This weekend, my dad and I replaced my motor mounts because the drivers side was broken off and the passenger side had no rubber left. in the process, the air ratchet slipped off the bolt as my dad was trying to thread the bolt through the hole. Little to our knowledge, this stabbed about a 1/8th inch hole in the oil filter. Took the Jeep for a test drive spraying all of my oil out without any idea until i hear the valves tapping. I pull the Jeep over, and call my cousin who brings my spare filter and oil. Change the oil on the side of the road and start it up. Within 20 seconds the valve tap is gone and I drive home. Today, three days later, the motor is knocking/tapping/ticking, whatever you want to call it. I'm running open downpipe to a cherrybomb out the side so it's hard to follow a noise over the exhaust noise and I can't tell exactly where it's coming from, but it definitely sounds like its something internal, not just a loose bolt. I've looked on youtube and searched these forums with little luck, especially considering my unique situation.

-1994 Jeep XJ 4.0 HO 144,xxx miles
-Had mustang injectors but two failed so i'm running stock for a few more weeks, don't know if that matters.
-Oil change consisted of a FRAM Tough Guard filter and Mobil Extended performance full synthetic 10w40
-About 10 miles put on since the incident but I go back to work tomorrow so that will add atleast another 50.
-Motor itself has been absolutely silent prior to this, minus the normal Chrysler noises.


I'm pretty mechanically inclined, but i've never really dealt with stuff like this before so be easy on me. I built my old 89 GTI with the help of my cousin who is a certified mechanic, but he did most of the work because I was working all the time to pay for it. I have a BASIC understanding of the workings of a gas powered engine but may need some things explained/described.

Update:
Was able to do some fishing around to locate the noise. It's much easier to hear under the Jeep, which leads me to believe it's in the bottom end somewhere. The noise is also only there at idle and fades out a bit once the engine is warm. Jeep runs a little rough at idle; almost sounds like 1 cylinder chokes for a fraction of a second every few seconds. Almost like a sputter, but only has a low, not a high. Throttle body is also covered in oil. Jeep runs slightly warmer than normal. I swapped out my thermostat early this spring to keep it running warmer for fuel economy, so it naturally runs warm, but this i'm uncomfortable with. Ran Seafoam through it today. My oil is JET, JET black and has been like that ever since I got the Jeep, so I was expecting a nice smoke show. Ran it through the CC, Gas Tank, and Throttle Body and got one little puff of unburnt fuel which leads me to believe it cleaned out the old injectors a bit. Gained better throttle response since the treatment, but less low end torque sadly. Best way I can describe the low end torque loss is that Before the Seafoam, if I put the Throttle to the floor from a dead stop i burn my 33x12.5's through the aw4 third gear. Since the treatment, I only chirp the tires doing the same exact thing. Noise is still just as present after Seafoam treatment.

 

WOW

Running an engine out of oil can have all kinds of results. Usually one of the first things to go is your rings. Then mains, rods, and cam bearings, then who knows...

If you could hear your valves knocking over your loud exhaust, with a full synthetic, you REALLY ran it dry. ALL kinds of crap can go wrong at that point. Judging from your description you are probably hearing rod bearings or piston slap, but Id go with rod bearings since the noise is loudest at low oil pressure. Either way your screwed. You can either run it until it goes and replace it, or rebuild it now.

There is no quick fix for running an engine dry.

 

Happened to me too. Broke the rear main seal on the highway and lost all the oil. Noise is first cilynder conrod bearing, it won't go away anymore. Jeep drives like champ though. How's the oil pressure?

 

Rod bearings would be my guess, too. Put some 20w50 in it as a test to see if it helps. If there is too much bearing clearance, the heavier oil should quiet it down, but it's still in need of bearings and probably a ground crank.

 

Yes i'm running 20W 50 and it is much quieter, oil pressure is acceptable.

 

The rings would be the last thing to go. Main and rod bearings would be the first to fail. But I do agree, the engine is done.

 

UPDATE on the Jeep with a noise I just noticed. After shutting the engine off, there is a prominant ticking for about a minute. Not the normal tick after you shut off an engine, but it sounds similiar.



What is involved in replacing rod bearings? Never done it before but I'm pretty quick to learn and mechanics work is in my blood so I'm positive I can do it.

Are there any disadvantages to running the oil you suggested? Any advantages besides dulling down the knocking sound? Will it make the engine last longer than what I'm using now with the engine in its current state?

I do not know my oil pressure. The sender got water in it last time I went wheeling and no longer works. Haven't gotten to replacing it yet. That's the main reason I didn't notice I was leaking oil so bad. My guage doesn't get any readings, Jeep ran like a champ, no smoke, wasn't overheating. Everything seemed normal until the valves started tapping.

I enheritted an oil compression tester that was left in our garage when we moved in, would that help me to diagnose any problems?

Would u guys suggest running it till it blows or rebuilding it now? Its currently my daily driver but I'm looking for a cheap car to hold me over while this gets repaired. Hopefully one better on gas too. 8mpg sucks (Period.) If the motor goes I plan to either build a turbo charged l6 or drop in a stock or mildly built chevy 350, so the motor blowing on it wouldn't be too bad as long as I get a second car before it does. Need transportation to job a, then to job b, then to the bank, then home, and repeat.

 

i would drive till it dies but thats me. star building your sbc so its ready when your motor finally goes though.

some guy here has been selling one of those advanced adapter kits for a sbc into a cherokee for a few months now. its for a standard as it comes with clutch and everything. i don't know how much they are from the shop but his never got installed and he is selling the whole shebang for something like 500 or 600 bucks.

 

First...fix the oil pressure sender. That would have warned you long before your engine went dry.

Two, you can pull the oil pan off the bottom and look around - that is the certain method. But if you just drain your oil and find metal particles, that will tell you something. If they are coppery, it is bearing material. Pulling the pan is the surest way to know...but since you're in there already and if the RINGS are not bad, you might be able to do a bottom end overhaul-in-place. This is done on tractors every day of the week. Pull the mains and big-end rod caps, refresh the crank and bearings, put it back together. Be DEAD SURE which main cap and rod cap goes where. They cannot be mixed up.

Three, a leakdown test will tell you whether you have damaged the rings or valve guides. Do the leakdown first if you have the guage set. If not, $50 will buy this tool and it is indispensible for saving you money. It will tell you a great deal before you remove a single part...like the oil pan. If you aren't confident what to do with the tool, just take the jeep to a shop that knows how to do a leakdown and pay them the $50. BTW, a leakdown is the first thing A&Ps do on airplane motors when problems arise. Aircraft powerplants are required to have their oil analyzed every 100 hours for metal particles. Even with that oil analysis, leakdown is the #1 test.

Finally...if it were me, I'd do a leakdown and if that was "inconclusive" or seemed OK, I'd fix the oil pressure sender, put some 20/50 in, and run it for a few thousand miles. If you don't have any problems other than some noises, that would not keep me awake at night. Besides, you're in Allentown...there are million XJ motors over there for $400-500 after the bodies return to the earth via corrosion.

 

Still haven't done anything with it due to lack of time/money. Can't even afford to buy oil for it right now because i'm in-between paychecks. Motor is still knocking but hasn't died yet. Would the Jeep now having a mild idle surge lead to a diagnosis? Happens more often with the motor cold than with it warm and is not consistant. Thanks for the replies by the way; gives me atleast somewhere to look to fix this.

 

It happened two years ago to me and it is still running, it doesn't die.

 

Try JUNKING THAT FRAM FILTER it a peice of SHxt,then see what happens.

 

Does anybody think switching back to non synthetic could get rid of this knock? I've heard a lot about synthetic oil letting out knocks in motors before, but is it true?

 

This is like burying a potato under an oak tree at 3 AM to get rid of warts. It works because you believe it works...mind over matter.

However, there is no doubt in the minds of most reasonable people that synthetics are more better than petroleum-based oils. The piston aircraft industry has not adopted syn oils but they don't do anything new out of fear they will be sued into oblivion. I hated to give up my trusted Valvoline 10/30...I hated to give up straight weight 30, too. But my F350 V10 specifies 5/20 synthetic and that is the most remarkable gas motor I've ever seen. I have seen the light. I use Mobil One in that motor.

Synth oils do not reveal rod knocks. If it knocks...it knocks. When you first start a motor with thick oil the extra viscosity might absorb some sound but it also might be too thick to readily get into the rod and main journals. If that happens the knock is going to get more pronounced because the engine is wearing out faster. Then if you change to light/multi weight synth you might discover that the fat oil was causing damage to accelerate. Whatever is happening, a knock is a knock and synthetic oil of the proper weight will protect the engine better than non-synth.

BTW, fifteen years ago Consumer Reports rebuilt the engines in 60 New York taxis to factory spec. They put various oils in them - even recycled oil from Tractor Supply - and ran them for 60,000 miles then tore them down and mic'ed every wear part. They found no difference between any of the oils that could be measured PROVIDED the oil was changed per manufacturers spec. They found changing the oil every 3000 miles had no effect either. They found if you changed every 8k or 15k, the wear rate was measurable even at 60k.

But, and it's a big but, 60,000 miles is not a true test of longevity today. They chose 60k because, when you run the numbers, the cost of all those extra oil changes when Mobil One was $6 a quart and Valvoline was 79 cents really added up - especially when people flipped their cars regularly. Their test was a "real world soccer mom" test. And they were worried about the effect of dumping all that used oil into the land fills.

Today, 200k miles is realistic. My wife's minivan has 110k and if I don't get 200 out of it, I'll be irritated. I change the oil per manufacturers spec: 6k miles. I use whatever is handy. I still expect to get 200k. But I believe if I used Mobile One I'd get 300k. Now that Mobil is not much more than regular oil, I'll use it.

Also, CR noted that filters are IMPORTANT. Junk filters...like Fram...are junk. Engine life-threatening junk, IMO.

 

You are not considering what the purpose of an engine oil is and the purpose of our rigs.
What does an engine oil do?
A. lubrication
B. heat transport
C. noise reduction
D. fuel cosumption
E. pollution reduction

When a car builder specifies a certain oil, the company takes into account the last two points more than the first two, due to federal laws.
Open your eyes.

The thicker the oil is, the more it is shifted towards A, the thinner towards E.

Now, personally i don't care a **** about points C D and E. What i want is LUBRICATION AT ALL CONDITIONS, especially for off road purposes, in the most severe oparating condition.
I use valvoline 20w 60 partially synthetic, mineral based.
A 20w 60 totally synthetic doesn't exist, also if the bottle says so, it's BS.
That's why piston aircraft industry still uses this oil, no jokes on engine breakdowns at 20000 feet height.

With thick oil, when you start the engine cold it knocks more than with thin oil.
Thick oil will flow slower and take more time to reach all parts of the engine, but it's a matter of seconds, maybe 5 instead of 2, not that big deal.
This is not a problem, since the engine is cold there is no risk, it doesn't wear out faster.
But a thicker oil will loose less viscosity when hot, and that's what is important.
The cause of a spun bearing is NOT the lack of lubrication itself, but rather the generation of excessive heat consequent to it, that melts the material.
When the oil burns on the bearing surface it creates tiny bubbles of smoke that take place of the fluid oil and act as a heat isolator. When you reach the fusion point of the metal it's too late.
A thicker oil will protect the engine more than a thinner oil.
Synth or Mineral is all BS.