BenKey Posted April 16, 2004 Report Share Posted April 16, 2004 I changed my oil a few days ago and did an engine flush (Amsoil product), just before the change. When I started the truck back up, my truck did the normal thing, start out low, then come back up on pressure. This time it took too long to come up in pressure and the low oil pressure light came on for an instant, then shut off after pressure starting coming up. After I ran it for a little while at idle, I took it for a test spin and noticed my oil pressure didn't come up as high as it used to. I have a Thunder Racing LS-6 modified oil pump and usually can nearly peg the gauge at WOT and idles at about 30 psi. I tried punching it a few times, but the pressure would not come up much past 20. I started wondering if it may have been the thicker oil that I had put in. I switched over to syn 20W-50 and thought that may have been it. That was the only thing that had changed from my normal, so I thought that must be it. So, I drained about half of it and put in 10W-30, and it did get a little better. This morning I drove it to work, babying it. Pressure stayed a little above 20. During lunch I changed the filter and 6 fresh qts of 10W-30. Not much change in pressure, so I tried to take it a little easy. So, after work I'm coming home and at idle I got the oil pressure low alert and pulled over - gauge had almost bottomed out. I checked for leaks everywhere - nothing. I cranked back up and alert was gone and pressure was up about 20. The only thing I can think of is the engine flush has broken so much stuff free, that maybe my screen is clogged (wherever that is located), or my pump has crapped out on me. __________________ Since then, I have lowered the front diff carrier and took off my oil pan and oil pump. I checked the pickup tube screen and pump. I took off the LS6 TR ported oil pump and put my stock pump back on. I put this pump on in Jan and have zero problems with oil pressure until now. I have a new sending unit that I have purchased and plan to install today - maybe. The truck, in the morning, starts up and will idle at nearly 20psi. While driving at 2k RPMs it will sit at about 20 psi. Under about 3k RPMs, it will go up to about 30psi. As it gets warmer, it starts to degrade slightly under power, and at idle and even will bottom out at idle at the red light. This acts like some electrical/electronic components I have dealt with before. The fault usually lies with the o-ring seal, but they usually don't just come out of nowhere? Right now I am throwing a few things around. The sensor (getting that on in a few), the neck that the pump turns on (a keyed collar that goes over your crank pulley) has cracked, or broke and is just spinning, or possibly the filter neck (threaded area you screw your filter into) has cracked. If it's not one of these, then it could be my bearing are somehow shot causing blow-by. If that's the case, then I'm really done. Link to comment Share on other sites More sharing options...
deezel Posted April 16, 2004 Report Share Posted April 16, 2004 Damm, that sucks! I sure hope you figure this one out, Ben. Are there any filter screens or restrictions in your aftermarket oil filtration system that might have become clogged? (Im not sure how complicated the Amsoil setup is) Best wishes Link to comment Share on other sites More sharing options...
BenKey Posted April 16, 2004 Author Report Share Posted April 16, 2004 I haven't done the double bypass filter system on this truck yet. The Radix is off now. Getting ready to replace the oil pressure sending unit. That thing cost $41. Link to comment Share on other sites More sharing options...
56chevywagon Posted April 16, 2004 Report Share Posted April 16, 2004 Hopefully you find out whats causing the low pressure. Good luck. Link to comment Share on other sites More sharing options...
BenKey Posted April 17, 2004 Author Report Share Posted April 17, 2004 Well, go the oil pressure sending unit replaced and everything back together and running. No change. Not sure what the hell to do next. More fun for me, I guess. Link to comment Share on other sites More sharing options...
PewterC3 Posted April 17, 2004 Report Share Posted April 17, 2004 That's why I would never do the "flush". Had a neighbor that did it to his truck many years ago.....things went from bad to worse. Link to comment Share on other sites More sharing options...
SuperSport Posted April 17, 2004 Report Share Posted April 17, 2004 Ben All i know that our motors are designed to run with thin oil and so the tolerances of our motors are made for thin oil. The thicker oil has a hard time going were a 5-30w will go. I hope you figure out what the problem is. Link to comment Share on other sites More sharing options...
whmayhew Posted April 17, 2004 Report Share Posted April 17, 2004 I'd be taking it back to the dealer Ben. Link to comment Share on other sites More sharing options...
Lee Posted April 17, 2004 Report Share Posted April 17, 2004 Damn, Ben, that's a LOT of work to keep getting no change. I sure hope you find the problem soon, buddy. Link to comment Share on other sites More sharing options...
detjoe Posted April 17, 2004 Report Share Posted April 17, 2004 Sorry to hear about these problems...it sucks to have your truck apart. I was following along on the other gm truck site and see you have covered your own butt troubleshooting this bad boy-dealer trips suck, and I am getting ready to take my truck in too...good luck man Link to comment Share on other sites More sharing options...
BenKey Posted April 17, 2004 Author Report Share Posted April 17, 2004 Removing the front, again, to see if a new o-ring gasket will make the difference, or not. I wasn't able to sleep last night from running everything through my head. There are a couple of ways to go here, if I have suffered internal damage. The internal damage would be shot bearings, causing too much clearance and blow-by occuring. 1. GM told me that they would work on my truck if I took the s-chgr off. This was back when I had an issue with them. So, could take my motor completely back to stock, about 2 days worth of work, and drive it in to them and let them figure it out. Obvioiusly, the less expensive route, but could encounter some resistance. I know they have my VIN tagged somehow. Maybe I could talk them into a deal where I pay for all the parts and get all forged parts from the crank up. 2. I could try taking to a local shop and see how much they would charge for new bearing install. A possibility exist that the cylinder walls could be scored if it has been staved for oil. So, could end up being very expensive. 3. Could try to pull and do the bearings myself. Don't have a clue how to do. 4. Last is getting a stroker shortblock. I already have feelers out for how long it would take to build and ship me one - a 396. As much as I want one, not sure that I like dropping $3500 plus into my truck. I could rip off my Radix and sell, to offset the costs. Then spray the new motor with a 150-200 shot of nitrous. But, that would render my heads useless, that I could also sell. I have yet to discuss any of this with the wife. She'll obviously hit the ceiling with a couple of the options. Not sure which I want to try and sell to her. Anyone know the best deal on a shortblock out there? Maybe just the rotating assembly? Link to comment Share on other sites More sharing options...
detjoe Posted April 17, 2004 Report Share Posted April 17, 2004 Anyone know the best deal on a shortblock out there? Maybe just the rotating assembly? What about an aluminum block? I am trying to put positive spin on your misfortune. Just like I tried to tell myself I backed up into a parking pole, just so I could get a roll pan If you had any questrions about the inner workings of your truck you sure will have a better understanding now... I am married and feel your pain of bringing this up with your wife, on the positive side my wife can now fully explain the workings of a supercharger I have to say I have though about your situation since I was reading about the problem a few days back and my auto prayers are with you. joe Link to comment Share on other sites More sharing options...
BenKey Posted April 17, 2004 Author Report Share Posted April 17, 2004 I have to say I have though about your situation since I was reading about the problem a few days back and my auto prayers are with you. Never heard of those, but I appreciate it. How do those prayers start, lol? Link to comment Share on other sites More sharing options...
BigTex Posted April 17, 2004 Report Share Posted April 17, 2004 Is your oil frothy, aerated, or bubbly? Did you check the spacer that came with the double roller chain between your oil pump and block? If the hole isn't lined up properly, the oil system won't function properly. Did you find any metal on your oil drain plug? Link to comment Share on other sites More sharing options...
BigTex Posted April 17, 2004 Report Share Posted April 17, 2004 Oil flush? Explain that to me please. Does this mean you completely removed all oil from the motor before you filled up with synthetic? Would it remove all the lube from all oil passages? FWIW - I'm running a mix of 20w-50 and 10w-30 Mobile1. I have normal oil pressure. Link to comment Share on other sites More sharing options...
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