I've Heard Some Hp 500 Carb Motors Have Had Valve Spring Problems, Breaking, Cracking, Etc. At About 200-250 Hours. Has Anyone Had This Problem Or Heard Anything About It? 1998 Is The Year In Question....

Its in the maintenance schedule for these springs to be changed at 200 hours... Give mercury a call....

Yes, if run up wards of 275, most have trouble with them.... I believe the 1998's had crane springs... Most are going to competition cams springs.... seem to last a little longer....

Yes

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Do you know if the same maintenance schedule is true with the EFI models (2002 year)??

Supposedly it is not. That said, it's not much work or money to replace them.

HEY ILL TELL YOU WHAT IVE SEEN IN THESE ENGINES BY THE TIME YOU HAVE 200 HRS THE VALVE SPRINGS HAVE LOST APROX 30 TO 40 LBS ON THE SEAT AND THE VALVE FLOAT WILL MAKE YOU LOOSE A VALVE IN A HURRY. THE BEST THING TO DO IS TO HAVE A COMPITENT SHOP GO THROUGH THE HEADS AND CHECK THE GUIDES ALSO FOR WEAR MOST LIKELY THEY WILL NEED GOING THROUGH ALSO THE SPRING WE USE IS A TIGHTER SPRING TENSION THEN THE MERC AND GENERALLY LAST MUCH LONGER BECAUSE IT DOES NOT HAVE AS HIGH TENDENCIES TO GO INTO VALVE FLOAT BUT YOU HAVE TO BE CAREFUL HOW MUCH TIGHTER YOU GO WITH THE SPRING BECAUSE AFTER A CERTAIN POINT THE LIFTERS WILL START TO MAKE NOISE. THE SPRING TENSION WE USE IS 145 LBS ON THE SEAT AND 400 LBS OPEN PRESS HOPE THIS HELPS YOU AND OTHERS OUT IF YOU NEED ANY FUTHER HELP YOUR WELCOME TO CONTACT ME AT 1-305-884-5368 LAZ MESA WWW.MESABALANCING.COM

When this happens valves do not get enough seat time to cool down and you end up sucking a valve. Very unhappy situation at that point.

BT

I have first hand experience on this If you have over 200hrs on you hp500 carb yes, replace your springs.

If you have a 500efi YES replace your springs no longer than 250 Hours, I replaced mine at 275hrs and already had a broken inner spring, and I baby my motor less than 3% WOT. They were the Newer Comp springs from merc, I replaced them with comp only because I had purchased them before I pulled the old ones to minimize down time never knowing one was already broken, it ran perfect. I will replace mine again in 200hrs and go with Isky Springs next.

Will Murray

I just did mine springs on my 500efi. I didn't relize till I got it back how noisy it was before! Now when I lift the hatch, just at idle, all I here is the drive. Big difference. I did mine at 230 hours.