no oil pressure after changing head gasket!!! why??

[91CoupeMike]

Lol, vacuum pumps can make more horsepower than just normal crankcase breathing, but the rings and oiling system need to be designed for it.

I was thinking that, my friend had added a vacuum pump to his bracket car and it dropped time. How does that work? Why wasn't mine super badass? Haha

[AMJ]

[QUOTE=91CoupeMike;1126354]Put them on upside down and blocked the oil passage.
QUOTE]

well its not a mopar

[91CoupeMike]

Mike there is no passage for oil through the hg


Dropped the op driveshaft.

Ah I was thinking cooling/ flipped gasket.

Lol but, oil still goes to the head from the block, through the gasket?? or is that just drain?

Edit; LOL yeah... Oil gets up there via pushrods right?

[Mach1]

Ah I was thinking cooling/ flipped gasket.

Lol but, oil still goes to the head from the block, through the gasket?? or is that just drain?

Edit; LOL yeah... Oil gets up there via pushrods right?

Yeah the oil return for the heads run through the HG

[mschmoyer]

I have an oil pump shaft bent in the middle to 45 degrees as a little token reminder of this issue...

90's 5.0 in an 84 mustang. The oil pump shaft did not have the little blocking ring that the one I replaced it with had. It looked like this part was in place to keep the shaft from falling down into the motor.

I could not get it with a magnet...had to drop the pan. If your lucky and/or it has that ring on it then it may still be sitting tilted in the shaft.

[racrguy]

I was thinking that, my friend had added a vacuum pump to his bracket car and it dropped time. How does that work? Why wasn't mine super badass? Haha

You have to account for it, it takes a worked over oil pump to overcome the affects of the vacuum, the reason it wouldn't idle is because your engine was leaking air like a sieve, so the engine was getting unmetered air. The way it works is it essentially sucks the rings against the wall, that does two things. 1) it seals the cylinder better and 2) it allows you to run a lower tension set of rings and reduce drag inside the engine.

[greenbullitt]

Oil pump shaft sounds like.

Pull the sending unit off and crank over the motor WITHOUT starting it.

Should see lots of oil squrting out, if not, pull the Dist. and see if you can see the top of a 5/16 hex shaft.
Thats the oil pump drive shaft or it should be.

Hopefully you didn't hurt the rod / main bearings running w/o oil pressure.

use a Huge magnet to slide the pump shaft around to the oil drain plug hole to get it out. That if its in the bottom of the pan. Sometimes it will hang vertical in the motor. Pull the pan then.

Been there. It sucks.

agreed, try this. There is supposed to be a clip on the shaft to prevent it coming out, however....we all know its not always there, or installed incorrectly

[terryd001]

Well the shaft came out and it was laying in the pan bent in half. So replacing it tomorrow and gonna see what happens.

[Kart21]

Damn it !

Strongly suggest getting an aftermarket shaft as the factory ones tend to twist.

Some, and I can't remember who, make a 5/16 hex on both end and a 3/8 main body driveshaft. They are the best. Extra good if you are using a high pressure / high vol. pump.

Might think about a windage tray install as the pan is off. Cheep horsepower.

Don't forget to put the little retaining ring on the shaft, as talked about before, to keep the shaft in place when you pull the dist. out next time.

Good luck.

[greenbullitt]

Damn it !

Strongly suggest getting an aftermarket shaft as the factory ones tend to twist.

Some, and I can't remember who, make a 5/16 hex on both end and a 3/8 main body driveshaft. They are the best. Extra good if you are using a high pressure / high vol. pump.

Might think about a windage tray install as the pan is off. Cheep horsepower.

Don't forget to put the little retaining ring on the shaft, as talked about before, to keep the shaft in place when you pull the dist. out next time.

Good luck.

arp

[Txstang1]

arp

yup

[terryd001]

Thanks guys

[terryd001]

ok so I got the new shaft with the retaining ring installed, my question is when I drop the shaft in does the ring stay on? cause now my distributor wont go all the way in

[Mach1]

ok so I got the new shaft with the retaining ring installed, my question is when I drop the shaft in does the ring stay on? cause now my distributor wont go all the way in

Gotta ditch the ring if you want to install from the top.

[jyro]

questions, I never ran a vacuum pump

You have to account for it, it takes a worked over oil pump to overcome the affects of the vacuum,

The most vacuum you could possibly have is -14psi. That could possibly change the oil pressure by 14 psi on a gauge but, since the complete oil system is under that vacuum, the internal engine pressure should be the same, the gauge reading would be 14 lbs low because it's calibrated to atmosphereic pressure 14lbs higher than the engine under vacuum. BTW, I don't thing you can even get close to 14lbs. vacuum inside the motor or 29.9" mercury.

but I never ran a vacuum pump. am I thinking right on this?