one_speed_heuer

In the past 2 days Ive had a major problem with my jeep, it suddenly started to burn oil. Ive put 50 miles on it and Ive put 6 quarts in(and its not even full), plus the oil change that was done about 900-1000 miles ago.

Jeep has 206,000 miles, was treated rough. Still the original engine. About 1500 miles ago I changed the water pump, coolant, transmission cooling line, and changed the transmission fluid. Spark plugs need to be changed soon.

It doesnt smoke any more than a normal car, its winter here in Wisconsin and about 10-30 degrees F.

Anyone have any clues? I cant afford a new engine, and I have a week off where I dont work and have access to a decent but unheated garage.

01SiennaXJ

Before you jump to the conclusion that it is burning oil, check for possible oil leaks. Some likely sources of an oil leak are the valve cover gasket, oil filter adapter, oil pressure sending unit, and rear main seal. Take a look and see if you can find any leaks. Take a look at your coolant and see if it looks contaminated at all.

If it was burning that much oil, i'd think it'd be pretty obvious.

one_speed_heuer

All of the fluids seem right so far. After a drive i filled the oil. Took off the cap and it was smoking fairly good, comparable to a few cigarettes. It was a 20 mile drive and I put in 3 quarts.

When I let it idle there are no oil leaks.

It's not leaking on the ground. Under where I park my jeep is clean, I park in the same spot every day. It's all dry.

EvstaG

Seems as though one or several of your rings might've let go, assuming there are no leaks. That being said, there are some missing parts to this story. Here's a little piece to think about: If you burned 3 qts of oil in 20 miles, that essentially means that you are burning 25 miles per gallon worth of oil. Assuming that your Jeep averages 15 miles per gallon, you are burning 10 miles per gallon worth of gasoline.

Using your measurements, your engine is running on mostly oil, which means that it would smoke like a house on fire, and I am doubting that even the trusty 4.0 could run well, if at all, using this much oil.

Long story short, the oil must be going somewhere, because there's no way it's going through the cylinders.

1991Jeep_Man

I second this BIG TIME. Idle means squat if it is the right seal going in just the right way. My '91 runs like top, and maybe burns just a tad of oil (normal spec, nothing crazy) along with the slight breather tube blow-by. I am losing oil via the Rear Main Seal (all other seals replaced). Look for the tell-tale drip under the bell-housing.. there is a weep hole that a drop of oil will usually sit in. Your XJ does NOT need to leave spots to lose oil here. Mine doesn't. You wouldn't find a spot at all on the pavement, even if idling. I lose it at highway speeds when the crank is actually spinning. My transmission pan and junk are the proof.

Also, smoking out of the oil filler cap when its off is normal (not a ton, but enough to notice). Especially if it is cold... it's just like you breathing hot air and making a 'cloud'. Your engine also steams as the heat evaporates tiny bits of condensation that forms in the engine (also why short trips require more frequent oil changes).

Look for the rear main signs and get back to us. This can be fixed in a few hours I am told with about $50 in parts and the cost of an oil chance. Def a plus if you have a shop to use, cold or not. Beats the hell out of gravel in the elements.

one_speed_heuer

It does lose oil pressure after about a mile. I'll have to wait til the weekend to fix it and check it out properly.

1991Jeep_Man

Perfectly normal for oil pressure to go down as Jeep warms up. My oil pressure is well in spec.

Cold Idle is 60 psi, Cruising < 2,000 rpm 60+ psi, 2,000+ rpm is about 70 psi

Hot Idle is 20-25 psi, Cruising < 2,000 rpm 30-35 psi, 2,000+ rpm is 40+ psi

The ol' 4.0 is a masterpiece. Not the fanciest thing in the world, not the most efficient thing in the world, but damn if she doesn't put the torque down for her size, make it stupid simple to fix her, and run for as long as you care for her.

one_speed_heuer

I know it drops but it dropped to less than 10 while going at about 2200. And the dipstick keeps saying to fill. I don't consider it normal.

hankthetank

OP, have you even looked under the jeep yet?

1991Jeep_Man

Well... oil pressure WILL drop if there is no oil chief. Check on that leak

one_speed_heuer

A lot of drippage landed on the exhaust pipe under the transmission. A bit of drippage on the oil drain plug. Oil Splatter pretty much everywhere up front. Back of transmission looks fairly clean. Can't check to well without lifting it up.

Firestorm500

"It doesnt smoke any more than a normal car"

Normal cars don't smoke. I'm talking real smoke, blue in color if its oil, or white if its antifreeze. You can smell either at the tailpipe. I'm not talking about steam burnoff after starting or in very cold temps.

10 PSI @ 2200 is too low. You need 10 PSI per 1000 RPM at operating temperature.

I'm thinking rings, head gasket, cracked head, valve stem seals, wiped bearings if it is burning it.

Rear main and/or timing cover seal if its dripping it.

Compression check is next.

one_speed_heuer

Sorry. I considered the steam the same.

I've never had or done a compression test. I guess I'll get one done.

This thing keeps takin all my money.

Miceanic

Hows the air filter look? Sounds like you have a bunch of leaks or a really loose valve cover. who did the oil change? Did they ensure the oring from the old filter was removed?

Firestorm500

"This thing keeps takin all my money."

JEEP = Just Empty Every Pocket