Oil pressure problems

10

Asked by Mar 07, 2016 at 09:22 AM about the 1999 Chevrolet C/K 2500

Question type: Maintenance & Repair

I have a 1999 chevy 2500 pickup not a silverado,
not even a week ago I had a head gasket blow do I
rebuilt whole top end and truck ran fine for a
couple days but noticed it wasn't holding good oil
pressure, 20 to 40 pounds when up on the rpms
and 0 when idling, think I may need to rerun my
rockers, but now 4 days after rebuild my balancing
pulls off the crank acts like it's out of balance
looks like it is trying to wobble and I have engine
noise now, check engine light is on and throwing a
crankshaft position sensor code. Any thoughts?

22 Answers

325

Mike, Just an observation.. We had to have a new header gasket installed.. and afterward, the vehicle did not respond as it once did. Lack of power and acceleration. We had the shop check the gasket and found out (even though it was listed for our vehicle) the gasket was molded incorrectly. I'm suggesting that you check the old gasket to the new just to verify there they are the same. Because they are not.. the new gasket could be obstructing the flow of oil, antifreeze etc.

10

I did the work my self and checks the gaskets lay out before I placed them they matched, and to also add my oil pressure is getting worse to where I can barely get 15 pounda of pressure while driving, and forgot to mention when I start it first thing in the morning it holds bout 40 pounds of pressure then drops as it warms up

1 out of 1 people think this is helpful.
325

My thought would be an oil sending unit error. Check this link: http://www.gm-trucks.com/forums/topic/169782-attention-anyone- with-oil-pressure-issues/

10

Link won't work

37,975

How many miles are on this motor?

10

213000

37,975

Just redoing the head increases compression and on a high mileage motor it will pull oil threw the piston rings thus an oil burner. With that many miles I'm sure there is wear in the bearings. So ya, a long block or total rebuild is your best bet. The harmonic balancer I bet you forgot to put the bolt in the end of it, if it had one, not sure what size this motor is,

10

It's a 350 vortec and never pulled the balancer left it in place, it just started wobbling acting funny couple days after I had rebuilt was fine to start with

10

Also to note when I was hand turning the motor to set the rockers I could barely turn it over with a 2 and a half foot breaker bar so good compression

37,975

Well I'm not liking the wobble with the harmonic balancer and they are suppose to have a bolt in the end of the crank to hold it in place. The wobble with it, what happen is now the bore of the balancer and the end of the crank are egg shaped. I went threw this once. So, ok here, I guess just need to investigate the oil pressure with a mechanical gauge to see what exactly the oil pressure is doing. If by chance it is all good, the fix I did on that balancer was to get a new balancer, fix up the key-way the best you can, new woodriff key, and bolt for the end of the crank, then I used J/B weld when I slid the new balancer back on, and installed the bolt. Still runs true. When it was wobbling it sounded like there was a knock in the motor.

10

Definitely sounds like a knock in the motor and if the end of the crank happens to be egged shapes will the new balancer still slide on accordingly

37,975

Thats what the J/B weld is for, to take up the void. And the balancer will go on easy, so you would definitely need a bolt to hold it on. The bore of the balancer is perfectly ┴ to the face that goes into the engine. It slides up against the lower timing chain gear face which is also ┴ to the crankshaft O.D. so the bolt holds it true & perpendicular against the face of the timing chain gear. You let the J/B weld dry for a few days to be sure. All this of course if the oil pressure is good, and the bearings are good. You could inspect one if it comes down to you wanting to replace the oil pump. And if you do that, get a high volume pump. FIRST tho before checking the oil pressure, get a bolt in the end of the crank to hold the balancer. Don't want to cause any more damage, and then also you will also see if it still knocks.

1 out of 1 people think this is helpful.
10

When I get off work I'll check the. Balancer out and see what I can figure out I really appreciate it, also would the balancer being egg shaped cause my crank position sensor to throw a code

37,975

Oh, yea, forgot about that, yes it could because the end of the crank is shaking around, the sensor is sensitive. But like I mentioned, put a bolt in the end of the crankshaft first before anything else you do, to see if the knock goes away. If it doesn't, then the main bearing is bad. All this is mainly just work, not costly to do, and maybe you'll get lucky.

10

Let's hope I'm lucky this time haha

10

So I checked an it's not the balancer, the noise it makes when driving is a deep kind of sounding noise and makes my trucks exhaust sound louder then hell, I'm kinda thinking main bearing on the crank

37,975

Can't be sure until you get a bolt in to hold the balancer. Mine sounded like you describe until I got the balancer to spin true.

10

I'll see what I can do

37,975

You just can't get that bolt anywhere, get one off a motor from a junk yard, or order one from the dealer, or Jegs has them.

10

Ok cool thanks I appreciate it i just got under there with a pry bar to see if it had any play in the balancer there's no play in it

37,975

Take the belt off and check by hand to see if there is any movement. Look if you can maybe use a mirror and see inside the bore of the balancer to see any signs of it moving also. Look next to the crankshaft.

10

Will do

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