SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: seapat on April 16, 2016, 02:19:24 PM
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Any one recommend engine builder in the oc. Rear main leaking gen 4 bbc. Considering doing it my self and renting engine stand. I just want it fixed right first time. Any guess estimates on $$$
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You don't need an builder for a rear main.
Two hour job once the engine hits the stand.
Grab a Lysle Sneaky Pete, a pan set ands the rear seal. Don't forget a tube of black RTV.
GT
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You don't need an builder for a rear main.
Two hour job once the engine hits the stand.
Grab a Lysle Sneaky Pete, a pan set ands the rear seal. Don't forget a tube of black RTV.
GT
you make everything seem easy Gt. One peace oil gasket? Rtv only on corners? Any recommendations on brand of seal?
Thx you are always so helpfully on the forum.
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you make everything seem easy Gt. One peace oil gasket? Rtv only on corners? Any recommendations on brand of seal?
Thx you are always so helpfully on the forum.
Felpro, Victor, GM, they're all good.
If you can find the one piece pan gasket, they are reusable. Just a tiny dab of RTV in the corners. Don't over torque the pan bolts.
The rear main cap needs to come off, as does the oil pump.
Good time to inspect those parts for wear and check the pan pick up for proper clearances.
http://m.summitracing.com/parts/lil-27000?seid=srese1&gclid=CjwKEAjwxce4BRDE2dG4ueLArHMSJADStCqMYmWNEH5QdL48a6qkNaMERfRV-M25vn2AV_gJRR40nBoCVoTw_wcB
GT
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http://m.summitracing.com/parts/fel-1884r
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In starting to wonder if my oil preesure is to high and forcing oil out of seal? 40 to 60 lbs idle 80 plus Guage maxed out on the gas. 20/50 weight. One breather, pcv on other valve cover of that matters.
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In starting to wonder if my oil preesure is to high and forcing oil out of seal? 40 to 60 lbs idle 80 plus Guage maxed out on the gas. 20/50 weight. One breather, pcv on other valve cover of that matters.
Doubt it seriously, but why 20w50 and why such high pressure?
Do you know what clearances the engine was built to?
GT
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This slot in the main cap is to provide a return path for oil coming off of the #5 main so the seal doesn't see direct pressure.
The crankshaft has a fairly large slinger that controls the forward thrust and shields the seal from direct pressure.
It is, however, possible that the oil is sloshing up the back wall of the pan, causing the seal to lose control and leak.
Any issues would be compounded from excessive blow by and/or lack of proper crank case ventilation.
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Doubt it seriously, but why 20w50 and why such high pressure?
Do you know what clearances the engine was built to?
GT
unfortunately no. Motor is fairly fresh. That was oil I was told to run. Pressure don't know. I thought it was normal. Should I try 30w. Going through 1/2 court a day
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Just fired her up in driveway, Ã s im cleaning up ugly oil mess in bulge. 60lbs at idle. Sounds like it is still seal that is bad. Putting on bigger breather will help?
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Putting on bigger breather will help?
You only have one breather and a PCV?
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Yes, motor has mild cam and 30 over. It's a common configuration. Breather is clean and new
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Because of the nature of a connecting rod, pistons move at different rates about Top Dead Center (TDC) and Bottom Dead Center (BDC).
Imagine a 2-cylinder "boxer" configuration. Cylinders are 180-degrees opposed and both connecting rods are on the same crank throw. At first it would appear that the volume of gasses in the crank case would simply move back and forth with the pistons. However, since the motion of the pistons are different, the gasses trapped in the crank case are actually being compressed.
Let's complicate matters further by adding six more cylinders. And yet again further by placing the cylinders in a V configuration. Now through into the mix, a dual-plane crankshaft where the rods are spaced at 90-degree intervals. The volume of the crank case continuously changes with each rotation.
If that wasn't complicated enough, even good sealing piston rings will have a percentage of leakage. Every time a cylinder fires, combustion gasses leak past the rings into the crank case.
Without sufficient ventilation, or better yet, evacuation the crank case becomes pressurized, increasing the stresses on gaskets and seals.
Now consider the rear main seal, it is being asked to maintain seal against a rotating shaft and to do so with a split design (not a continuous uninterrupted sealing edge). At 3000 RPM there are 2,159.7 surface feet of bearings journal moving past any point on that seal every minute. At 5000 RPM, the Surface Feet per Minute (SFM) is 3,599.5. It's a lot to ask of a little $3 piece of rubber, or worse yet, a piece of rope.
Some engine builders insist on installing the seal where the joint has an international mismatch with the mating surfaces of the block and main cap. The theory is that the path that the oil has to take to leak is more difficult than if everything is lined up.
Other engine builders prefer to align the joint of the seal with the main cap surface (this is the way the factory does it). The theory is that the ends of seal are pressed together harder, when the main cap is installed, forming a tighter joint at the ends of the seal.
Either way you choose, It is good practice to put a dab of RTV (I forget which color is most resistant to oil) on both ends of the seal to prevent any voids.
If you are still bearing with me after all of this, here is my current thinking on your situation: I'm thinking that you possibly have a bit too much oil in your pan, either allowing the oil to slosh up the back surface of the pan and cover the seal. Or you have a bit of a windage issue, again overloading the seal with oil. Excessive pressure from lack of crank case ventilation is blowing the oil right past the seal.
It is entirely possible that the seal has failed and/or was installed wrong, but I do believe that breather capacity is an issue here.
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Because of the nature of a connecting rod, pistons move at different rates about Top Dead Center (TDC) and Bottom Dead Center (BDC).
Imagine a 2-cylinder "boxer" configuration. Cylinders are 180-degrees opposed and both connecting rods are on the same crank throw. At first it would appear that the volume of gasses in the crank case would simply move back and forth with the pistons. However, since the motion of the pistons are different, the gasses trapped in the crank case are actually being compressed.
Let's complicate matters further by adding six more cylinders. And yet again further by placing the cylinders in a V configuration. Now through into the mix, a dual-plane crankshaft where the rods are spaced at 90-degree intervals. The volume of the crank case continuously changes with each rotation.
If that wasn't complicated enough, even good sealing piston rings will have a percentage of leakage. Every time a cylinder fires, combustion gasses leak past the rings into the crank case.
Without sufficient ventilation, or better yet, evacuation the crank case becomes pressurized, increasing the stresses on gaskets and seals.
Now consider the rear main seal, it is being asked to maintain seal against a rotating shaft and to do so with a split design (not a continuous uninterrupted sealing edge). At 3000 RPM there are 2,159.7 surface feet of bearings journal moving past any point on that seal every minute. At 5000 RPM, the Surface Feet per Minute (SFM) is 3,599.5. It's a lot to ask of a little $3 piece of rubber, or worse yet, a piece of rope.
Some engine builders insist on installing the seal where the joint has an international mismatch with the mating surfaces of the block and main cap. The theory is that the path that the oil has to take to leak is more difficult than if everything is lined up.
Other engine builders prefer to align the joint of the seal with the main cap surface (this is the way the factory does it). The theory is that the ends of seal are pressed together harder, when the main cap is installed, forming a tighter joint at the ends of the seal.
Either way you choose, It is good practice to put a dab of RTV (I forget which color is most resistant to oil) on both ends of the seal to prevent any voids.
If you are still bearing with me after all of this, here is my current thinking on your situation: I'm thinking that you possibly have a bit too much oil in your pan, either allowing the oil to slosh up the back surface of the pan and cover the seal. Or you have a bit of a windage issue, again overloading the seal with oil. Excessive pressure from lack of crank case ventilation is blowing the oil right past the seal.
It is entirely possible that the seal has failed and/or was installed wrong, but I do believe that breather capacity is an issue here.
Thank you Flusher, unfortunately I think this is going beyond my technical skills. I will try lighter weight oil and bigger breather. Oil was not over full according to dip stick floating on water.
Hate to take it apart and not see obvious problem
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Thank you Flusher, unfortunately I think this is going beyond my technical skills. I will try lighter weight oil and bigger breather. Oil was not over full according to dip stick floating on water.
Hate to take it apart and not see obvious problem
Try leaving out a quart or two and monitor for fluctuations in pressure and changes in the leak.
Keep in mind that the engine will be at different angles while on the trailer, floating, and on plane. I don't have a good solution other than by trial-and-error.
Good luck,
Joe
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Finally got around to pulling motor. Think I found oil leak. Pressure sender to block.
Not sure if it is rear main now?
Replace anyways
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Pulled motor again, thinking it was oil drain hose again. It's Nothing obvious. Getting frustrated, slight head gasket leak? There is definitely oil coming from somewhere. Who in oc can help. I live in garden grove.
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Oil is spinning on ring gear getting on starter, would head gasket leak oil or just water. Looks like oil is coming from back of head, dripping down
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