I'm Stump On Removing Oil Pan On 96 Seville SLS 4.9

[SVRIDER01]

Hello. I had tried to search on how to remove the Oil Pan on my 1996 Seville SLS 4.9L to get to my Oil Pump because the Oil Pressure Light comes on intermittently. I am sorry I cannot get the right answer.

Took it to an independent shop and they said the Pressure Swith because it was leaking. So they changed it. Second time I came back because light came on again. They figured out it was the Oil Pump. It's gonna cost me $550 Total. I said will just change it myself.

A couple days later, I'm stuck with this project. I cannot figure out how to remove the Oil Pan. It looks like the Crossover/Crossunder will be hard to remove nor the bols to access.

I read that prior to replacing of any parts, you have to this kind of checks where you overfill the Oil Level and rev it high? If so, how much you put in there, how many RPM's you rev it and how long you rev it?

I desperately need help you guys. I need to this car to get around! Thank you in advance and any advise is greatly appreciated.

V/R,

[KHE]

Your '96 SLS has the Northstar engine, not the 4.9. Oil pump failures are very rare on those engines. You don't need to remove the oil pan to access the oil pump on a Northstar. The oil pump is behind the timing cover - it is a gerotor style pump and is very durable.

Was an aftermarket sensor used when the pressure sensor was replaced? If so, they have been known not to have the same trip point for the low pressure light.

You need to temporarily install an oil pressure gage and see what the actual oil pressure is when the low pressure light goes off.

[Cadillac Jim]

The quickest, simplest thing to do is to get an OEM oil pressure sensor and change it yourself. If that doesn't fix it, then put a tee on the same fitting and connect an oil pressure guage.

[BodybyFisher]

You might get away with retorquing the crank pulley bolt to spec, that sometimes helps. If that bolt is not torqued right your oil pump will slip.

Are you leaking oil? My guess is that your case half seals are shot, and you are losing pressure at idle

What kind of oil are you using? Do not use synthetic or 5W30. If you get the light with 10W30 try using Rotella 15W40 that should stop the light. If you are due for an oil change change it.

How are your temps? If you are running excessively hot your oil thin out and your oil light will come on. About a month ago I hit 233 and my oil light came on at idle, once the car cooled down and ran at normal temps it was ok. I am due for an oil change, I use 15W40, but as it needs oil I have used 10W30. I leak bad, and need case half seals.

[SVRIDER01]

Thank you guys for your quick reply. Where is the timing cover? How does it look like? Thank you.

[winterset]

Sounds like you are determined to change the pump. As BBF said, the flickering oil light is common as the half seal leak is a issue faced by many on these aging N*'s. As with many issues on these engines, very simple changes to routine maintenance can save you alot of unecessary work and $$. that's the purpose of this board. - you're communicating with many people who have the same engine or older that went thru the same issues you are. - it's worth it to learn from this board, and not just to go ahead and change parts. in either case, please keep us updated on your work so others can learn that someone changed the pump, and it fixed the problem. To date, I have never heard of anyone changing the oil pump to fix this. Seems changing the oil viscosity, the switch, and the O ring fixed the leaky switch, and supressed the flickering oil pressure light.

Edited August 20, 2008 by winterset

[BodybyFisher]

Thank you guys for your quick reply. Where is the timing cover? How does it look like? Thank you.

This is not likely an oil pump. As Jim noticed put a T on the oil pressure switch at the oil filter adapter and see what you see for pressure.

Change your oil, put in 15W40 diesel oil it is high in zinc also, good for our older engines. (Rotell and Mobil sell 15W40)

What are your running coolant temps? When do you see this light?

The timing cover is on the passenger side of the engine, the engine carriage must be dropped to get at it I believe.

Did you start to drop the oil pan?

[KHE]

Thank you guys for your quick reply. Where is the timing cover? How does it look like? Thank you.

The engine cradle must be lowered on the passenger side to remove the balancer pulley. You will then need to use a flywheel lock to lock the flywheel in place. The cam covers must be removed in order to remove the timing chains to gain access to the pump. As you can see, this is a TON of work and you will only be disappointed when you replace the pump (gear) only to find the problem still exists. The independent mechanic is treating the Northstar engine lilke a small block Chevy engine as based on his analysis that a bad oil pump must be the cause of the low oil pressure. It may be true in a small block Chevy but not so with a Northstar.

[Cadillac Jim]

What KHE says is borne out in the mechanic saying that you need to drop the pan to get to the oil pump. If the mechanic doesn't know where the oil pump is on a Northstar, then he's never taken one apart, or anything like it -- that is to say just about any engine introduced since 1985 or so.

In older engines, the system is to use a camshaft running at half crank speed, with a distributor running at the same speed as the camshaft. Most ordinary engines geared the distributor to the camshaft but some were simply put on the end of the camshaft; see aircraft engines where this is common. When a geared distributor is used, the oil pump is run on the same shaft as the distributor and is in the oil pan.

Modern engines don't use a distributor at all. They use sensors on the crankshaft, manifold vacuum, and camshaft with a computer that fires the coils and keeps track of the RPM and timing, and the ignition is nearly always a capacitive discharge type which produces a superior spark to points-and-condenser type ignitions. Coils either drive two cylinders that fire 180 degrees apart or just one cylinder, and there is no distributor. The oil pump is usually run from the timing chain and is on an idler, and is thus behind the timing cover on the front of the engine. The water pump is run from the timing chain, the serpentine belt, or, in the case of the Northstar, from one of the four camshafts.

In addition to these things, the Northstar engine is built with case halves like a motorcycle engine. The bottom case half contains the main bearing web and seals against the block with a really big O-ring. The oil pan bolts to the lower case half. This, with the steel crank and cross-bolted main bearings, gives the Northstar crankshaft rigidity to provide exceptional smoothness and reliability in a four-cam 32-valve V8 with a redline above 6,000 RPM -- and enough strength to be used as an Indy car engine in 4.0 liter form, as it was for a few years. For Northstars tricked out to several hundred horsepower, see chrfab. They don't need to beef up the bottom end to do this.

[SVRIDER01]

Thank you guys for your replies and advice. I decided not to pull the oil pan out. On the process re-installing it back on, I stripped one of the bolt. Leaving half of the bolt in the engine.

I took it for a test drive about 5 miles. The Oil light flickering and info says, LOW OIL PRESSURE. TURN ENGINE OFF. I then cool down the engine and saw no leaks under.

I talked to the independent mech and said he put a pressure gauge where the pressure switch goes and he said it didnt have enough pressure. So are we assuming the Pressue Switch is NOT the problem even though it's an aftermarket part right??? I just bought the OEM AC Delco Pressure Switch. Should I even try replace the aftermarket one?

I still wondering about this Guru that I read about adding 10-12 quarts in top of the 7 quarts that's in the engine. And rev 3500rpm to clean out debris in the valve of the oil pump.

Does that make since? Sorry no disrespect and forgive me. Would it not flood everything up in the engine and piston, spark plug blah blah ....etc ??? Does this really work? Anyone tried it?

What is my next step? Please???

[KHE]

What was the oil pressure at idle? I think overfilling the crankcase was for the '93-'94 engines that would get a piece of debris stuck in the relief valve. If you have any oil pressure, that wouldn't be the case with your car.

If the pressure is slightly low but there is oil pressure, I'd change the oil and put some 15W-40 Rotella in there - it may solve the problem.

[SVRIDER01]

Thanks man. I was about to do it. That could of done a lot of damage. Aside the broken bolt.

I asked the store clerk and he said 15W40 is only for diesels and trucks. Is he right? Thanks.

[BodybyFisher]

Thanks man. I was about to do it. That could of done a lot of damage. Aside the broken bolt.

I asked the store clerk and he said 15W40 is only for diesels and trucks. Is he right? Thanks.

Up above I posted this:

Change your oil, put in 15W40 diesel oil it is high in zinc also, good for our older engines. (Rotell and Mobil sell 15W40)

Is he right, yes techically but he is a CLERK. We were advised to use this oil by a reputible source familiar with the NS

[winterset]

Did the low oil pressure warning/flickering light only come on after a high RPM run, followed immediately by the car sitting at idle? or was it on when you were driving? - what were your RPM's when the light came on?

Mine only came on after WOT in hot weather. When the RPM was at 625. I cleaned the connectors on the sending unit, and added a little Marvel Mystery oil to the crankcase, and I never saw it again.

I am glad to see you are open to input from this board. You will have better results.

[SVRIDER01]

It only comes on when idling. If I give it gas, driving around or just rev it at park, oil light turns off.

[SVRIDER01]

Okay I had changed the Pressure Swith to OEM, replaced oil with Rotella 15W40 and added Mystery Oil. Still the Light is flickiring on idle. And at the same time, the highest I get from my temp gauge is 1 bar next to the red. Then it would go back to middle. Is it time for the thermostat to be change? Please anyone help. I appreciate all the help so far. Thank you. What should I do now? What could be wrong.

[Ranger]

Just a chance that the relief valve is slightly stuck. It's worth a try. Over fill the crankcase by 8 qts. Rev the engine to 4K a few times. Then drain it back to the mid point on the dip stick. I really doubt that this will help, but it will only cost you 8 qts. of oil to try it.

[Dennis Herron]

On 8/20/2008 at 9:01 AM, BodybyFisher said:

This is not likely an oil pump. As Jim noticed put a T on the oil pressure switch at the oil filter adapter and see what you see for pressure.

Change your oil, put in 15W40 diesel oil it is high in zinc also, good for our older engines. (Rotell and Mobil sell 15W40)

What are your running coolant temps? When do you see this light?

The timing cover is on the passenger side of the engine, the engine carriage must be dropped to get at it I believe.

Did you start to drop the oil pan?

I just bought 96 deville the owner said it has low oil pressure and needs to fix it before I ruin the motor any suggestions? 

[BodybyFisher]

You can check the oil pressure switch and its connector first.  I would replace it with an ac delco to remove it as a potential problem.

Use an OEM ac delco oil filter, it has been calibrated for your engine.  

Does the oil pressure message/light go out when the rpm increases above idle?  Typically we see these engines have internal leaks like the case half seal, main bearings etc, that drop the oil pressure at idle, just enough to cause a flicker in the summer months when the engine is hot.

Be sure the cooling system is keeping the engine cool.  Oil thins out when it is hot, dropping the oil pressure just enough.  

Stock oil pressure spec is 10 psi at idle, the oil pressure switch is set to come on at about 6 to 7 psi.  As the engine ages clearances widen, and internal leaks occur that drop the pressure enough to trigger the light.  I think the pressure is 30 psi at 2,000 rpm, but don't quote me.  

If any engine work has been done that required removal of the crank pulley, torque it to spec, the balancer traps the oil filter drive and turns the pump, if this bolt is loose oil pressure will be compromised.  You might have the crank pulley bolt loosened and tightened to spec to eliminate it as a cause.  However, it will be necessary lock the engine from turning with a special tool that engages the teeth in the flexplate keeping the engine from turning.

If he is using synthetic get it out and use standard mineral oil.  Synthetic flows 7 times better and will drop the oil pressure at idle just enough to turn the light on.

Try using Rotella 15W40 diesel engine oil, not the synthetic.  That will help keep the oil pressure a little higher and help with the oil light flickering.  If you can't find Rotella look for Mobil DelVac 15w40.  Diesel oils also have a higher concentration of zinc which is a anti-wear compound, the 32 lifters are the rubbing element type and cause significant oil sheer and the increased zinc is good for them.

Good luck.  Keep us posted