I need a little help again Vinny, others!!

[lt133]

I haven’t been around the board much over the summer, but that’s another issue, I did have a great time at Sebago, looking forward to next year. So here’s the problem in a nutshell. I experienced a sudden power loss while throttling up after a 30-minute cruise through a no wake zone. Heard all kinds of bad noises, sounded like drive train. Pulled the motor and found a push rod broke through the rocker arm #2 cylinder exhaust. Further invest showed a couple of valve seals lying in the head on the port side also. There was no other damage, pistons, valves, everything else looks good. There is absolutely no sign of any water or fluids in the cylinder. Any ideas on what would have caused this? People I purchased the motor from don’t want to cover it under warranty telling me it was not a factory defect and that I must have reverted some water and that was my problem, which is definitely not the case. The motor is a stock 502; cam has been changed (don’t have the specs in front of me but it’s somewhere around 561 lift, 114 LSA nothing radical) Hardin Marine XS Extreme intake, Holley 800cfm, Gil Offshore exhaust. My plan for right now (budget restrictions considered) to get back up and running is to replace the stock rocker studs with the Comp Cams Adjustable Rocker Conversion Kit and replace all the rockers with the Comp Cams Pro Magnum Rockers as well as all new valve seals. Springs look fine; engine only has about 20 hours on it. Any ideas or suggestions? Thanks in advance.

 

[ezstriper]

Were you running stock stamped rockers ? if so and it sounds like it just could have had a rocker failure, need to run some decent rockers and pushrods...Rob

 

[Big Red]

A few things could have caused this problem.

1. Water but you ruled this out.

2. the valve stuck

3. spring bind == the wrong springs for the cam

4. Bad rocker


Valve seals laying around in the heads come from few things

1. They are rotton or

2. The spring is hitting them from spring walk

3. wrong seals for the guide

If I was you I would find my Cam card and bring your heads down to a good performance speed shop and let them fix your heads right. You need to measure the springs heights. You need to have your open and closed spring preasure right with the right springs if not you will get spring bind and jerk studs out and bend rockers. You can not look at a spring and tell if its fine or not it needs to be preasure tested.

If you don't your taking a chance in bending a valve and then the piston is going to smack it .

 

[ezstriper]

Also on your valve seal issue sounds like you do not have enough installed height on your valve springs or the retainers are crushing the seals on the valve guides, and the engine builder should have checked this if they installed the cam, also could be the reason put the push rod thru the rocker, Rob

 

[vinny p.]

Hello Bob,

I havent been home for a couple of weeks. Thats why I havent checked in here for a while. We went out west again. We came very close to buying a home in Lake Havasu. My better judgement kept me from completing the deal, at least for now.

Anyway, sorry to hear of your troubles. I agree with posts 3 and 4 . Making sure your spring heights are set correctly is most important on any engine, especially marine. BUT, dont let anyone talk you into just taking out a few shims to get more installed height. That will lower spring pressure, which will cause a host of other problems. What guides are in the heads? If they are not bronze, have them installed while you have the chance. Stock heads dont come with bronze guides. That can cause valves to stick, which can break valve train parts. However, that in itself wont cause the seals to crack off. Something is hitting them.

Vinny