The Stovebolt Site Forums The Shop Area Engine Shop New rebuilt GMC 270 NO OIL PRESSURE....HELP!!!!

I started the new 270 engine and let it run for about 5 sec. No oil pressure. I un coupled the oil supply line to the gauge and started it up for about another 5 sec and no oil. What now???? Is there a way to prime it or do I need to take the e4ngine back apart and replace the pump. Thanks in advance for any advice.

Trey

Pull the distributor out and put a long screwdriver bit in an electric drill. Use this to turn the oil pump. If turning the pump with a drill doesn't produce a flow of oil, there is something wrong. You do not have to disassemble the entire engine to get to the oil pump. Just drop the pan, and it will be right there in front of you. Are you sure you installed a pump on the engine in the first place?

Yes. The oil pump is present. I have turned it by hand with a screwdriver and noticed it had somewhat of a drag to it. It did not turn as freely as I exspected it to.

What crenwelge said...
If you put a long flat bit in a drill motor, and turn it clockwise it should build up pressure, If it doesn't build up pressure, DO NOT TRY TO START THE ENGINE AGAIN. The drill might slow down as pressure builds up. This is normal. No oil pressure is not normal.

Yep, I mirror what’s been said above. This is the kind of set up that they were talking about to turn the oil pump and build up the oil pressure. I ran the drill on my newly rebuilt 216 and had 30lb (pegged the gauge) oil pressure with in a few seconds. Ran it till all the rocker assembly was oiled which should have assured oil to the bearing also.
http://www.pbase.com/dennygraham/image/136174545
http://www.pbase.com/dennygraham/image/136174550
Denny Graham
Sandwich, IL

Also make sure the distributor is installed correctly.
Although the engine will run, it will not turn the oil pump.

Did you pack the pump gears with Vaseline before you installed it, or at least get them wet with oil? Unless a pump is able to develop enough suction to pull oil out of the crankcase, it can't build any pressure.
Jerry

Not to say that's not a good idea but, I didn't pack my pump with grease Jerry. Just a squirt of oil, enough to wet the gears and shaft. Had my "big old wife" watching the gauge. Came up almost as soon as I pulled the trigger.

But maybe I missed it, but did he mean "new" to him or "new" as in brand new or newly rebuilt??? If this was just an old engine but "new" to the "new" owner than it could be clogged up tight.
DG

I never use grease, as the fibers in it can clog things up. Vaseline dissolves completely as soon as the oil hits it. We build up automatic transmissions the same way, lubricating clutch piston seals and valve body parts with petroleum jelly to prevent dry assembly problems.
Jerry

OK,

Lets say the pump is dry. Is there a oil line or gally that I could pour oil in that will get to the pump?

Or could I add an extra gallon or so of oil to where it would find its way to the pump. I am going to stop by home depot and pick up some metal roundstock and cut a flat on it and try the drill idea. I do not have any screwdrivers that will fit in my drill chuck.

Thanks again for the ideas....

Overfilling the crankcase might work, but it would need to raise the level enough to submerge the pump. Try the screwdriver in the drill motor trick first, and then add a few quarts of oil if necessary. Is this a fresh rebuild, or has the engine been run before with good pressure? I have seen oil gallery plugs left out after a block was pressure washed or steam cleaned, resulting in a wide-open path back to the crankcase for oil instead of a pressure buildup. If that oil passage isn't to the outside, the oil just recirculates back to the pan with no external leaks. The first time that happened to me, it was on a 283 engine my high school friends and I installed in a Model A coupe. We forgot to put the oil gallery plugs back in behind the timing chain when we rebuilt the engine.
Jerry

It is also possible the oil supply tube was not reinstalled during rebuild. A tube runs out of the oil pump and up into the block to supply the oil galley. The oil galley runs the length of the block on the left side about 4 inches up from the oil pan rail. Ther should be a junction block in the front of the engine that sends oil up to the head and the external bypass filter if so equiped.

A 270 gmc will easily take 6 quarts of oil.

OK,

I spun up the oil pump with a drill. It took a little while but I finally saw oil. I re-connected the gauge and spun it again and the gauge registered 60 I also took out the oil filter and spun the pump. There was a nice stream of oil. I am going to install the distributor in and give it a test run. I think the distributor may not have been fully ingaged in the oil pump. I noticed the vac advance was not clamped at the top of the distributor shaft so I have scooted it up to allow the distributor to seet ferther down into the engine.

Thanks again for all the help...
Trey

Trey,

Keep the vacuum advance loose until the distributor is installed.

Are you gonna set the distributor, #1 wire, to the correct factory location
or install it where ever it falls in place.

You should be able to pull all the plugs and produce some oil pressure with the starter.