Crankshaft oil seal only lasts for about 600 miles before starts to leak, what could cause this?

Oil dripping off the front of the engine of a 3.4 liter Chevy Venture motor could be caused by several issues. The wire that you mentioned may be the oil pressure switch wire, which is located near the oil filter. Here are a few possibilities:

Valve cover gasket leak: The valve cover gasket seals the valve cover to the top of the engine and prevents oil leaks. Over time, the gasket can become brittle and crack, causing oil to leak out. Check the valve cover gasket for signs of damage or wear.

Oil pan gasket leak: The oil pan is located at the bottom of the engine and contains the engine oil. The oil pan gasket seals the oil pan to the bottom of the engine and prevents oil leaks. Check the oil pan gasket for signs of damage or wear.

Oil filter leak: The oil filter screws onto an adapter that is located on the engine block. If the filter is not installed properly or if the gasket on the filter is damaged, it can cause oil to leak out. Check the oil filter and adapter for signs of damage or wear.

Front crankshaft seal leak: The front crankshaft seal is located at the front of the engine and prevents oil from leaking out of the crankshaft. If the seal is damaged or worn, it can cause oil to leak out. Check the front crankshaft seal for signs of damage or wear.

I recommend having a qualified mechanic diagnose the source of the oil leak to ensure proper repair. They can inspect the engine and identify the exact location of the leak

These engines do have chronic oil leaks onto the exhaust, hence the burning smell. When cam cover gaskets are replaced it is best to use the genuine Toyota parts, they seem to have some quality which lasts better.

Other places which leak are the distributor shaft o-ring seal, and crankshaft nose seal, behind the timing belt sprocket. These can be replaced. The crankshaft rear main seal will leak, but is expensive, so just leave it.

YOU CRANKSHAFT FRONT OIL SEAL IS LOCATED IN THE TIMING COVER WHERE CRANKSHAFT STICK OUT.THATS WHERE OIL LEAK IS MORE LIKELY.

valve cover, intake manifold, front crank seal,timing cover, a quart per 1000 miles isnt a small leak.

This is most likely a leak from your rear main seal. It happens and can be a pain to replace if you're a DYI kinda person without the nec. equipment.

1. Raise and safely support the vehicle with jackstands.
   
2. Remove the transmission.
   
3. If equipped with a manual transmission, remove the clutch and pressure plate.
   
4. Remove the flywheel assembly.
   
5. Using a suitable prytool, carefully pry the old seal out.
   

6. Inspect the crankshaft for nicks or burrs, correct as required.
Crankshaft rear main seal - 5.7L engine

To install:

1. Clean the area and coat the seal with engine oil. Install the seal onto tool J-34686 for 3.4L engines, J 41349 for 3.8L engines or J 35621 for 5.7L engines.
   
2. Install the tool (with the seal mounted to it) onto the rear of the crankshaft. Tighten the screws snugly to be sure the seal will be installed squarely over the crankshaft.
   

Exploded view of the rear main seal installation - 3.4L engine
Click to Enlarge

1. Tighten the wing nut on the installation tool until it bottoms out.
   
2. Remove the tool from the crankshaft or rear oil seal housing, as applicable.
   

Rear main seal and installation tool - 3.8L engine
Click to Enlarge After position the seal on the tool, install it to the crankshaft housing

1. Install the flywheel.
   
2. If equipped with a manual transmission, install the clutch and pressure plate.
   
3. Install the transmission.
   
4. Check the fluid levels, start the engine and check for leaks.
   

crankshaft seal,and don't overfill oil level

Valve stem seals can cause this problem, but normally only when first started. Oil in the rocker cover seaps through the oil seals into the cylinders and is burnt up on start up.
Try a "STOP A LEAK" additive and it may reduce the oil consumption and smoke.
I found some on e-bay and it worked on my tired old escort. It even stopped the rattling tappets.

check first to see if the leaking fork has any rust pitting on the chrome,if it has and its a very small blemish then fettle it off first,and just replace the leaking seal,as the saying goes..if it aint broke dont fix it,if the seals had been in the forks for years and the bike not used then consider replacing both..

The fix is replacement of motor!! I have the same problem and have already paid $700 in repairs to fix seal just to find out that the seal is being knocked out by loose crank shaft..Car had 60000 miles when I bought it 4 months ago, from a dealership, and now it needs a motor replacement..I stiil owe $5000 on a car that is worth $0..Dodge did not give the 100000 mile warranty they love to advertise on TV for the '06 Stratus..They only gave 36000 warranty because they did not think it would last much longer..Will never buy Chrysler product again!! They do not stand behind what they sell or they would have 100000 mile warranty on all their cars..

If it's the org. engine it will has over 90,000 miles on it.

When was your last valve adjustment?

Timing belt is due if it's over 120,000 miles. Incorrect timing will cause late timing.

Can your shop do a compression test?

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.