tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 9, 2006 22:53:02 GMT -5
Hey guys. I've got a '96 R/A T/A that runs great, sounds great but I'm afraid to drive because as the temp goes up the oil pressure slowly drops to 0. I'm thinking bearing clearance(no noise even at 0 pressure) or oil pump. I've confirmed the pressure with a mechanical Snap On gauge. My other car is a '67 Firebird and this is my first endeavor with an F-body newer than '79 so the LT1 oil pump setup is unfamiliar to me. What do you think? Engine or oil pump?
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Post by 1bad2k2ta on Oct 10, 2006 7:57:37 GMT -5
Hey guys. I've got a '96 R/A T/A that runs great, sounds great but I'm afraid to drive because as the temp goes up the oil pressure slowly drops to 0. I'm thinking bearing clearance(no noise even at 0 pressure) or oil pump. I've confirmed the pressure with a mechanical Snap On gauge. My other car is a '67 Firebird and this is my first endeavor with an F-body newer than '79 so the LT1 oil pump setup is unfamiliar to me. What do you think? Engine or oil pump? I am not an expert on LT1s, but I think it is your oil pump. It is normal for pressure to drop a little as the engine warms up and the oil thins a bit, but to drop to 0 is not good. When pressure drops to 0, it is due to the pump not pumping enough oil, either because there is insufficient oil and it is sucking air, or the pickup is clogged, or the pump is just worn out. What weight oil are you using? |
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Post by 93yellowfbody on Oct 10, 2006 9:16:51 GMT -5
does it drop pressure at idle?or when running?down the road,and i have read you only need about 4psi per 1000rpm!it's crazy how little you need to run(that's why it doesn't make noise).what could be happening is the coupler between the pump shaft and the camshaft is worn or broken (alot of them have a plastic coupler)you can pull the pan down and check it.
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Post by AAron on Oct 10, 2006 9:45:44 GMT -5
you might also replace the oil pressure sending unit, i have seen those go bad and do the same thing your are talking about
oh and as far as changing the oil pump on an LT1 it is very similar to old smallblocks. you have a 1 piece rear main, and thats about the only major change from the '70s on the bottom end. you can still change on the car without pulling the engine.
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 10, 2006 16:25:50 GMT -5
Gentlemen, thanks for the response. I wish it were the sending unit, but I plugged a quality mechanical one in and confirmed the pressure drop. The car has 137K miles on it and has always had Mobile 1 5w-30 ran in it. As the engine warms the pressure drops to 0 at idle but will come back up to 20-30 when revved. Havent revved it real hard out of concern. I'll begin pulling the pan this evening to get the pump out. Seems like a good place to start. If that doesnt show cause then it seems logical to yank and build. I've got about $4600 in the car right now so I'm not hurting real bad......yet.
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Post by 1bad2k2ta on Oct 10, 2006 16:41:16 GMT -5
Gentlemen, thanks for the response. I wish it were the sending unit, but I plugged a quality mechanical one in and confirmed the pressure drop. The car has 137K miles on it and has always had Mobile 1 5w-30 ran in it. As the engine warms the pressure drops to 0 at idle but will come back up to 20-30 when revved. Havent revved it real hard out of concern. I'll begin pulling the pan this evening to get the pump out. Seems like a good place to start. If that doesnt show cause then it seems logical to yank and build. I've got about $4600 in the car right now so I'm not hurting real bad......yet. What part of the country do you live in? 10w30 should be more than adequate for most climates down to about 5 degrees. That should help boost pressure a little bit; 10w40 even more. |
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Post by 93yellowfbody on Oct 10, 2006 17:36:21 GMT -5
exactly what i was going to suggest but check that clearence on the pump gears.make sure they are in specs.
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Post by AAron on Oct 11, 2006 12:59:40 GMT -5
keep us posted, id like to know what you find.
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Post by 94m6hardtopz on Oct 11, 2006 14:05:58 GMT -5
put some redline 10w40 in it. that should help raise the oil pressure and still maintain good cold start flow. it probably a combination of a high mileage oil pump and a lot of bearing clearance. run it til it dies. but start saving for a rebuild for a freshening. if you do most of the work yourself you should be able to just freshen the motor for about $1500, the the walls are still nice and you dont need pistons or any boring done, cheaper then that.
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 11, 2006 18:13:22 GMT -5
Yep. I think your probably right. I put the car up on jackstands with the intention of pulling the pan, but I think I'll just drain the skinny oil and replace it with some fat oil. Just to see what happens, then give it to my wife........
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 11, 2006 18:15:45 GMT -5
By the way, I've read that switching from the synthetic oil to "dino" oil is not a good thing. Any thoughts?
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Post by 1bad2k2ta on Oct 11, 2006 18:59:21 GMT -5
By the way, I've read that switching from the synthetic oil to "dino" oil is not a good thing. Any thoughts? I have never heard anything about switching from synthetic to dino other than the same reasons for switching from dino to synthetic in the first place. Just change the oil every 3000 miles and you should be fine. There are thicker synthetics available, like Clem stated. Just depends on whether you want to spend the $ for it, and how you plan to drive the car. |
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 11, 2006 20:20:35 GMT -5
Drinks for everyone!!!! One quart of Lucas oil stabilizer and topped off with GTX 20w-50 and I got 10-15lbs at idle. It even runs cooler!! I let it idle for 45 minutes and it never dropped oli pressure below the 10-15, never got hot enough for the fans, and registered higher pressure(40-50lbs) when revved. I'm on my third Jim Beam and Pepsi, what would ya'll like?
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Post by 1bad2k2ta on Oct 11, 2006 20:29:59 GMT -5
Drinks for everyone!!!! One quart of Lucas oil stabilizer and topped off with GTX 20w-50 and I got 10-15lbs at idle. It even runs cooler!! I let it idle for 45 minutes and it never dropped oli pressure below the 10-15, never got hot enough for the fans, and registered higher pressure(40-50lbs) when revved. I'm on my third Jim Beam and Pepsi, what would ya'll like? Great news!! Glad it worked out for you.  |
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Post by 93yellowfbody on Oct 12, 2006 9:15:11 GMT -5
sweet!!so it's a worn down pump.............
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Post by AAron on Oct 12, 2006 9:49:27 GMT -5
gratz
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Oct 12, 2006 18:59:36 GMT -5
I may go ahead and pull the pan and pump. I think we all would like to see an autopsy on this oil pump. I've never built the kind of all out motor that needed a blueprinted type pump so I have no experience tearing down a pump or knowing what I'm looking at. In fact I've only built one Chevy in all these years(but about 20 or so Pontiacs). Lots of high volume Melling pumps with the pickups all welded is all I've had to know so far.
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Post by 93yellowfbody on Oct 12, 2006 21:55:51 GMT -5
high volume is a real good choice but you may need a bigger pan.
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Post by AAron on Oct 14, 2006 10:46:05 GMT -5
high volume and/or high pressure pumps just take more HP to run you dont really need them.
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Post by 94m6hardtopz on Oct 15, 2006 12:15:56 GMT -5
high volume and/or high pressure pumps just take more HP to run you dont really need them. i agree, especially if you run a good oil. i like redline. |
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Post by Fire67 on Oct 16, 2006 8:50:57 GMT -5
high volume and/or high pressure pumps just take more HP to run you dont really need them. I agree for the most part, but there are some benefits in all out race motors. Would like to add that you shouldnt run one without a higher capacity oil pan, you will find that the pump is quite capable of sucking a stock pan dry at WOT. Were actually removing one from my buddys turbocharged 355 Camaro, because of the PTK header design we couldnt run the Canton pan on it. Had no choice but to run the stocker  |
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Post by AAron on Oct 16, 2006 9:52:25 GMT -5
oh yeah i didnt qualify that most in the range of 400 and below dont need them, i maybe wrong about the number
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tikler
Junior Dragster
Posts: 9
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Post by tikler on Nov 22, 2006 23:22:16 GMT -5
Ok all. Here's the verdict. The pressure problem slowly returned so the engine came out for autopsy. The pump revealed no excessive play or clearances but when we began to remove the balancer hub, big time endplay was found in the crankshaft. Then we noticed the circles wore into the front of all the main surfaces. When we pulled the rear main the thrust bearing was worn almost paper thin. The back of the crankshaft is totally wasted. Oil pressure problem found. I bought a wrecked '95 T/A Monday for the engine in it to build. I'll start pulling it this weekend and I'll let ya'll know if it's good. The car lot I bought it from claimed it "ran good" when they got it in. My car is a '96. Anybody know if I can install all the crank position hardware from my engine to this '95?
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Post by AAron on Nov 26, 2006 17:40:14 GMT -5
ooo not sure those OBD II motors are a bit different and i forget how exactly. you might just have to swap sensors, but i think the cranks are the same,
sorry about slow reply turkey day messed up internet usage
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