308 Water Pump - Scoring on Housing

Depends on the depth of the scoring. If the assembled dimension still meets the spec given in Fig 7 page C8 of the 308GT4 WSM, I wouldn't worry about it; if the dimension is way out of spec, then something to address -- JMO.

 

I agree with steve. So lets say you are out of spec. Here is how you do ferrari blasphemy that it totally wrong but it works. If the scoring is even and you lost metal on motor and on impeller you use an indicator similar to plastiguage and assemble the pump to check the clearance. If it is out just a bit you can be cheap and cheat by custom making your own paper gasket. Gasket raw material comes in many different thicknesses and compressibilities. There are decent sealants today like hondabond where you can do a metal to metal bonded surface. Under some conditions that will just not work and on others it will get you by. A proper fix can be expensive and time consuming which could include a weld up cut down or few mil coating like the header ceramic stuff. A while ago guys were coating pistons tops/combustion chambers and water pump guts to gain small performance advantages and heat tolerance under turbo conditions.

 

If it's not way out of spec, say measures 1.3 mm, then most likely it will work just fine as long as you aren't tracking the car on really hot days. Put it back together & see how it works. At worst you'll have to pull it out again & do as fatbillybob suggests. Or there's also the option of trying to pick up a good used WP body. There's not a lot of demand for them, so worth shopping around.

 

sometimes you can shim an impeller too. I forget exactly how a 308 one looks like

 

wouldn't the scoring add more clearance and wouldn't a rebuilt pump have the proper clearance to begin with??

 

yes and no. The rebuild comes with exposed impeller. the clearance needed is a spec like 1mm from the scored surface to the impeller blades. Some impellers can be shimmed some cannot. So you only adjustment becomes the gasket thickness. This is not a very precise issue and only is important when you are pushing limits as in racing or when everything else in your system is at its limit. So the spec listed is a working spec for what ferrari engineers as 100% efficient. If you open up the clearance by scoring then the output flow drops off or you get turbulance and cavitation which makes the 100% less like 90%. And if your radiator is kind plugged up with leaves, and you are idling in traffic and one of the cooling fan blades is broken well you get the idea...somewhere a straw will break the camel's back.