Does the cam shaft on a 1987 sentra 1.3 E13S engine take a spacer or washer between the oil seal housing and cyclinder head

O-ring where? The drain plug? Distributor shaft? Or do you mean oil seal?
Geo oil drain plug specifies a compressible copper ring washer I think? Need to clean the surfaces well, and torque to spec. My own plug's seal is not perfect, but only a drop here and there usually. Autozone or NAPA can supply you a new plug and washer if needed.

You don't give make or model. Here goes , The engine has a rear maim seal behind the fly wheel if it leaks the leak will be from the clutch housing. It has a front seal behind the crank shaft timing cover.it can leak from there . it can leak from the oil filter and oil pressure switch . Can also leak from the top timing cover gasket and cam shaft seals.

Check your owner's manual for the recommended mileage for replacing your timing chain. Replacement for a Nissan Maxima is 60,000 miles.2 Locate the timing chain. Replace it if the automatic chain adjuster (also known as the tensioner) is damaged or worn.3 Release the pressure in the fuel system, drain the cooling system and disengage the negative battery cable. 4 Undo the upper radiator hose, engine drive belts, power steering pulley and pump with bracket, air duct, passenger front wheel and engine side and undercovers, front exhaust pipe, cylinder head front mounting bracket and head cover, rocker cover, distributor and distributor cap and spark plugs.5 Take off the intake manifold support and move the No. 1 piston at "Top Dead Center" (TDC) of the compression stroke.6 Disconnect the cylinder head front cover, water pump pulley, thermostat housing, upper and lower tensioner and slack side timing chain guide, idler sprocket bolt, camshaft sprocket bolts, sprockets, mounting caps and camshafts. 7 Disengage the cylinder head with the manifolds, idler sprocket shaft, upper timing chain, center crossmember, oil pan and strainer assembly, crankshaft pulley, engine front mount and bracket and the front timing cover. Remove the oil seal and unfasten the timing chain cover, idler and crankshaft sprockets and the oil pump drive spacer. 8 Unfasten the timing chain guide. install Your Timing Chain 1 Grease the oil seal lip with engine oil and place it in the front cover. Verify that the No. 1 piston is at "Top Dead Center" (TDC) of the compression stroke. 2 Reconnect the crankshaft sprocket (marks should point toward the engine's front), oil pump drive spacer and timing chain guide and the lower timing chain. Line up all mating marks.3 Hook up the crankshaft sprocket and pulley, lower timing chain, front cover assembly, engine mount and front mounting bracket, oil strainer and pan assembly and center crossmember.4 Reattach the upper timing chain, idler sprocket (to the back side), cylinder head assembly, idler sprocket bolt and exhaust and intake camshafts. Place the intake camshaft knock pin at 9 o'clock and the exhaust pin at noon. Connect the camshaft bearing caps and distributor brackets and secure all mounting bolts.5 Eliminate any old material from the pan and cylinder block mounting surfaces. Rub on a 3.5 to 4.5mm bead of liquid gasket over the oil pan and cylinder block.6 Attach the upper timing chain to the idler sprockets and secure the cylinder head bolts.7 Refill the cooling system. Hook up the negative battery cable and any other disconnected items. Start the engine and look for leaks.

Removal

1. Raise and support the vehicle.
2. Remove the wheel and tire assembly.
3. Remove the differential housing cover and drain the lubricant.
4. Remove the rear brake drums.

1. Remove the differential pinion shaft.

1
Remove and discard the differential pinion shaft lock bolt.
2
Remove the differential pinion shaft.

1. CAUTION: Do not damage the rubber O-rings in the axle shaft grooves.

Remove the U-washers.
1
Push the axle shafts.
2
Remove the U-washers.

1. CAUTION: Do not damage the inner wheel bearing oil seal.

Remove the two axle shafts.

Installation

1. Lubricate the lip of the inner wheel bearing oil seal.

• Use Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B.

1. CAUTION: Do not damage the inner wheel bearing oil seal.

Install the two axle shafts.

1. CAUTION: Do not damage the rubber O-rings in the U-washer grooves

PINION FLANGE & OIL SEAL

CAUTION: Following procedure must be used to retain proper pinion bearing preload. Failure to follow procedure may result in premature axle assembly or component failure. Ensure pinion bearing preload is checked before disassembly, as previous pinion bearing preload will be used during reassembly.

Removal

1. Raise and support vehicle. Scribe reference mark on drive shaft-to-pinion flange on differential for reassembly reference. Remove bolts and "U" joint straps at pinion flange on differential.
Disconnect drive shaft from differential.
2. Remove rear wheels and brake drums to prevent any drag that may affect pinion bearing preload reading. Using INCH-lb. torque wrench, measure amount of force required to rotate pinion. This is pinion bearing preload. Record pinion bearing preload for reassembly reference.
3. Using Holder (6719), hold pinion flange. Remove pinion nut and washer. Scribe reference mark on pinion flange-to-pinion for reassembly reference. Using appropriate puller, remove pinion flange from pinion. Remove oil seal from axle housing.

Installation

1. Ensure oil seal surface in axle housing is clean. Coat lip of oil seal with gear lube. Install oil seal using appropriate seal installer. Drive oil seal into axle housing until oil seal installer contacts axle housing.
2. Install pinion flange on pinion with reference mark aligned. Using appropriate pinion flange installer, install pinion flange on pinion.

CAUTION: Washer must be installed on pinion with convex side of washer facing outward (away from pinion).

3. Install washer on pinion with convex side of washer facing outward (away from pinion). Install NEW pinion nut. Tighten pinion nut to 210 ft. lbs. (285 N.m). Rotate pinion several times to seat pinion bearings.

CAUTION: DO NOT overtighten or loosen then retighten pinion nut when adjusting pinion bearing preload. If pinion nut is overtightened, collapsible spacer on pinion must be replaced.

4. Rotate pinion using INCH-lb. torque wrench. Rotating torque should be equal to reading recorded in removal step 2) , plus 5 INCH lbs. (.056 N.m). If rotating torque is low, tighten pinion nut in small increments until proper rotating torque is obtained.
5. To install remaining components, reverse removal procedure using NEW "U" joint straps and bolts. Ensure all reference marks are aligned. Tighten bolts to specification. Check lubricant level and add if necessary.

sounds like valve stem seals...if it is white smoke that is antifreeze , blue smoke is oil....hope that helps

this easy, drain oil from gear box remove that drive shaft (u need a ball joint splitter)
replace gearbox seal, pry out old 1 with screw driver, gently tap new in, oil edge of new seal 1st. replace oil, ps dont leave to long as will damage gearbox when lack of oil

When was the last valve adjustment?
An old timing belt and T-belt guide will offset the timing.
Can a shop do a compression test on the engine?
Do a motor flush before the next oil change to free up the rings and clean out the head.
This is the inexpensive method to restore compression.

If it's the org. engine it will has over 80,000 miles on it.
It's normal to has the valve stem seal/oil seal on the head to leak oil into the cyclinder.
The smoke you see is the motor oil drop from the seals.
It land on the top of the cyclinders and it create black smoke at start up.

The inexpensive fix is to start using high mileage oil with seal conditioner.
This will help soften the rubber seals and help reduce internal oil leak.

The correct fix is to wait until it's time for a head gasket replacement and let the professional service the head.
Complete head service is the only method to stop this internal oil drip problem.

If it's the org. engine it will has over 85,000 miles on it.
It's normal to has valve stem seal/oil seal on the head to leak oil into the cyclinder on high mileage engine.
The smoke you see is the motor oil drop from the valve stem seals. The oil drops land on the top of the cyclinders and it create black smoke at start up.

The inexpensive fix is to start using high mileage oil with seal conditioner.
This will help soften the rubber seals and help reduce internal oil leak.


The correct fix is to wait until it's time for a head gasket replacement and let the professional CRC/service the head.

Complete head service is the only method to stop this internal oil drip problem.

Is it white,black or blue smoke?
If it's the org. engine it will has over 200,000 miles on it.
It's normal to has the valve stem seal/oil seal on the head to leak oil into the cyclinder.
The smoke you see is the motor oil drop from the seals. It land on the top of the cyclinders and it create black smoke at start up.
The inexpensive fix is to start using high mileage oil with seal conditioner.
This will help soften the rubber seals and help reduce internal oil leak.

The correct fix is to wait until it's time for a head gasket replacement and let the professional to service the head.

Complete head service is the only method to stop this internal oil drip problem.
I will monitor the oil and coolant level.
White smoke AFTER warm up is the first sign of blown headgasket.