gp1991 Posted July 31, 2013 Report Share Posted July 31, 2013 Hi guys, i know its been a while but i need to ask you how to get the oil pressure sending unit off of a 91 grand prix 3.1. Its just to the right of the oil filter, so i took that off and tried to use one of the sockets made for the opsu, but it will not fit the old part, just the new one i bought. Im only doing all this because it is leaking a good deal of oil out and i need the car to get to work tomorrow. I cant get the damn thing loose and was poking around the fourm and saw someone took off the oil filter adapter and that helped, im not quite sure how that even comes off tho. Any advice on how to get this damn irregular shaped oil pressure sending unit off of my vehicle would be much appreciated and im sure that the new one will take 30 seconds to screw back in. Thanks. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted July 31, 2013 Report Share Posted July 31, 2013 I didn't have any trouble replacing mine on my 3.1l. Maybe remove the passenger side fan, so you have more room. I would put some Teflon tape on the threads that way it will prevent it from leaking in the future. Quote Link to comment Share on other sites More sharing options...
gp1991 Posted July 31, 2013 Author Report Share Posted July 31, 2013 Thanks i got it, actually the new part comes with teflon tape i was surprised, The part was actually leaking out of the part itself not through the threads. I used channel locks and in my typical fashion got it right after i go post a question about it after trying at it for two hours lol. The socket that is made for those tho did not even come close to fitting it when i took it out and looked at it. im not sure what kind of assed up size GM used. O well got it out any way and new one in, thanks a lot. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted July 31, 2013 Report Share Posted July 31, 2013 At least it is out. You need a specific socket to get the GM sending unit out they are goofy. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted August 1, 2013 Report Share Posted August 1, 2013 Very poor practice to install a fitting into the oil system of an engine using Teflon tape. 1. Many folks wind the tape on backwards. 2. If the tape is installed correctly, when the part is removed at a later time, the Teflon tape shreds. Bits of Teflon tape can then be circulated through the oil system, potentially blocking lifters, or other small-clearance places in the oiling system. You must now be EXTREMELY careful to clean all the Teflon debris if you ever remove the oil sensor again. Teflon-based paste is much better than tape. I especially like the Loctite/Permatex "PST" versions--any one of the three part numbers: 565, 567, or 592. Quote Link to comment Share on other sites More sharing options...
DavidHowell3633 Posted November 22, 2013 Report Share Posted November 22, 2013 I was thinking you might have mistaken the knock sensor for the oil pressure switch. Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted November 22, 2013 Report Share Posted November 22, 2013 I was thinking you might have mistaken the knock sensor for the oil pressure switch.They are next to each other on the block, and the oil pressure switch is sort of hidden above the starter. Once I get some more cash maybe early next year I`ll install an actual numbered oil pressure gauge and mount it on the dash. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 24, 2013 Report Share Posted November 24, 2013 I have a 1994 chevy camaro 3.4 when i first start the car the oil gauge reads high, but after it warms up at idle the gauge needle drops well below the center line. but i get no engine rattle and the engine still runs good, when i excellerate the needle goes back up. Yup. They do that. Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted November 24, 2013 Report Share Posted November 24, 2013 Schurkey:lol: Camaro guy----- pull the switch out and install a pressure gauge, take a reading at startup and after driving around to get to op temp. If the reading is in spec for your F-Body replace the switch or look for damage in the wiring, if out of spec then you actually have low oil pressure. Even though yours is GM its a different 3.4 V6 but I`ms sure a lot of misc. parts are the same. See http://www.FBody.com for Camaro/Firebird forums similar to this. Quote Link to comment Share on other sites More sharing options...
gp1991 Posted November 25, 2013 Author Report Share Posted November 25, 2013 Yup. They do that. lol Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 25, 2013 Report Share Posted November 25, 2013 (edited) Schurkey:lol: lol The guy is stating that his oil pressure is high when cold, drops when warm, and then increases with RPM. He has no actual problems with the engine. Yup, that's exactly the way it works. If he's got 10 psi at hot idle in-gear, or more, I wouldn't bother to test the pressure with a mechanical gauge. Edited November 25, 2013 by Schurkey Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 25, 2013 Report Share Posted November 25, 2013 10psi? That's it? I've never read the spec on it, but I thought it would be more. My 350TBI runs about 25-30psi warm idle. Sent from my iPhone Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 25, 2013 Report Share Posted November 25, 2013 10psi? That's it? I've never read the spec on it, but I thought it would be more. My 350TBI runs about 25-30psi warm idle. 10 psi hot idle IN GEAR is the MINIMUM I would accept. More is nice. 20--30 is lovely. The 350 TBI in my K1500 truck shows at least that on the gauge, but I don't trust the sending unit. They're known as a high-failure item, and mine is no spring chicken. The previous one filled up with oil to the point that when I unscrewed it (due to the gauge showing almost no oil pressure) the supposedly "sealed" sending unit was 2/3 full of oil, and sloshed as I lowered it out of the chassis. I think my current sending unit is reading high instead of reading low like the original. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 25, 2013 Report Share Posted November 25, 2013 The guy is stating that his oil pressure is high when cold, drops when warm, and then increases with RPM. He has no actual problems with the engine. Yup, that's exactly the way it works. If he's got 10 psi at hot idle in-gear, or more, I wouldn't bother to test the pressure with a mechanical gauge. 10psi? That's it? I've never read the spec on it, but I thought it would be more. My 350TBI runs about 25-30psi warm idle. Sent from my iPhone i'm basically X2'ing Schurkey, but yes, 10PSI is generally enough pressure for any 60V6 to be happy at idle. some engines do not follow this trend. the S2/S3 3800s(possibly S1?) seem to need a LOT of pressure at all times. to the point of i see people get antsy around 30PSI. i'm not sure why, either. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 26, 2013 Report Share Posted November 26, 2013 (edited) yes, 10PSI is generally enough pressure for any 60V6 to be happy at idle. some engines do not follow this trend. the S2/S3 3800s(possibly S1?) seem to need a LOT of pressure at all times. to the point of i see people get antsy around 30PSI. i'm not sure why, either. Are the 3800s 60 degree, or the 90 degree Buick-based job? The older Buick V-6 and V-8 engines often had so little oil pressure at idle that the lifters would rattle and the oil light would come on. The typical cause was a wiped-out front cam bearing aggravated by a scored aluminum oil pump housing; and the fact that the oil pump wasn't submerged in oil, but had to suck through a foot-and-a-half of drilled passages and tubing. I remember installing special oil pressure sending units in the '70's and early '80's Buick engines--The shop owner had a line on sending units that'd trigger the light at four or five psi instead of eight. It was all the customer would pay for, but they wanted the oil light off at idle. The only customers worse than Buick owners were Lincoln/Cadillac owners. They'd cry about anything and everything. Like the car OWED them a lifetime of service because it was so expensive to buy originally. They had an unlimited budget to fill the gas tank; but holy crap--"don't expect me to buy spark-plug wires." Edited November 26, 2013 by Schurkey Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 26, 2013 Report Share Posted November 26, 2013 3800 = buick 90V6, specifically, the variants that came around in ~87 or so and lasted until ~2009ish. from what i can tell, the oiling system was never really updated from the buick V8s. your description of the older oiling system seems correct based on this diagram i pulled for a 00 model year. and FWIW: the rear bearing of the balance shaft is pressurized oil, but the front relies on splash. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 26, 2013 Report Share Posted November 26, 2013 (edited) 3800 = buick 90V6, specifically, the variants that came around in ~87 or so and lasted until ~2009ish. from what i can tell, the oiling system was never really updated from the buick V8s. your description of the older oiling system seems correct based on this diagram i pulled for a 00 model year. and FWIW: the rear bearing of the balance shaft is pressurized oil, but the front relies on splash. I'm going way off-topic here, but the '87-newer Buick-design V-6 were actually the GOOD ones. Your schematic shows the Vega-style crank-driven oil pump instead of a horrible external spur-gear oil pump built into the (expensive and easily-damaged) aluminum timing cover (so, when hot, the cover expanded at three times the rate of the steel gears, leading to lots of oil getting stirred rather than pumped.) Seems to me they finally routed oil behind the #1 cam bearing instead of transferring it on the babbit side--so when the overhung distributor gear overloaded the front cam bearing which wiped out the babbit, it was an uncontrolled oil leak into the timing-chain area. This starved one bank of lifters, leading to the Buick Death Rattle, and Dumbass Schurkey installs a four-pound oil switch and 20W50 oil on another one, instead of doing a complete overhaul with replacement timing cover and front-cam-bearing oil-passage mods. Keep in mind that Chevrolet made exactly the same mistake on their cam-bearing oil passage in '65 and '66 on the Big Block, but had enough sense to fix it for '67. Took Buick another twenty friggin' years, and the Buick design was actually worse than Chevy, because Chevy had enough sense to put a cam bearing on both sides of the distributor drive gear, they didn't just leave the gear hangin' in the air on one side. The Buick design puts enormous load on the front cam bearing. Really, by '86 or '87, all the Buick-engineering TOTAL FUC*KUPS had largely been corrected, with the possible exception of using a Vega-style (!!!) oil pump instead of a proper, submerged oil pump like any reasonable engine family. (The Mopar B/RB, and Cadillac seem to get by with an external oil pump, and still survive serious horsepower. They, and the GM LS-series (another Vega-style pump) are the only real exceptions to my rant against "sucker" oil pumps rather than "pusher" oil pumps, and both Mopar and Caddy had enough sense to make the oil pump housing out of iron instead of aluminum. If you guys haven't lived through wrenching in the Sh!tless Seventies and Icky Eighties, you would not believe the piss-poor engineering we dealt with. GM, Ford, Chrysler, and all the imports were so focused on meeting emissions regulations while spending the minimum possible amount of money, that they didn't have one spare brain cell to correct obvious problems in the rest of the product. There's reasons behind my signature line! Edited November 26, 2013 by Schurkey Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 26, 2013 Report Share Posted November 26, 2013 off-topic or not, at least it's informative. more than i ever needed to know. Quote Link to comment Share on other sites More sharing options...
gp1991 Posted November 26, 2013 Author Report Share Posted November 26, 2013 The guy is stating that his oil pressure is high when cold, drops when warm, and then increases with RPM. He has no actual problems with the engine. Yup, that's exactly the way it works. If he's got 10 psi at hot idle in-gear, or more, I wouldn't bother to test the pressure with a mechanical gauge. yea i was not trying to say you were wrong because I believe you are correct, i was just laughing at the simplicity of the comment. his sensor could be broken like mine was for the longest time, it would shoot to the maximum spot when i start it, and then at the slightest tap of the throttle would shoot back up there, but probably nothing wrong with his engine. Quote Link to comment Share on other sites More sharing options...
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