This is my first attempt at rebuilding a GM product, so I'm assuming I'm probably doing something wrong. Here's the issue: the motor is installed with the distributor in (I prefer it to a priming tool). I get an immediate 60 PSI reading on the oil gauge as soon as I get on the starter. However, I could be cranking the motor for a straight minute and won't see any oil coming out up top.

The motor has all new components inside, including Sealed Power lifters and M-155HV oil pump. Please note that the lifters were kept in oil for about two months prior to their installation :P

There's one scenario that I believe could have botched the rebuild job--the rear end of the main oil galley. I had to outsource that job due to time constraints, and that was about the only thing I outsourced. Refer to the pic below:


The guy who reinstalled that plug reassured me that he had screwed it in "almost all the way". Do you guys think that he got that 1/2" plug so far in that it's now blocking the feed to the oil galley? If so, why do I have any oil pressure reading?

I don't want to try my luck by starting the truck to see if oil squirts out the top.

Thanks guys.

 

If you are worried about it then simply use a real priming tool. They are available from Jegs for under $20. pretty cheap engine insurance. You will need an appropriately sized drill to run it with the engine installed. Go for 30-60 sec, turn crank 1/4 turn, go for 30-60 sec more, turn crank 1/4 turn and so forth until you have completed two revolutions. Then pull the valve covers and look for oil out the rockers.

There is no way you hit the starter and got instant 60# oil pressure through the oil filter, cooler lines, oil cooler, and engine oil galleys. That is simple BS. If you had bad bearings or anything metal ground down in your old engine, I do hope you replaced your radiator (oil cooler with significant volume you know), and cleaned out your remote filter oil lines, remote oil cooler lines adapter (on block), and remote oil filter adapter (up front) - as well as all the oil passages in the block. All places for metal to hide and do damage to new stuff.

That oil galley plug is not screwed in enough to be blocking anything, and the oil pressure sending unit is after that plug anyways (FYI it's not a 1/2" pipe plug).

You did use break in oil, right?

FYI high volume oil pumps are only useful for engines that are set up with loose bearing clearances (like race engines). With normal bearing clearances, it will be bypassing oil at max pressure a lot of the time and wearing out that distributor gear prematurely. More is not necessarily better! As a general rule, you need to maintain at least 10psi of pressure for each 1000rpm. My stock pressure/volume GM pump on my new GM motor is 25psi completely hot at 550RPM in drive, 45psi completely hot at 2200RPM (highway speed in OD) with 5W30 oil. Max pressure is 60psi when cold, but is only there for a couple of miles.

Good luck

 

Thank you for your reply. Here's my response:

- I do own a priming tool, but didn't use it.

- The M-155HV is capable of dumping out ~4 qts of oil in less than 10 seconds. It happened to me when the line at the adapter wasn't installed at all. So, unless a Bosch mech gauge and the truck's OPSU were both faulty, it should be credible that I actually got 60psi within a matter of seconds.

- I forgot to mention that the 1/2" was actually the length of the pipe plug.

- Not the first motor I am building. I am a 351W guy..


- The problem automatically rectified itself this morning when I backed off both the plugs quite a bit. I was going to record my findings in this thread tonight..

Thanks again.

 

Most of the engines that I have torn down over the years have had plugs in the rear oil galleys that used a Allen socket too install them - Seems too me the threads are not tapered much if even at all so they can't be run in too far - Also by your picture that you posted there is two different style plugs installed which makes me wonder if they were just something he had laying around and used.

 

Run the priming tool and see what happens. I rebuilt a 304 once that wouldn't prime until I manually spun the oil pump. Different setups, I know, but similar issues.

Josh