Hello.. I drove my car on the freeway today, and I floored it.. When I hit 120 mp/h the car "misfired" and I lifted.. The car acted normal after, no problem there, but it seems like my oil pressure is a bit lower now? I had 5-7 psi hot idle, now the needle goes all the way down to 0.. It dosnt act different than before, but it worries me about the gauge anyway.. I have 36 psi driving and no bad sound in idle at all.. Any succestions? Houmark
Does the oil pressure idiot light in the dash still work? I'd try a different gauge, because if you actually have 0psi at idle, your in trouble...
Installed the gauges this winter, so they are all brand new.. When i touch the gaspedal the needle goes up and show normal driving pressure.. The oil is normally 200 degrees, but when i hammered it, it were like 230... I checked the oil level, and it was full.. I run 5w30, and when the oil was that hot, it was like water.. Can the pump etc take damage by high revs or something?
Maybe you broke a rocker arm or a pushrod. That would bleed off oil pressure and if it was an intake valve the misfire wouldn't be horribly bad. Pull the valve covers.
Ill have a look tomorrow.. Its sounds like a reasonable explanation.. The engine starts right up and dosnt drive differently, so I hope its just the gauges that have a loose connection or something.. Thanks to you both
All pushrods and rocker arms er intact and rocking good.. Had both valve covers off and inspected the pushrods, then unplugged the wire from the coil to the dist, so it didnt start, and got my wife to turn the key.. All rocker arms moved.. Checked all the wires from the pressure sensor to the gauge and no loose connections.. Checked the engine for leaks, but it was dry all over.. The oil level is at full.. Cant wrap my head around loosing oil pressure "without" reason.. Any more succestions?
Houmark - did you pull the plug on the pump to see if the check valve flipped? I had that happen when racing many years ago. Had the same action - personally, I woul not run until you check the bypass valve (bypass). good luck byron
I didnt.. Afraid of sounding like a retard, but i couldnt find the oil pump ( Dont know what to look for :-( ) Where should i look, and what to do if the check valve is flipped? Pictures would certainly help Thank you.. Houmark
The oil pump is hidden in the oil pan. The bottom of the distributor turns the gear for the oil pump. You have to drop the oil pan to get to it. Below is a link to the '66 Chassis Service Manual. It wouldn't be a bad idea to pick one of these up for your year car if you don't already have one. For all intensive purposes this electronic copy should do you OK for the engine itself, if not most of the car. http://www.teambuick.com/reference/library/66_chassis/ http://www.teambuick.com/reference/library/66_chassis/files/60-c.php - This link will take you to the Engine - Mechanical Section. If you go to PDF page 30 or page 60-120 of the manual. On that page you will find the instructions on accessing the Oil Pump. Also, do you know how many RPM's the engine was turning when it "back fired". Depending on what gears you are running you could have started to "float" the valves. Which is not a good thing. The Nailheads don't turn much over 5500 RPMs depending on how they are setup.
The oil pump on a Nail Head is internal,the previous poster may of thought he was posting in the sb or bb section. The pump is run by the distributor located in the rear of the engine on a Nail Head and is inside the oil pan area. Not sure on a Nail Head,but the bypass could be under the oil filter like other internal oil pump engines. Derek
So I have drain the oil and drop to oil pan, and then check what? Im 100% green on this.. Bulldog, I dont have a rpm gauge but its all stock.. So if ~124mph ( 200kmh ) is above 5500rpm Im guilty :/ Thanks for all the answers.. Houmark
I am not exactly sure what to tell you to check either. Just giving you some insight on where the oil pump is located. Hopefully one of the Nailhead guru's will chime in with some ideas. I am still kinda green myself, but learning quickly. As for RPM, if you are running the stock transmission, ST400, and if you know your rear end gear ratio, and your tire size, then we can calculate out approximately what your RPM was at that speed.
No worries, a stock engine and drive train won't pull rpm up to valve float in high gear, especially not a 120 mph, too much load on it. Change the oil and filter and go with 10w30 and try it. It may be fine.
The oil and filter has only driven for 200miles.. The thing that keeps my mind going, is why the gauge show less pressure without anything other than a misfire when wrong.. In my logic, the pump either work or dosn't.. Offcause it can be worn out, but that should show little by little.. Is my logic way off? Bulldog, I have the st400, stock rear end and some 19" wheels with 245/30-19 tires.. Houmark
Maybe a long shot, but the pressure sensor could be bad? Could call the shop and ask for another to test with..
The gauge in my car quit working, it's electric .Anything is possible You could try a manual gauge with a pressure line and see what that gets you.
drain the oil and put it through a paint strainer.. make sure you didn't hurt the motor. how long did you hold it on the highway for? big blocks don't like big revs.. change the oil and put a mech oil pressure gauge on it. tap in right above the oil filter, if you need a picture let me know. Paul turbocharged nailhead
Before you go pulling pans or anything else drastic, get another oil pressure gauge and confirm that you actually have low oil pressure. That's why I asked about the dash light, as it would be a secondary indicator if it was hooked up and working properly. Paul's suggestion of straining the oil is also good.
I must have missed something. 5w-30 in a big block??? :eek2:unless that engine was blueprinted and built for 5w-30 that's your problem. Its water thin even cold and the tolerances in older Motors are huge compared to todays specks. Ive noticed that my 455 very slowly looses oil pressure at idle with time and mileage. when it gets to about 15 psi at idle hot its time for fresh oil. the general says 10w40 so that's what t gets.
The idiot light didn't come on.. I were only up there, and then it misfired so i lifted and got back down.. I put on a mech gauge, in my adapter between the engine and oilfilter.. Was looking into how much zddp there in the the elf 20w50 Retro 2, or is 10w40 better?
