My drag only 388 small block chevy has to much oil pressure and keeps blowing oil from the back of the intake and bottom of the distributor. It's a 12.5:1 motor that runs on E85 with a 5500 stall that I shift at 7000 and pass through the traps at about 7500. The cam is a solid lifter flat tappet and I have been using Rotella T or Scheaffers 15W40 in it. The block has a tall fill and I still have difficulty keeping the motor warm. The oil pressure is at 80 pounds at a 1200 RPM idle and off the scale when the rpm comes up. Once I get the motor up to temp in the shop after running it for 40 minutes or so it will idle at 30 pounds and move to 80 when rev'd up. Problem is that the car never gets ran enough at the track to heat the oil up enough for the pressure to drop. I'm thinking of stepping back to a 30 or maybe even a 20 weight in it. Am I barking up the right tree here?
Thinking of going to a thinner oil
- Thread starter KW
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Would this be a candidate for a HDEO 10w30?
That oil problem is not from oil pressure. The problem is from crankcase ventilation. If the oil pressure is high you have an[maybe]oilpump problem do you have a high output/high pressure oil pump?.May or may not be the problem but did you block off the oil filter bypass. at the oil filter adaptor? I think the oil viscosity approach at the moment is barking up the wrong tree. Make sure the lower visc oil has high additive levels for the cam.
Steve S, The distributor on a SBC passes through a main oil galley then is driven by the cam and drives the oil pump. The pump is a Melling HV55 which is a very common pump for hot rods. What's happening is that oil is blowing past the distributor shaft and blasting the back of the intake manifold with oil. Clearance on the mains are at .015 and I'm guessing it's easier for the oil to pass past the distributor shaft than get forced past the mains. The water temp might get to 140 at the track even with a 180 thermostat, the E85 seems to do a very good job keeping everything cool.
Smokescreen, I picked up 6 quarts of Rotella HD30 for it but now have started wondering if I should go even thinner. It sees maybe two 1/8 mile passes in a row 7 seconds or less then a cool down of at least 30 minutes for the transmission.
Smokescreen, I picked up 6 quarts of Rotella HD30 for it but now have started wondering if I should go even thinner. It sees maybe two 1/8 mile passes in a row 7 seconds or less then a cool down of at least 30 minutes for the transmission.
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One of the few things I can say I know is how small and big block Chevs work especially big blocks .I had a love affair with boats for many years . The H.V. denotes high volume? usually the H.V part in an oil pump is not needed. The clearances are nice and tight you definatly could go down in visc. . Did you block off the oil filter bypass at the adapter? unless the 30 is a multivisc is could be thicker than the 15w-40 depending on the oil temps.If oil is exiting the intake manifold the manifold is not sealed well.About 5 years ago I sold my boat when I needed to replace the motor the block was having problems with the head bolts pulling from the block They already had threadserts installed .I was thinking of one of the Aluminum World products 6oo cube crate motors but I walked out of the shop amd saw my wifes and daughters horses and I like to save a % of my money so I made the sacrifice amd sold the boat. I like chev engines for hot rodding because they are the cheapest to build and work well.
"keeps blowing oil from the back of the intake and bottom of the distributor."
I thought you meant it was shooting oil out of the rear intake seal as well. I was thinking how is that possible?
Too much pressure and volume maybe? I kinda agree with Steve on the high volume maybe not being needed. Just because everyone does it does not mean it's best.
That is some really high idle pressure when cold....... I would probably stay 30 wt or less. I would also be wondering am I running the too much oil pump. That sounds like your putting a lot of stress on your oil pump shaft, distributer gear etc.
Even Straight 30 may be too thick? How cold of temps do you start at?
Thinner oil and or less volume/pressure pump? Or less of both?
I thought you meant it was shooting oil out of the rear intake seal as well. I was thinking how is that possible?
Too much pressure and volume maybe? I kinda agree with Steve on the high volume maybe not being needed. Just because everyone does it does not mean it's best.
That is some really high idle pressure when cold....... I would probably stay 30 wt or less. I would also be wondering am I running the too much oil pump. That sounds like your putting a lot of stress on your oil pump shaft, distributer gear etc.
Even Straight 30 may be too thick? How cold of temps do you start at?
Thinner oil and or less volume/pressure pump? Or less of both?
Yes too much oil pressure is the problem. Before I pull the motor out and change the pump I think a thinner oil might be a fix. Before I moved over to E85 keeping the thing cool was a problem. Now with the E85 it does not warm up. I uses about a gallon of E85 per pass, enough to frost the carb. I have an OEM filter adapter that is not plugged and use an AC/Delco 454 filter that is the new number for a PF25, a SBC short filter.
Dang I probably should not have picked up the HD30. during a 60 degree start up I will be no better off than the 15W40. What do you think -- 5W30 or 5W20 in this application? Right now I can get over 60 pounds of oil pressure on the starter before the engine even hits on a cold motor, and the little oil pump is nothing special.
Dang I probably should not have picked up the HD30. during a 60 degree start up I will be no better off than the 15W40. What do you think -- 5W30 or 5W20 in this application? Right now I can get over 60 pounds of oil pressure on the starter before the engine even hits on a cold motor, and the little oil pump is nothing special.
That high volume pump at 7500 rpm is sucking your oil pan dry. Instead of a bandaid fix of too thin oil, you really need to go back to a standard volume/standard pressure pump first. I use to use a high volume / high pressure pump on my offroad vehicles that would practically idle for hours offroad and really thin the oil out. That is the perfect application for those pumps.
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Steve and bubba are are on the right track.
The intake manifold and distributor are not pressurized, therefore the oil viscosity is not directly related. I realize thicker oil will not drain as fast, but that is not the core problem.
Excess oil from not being returned to the sump, bad ventilation, or bad sealing is the problem.
Opening up the oil drain holes is a standard modification for racers. BTW.
The intake manifold and distributor are not pressurized, therefore the oil viscosity is not directly related. I realize thicker oil will not drain as fast, but that is not the core problem.
Excess oil from not being returned to the sump, bad ventilation, or bad sealing is the problem.
Opening up the oil drain holes is a standard modification for racers. BTW.
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While you're ditching the HV pump ..fix that bypass valve.
to quote oily123:
Just because everyone does it does not mean it's best.
There is absolutely no upside to this alteration.
to quote oily123:
Just because everyone does it does not mean it's best.
There is absolutely no upside to this alteration.
Maybe you need a Crankcase Evacuation Kit that Moroso sells.
I hope you are not running a stock oil pan. I believe Moroso and Milodon both sell 7 quart oil pans. Hopefully you have a windage tray, and crankshaft scrapers on the oil pan. Another thought is a rear pan baffle that keeps oil from being thrown back and gets caught up in the crankshaft.
What type of cylinder heads are you running, you may need to open up those drain holes.
Summit and Jegs sell the Crankcase Evacuation kit, I think it goes for $40.00
Shouldn't there be a relief valve on his oil pump.
I hope you are not running a stock oil pan. I believe Moroso and Milodon both sell 7 quart oil pans. Hopefully you have a windage tray, and crankshaft scrapers on the oil pan. Another thought is a rear pan baffle that keeps oil from being thrown back and gets caught up in the crankshaft.
What type of cylinder heads are you running, you may need to open up those drain holes.
Summit and Jegs sell the Crankcase Evacuation kit, I think it goes for $40.00
Shouldn't there be a relief valve on his oil pump.
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Shouldn't there be a relief valve on his oil pump.
Sure there is. He just needs to re-enable his in block bypass valve. This is the most widely done mod ..and, while people feel the need for it, no one can trace where the practice started (AFAIK). I imagine that it's (somewhere in there) some "trick" thing that Ford and Mopar cannot do ..but I don't think anyone will point to Fords and Mopars having bypass valves installed in their filters, eliminating the option, having lost any races that they deserved to win ..or destroyed any engines for the alleged vulnerability that it allegedly allows.
"If only I had used a 51410 WIX filter ..without a bypass valve, I may have won ..or not lost my engine
"
It's a mistake.
Shouldn't there be a relief valve on his oil pump.
Sure there is. He just needs to re-enable his in block bypass valve. This is the most widely done mod ..and, while people feel the need for it, no one can trace where the practice started (AFAIK). I imagine that it's (somewhere in there) some "trick" thing that Ford and Mopar cannot do ..but I don't think anyone will point to Fords and Mopars having bypass valves installed in their filters, eliminating the option, having lost any races that they deserved to win ..or destroyed any engines for the alleged vulnerability that it allegedly allows.
"If only I had used a 51410 WIX filter ..without a bypass valve, I may have won ..or not lost my engine
It's a mistake.
What's wrong with the bypass valve? It works just fine, new from the GM parts counter, you won't talk me into plugging it an blowing the oil filter off.
The car has a windage tray, the oil pan is a 7 quart wide sump with trap doors, RHS 210cc aluminum heads, Super Victor manifold. I have it vented to open air with 1" breathers on each valve cover. No oil is shooting out of them. Only the vapor that you would expect an alcohol drag motor to have. It holds good oil pressure pressure all the way down the track.
The block has a tall file with hardblock, 7 quart pan with 6 quarts in it to be sure the counter weights don't whip the oil up.
The car has a windage tray, the oil pan is a 7 quart wide sump with trap doors, RHS 210cc aluminum heads, Super Victor manifold. I have it vented to open air with 1" breathers on each valve cover. No oil is shooting out of them. Only the vapor that you would expect an alcohol drag motor to have. It holds good oil pressure pressure all the way down the track.
The block has a tall file with hardblock, 7 quart pan with 6 quarts in it to be sure the counter weights don't whip the oil up.
Originally Posted By: KW
I have an OEM filter adapter that is not plugged and use an AC/Delco 454 filter that is the new number for a PF25, a SBC short filter.
Nope I never plug them Gary.
I have an OEM filter adapter that is not plugged and use an AC/Delco 454 filter that is the new number for a PF25, a SBC short filter.
Nope I never plug them Gary.
Originally Posted By: KW
What's wrong with the bypass valve? It works just fine, new from the GM parts counter, you won't talk me into plugging it an blowing the oil filter off.
The car has a windage tray, the oil pan is a 7 quart wide sump with trap doors, RHS 210cc aluminum heads, Super Victor manifold. I have it vented to open air with 1" breathers on each valve cover. No oil is shooting out of them. Only the vapor that you would expect an alcohol drag motor to have. It holds good oil pressure pressure all the way down the track.
The block has a tall file with hardblock, 7 quart pan with 6 quarts in it to be sure the counter weights don't whip the oil up.
It seems like you have the oil pan and windage tray, I am not a fan of the breathers you have, they are just venting, you need something to suck that crank pressure out of the engine.
I would look into the Moroso Crankcase Evacuation Kit, or maybe putting on a PCV Valve.
What's wrong with the bypass valve? It works just fine, new from the GM parts counter, you won't talk me into plugging it an blowing the oil filter off.
The car has a windage tray, the oil pan is a 7 quart wide sump with trap doors, RHS 210cc aluminum heads, Super Victor manifold. I have it vented to open air with 1" breathers on each valve cover. No oil is shooting out of them. Only the vapor that you would expect an alcohol drag motor to have. It holds good oil pressure pressure all the way down the track.
The block has a tall file with hardblock, 7 quart pan with 6 quarts in it to be sure the counter weights don't whip the oil up.
It seems like you have the oil pan and windage tray, I am not a fan of the breathers you have, they are just venting, you need something to suck that crank pressure out of the engine.
I would look into the Moroso Crankcase Evacuation Kit, or maybe putting on a PCV Valve.
Thanks but crank case venting isn't the problem. Excessive oil pressure in a motor that won't really ever warm up is the problem.
Your engine sounds well done. Try a HDEO 10w-30. I would guess you change the oil often anyway. I looked up some records from my boat with a regular output oil pump with a higher pressure oil pump relief spring and 2 thou clearance crank and rods I would get 60 psi cold idle 950 rpm and peg the gauge when warm around 30 idle and 70 when hot ......I think you are right on about the oil visc. What is sealing the intake manifold ends?
Black RTV. This next time I'm going to try the gray stuff GM sells for aluminum. I never had a problem before with the black stuff but I sure am tired of having a leaky engine.
It is a sucky area to seal. I used 15w-40 in the above engine.
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