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Discussion Starter · #1 ·
OK, Just got done with the "timing chain project from He!!" (The car fought me every step of the way.) I did all the suggested other things while it was apart like; pickup screen, new front cover from GSCA, Melling plate, Biggie oil filter, new cam sensor, and so on. Everything went back together fine and within spec. I also added an oil pressure gauge, first electric and now mechanical. I didn't have one before so I have no baseline to compare to.

My oil pressure is as follows: (10-30 oil with gm eos)

Cold around 70#
Hot idle in gear 17#
3000 rpm 28-30#
4000 rpm 30#

Once it is hot it will not go over 30# I installed an adjustable oil pressure relief kit and it did not help. How can I have such good idle pressure and crappy upper rpm pressure? Could the relief plunger be stuck?

Thanks for your help, Dave
 

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I would guess that is the easiest to check.

Did you check the end clearance on the pump gears and the clearance between the gears and the side wall?
 

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How many miles on the engine. It maybe tired. :6:
 

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Discussion Starter · #4 ·
The timing cover was a new GM/Canadian piece I got from GSCA. I did not check the side clearence. GSCA said if I re-used my oil pump gears all should be fine. Well my punp cover was groved so I used a Melling plate and then used the thinnest gasket I had. ( I had three to choose from.) I did not check the clearence with a gauge. Of course now I wish I would have. Can it be done with the motor in the car?
UPDATE:
I just took the relief spring apart to see if I could move the plunger with my finger and I cannot. Is this normal? I also just changed the oil to 15-40 rotella with gm eos and I got about 5# more pressure.

The car has 117K miles on it and when tI pulled the pan it was clean.

Thanks, Dave
 

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Dave,
You went through all that trouble and didn't put a new set of $12 gears in it?

That plunger should move. It seats at idle and bleads off extra oil when the engine revvs up.


As far as the end clearance, you said you used the thinnest gasket you had. Did you verify that the pump would even spin before buttoning it back up?

The last pump I built with a new GM cover, I had to stack two .006 gaskets together as the thickest one I had would lock the pump up.

I'm not trying to scare you, but if it were me I'd take that pump back apart and see if there's any damage.


Earl
 

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Discussion Starter · #6 ·
Earl,

Your probably right, I should have bought the new gears along with everything else. I did test spin the pump, by hand, before I put it in and there seemed to be no binding.

So if I understand you correctly, I should be able to pull the plunger out with my finger?

Thanks for your help, Dave
 

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That plunger should float but I don't know if you should be able to pull it out with your finger. It should have some oil back there kinda vacuume locking it in place. Since the bore is so small I wouldn't be surprised if you can't get a good grip on it. I've never tried.

The plunger shouldn't be a factor anyways. If it is stuck in the closed position you should have normal idle pressure. With it stuck your upper rev pressure should be off the chart without the bleed circuit working.

Since that doen'st fit your situation it sounds like your pump just can't put out at upper RPM's.
 

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how many miles on the engine? Is it a pump problem or an engine problem?

Did it have oil pressure before you rebuilt the pump?
 

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He didn't know what is was before replacing the front cover so there's no baseline.

I'm wondering what brand the new cover from GSCA actually is.

Although I'm thinking it's just a tired engine that had low oil pressure before. It'll go to 70 cold, but not warm.

Or a combination of cover + bearings together.
 

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I think all the brands are the same castings....just luck of the draw.

Bad advice on using the old gears.... :rolleyes:
 

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I don't know if I'd say that. I just got another GM timing cover in the other day and it has a 255 GM part number cast in the front and the seal loads from the back. (this one even has a rope seal installed and isn't drilled for a 14 bolt pan).

It also has alot of meat on the pressurized section of the pump to drill out to 1/2. A few weeks ago SteveV and few others posted about ventalating that passage drilling it out. I believe I could do 9/16 with this cover easily.

Castings aside, I wonder how many diffrent people do the final machining. When I wrote my front cover article last year I posted that the gears stick up higher than the cover does by a few thousandths. Steve said his cover had it's gears below flush. I can't remember what aftermarket one it was but it wasn't a GM cover.

If I had the money I'd by and Elgine, a Silver Seal and a Pioneer and put them side by side with my GM cover. I'm really curious which one would be the best candidate for my upcumming "EarlBrown super lubing system". I have a feeling the GM one is the best bet.
 

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Discussion Starter · #12 ·
Cover update

Steve, Earl,

I wasn't planning on changing the cover when I got into this but I missed a lower stud with the old cover and was afraid I had damaged the cover trying to get it off. It also had a lot of hairline stress cracks inside.

GSCA said they get covers from Canada and that Canada is still putting out the GM covers. The seal went in from the front and there was only a little casting sludge in the pressure side that I cleaned out. Everything lined up (camsensor) just fine and I primed the engine first. The car has 117K miles on it and it did not have an oil pressure gauge before so I have no baseline.

With the Rotella 15-40 I get 90# cold, 20# hot idle and upper rpm is 35#.

My plan is to;

1, order a shim kit from TA performance
2. take the oil pump apart, put new gears in it and use plastigauge (This can be done in the car right?)
3. Ensure the plunger has travel

Any other suggestions?

Thanks for your help, Dave
 

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Earl,you are right on about all of my findings. How much did that GM cover cost?
 

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Steve V said:
Earl,you are right on about all of my findings. How much did that GM cover cost?

I scored it on Ebay last week for $90 shipped!

What's amazing is that it had "Grand National" in the title and still sold that cheep. That's the only one I've found like that with the rope seal already installed. I'm guessing that's how they used to sell them a long time ago.
 
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