JMPH

iTrader: (1)

Doe anyone know -the 500 hp carbed have all the water reversion problems and valve spring issues in the earlier models 95,,97. Did they correct the problem in the later models 99 2000. I know the 2000 still ran the gill exhaust but noticed the riser are higher.You would think the problem would have been corrected by then.
Thanks Joe

rmbuilder

Joe,
It is correct, there were some problems with a run of springs used in the 500 series of engines (due to improper heat treat) that have since been resolved. However, it is impossible to determine which individual engines had springs with this wire.

Back in the late 90’s, early 2000’s, there was a problem with spring wire that suffered from improper heat treat. Because there are only two companies that supply 95% of all spring wires worldwide this wire made its way into the system of multiple suppliers, one of which supplied valve springs for Mercruiser. Limited numbers of the springs made there way into production engines and failed. This was an anomaly, and all the inferior wire/springs has since been removed from the system and the situation corrected.

Spring life has so many variables it’s difficult to put a cycle value on them. Because they are affected by heat, RPM (one “zing” can potentially kill a spring), wire quality/heat treat, and camshaft profile, the degradation curve is not linear and varies greatly from application to application. Heat is generated in the spring from multiple sources. First by cycling the spring through compression and extension. Secondly the friction between the coils generates heat. Third is heat absorption.

If you are in doubt, I would suggest that you check your springs for current values at seat load and open load, compare that to spec and see if you are within tolerance. These figures will give you baseline references for future fatigue evaluation and alert you to other potential valve train problems. Many cam/lifter failures originate with the springs inability to maintain dynamic stability. Check springs for discoloration and/or cracks regularly. If you do find a break that is jagged, that is due to harmonic resonance. A clean break is a sign of improper heat treat. Monitoring your springs for degradation is cheap insurance. Below are links to on head spring test tools of various prices.
http://www.power-t.com/spring/pt-700.html
http://www.intercomp-racing.com/fr_springtorque.htm
http://www.intercomp-racing.com/detail.cfm?ItemID=121
http://www.jegs.com/cgi-bin/ncommer...252&prmenbr=361
http://www.moroso.com/catalog/categ...p?catcode=27105
http://www.lsmproducts.com/p3.htm
Bob

JMPH

iTrader: (1)

Thanks Bob for the info

Griff

The reversion problem was fixed with the taller risers. Not sure when exactly they changed. I think it was second or third year of the 500hp.

performancemary

I had a pair of 500's ( carb) that were built in early 1999 and had the springs looked at after 270 hrs. They were fine but had them replaced anyway. Never had a reversion problem and I had the factory CMI's .

RaggedEdge

JMPH ,
I own a '99 Fountain with 500's and my opinoin , after complete , and expensive rebuilds at 168 hrs , is that anyone with 500's with stock Merc springs should take them out , throw them away , and replace them with some quality pieces. In my case one failed , dropping a valve , allowing it to kiss the piston. Not a lot of damage as it let go at idle , heard the ticking and assumed it was an inner spring , normally the first to fail , so made the mistake of idling back to the marina , it let go 100' from the slip.Fortunate for me it did not fail the day before at 5400 RPM , that gets real expensive. On tear down we found 18-20 of the 32 , did both motors to be safe ,inner springs and dampers broken and the resulting metal thruout both motors making complete rebuilds a must do. I , like everyone out there , was aware of Merc's spring "issues" with the 500's when I purchased this boat that had 120 hrs on it. No reason to think it had been used in anything other than a normal manner, it is an 11 on a 10 scale. Working in the sales dept. at a Merc dealership I called the H.P. tech guys we deal with for service related issues and was told about the service buletin which recomends you check spring rate etc. around 200 or so hrs., I assumed that I was in ok shape based on my opinion of the boat I purchased and the 120 hours. After the failure the same tech dept. explained how they had changed to a different spring on the 500 EFI's , I asked if I should use those as the replacements , was told they had worked out better but still needed to be checked around the same hours of use. A B.S. answer in my opinion. The original 500 springs are Crane and the later 500 EFI springs are Comp Cam pieces. Both are medium quality / price pieces and not long for this world in a roller camed marine engine. And both have had high failure in these engines.
I agree with rmbuilder that there are many reasons for valve spring failure , heat , harmonics , coil bind , etc. and do not have any knowledge regarding the spring wire issues. I assume he's correct , sounds very knowledgeable. My basic assumption regarding valve springs , like all things in life , is that you get what you pay for ! These 500 Carb / EFI springs , be they Crane or Comp , are budget hot rod parts , not real high dollar items that one would expect in an engine selling for the money Merc H P commands for them. I agree that testing pressures can give one an indication that they are begining to go away. To me a set of springs that are going away need throwing away ! Valve train issues are the most common reason for failure in a big block Chevrolet engine , Hydrolic roller cams are harder on the valve train , and therefore require high quality components. I do not specifically fault Merc for the spring failure , but do fault them for the misleading information. I would have been fine with being told " Our springs have a tendency to chit out at 200 or so hrs and if you have a brain in your head you will change them out long before you get there ". That at least would have given me a chance to prevent this. My lower ends were all fine , rings , bearings , etc. all great shape except for the broken spring metal thruout , take it all out and start fresh . Soon after my failure I had two close friends go thru the same problem , they both dropped valves , due to spring failure , unfortunately at 5000 +, real nasty mess !
On a positive note , I now run Isky SP's , one step down from their Tool Room series. A real quality piece , made from high quality wire , subjected to Spintron testing and all. Not cheap , but then in life " YOU GET WHAT YOU PAY FOR." I would have spent the extra money for their Tool Room springs but they did not have the pressures required and I went with their tech's recomendation. Their tech department was honest and straight foreward regarding the quality levels of their products , much more so than any of the others contacted. They have worked out really well , no more worries at WOT. This springs , the season , project is to change out the Crane Gold rockers. Mine now have 200 hrs on them and their reputation leads me to believe they need to find a new home. They checked out fine at rebuild. My engine builder felt good using them. But again "YOU GET WHAT YOU PAY FOR " so now that the wallet has had some time to heal from it's last wounding I am going to change them out before I get bitten by the bargin bug again. My engine " GUY " is a real Crower fan , and I trust his opinion. His work for me has been nothing but perfection so far and his faith in Crower is based on 20+ years of building and running with nothing but Crower rockers and not a single failure. This is all just my two cents ,for what it's worth. But maybe it can give someone an honest heads up to the potential problems and save them the same expensive education.

performancemary

OUCH Thats a sad story but it seams these factory springs are not all the same even though they have the same part #. When I had mine replaced at 270 hrs they were all fine and the motors were running great. There may be something to the raw material issue relative to metal used for some springs back when these motors were beiing built..