787 eating rave valves

[Havinfun]

My 97 challenger 1800 has been destroying rave valves, in about 10 hrs. I have replaced 4, any ideas why this is happening? Getting quite expensive!!!

 

[racerxxx]

What parts are you replacing when you replace them?

 

[Havinfun]

Have been using mostly used parts from local shop, some from eBay. Most are breaking shaft about O ring area, have replaced blades only, blades and pistons, (piston and cap melted) also couple complete units with housings.

 

[Havinfun]

Purchased boat about a year ago, SUPPOSEDLY engines had both been rebuilt, have found out since the seller/rebuilder is known for not being very truthful

 

[mikidymac]

I would say stop buying used parts. The valves and housings can become worn.

Also if the cylinders were bored oversized you have to trim the valves so they will not hit the pistons. So if you have oversized pistons and put standard length valves in they will hit the pistons.

In very rare cases the slots in the cylinders can become too worn and new valves and housings will not fix the issues but this is really rare.

 

[Havinfun]

Cylinders are stock bore (81.89), Pistons show no damage, usually front cyl.,valves show signs of piston contact,, would double gaskets possibly help?

 

[mikidymac]

No, only single gasket.

If the valve contacted the piston your pistons are shot also.