dstrick32

To make a long story short, I've had trouble with the oil pressure on my 3.0 ever since changing the first engine out and have had to rebuild it 3 times. Always #5 & 6 rod bearings. Nobody has came up with an answer to this problem. Good oil pressure when cold but dropps to 0 after warming up. Now it has broken the flexplate. I was told that this could be cause by the crankshaft not being shimed to the proper size for the torque converter shaft size. This was a suggestion from a Nissan Tech but he didn't know for sure whether the Toyota was the same. I will measure this when I pull it this time but wanted to know if anyone knows about this problem are have other suggestions. Thank you for your assisance in advance!! Love reading your site and post!! 94 PK 3.0 Auto 4WD.

nunsa

Greetings,
Ah yes, the old 3.0 oil preesure question. The 3.0 doesn't have the greatest oil pressure to begin with, I've seen it time and time again. On my 3.0, I rebuilt it at 297,000 miles with new oil pump, sender..., when fully warmed up the op doesn't go past 1/4 on the op gauge, worried? Not at all because this is so normal for the 3.0, it comes with the payments! As far as dropping to 0, now that's not good, you should get yourself an oil pressure gauge and see exactly what your op is at operating temp, these gauges on the Toyotas are not the most accurate around either! One more thing, Toyota recommends 5-30 oil for the 3.0, I never liked that weight so I run Valvoline 10-40 in the winter and 20-50 in the summer, probably the reason I got 297,000 original miles on my 3.0 before the HG leaked. The problem with the 3.0 is that the oil journals are so small and restrictive.

Good Luck!

dstrick32

Thanks for the reply!! I've checked with mechanical gauge since it had the idiot light. The second two rebuilds never made it off the starting block before the pressure dropped. All clearances were checked and within specs. Finally changed blocks and it did good for about 7,000 miles before starting to drop and developed a knock. The only thing that I can link all this with is the first engine was a rebuilt long block and it developed a front trans seal leak replaced seal twice before changing out torque converter leak stopped but oil pressure problems begin. Never found the reason for the oil pressure drop everything was changed inside the block crank, bearings, rods and pistons. Block was cleaned everytime it was reworked by machine shop, finally changed everything over to another block and oil pressure was fine for about 7,000 miles like I said and then it started the noise and flexplate gave way. The main thing I was concerned about was that I could have possible been given the wrong torque converter or that the crankshaft might require an adaptor like shim, as the manual trans requires a pilot bearing. Any info would be appreciated. The original engine had 192,000 miles on it when the son let it leak all the oil out from a bad rear seal and throwed two rods through the block!! I'm running Autometer gauges now and I have about 25 psi cold and after warm up it drops to 5 to 0 psi.

nunsa

That oil pressure really isn't that bad, when mine is all warmed up and at idle I run around 5 - 7 psi when I accelerate to around 2500 - 3000 rpm's It will go to 18-25 psi, pretty much normal! All the 3.0's I've ever worked on or owned had pretty much the same oil pressure! What type of oil and weight do you run? If it was a shimming problem with the crank the oil pressure would have been low from the get-go it wouldn't drop after 7000 miles.
Me personally, I've always run Valvoline, never had a problem with it and I never put those crap oil additives in my engine either. If your crank wasn't shimmed as mentioned, you'd get a lateral slap. If you were to get a wrong torque converter you'd have other problems, not engine problems but tranny shifting problems...! You could try a differnt oil and you could try an oil cooler but like I said, low oil pressure is pretty much normal on the 3.0!

Greg'sToy

how many miles can you expect to get out of such low oil pressure?

dstrick32

I'm running Havoline 10w40 right now, just changed and the oil pressure light will come on if it idles long enough after getting warm. I run the gauge and the light and when the light comes on the gauge shows a hair over 0 psi, probably 1 to 3 psi, at 2500 rpm it will be lucky to get 17psi. When first put in it showed 30 to 35 psi at idle (cold) 25 to 30 psi warm and about 65 psi at 2500 rpm. I thuoght the noise was from the flexplate but after replacing the flexplate it's still there. Doesn't really sound like a rod knock but it sure has me worried. I'm fixing to pull it and see what I find. I'm getting to know this engine real personally. What always led me to the T/C was the rear seal and front A/T seals leaking so quick yet no viberations as if it was out of balance!! The manual says 4.3psi or more warm at idle and 36 to 75psi at 3000 rpm. Can't figure it out but if it's the #5 & 6 rod bearing again it's gonna blow my mind!! I'll be going back to my Chevrolets!! Thanks again for the info!!