98 Grand Prix GT curious engine issues

[98BlackGT]

First off, I'm new here, so go easy on me.

 

I've had this car for a while now, and it's been more than a lemon for me, but I am still driving it. It had an overheating issue about 2 months ago, which was a real fun ordeal to realize both the thermostat had failed, and the water pump was right on the edge of life since the bushing was wobbling like no other.

 

Anyways, I changed the oil about a month ago and drove it despite a slight oil leak that was dripping off the bottom of the oil pan. I figured it might have been the drain bolt, so I replaced that and added a gasket and the oil still shows up there, so it's leaking oil somewhere...probably around the oil pan gasket or maybe around the valve covers, but either way, that's been a relatively minor issue as it's so slow.

 

What's been the bigger issue since changing the oil is that the oil level has been all over the place. When stationary the oil level seems fine(7/8 full). When running and checking the engine oil level, it goes way up about twice as high up the dipstick and well past full. Now, I know you shouldn't check the oil while running, but I don't remember having this issue before. Oil itself seems to be perfectly fine in color(running only water and no coolant as of now). I did find a coolant leak around the heater core inlet hose by the "prestone" cap. If it was just this issue, I might just believe it was just a small leak by the heater core inlet hose that was giving me the "low coolant" light, but it also has periods when I accelerate that it sputters pretty heavily and then continues. For all I know, it might just be a dirty MAF sensor, but it feels more mechanical and the culmination of all of these signs together leads me to believe that it's something else such as a lower intake manifold gasket leaking, but I don't see any external signs of this failure(although that doesn't mean it hasn't failed inside).

 

My question is if the lower intake manifold gasket failed(assuming it did) and water is getting in to the engine causing it to stutter every now and then and it is giving me a more than full oil rise, why is it that when the engine is sitting stationary and off that it is at it's regular 7/8ths full mark? I feel like I'm asking a real dumb question, as I know most of it, but it is confusing me a bit. I would just expect the water to sit in there and keep the oil level elevated if the LIM failed. Either way, the engine is running rough at times and I'm not sure why.

 

I plan on doing a compression test here soon and might pop the drain plug and see if I can see any water, but after that, it's tough to tell.

[l67ss]

Every engilne ive worked on showed higher running thats why you check oil with the engine OFF

First off, I'm new here, so go easy on me.

 

I've had this car for a while now, and it's been more than a lemon for me, but I am still driving it. It had an overheating issue about 2 months ago, which was a real fun ordeal to realize both the thermostat had failed, and the water pump was right on the edge of life since the bushing was wobbling like no other.

 

Anyways, I changed the oil about a month ago and drove it despite a slight oil leak that was dripping off the bottom of the oil pan. I figured it might have been the drain bolt, so I replaced that and added a gasket and the oil still shows up there, so it's leaking oil somewhere...probably around the oil pan gasket or maybe around the valve covers, but either way, that's been a relatively minor issue as it's so slow.

 

What's been the bigger issue since changing the oil is that the oil level has been all over the place. When stationary the oil level seems fine(7/8 full). When running and checking the engine oil level, it goes way up about twice as high up the dipstick and well past full. Now, I know you shouldn't check the oil while running, but I don't remember having this issue before. Oil itself seems to be perfectly fine in color(running only water and no coolant as of now). I did find a coolant leak around the heater core inlet hose by the "prestone" cap. If it was just this issue, I might just believe it was just a small leak by the heater core inlet hose that was giving me the "low coolant" light, but it also has periods when I accelerate that it sputters pretty heavily and then continues. For all I know, it might just be a dirty MAF sensor, but it feels more mechanical and the culmination of all of these signs together leads me to believe that it's something else such as a lower intake manifold gasket leaking, but I don't see any external signs of this failure(although that doesn't mean it hasn't failed inside).

 

My question is if the lower intake manifold gasket failed(assuming it did) and water is getting in to the engine causing it to stutter every now and then and it is giving me a more than full oil rise, why is it that when the engine is sitting stationary and off that it is at it's regular 7/8ths full mark? I feel like I'm asking a real dumb question, as I know most of it, but it is confusing me a bit. I would just expect the water to sit in there and keep the oil level elevated if the LIM failed. Either way, the engine is running rough at times and I'm not sure why.

 

I plan on doing a compression test here soon and might pop the drain plug and see if I can see any water, but after that, it's tough to tell.

[EGTGP]

My 98 has a small oil leak just like yours showing up on the oil pan bolts mine is a slow leak from the timing cover gasket. easy enough to tell if its your valve covers.. Does it stink of burnt oil once It heats up? If not get under and peak behind the balancer/crank pully If thats clean honestly there are a few other places it could be leaking. always check your oil while the engine Is off It will read high while running.

 

As far as a lim failure check the under side of your oil fill cap for goo. If it failed in a manor causing it to leak into an intake runner in a large enough amount to cause a stutter I would think you would have some white smoke.

 

When It stutters does the tach ever stop working? If so does the trac off light come on?

[Andrew]

i dont think any of your issues are related.

 

like he said, check your oil with the engine off. its gets sloshed around with the engine running.

 

clean your engine thoroughly, then run it while under it to locate the oil leak.

 

if you know where your coolant leak is, fix it. Its likely letting air into the system, giving you false 'low coolant' readings. Also, cold nights are coming up soon. Get some coolant in there ASAP so you dont crack a block.

 

sputtering under accel could be caused by many of things. Get a scantool on there and see if you have any codes or readings out of spec.

Edited September 28, 2013 by Andrew

[AL]

If you still have the metal heat shields on the plug wires, take them off and see if that helps your misfire, those caused my car to barely run and it ran perfectly once they were taken off

[Schurkey]

If you still have the metal heat shields on the plug wires, take them off and see if that helps your misfire, those caused my car to barely run and it ran perfectly once they were taken off

Indicating either faulty plug wire/plug boot insulation, or excessive firing voltage, or bent/damaged heat shields.

 

The shields are there for a reason.

[Imp558]

Valve cover gaskets are a nice thing to replace on the L36, any time I get a new 3800 that's the first weekend,along with the coolant elbow. It's also pretty common for the upper intakes to crack and leak water in, if there's water getting in that's where my money is. They tend to hydro-lock when the upper fails well enough though.