HP500 valve spring life
 

What kind of hrs is everyone getting out of their HP500 (carb) motors without tearing into the motor, considering they are ran fairly conservative?
Aside from the Mercury recommended 200hr spring change, are the lifters lasting longer?
Thanks

IM GETTING AROUND 230 HRS A YEAR ON MY MOTORS. I FOUND MY FIRST BROAKEN SPRING THIS YEAR.FOUND IT WHEN REFRESHING A 500 HP. WHEN THEY ARE OUT OF BOAT I ALWAYS PUT NEW SPRINGS IN THEM JUST FOR CHEAP INSURANCE. I NEVER RAN ANY OF MY SPRINGS OVER 250 HRS.MY LIFTERS HAVE NEVER WENT TO THE POINT OF NO RETURN.I REPLACED THEM AFTER ABOUT 500 HOURS, AND THEY WERE STILL WORKING.SOME WERE A LITTLE NOISY SOME TIMES BUT KEEPING OIL CHANGED REG. WILL EXTEND LIFE MANY TIMES.I RUN WILDTHING PRETTY HARD.JUST MY OPINION FOR WHATS ITS WORTH. RON BENDER

Doing mine now. Approx. 250 hrs on HP500 carbs. First motor no broken springs, but both head gaskets leaking between cylinders. Second motor - we'll see next week.

Jeff

Jerry,
Got 5-HP 500's and 2 HP465's running the 465's had rocker arm Issures at 500hrs(flat tappets).2 -1996 HP500's (carbs)1 spring broke at about 50hrs.(nice mess in the oil,put in a new long block)they now have 250 hrs gonna replace the springs and check lifters.3- 2001 HP 500's EFI about 50 hrs. may look at them .Those engines properly maintained are almost bullet proof

Thanks Guys!

Doug, .......50 hrs? ouch!

My 98's expired some time before 180 hr's,
I say some time, because, the only reason
I knew they was a problem was when
a lifter failed on the l/h engine.
Both engines were found to have
broken inner springs.
Luckily, this happened at the end of the
2000 season, and my dealer took
very, very good care of me (if you know what I mean:D )
My buddies 99's failed earlier than 180 hrs,
we decided to check them, after my disaster.

jt.

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.

"The heads can be removed with out even removing the motor from the boat."


I wish:rolleyes: :rolleyes:
The inner Gill manifolds won't clear the studs you have to pull one motor to get both heads off of twins.:crazy:
Whats sad is I had them both apart last spring and never replaced the exhaust studs with bolts.

jt29olhp500s

Is that the same Vandelay Industries that makes Laytex?

Scott,
Yes, their in laytex,
also in the inport/ export
business, they sometimes
dabble in architecture.

They even sponsored
me last year at the
LOTO shootout. :D :D :D

jt

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!

The broken springs I have experienced you have a miss that comes and gos.The oil got dirty fast.

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 !!!!!!!!:eek: :eek: :eek:

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

Findme.
That is very good advise with presurizing the cylinder. That would be an excellent way off changing the springs and retainers with minimum down time.

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

US1,

Was contemplateing your method. Glad to hear that it works. May use combo of that & "low" air pressure.

Mark

What brand/part numbers are you guys using? There are a LOT of really good springs out there that will go several hundred hours on a cam of .650" or less lift.

Blown1500,

What springs do you recommend for a stock '99 454 magnum? Also, what seat pressure and installed height?

checkmate454mag, I don't like the springs Mercruiser uses and always file them in the round file. I like Isky the best, but Crane and Comp have some very good pieces. Always use the "premium" springs for the application and FOLLOW INSTRUCTIONS.