Knocking on start-up and Leaking Oil
 

Hey Guys,

I purchased my 96 XJ 4.0 Liter about 6 months ago and I drove it down from New York to Florida. It worked fine.

I've since changed the oil, flushed the coolant, and had the transmission fluid and filter changed.

Now I'm getting weird oil readings that show the oil above the full mark on the dipstick(was perfectly normal a month ago), I've got oil on the ground underneath the Jeep, and there's a light knocking on startup. The oil just went black in the last 2 or 3 weeks and I've got a little bit of smoke coming out of the tailpipe. I've smelled the oil and I don't smell or see any coolant.

Can anyone suggest a solution?

The 4.0L tends knock a bit at startup, but should stop once it warms up. A loose or cracked flexplate can sound like a knock as well, among other things. Get yourself a stethoscope and try to track it down. That is the only way you will know for sure. We can only guess.

The oil leak could be the oil filter adpater, valve cover gasket, rear main seal, crank seal behind the balancer, distributor gasket, or the oil pan gasket. Drain plug, even. The engine sits higher in the front so check for leaks starting from the top and work your way down as it is possible to have more than one leak. You may find the starter covered in oil and dirt. Clean it off using electrical cleaner and it should be good to go. And make sure the old oil filter gasket comes off with the old filter or that will leak, too.

What color was the smoke? White, blue, or black? And have you given it a tuneup since driving it home? Even if a seller says it was just done, i still do it.

Not sure about the oil dipstick. You are leaking oil, but it reads high? Are parked on level ground?

What oil,,and oil filter did you use?




My 95 and 2000 doesn't knock on start up.. Ive bought both off the lot new..Never have they knocked on start up

Its not common unless you have a crappy brand oil filter.

My 96 doesn't either, knocked with a Mopar filter and then put a Fram Tough Guard on it and it stopped.

Does the oil smell like it could have gas in it?

I used a fram oil filter and Pennzoil Platinum.

Would replacing the filter stop the knocking? I'm about due for an oil change anyway.

Look for something with a silicone ADBV (antidrain back valve).
Wix, Napa Gold, Fram Tough Guard or Ultra, Motorcraft.
Not the Purolator classic, actually not any Purolator given their recent quality issues. Look them up, they've had tearing issues lately. I do believe Mopar is made by Purolator.

Get rid of that fram..get Wix,,trust me you will thank me down the road.. Fram has the worst anti drain back valve.

How so? Not trying to start anything, but Fram has come a long way since the old days. I didn't believe it either until I joined BITOG and did some reading. Very good reports from them after cutting them apart after 5k OCIs, 10k OCIs and even 20K OCIs on the Ultras.

Used to run only Purolators on my XJ and KJ. Both had start up clatter. Now, both using Fram Tough Guards, I don't have any clatter.

Its all about the anti drain back valve and bypass valve along with wash over . Fram use the cheapest rubber they can find.. The bypass valves are a joke also.


watch this vid
VVVVVVVVV

https://www.youtube.com/watch?v=Lny2yNBy15c&t=1s

Well, they work better than Purolator for me and I trust the people on BITOG.

wix is where's it's at.

Well if Fram is so good and great why did they put a screen over the Tough guard and other high end ones they have trying to stop the wash over.. Instead of new bypass valve design just stick a screen over it?..come on give me a break Fram.

They know wash over is an issue,, But the low end orange can of death dont have no screen.. I can go on and on about Fram,,and lots of other ppl too..Get what filter you want.. Just try and stay away from the big hype monster Fram

https://cimg2.ibsrv.net/gimg/www.che...372e3ff49d.jpg

Hate to scare you... but a heavy knock on start up could be a bad rod bearing. Basically the space between the bearing and the crank journal are bigger than what they should be and the oil seeps out from in between...so it knocks a few times on startup before the oil pump pumps more oil in.

How far above full on the dipstick?

What color is the smoke coming out of the tailpipe? Have you ever performed a compression test? When driving with the engine under load and you stand on the gas is the knock present?

What about getting an oil analysis done?