocked. Then you have the chance of the valve dropping down. By using no air and on TDC, the valve will just drop abit until it hits the piston. It ain't going no where. No way to drop it in the cyl.
Again, Thanks
Also, as far as filling cylinders with air to hold the valves closed, while it sounds all good, (and have done it this way before myself)
I myself just prefer to have piston at TDC with no air and just use a spring compressor that has the fingers to compress the spring. Reason being, compressed air has a way of rotating a motor over if not positively blocked. Then you have the chance of the valve dropping down. By using no air and on TDC, the valve will just drop abit until it hits the piston. It ain't going no where. No way to drop it in the cyl.
Again, Thanks
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