Dirthead

PLEASE HELP!!!!! This past winter I completely rebuilt a Gen 5, 454 to around 500 HP. I installed a cam that is 224 duration at 50 and has lobe separation of 112. I installed a Lightening header system which has 4 “ of riser and the Lightenings switchable exhaust diverters which exhaust out a the factory Y pipe or through a pair of tips that have internal flappers to keep the lake water from reentering the engine. Here is my problem. This motor only has 4 hours on it and I keep getting water in my oil. After about 3 weeks of troubleshooting I have narrowed it down. I have done leak down tests and they were fine. I have done compression tests and they were fine. I removed the thermostat and put a plate over the thermostat opening on the intake manifold and placed a fitting on it so I could put a garden hose on the cooling side and held the water at about 60 PSI for 12 hours and still had no water in the oil.

I continued to eliminate sources for the problem and even though I was reassured by my marine parts supplier that reversion was not the problem, I continued to think that reversion may be the problem. I put the boat on the hose and have ran the boat 4 times at 30 minutes, with RPM's between 400- 1800, and with the water exiting through the Y pipe and never get water in the oil. Then I switch the exhaust and have the exhaust exit through the haul tips and every time I get water in the oil after 10- 20 minutes. I have done this 5 times and every time I get water in the oil.

This has me baffled. I would think that when the exhaust is open out the rear tips that there would be less restrictions for the water to be sucked back into the engine oil. When the exhaust is switched and exiting through the prop, I would think that there is more restriction as the exhaust hits the diverter and has to travel down the Y pipe. At 400- 1000 RPM’s I can hear the internal flappers bouncing inside the tips. They really make a lot of noise. Initially I thought that the exhaust water might be hitting the flappers at the point when they have fallen shut and at that point was being sucked back into the engine. Therefore I wedged the flappers open and retested. At the end of another 20 minute test again I had water in the oil.

What should I do and can anyone explain to me why this is happening. I understand that reversion is caused mainly by where the water is being inducted in the exhaust and by the cam that you have. But under my tests, neither has changed. Under each test, my cam is the same and the water is inducted in the exhaust the same ,just as it leaves the headers and before the diverter valve. So how can having the exhaust closed eliminate this problem???

Please help!!!!! Any ideas would be very welcome. Please feel free to email me at [email protected]

dyno

I guess you could dry up the pipes....did you use sealent on the head bolts? I've had them leak before....

Ted G

iTrader: (1)

When you have a "Y" or "H" installed in the exhaust on most vehicles it causes a scavenging effect to occur in the exhaust system. The gases traveling downstream from one head sort of pull the other sides gases along with them. I suspect this is happening when you are switched to the prop. You are creating a slight low pressure area in the exhaust at low rpms that is pulling the water away from the engine. When you go thru hull the effect is gone and your cam profile/timing is causing some reversion of water.

hillbilly24

does it only happen on the hose, or does it happen in the lake too?

Dirthead

I had water in my oil after I was on the lake( I have only been on the lake once for an initial break in period and ran the boat with the exaust both open and shut), however since I have isolated the problem to the exaust I have only been able to have it on the hose. What are you thinking?

scarrab30

Hillbilly,Your on the right track! If this only happens when its on the hose, I think you need to turn the boat around in your driveway. You may not have enough pitch in the transom exit pipes if your driveway is pitched so that the bow is lower than the stern.

JCPERF

What head gaskets and how did you install them?The threads on the deck surface are blind so most people use a lubricant instead of a sealant.I have seen where some hole have broke through into water.You cant assume,you have to use sealant on all the head bolts.

Dirthead

I don't think that is the problem. I am testing my my shop so the floor does not have that sever of a pitch to it. Also, I have placed a level ontop of my valve cover and leveled the engine from that.

Cord

iTrader: (2)

What is your water pressure?

Dirthead

not sure. I do not have a gauge on it. However when I removed the thermostat cover and installed a block off plate and a fitting to hook it up to a garden hose it did not leak any water into the oil. The garden hose had 60 PSI going to the block off plate and I held it for 12 hours and had no water in the oil.