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1991 Wellcraft Scarab LOOSING MY MIND WATER IN OIL

R

russsb

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"I have a 1991 Wellcraft scara

"I have a 1991 Wellcraft scarab Excel 28ft. i bought this boat approx. 3 years agao...it came with a 454 which ran perfect for 2 years... I ran it aground in a shallow part of the lake. Right after that my raw water pump went out....causing the boat to run hot. Starting getting water in the oil. I thought it had a blown head gasket, so i replaced them....didnt solve it...so i just bought me a new 502 from GM...installed it...same thing...ran it for approx 1 hour, water in oil again....ended up pulling the manifolds off the motor and left all the hoses attached...and started the engine...water was running out of the exhaust ports...manifolds were cracked...replace them with new ones. Just ran it again today....noticed steam coming from my crackcase vent just like before...! Water in oil again...this is driving me crazy...can anyone help, with any advise? Motor still runs fine...i dont know where to go form here?
Thanks Russ"
 
Did you change the oil after c

Did you change the oil after changing the manifolds? Could still be some residual water in the crankcase which will burn off in a short time. Rod is right about the cooler but what are the chances that the manifolds and the cooler are both bad?

Why don't you pressure test the cooling system? That would have saved you the thousands of dollars you spent on the new motor.
 
The 454 had already started kn

The 454 had already started knocking....after so much water going thru it. And it had 600 hrs on it. I bypassed the oil cooler .....this time to be sure that was not the problem...not it. How do u go about pressure testing the system. It is totally cooled by lake water? thanks for your help!
 
Oh yea and yes....i changed th

Oh yea and yes....i changed the filer and everything! Doesnt seem to leak in the engine running it off a water hose out of the water. But when u put it in the water....and run it semi hard...after about 15 minutes thats when u notice it!
 
"Just curious.....when the eng

"Just curious.....when the engine overheated, after the raw water pump went out! My manifold got hot and cracked. Is it possible that my exhaust flappers at the rear of the boat could be a problem.....when the boat sits in the water....the exhaust ports are barely out of the water...any advise would be appreciated!"
 
Your risers should prevent wat

Your risers should prevent water from getting back into the engine when the boat is sitting. But the flappers are an essential part to prevent swells and backwash from from getting in . The flappers could be toast from overheating; you should check them.

Rod
 
Russ ... I have a 3.7L that ha

Russ ... I have a 3.7L that had this water in oil and steaming valve train problem. For me it turned out to be a rot hole in the riser where the water expels out with the exhaust. the rot hole was in the elbow cooling jacket and allowed water to leak back down into the exhaust manifold. steaming when running and into the sump through an open exhaust valve when not running. As for the shutter... I don't know how necessary they really are... I have recently been running without it and have had no problems. I plan to replace them anyway though two local marine mechanics told me that I really don't need to. check out the riser and or gasket for leaks. Good Luck
Scott S
 
"I used to work for Wellcraft.

"I used to work for Wellcraft. Exhaust flappers were a huge problem. As noted by others, when you overheat, you can help them cook them out. It's real easy for the engine to get some water sucked backwards without them and smaller boats like the 21 did not allow alot of riser to compensate.
You can usually see them from the outlet end."
 
"it was my riser gaskets, than

"it was my riser gaskets, thanks for all your help....trying to make sure my coolant hoses are routed correctly now!"
 
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