[cleancut]

I need some serious help and soon. I am going to Las Vegas in two weeks to play in the National Eight Ball Championships and my truck has no oil pressure at all.

I have an 89 GMC 2.5 L S15 with a 4 cyl TBI. I recently rebuilt it completely. Everything is new except the piston rods and the block itself!!!

I had the block bored .40 over and the same machine shop installed the cam bearings. I installed a new cam, a new crank .10 over with there correct size bearings. All clearances are according to specs. New main bearings and rod bearings were also installed as well as a new oil pump.

My problem is that I am showing no oil pressure at all. I removed the oil filter and turned it over and it nearly emptied my oil pan in a short time. I replaced the oil sending unit and it still didn't work. So I installed a dash mounted oil gague and still no oil pressure.

I not only do not have oil pressure, but I am getting no oil up to my rocker arms. It is not pumping through my hydraulick lifters. Could I have received a batch of bad lifters? Or could there be something else causing the problem? Any help would be greatly appreciated.

[poncho62]

Wonder if the oil pump pickup fell off?

[DoubleVision]

If it pumped oil when you removed the filter, then the oil pump is obviously working, but doesn`t pump any oil to the top end of the engine with the filter in place, then it sounds like you have a major internal oil leak, I would check to see if any of the oil gallery plugs came out.

[4 Jaw Chuck]

Yank it now while you still have time, get it to your machinist, sounds like a plug fell out or was not installed or perhaps a cam bearing was installed incorrectly. DOH!

Good luck, let us know how it works out.

[11echo]

Another guess ...On SBC blocks there is a set of oil galley plugs in back of the timing chain gear around the the cam. I'm NOT familiar with your 2.5L, but I'd guess it has something similar. If these are left out, you'd get no oil pressure (been there!) ...worth a check. Good Luck! ...Mark

[machine shop tom]

What kind of oil filter are you using? Replace it with a good one (Wix, Baldwin, etc.). DO NOT use a Fram oil filter. I've seen multiple "no oil pressure" problems with the oil filters being the culprit.

[cleancut]

I APPRECIATE ALL YOUR HELP! I called the machine shop that bored and cleaned my block and they told me that they took out the oil gallery plugs. I removed the timing cover and cam gear and there was no oil gallery plug. I installed one and now I have 40 psi at idle.

[Jmark]

Seems to me that the machine shop should have re-installed them before giving you the block back. If I had that problem, i'd be mad as heck at them!

But glad its better and no damage ( hopefully ) was incured.

Mark

[tresi]

This is why you should always spin the oil pump with a pre oiler shaft or dummy distributor befor installing the distributor, or at least disconnect the power to the distribution and crank the engine over until you've got oil pressure beforestarting. If you don't have oil pressure don't start it.

[machine shop tom]

They should at least buy you a good lunch for doing that to you!!

tom

[camaroman7d]

WOW Tom, I am surprised to hear you say that. If they built the engine for you, then yes they made a big mistake. If you built the engine yourself, that is on you as this is part of building an engine. I am sure they "assumed" you were going to install them.
The good news is you figured out what is going on.


Royce

[willys36@aol.com]

A related tip; on engines like the GM V6 that came in 80s Malibus, Skylarks, etc., with external oil pumps, THESE WILL NOT SELF PRIME!!!! I've never worked on one but the 426 Hemi has the same pump so probably needs this too. I spun all the bearings and ruined a crank on a V6 rebuild because I was not aware of this characteristic and didn't read the manual. The pump MUST prepacked with Vaseline when installed to start the prime.

I won't talk about the looks my son-in-law and I got when we went into the local pharmacy and bought two big jars of Vaseline!

[BstMech]

Originally posted by machine shop tom
They should at least buy you a good lunch for doing that to you!!

tom

He's right, no matter how redundant, my machinist will always remind me of "little things" like that to ensure there'll be no problems for me. I believe it's just a matter of the machinist giving a crap or not.

I'm glad you didn't have too hard a time finding the problem.