OK guys - I'm about to eat a gun barrel. My original 305 died last year. Lost oil pressure and then knocked itself to death - I assumed because it was old and abused (150,000 hard miles). I bought a 350 'just rebuilt' off a local builder. Within 2 hours, it lost all oil pressure and was knocking. Had to pull the thing and have the crank reground. Same thing happens 3 weeks later. Took it to the 'Best' shop around. They told me the engine was probably way out of tolerances and that I needed a new one (even though it had never really been driven!). I bit the bullet and had them put in a new long block, as well swapping over to a carb setup.

This was last fall. Car was running fine - max oil pressure when cold, and still well above the red zone when hot at idle. On Monday I noticed my oil pressure was getting low at idle. By Tuesday it was 0 at idle and only coming up to 200 at part throttle. By the time I got home today, it was 0, and revving it a little had no effect (stays at 0). I changed oil just now from 10W30 synthetic to 20W50 dino oil, but starting pressure is still negligible, and drops to 0 as soon as the car warms up.

How can this be? There is NOTHING constant between my original motor and this one. I am going to see the shop that put in this motor on Tuesday. But it's going to be a long weekend of worrying (plus I have a friend in from out of town who drives a Mustang, and it's going to kill me not to be able to scare him in the IROC!)

Any thoughts guys? I'm seriously feeling sick.

 

Did you put a new distributor in it. Maybe its breaking that clip that hold the dissy. shaft and oil pump shaft together.
I would take the dist. out, spin the rod with a drill and see what you get. I don't know if the you can see the pressure on the instrument cluster or if you'd have to hook up a seperate gauge

 

I guess I would have to ask does the engine make any apparent noise when the oil pressure drops to zero?? Does it run ok?? Mabey the oil pressure switch is bad, seem like a common thing w/third gens due to our aging cars. My guess would be that the last shop reused the old oil pressure switch on the engine block and it could be the real issue and not the oil pressure itself.

 

I concurr. You didnt mention knocking this time around, so I would have to say to read it from a mechanical oil pressure gauge and make sure.

 

Happy Day! Hooked up a mechanical gauge today and pressure was excellent!!! Talk about relief!! Just a problem with the sending unit. I ordered an Autometer full A-pillar 2-gauge holder(anyone want to guess if the t-top a-pillar is the same as a convertable a-pillar?) with electric water temp and oil pressure guages. I phoned back and changed the order to a mechanical oil guage - I don't care about live oil line - I just want accurate readings!!!

 

YOu should have kept the electric setup. The line lines, I have a good friend with personal experience...well me too in a way.

Going to a cruise in/meet, I was riding in his 79 Z28. He had the mechanical Oil pressure gauge. Had the copper line and all of a sudden, BAM, popped right out and gotabout 3 quarts in his floorboard and about 1 quart on my pants, it sucked so bad. blocked it off and ran to his house refilled oil, took ALL the mechanical line out and hooked his brand new electric gause he had just ordered a few days prior. I have sworn to never use the POS line gauges, they suck majorly.....and Ive seen this happen on differant cars/trucks on more than one occasion. First thing I did was throw the mechanical gauge in a box of junk parts...cause I refuse to use it.

 

loc-tite is your friend

 

I used a mech gauge with nylon tubing once that cought a pinhole in the engine bay of one of my project trucks I had. I usually only use the mech gauges on a new motor to monitor oil pressure for a few hundered miles of driving and then hook the factory gauge back up.

 

Hmmm...now you guys have me second guessing my second guess...if it's installed right (loc-tite IS my friend) why should it ever leak? And isn't it more reliable/accurate?

 

Like stated in the post above, if you knick it on something (maybe route it through the firewall without a grommet and the firewall cuts it in a small spot) then you get oil all over the place.

It is probably best to keep your mechanical oil pressure gauge in your trunk, then when you go to the track you can install it, then put it back to the electrical one once it's done. Or whatever suits your fancy.

Me, I dont want to have to worry about going back and forth all the time. I have a mechanical oil pressure gauge that I use when I wonder how accurate my electric one is, but it's more of a safety item than a permanent usage item.


Some people like to use the mechanical ones all the time, some dont. Whatever floats your boat

 

where do you hook the mehanical gauge to, the oil pressure port?? where the sender is?