98 GMC ENVOY oil pan has two partialy blocked bolts,how do i remove them?

Hello. Your GMC's oil pump at the bottom of the engine block; covered by the oil pan. To access it; drain the oil and remove the oil pan. The 'oil pickup tube' is bolted to the oil pump 'cavity'. Good luck and keep me informed; if you want to.

Raise motor with an engine crane enough to clear cross member, and space to remove oil pan.

Last I looked around 14 ft lbs. I advise you to convert to inch pounds and evenly tighten as per manual bolt sequence in three steps. I will mention you should double check my memory... I am fairly certain 12 to 18 ft lbs, but just the same go to youtube for a bid showing the correct method of torquing bolts.
For what it is worth many parts stores will let you get a peak at a manual.

I just changed my oil pan gasket on my 2001 GMC Yukon Denali. Once all bolts are off the oil pan, the pan and off the block it has no clearance because the differential is in the way. I removed half the diffential since the housing is split in the center. You will see bolts on the differential housing, remove those. But before the diff can come out to make room for the pan to drop you have to remove the axel attached to the diff on the passenger side. Once the axel is off the diff you have room to remove half the diff. Make sure to drain the gear oil first. It take a bit off pulling and wiggling but it will come off. Once that's clear the oil pan is completely free to come out. Hope this helps.

Pump replacement is fairly involved, but the issue is rarely the pump, as it is pretty indestructable. If you have low pressure, usually some clearances are too loose, somewhere. There is also sending unit issues, so measure your pressure with an external "known good" gauge.

try heating it with a heat gun, then slide a paint scraper in between the pan and trany

Step 1 Raise the truck using the proper equipment. Use a ramp or a jack and jack stands to support the vehicle securely by following all directions for use provided by this equipment's manufacturer.

Step 2 Drain all oil from the Silverado by placing an oil drip pan under the vehicle's engine block, directly under the oil drain plug. The drain plug is located on the oil pan, between the vehicle's tires underneath the vehicle. Use a wrench to loosen and remove the plug allowing the oil to drain into the pain below.

Step 3 Notice the various items attached to the oil pan or in the way of the oil pan dropping. For the oil pan to drop, remove the negative battery cable, front differential (only for four-wheel drive vehicles) and the under body shield by using a wrench or socket set.

Step 4 Remove the oil pan shield by loosening the four bolts holding it in place along the edges of the shield. Then, remove the cross brace, oil filter, the transmission to oil pan bolts and the oil level sensor.

Step 5 Follow the removal of those pieces by removing the bolts from the two front wiring harness, the engine wiring harness retainer, engine oil cooler pipe to oil bolts and the transmission oil cooler pipe retainer using a wrench. Located the closeout covers and bolts located on each side of the engine and remove them.

Step 6 Disconnect each of the oil pan bolts using a wrench that will allow the oil pan to drop. The oil pan gasket will also fall off and replacement should occur before reinstalling the oil pan.

Read more: How to Drop the Oil Pan in a Chevy Silverado | eHow.com http://www.ehow.com/how_4508109_drop-oil-pan-chevy-silverado.html#ixzz0wi82Ul2u

2wd Models

1. Disconnect the negative battery cable. Drain the engine oil.
   
2. Remove the oil dipstick.
   
3. If necessary remove the exhaust pipe crossover.
   
4. If equipped with automatic transmission, remove the converter housing pan and the transmission oil cooler line retainer from the bracket.
   
5. On 1996-98 models, remove the oil filter and if equipped, the oil filter adapter.
   
6. If necessary, remove the starter brace and bolt and swing the starter aside.
   
7. Remove the strut rods, if equipped.
   
8. Remove the oil pan and discard the gaskets.
   

To install:

1. Apply a suitable sealant such as GM part number 12346192 or its equivalent to the front cover-to-block joint and to the rear crankshaft seal-to-block joint. Apply the sealant about 1 inch (25mm) in both directions from each of the four corners.
   
2. Clean all gasket surfaces and use new gaskets to assemble.
   
3. Install new gasket and seals.
   
4. Install the oil pan.
   
5. On 1988-95 models, tighten the pan bolts to 100 inch lbs. (11 Nm). Tighten the pan nuts to 17 ft. lbs. (23 Nm).
   
6. On 1996-98 models, tighten the oil pan nuts and bolts to 18 ft. lbs. (25 Nm).
   
7. Install the strut rods, if equipped.
   
8. If removed, install starter, starter brace and bolt.
   
9. If equipped, install the oil filter adapter.
   
10. If removed, install the oil filter.
    
11. If equipped with automatic transmission, install the converter housing pan and the transmission oil cooler line retainer to the bracket.
    
12. Install the exhaust pipe crossover.
    
13. Install the oil dipstick.
    
14. Fill the engine with oil and check for leaks.
    

Changing the oil pan gasket on a GMC Yukon XL is realtively simple, but does require removal of the exhaust pipe. You will need a new oil pan gasket and a new exhaust pipe flange gasket.
Put the car on ramps or jacks to access the undercarriage.
Remove the exhaust pipe by removing the 3 nuts holding the exhaust pipe flange to the exhaust manifold. These nuts often rust and prior application of penetrating oil may be required to remove them without damage. Once the pipe is unbolted, work the exhaust system loose from the hanging brackets. In most cases the entire system does not have to be removed since there is enough room to remove the pan with only the front hangers removed.
Drain the oil from the engine
Remove the 10 mm bolts holding the pan to the block.
Remove the old gasket material and scrape any remaining gasket from the block and pan.
Install the new gasket. Forma-Gasket or a similar product may be used in small quantities to "glue" the new gasket in place and prevent shifting while the pan is reattached to the block.
Reinsall the 10 mm bolts in a cross pattern to ensure the gasket is compressed evenly. Do not overtighten the bolts.
Replace the pipe to flange gasket between the exhaust pipe and the exhaust manifold with a new part.
Reattach the exhuast pipe to the hangers.
Install the 3 bolts connecting the pipe flange to the exhaust manifold.
Fill the engine with oil.

No big job Really. Just locate your Drain Plug for the Oil. Thepan is right there, Remove the Bolts around the Pan and Remove. You will lose all of your oil so, Have something there to catch it all. Clean it all around the Edges of the Block where the Pan mounts with Degreaser and Make sure that you Scrape the Old Gasket off of Both the Block and the Pan. Run a Thin Bead of Blue ATV Silicone around the Pan Edge, Lay the Gasket on top of this Silicone. Put another Thin line on top of the Gasket and Reinstall. This Silicone is High Temp Silicone and will Seal Very Well. Make sure to put oil Back in the Motor! Please Rate my Response, I need all the Help That I can Get! Thanks!