I'm sure this has been discussed here but I can't find what I need to know. Just bought a 73 Regal with a 350 V8. (Vin H) My problem is low oil pressure. Put a mechanical gauge on it and with 10W-40 oil it starts out 30 to 60 PSI when cold, then as the engine warms up goes almost to nothing. This started out as a lifter problem. They would collapse and quiet down only after changing the oil filter. Not the oil, just the filter. Cut a filter open and see no reason for it to block the oil flow. So far I've looked at the bypass. Looks normal. Put a 3/16" thick nut in the pocket in the large plug, oil pressure did not change. So I put a large sheet metal screw with a 3/8 head and a flange in the plug. It adds lots of pressure to the spring. Still no change. My questions: The auto parts stores sell a high volume oil pump kit. I know about the added strain on the pump drive, and that's something I'll deal with. In the catalog it mentions that the timing chain cover "might" have to be removed. What determines if it needs to come off? They also say something about a drill bit. For what? Any ideas why the oil pressure would be so low? The car has 35,000 miles and and it's all short trips. Is the oil pressure port before or after the filter? Trying to figure of the oil is cooling off or the filter is restricting the flow. Also, I see no way oil can bypass the filter. That seems strange to me. Can anyone suggest a better path to getting past this? I'm going to pull the pump in a few days and see if the bottom plate is worn and look at the gears. Maybe that will tell me something??? I'm also in the process of trying to get the title transfered and I have to drive the car. As soon as the engine warms up the oil pressure goes away and I'm trying not to damage something. Would appreciate any and all help. Thanks, Al
What is your hot idle pressure? Cruising pressure? These engines don't need a tremendous amount of pressure.
Ill be watching your thread close, your going where I fear to go. Afraid to put an oil gauge on mine, I like not knowing better in some ways. [As right now my 3rd gen has a oil gauge and its scary sometimes as it drop down to around 10 when it gets warm. Which just makes me worry more about it. Though with 220K on it, not suprising.] But have considered doing that same kit just for peace of mind. If it gets yours back some psi I may just have to see what I got and do it too.
It's all a matter of pump clearances. Take the oil pump cover off and check the bottom of the pocket for wear. All this has been discussed. All you need to do is put "oil pump end clearance" into the search option on this bulletin board. Then start reading. Basically, you need to blueprint the clearances inside the pump and add a booster plate.
Short term you might try switching to a heavier oil. I've run 50 wt racing oil (Valvoline) to bring up oil pressure and it's worked out fine. Jim
Al, The oil pressure relief valve only does it's job at high pressure, i.e. cold startup, or high rpm. Adjusting the pressure relief spring won't do anything for hot idle pressure. Pressure reduction with increased temp is normal, but as rpms increase, pressure should rise about 10psi/1000 rpm for a small block (is that a safe rule of thumb SBB folks?). Don't worry if you've only got 10psi at hot idle as long as pressure climbs with increased rpm...or are you seeing even lower numbers than this when idling hot? If you're not reaching the desired 50psi @ 5000 rpm, there are some things to consider: Internal leakage (galley plugs, pickup gasket, pressure relief valve stuck open, etc.) Excessive bearing clearances (too loose or worn out) Excessive pump gear endplay Excessive pump housing and/or gear scoring Plugged oil pickup Plugged filter Oil viscosity too low (thin) Starvation (sludge preventing drainback, low oil level, poor oil control with pos/neg acceleration, cornering) I'll take a shot at your questions... High volume pump? It might not hurt anything, but it would be better to ID a root cause rather than band-aid it with the hi-vol pump just yet.Why is pressure low at 35K miles? Is that 35K on a rebuild, or original engine? Has it always been like this, or is it a recent development? If it's recent, did the problem come on gradually, all at once, or is it sporadic? Are you hearing any funny noises that might be associated with the low pressure situation?Is the pressure read before or after the filter?After; so you might think that any restriction in the filter would show on the gage, but...there's a bypass valve in the oil filter housing to which the filter attaches. The valve in the housing opens to allow flow in case the filter is restricted or plugged. So, I think you're on the right track to closely inspect and measure the oil pump gears and gear pocket. Don't forget when you button it up again to make sure you pack it with petroleum jelley to ensure a quick prime on start up. Sorry, you probably have more questions than answers at this point, but it's best to get started this way with the diagnosis. Devon
quote=DaWildcat;1251260]Al, Is the pressure read before or after the filter?After; so you might thing that any restriction in the filter would show on the gage, but...there's a bypass valve in the oil filter housing to which the filter attaches. The valve in the housing opens to allow flow in case the filter is restricted or plugged. Not true. At least for the filter I cut apart. Can you tell me how the filter's bypass works? The reason I asked is I checked the oil pressure, quickly changed the filter, and checked it again. It went up. The filter I replaced had about 80 miles on it. Cut that filter apart. Nothing I could find that would hinder oil flow. This pump is just not pumping oil. You mentioned the pickup screen being plugged. Been tossing that around but it does not seem reasonable with my symptoms. I'm having problems finding filters for this engine. I bought out two AutoZones, and a NAPA store. None had more than two filters. On the road I stopped at a Super K Mart and two Wal*Marts, no filters. AC filters are impossible to find except for the popular new GM cars. So far I've gone through about ten filters. Changed five last Wednesday, two yesterday. My oil pressure gauge is a cheap dash gauge adapted to a grease gun hose and that is adapted to the 1/4 pipe thread in the filter housing. It's not accurate but gives me an idea. It shows 5 PSI at idle and 15 at RPM when the engine is hot. As I said, cold I get 30 and 60. And, cold the lifters quiet down, as it warms up they start getting noisy. I'll yank the pump and look it over. I'm not at all happy about the way they designed the oil pump. Was thinking if the pump housing is worn the extra section in the high volume pump might help. I'm assuming the pump will come right apart. Hope I'm right BTW: The car is all original. Never rebuilt, always serviced by Buick but about five years ago they started refusing to service it because they had no parts, no manuals and no one that wanted to work on it. Thanks, Al
Assuming the engine has never been apart (oil pump and timing cover also), be prepared for seized bolts that will break off on the timing cover,(due to dissimilar metals in contact causing galvanic corrosion). This will require you to pull the timing cover to repair. Again, expect good old dissiliar metal corrosion of the bolts from the housing to the block. Thoroughly clean or replace bolts and coat all thread areas with LIQUID pipe sealer, not teflon TAPE. Everything else that Da Wildcat says applies and is true... High volume pumps are a crutch for some other problem. You really need to remove the timing cover to best align and install the plate with the provided side clearance shim and drill the locating pin holes dead square.Search forum for oiling mods for tips and improvements. Good luck!
Al, the bypass I'm referring to is not in the filter, it's the small spring-loaded disc you'll see on the filter housing that's bolted to the front cover...the "end cap" for the oil pump gears, if you will. You can see the little disc when the filter's off. But in thinking about this for a minute, I'm realizing that a stuck bypass valve really shouldn't affect pressure, it would just allow recirculation of unfiltered oil. So scratch that one off the list for pressure problems, but it would be good to make sure it's fully seated anyway. Devon
I don't think your filter change has anything to do with your oil pressure. In the short time it takes to change the filter, the oil can cool sufficiently to temporarily increase the pressure a bit. Your problems are most likely pump clearances. The gears sit in a pocket and protrude above the gasket surface. The gasket gives the proper end clearance which is critical to hot oil pressure. If the gears are not .002-.006 above the gasket surface, then the pocket is worn. TA Performance sells a gasket assortment that helps to get the end clearance right.
Larry is right....you can easily adjust the pump end clearance with the ta gaskets of diff thicknesses...as well as by adding the booster plate, ( the original bottom is aluminum and really shows wear easy) and adjustable pressure setup. really works well...my gs before rebuild was low pressure ( maybe 5lbs at idle) with the pump changes was at 10 idle and climed easily to 50 or so running...then adjusted to where you want.
Avoid adding a High volume pump to fix oil pressure as you tend to build too much pressure internally inside the pump that eats gears. The pump is not designed to flow high volumes of oil. A better fix is just thicker oil to slow down the flow thru the motor. If it takes 50w then so be it. A booster plate a proper clearances is a good start for a fix.
I see. I can change the filter in less than 5 minutes, and then the lifters stay quiet for more than 100 miles. So the oil cools in 5 minutes and takes a hundred miles or more to warm back up. One Wix filter went 104 miles, the next one went 126. Frams went longer by about twice. This was at highway speeds. On a filter that was still quiet, about 80 miles on it, I checked the oil pressure. Swapped the filter for another one and the pressure went up 5 psi. The engine was cold when I took the first reading. It ran less than a minute so I don't think the oil got hot and cooled back down. I'm really drawing at straws here as none of this is making sense to me. Now I'm wondering if the small piston in the bypass is doing something I'm missing. Like sticking when hot or??? When I took the plug off, the piston came with the spring. When it was almost out the spring came off. I pushed the piston back in with the spring and it seemed free. What I don't know is if it really went all the way back in or if it's hanging up. Would be nice to have a blueprint of this assembly. Went to the local real parts house. Parts for this could be as much as five days away. So I'm going to rat hole it and pull it apart. Hope I can recognize what I find Al
Hey Al, I know you are frustrated, but I am trying to help. If your lifters stay quiet for 100 miles, then there is something else going on. There really is nothing that happens to a filter that would cause your symptoms unless the filter is becoming clogged, and that isn't happening. It is unusual to have pressure problems with the low mileage engine you have. Pump wear is the #1 problem from not changing the oil. How much do you know about the history of the engine? Was it well maintained? The OE timing sets had nylon tips on the cam gear that have a habit of breaking off and ending up in the pan. There they clog the pick up. That could cause the symptoms you describe. It wouldn't be the first time we have seen that. If the debris is becoming stuck to the pick up, and then maybe falling off only to become stuck again that could explain it. Just trying to give you a few ideas. As long as the pressure relief piston is free of nicks and slides easily in the bore, it shouldn't be a problem. You might want to post your location, a V8 member might be around the corner and you'd never know it, even if it's just for moral support.
Today I removed the bypass piston. Looks good. Used a 3/8" drill bit and it came right out. Since I'm getting nowhere I took the pump apart. Looked it all over and figured out how it works and that I'm chasing my tail. There was some debris under the "idle" gear that cut some light rings in the bottom plate. And that is it. The pump is fine. And that explains why shimming the relief spring does not change the pressure. What ever is wrong is internal to the engine. What and why is beyond me. Being a dummy I did not rat hole the car. So now I need some quick action as I've blocked access to my shop. I know the history of the car because my Aunt bought it new. She died and I picked it up at the estate auction. She tried her best to keep it up but being an old lady I sure she was taken to the cleaners. I drove the car about 20 miles from the auction when the water pump died. It was making noise and I was pulling into a CarQuest in St. Louis when it let go. Of course they did not have a pump but they located one and I was able to get to it by leaving the cap off. Changed the pump and headed for Tucson. At the first fill up I could hear a lifter rapping so I put 1/2 quart of Rislone in it. About 50 miles later it started loosing power. All the lifters were banging, so I stopped at a Jiffy Lube and had the oil and filter changed. They did not have a filter so I went to AutoZone and bought a Fram and an STP filter. All they had. Went back to the lube place and had 15W-40 Delo put with the Fram filter. Headed to a friend's house thinking I would need to go to Tucson and get my truck and trailer to get it home. About 50 miles from her place it started banging again. Next morning I started it and drove it two blocks. Lifters still banging. Had breakfast and changed the filter only. Fired it and it shut up. Now it had the STP filter on it. Drove to an AutoZone and bought both filters they had, again one STP one Fram. Off I went, then the lifters started again. Stopped at a NAPA store. Changed the filter and bought the two NAPA filters they had. All day I drove and changed filters. Never changed the oil, just added to it. When I got to Tucson I put a new filter plus 3 quarts of 10W-30 and two quarts of ATF in it thinking it was sludged up. The filter I took off was on for around 80 miles. That was the filter I cut open and found nothing in. Drove it about 40 minutes total in three separate short trips, and drained it out, changed the filter. Put 10W-40 in and here I am. Yesterday with the 10W-40 I tried to drive to ADOT to get the title in my name. Lifters started lightly clicking about 3 miles from my shop. So I stopped and checked the oil pressure. 5 to 15 PSI. (BTW: This morning it was 35 and 65 cold. And the lifter shut up) Frustrating? I guess I'm not wanting to tear into the engine as once I start I'll have to replace everything from the radiator cap to the tail pipe. I'll end up with a giant money pit. I'm going to think about it for a while and then decide if I should try a hi-volume pump as a band aid. If I can get it to hold oil pressure I'll sell it. If not I may do something horrible like sell it for scrap. If there is a place to post a picture of it, let me know. Al in Tucson, AZ.
Al, Let's get back to the potential problem with a clogged oil pickup... Opening the oil fill cap on the valve cover and peering inside, how do things look? Gummed up, flaky residue, or fairly clean? One big problem with cars that aren't driven much is buildup due to short driving distances without time for the oil to get up to temp. After years of this kind of driving, a different sustained driving habit can cause a lot of that stuff to come loose and head for the oil pan. This can be aggrevated by attempts at "flushing" the system. Just another thought. Devon
It's cool Al, I've been in your shoes too. I'm guilty of overlooking the simple stuff, so I try to point things out when I can. Wishing you the best and trying not to add to your frustration... Devon
I still don't get why changing the oil filter restores pressure, and quiets the lifters for 100 miles or so. Oil pressure drop off as the oil warms up and the timing cover expands is normal for any Buick engine. When I start my engine, oil pressure is 70 PSI at idle, and will go to 80 if I raise the idle to 1500 RPM. Within 15 minutes of driving in warm weather, my idle pressure will drop to about 20-30 PSI, with pressure of 50-55 on the highway. After driving it for 45 minutes at highway speeds, and then stopping, my in gear idle will drop to about 15 PSI.
