Port motor ...454 ...is consuming oil at an alarming rate ...about 1/2 quart an hour ....maybe more .... this motor has about 40 hours ....had an overheat issue last summer and pulled the motor redid the heads ...it recently has some back fire issues at WOT but new plugs , fuel filter, a merc fuel additive and some MMO seemed to clear the backfire issue. when I changed the plugs I took compression and it was very good all about 168lb ....there are NO leaks ....doesn't it either need to be rings or maybe valve guide issues ? It doesn't seem to smoke and runs well ......

May be an oil cooler leaking into the water line if you have them. We had one blow and were using 2 quarts an hour-ran great but was dumping oil all over the port drive and strg plate. Look for oil slime in the water line after the oil cooler.

I have thought of that and should check it ...someone said though that you would get water in the oil too ...leaks both ways ....but I guess oil pressure is higher .... motor is in 311 formula with Silent thunder ..but i can check for oil slick with just port motor running ....

We got virtually no water in the oil with a big leak. It might be hard to see oil because of the platform box. You could bypass the cooler with a piece of tubing in the hose ends, then run the engine (not hard) and see if oil forms in the water passage of the cooler.

I had an a PS cooler do that last summer. Would empty the PS pump in about twenty miles. At an idle I was getting "milk" out of the starboard exhaust. That was the giveaway . PS showed no signs of water. All this was visible out of my Silent Thunder.

will do guys ....believe me ..not looking forward to pulling another motor .....

The problem may still be rings. If during overheat, one or more of the oil control rings were stuck or damaged, could cause oil consumption, If top rings (compression) are still good, compression check will still be OK. Are 1 or more of your plugs oily? If consumption is in the combustion chamber you will see it on them.

just an update on oil thirsty port motor ..I pretty much juat been runnin it and keep it topped off ..but one interesting thing I've noticed is that everytime I go to check the oil the dip stick is pushed out 2-3 inches ....there is pressure in the crankcase comming from somewhere ...the motor runs perfect ....

What do you have for breathers?

Stock breathers ... Someone sujested it could be the PCV valves ....which I believe there are two ....one to each side ...

looking for oval stainless or Aluminum breathers but most are like 3-400 bucks ....each !!