Oil Pump Diagram
- Thread starter Fishtaco
- Start date
So it sounds like a rapid semi silenced machine gun for around 1/2 second or less. It isnt at initial start fire up but delayed around quarter second then half a second rapid rattle.
I cant pinpoint where its coming from? Even had my wife up early a few times to try and record it while i start it but it doesn't happen all the time and we keep missing it.
I cant pinpoint where its coming from? Even had my wife up early a few times to try and record it while i start it but it doesn't happen all the time and we keep missing it.
So seems after a lot of searching and reading its quite common in the 4.0,s as well as the later 3.6 jeep engines to rattle at start up, just cant see why too many here have not or are not experiencing it?
The 2 possible causes are lifter drain back and or oil filter drain back with even dealers saying it is normal if jeep is let sit for over 24 hours and not to worry about it? Other mechanical advise online addressing this issue seems to be just don't rev it at start up.
I only change my oil about 10 weeks ago and I just noticed it again recently so I think I will start with just replacing the filter even though my most recent filter was a synthetic high quality performance non drain back costing me $28, I will soon see if there is oil in the filter or not when I take it off cold!
Apparently one cure is to use a bigger oil filter that holds more oil, I have read a few members mention the bigger filter but cant remember make and possibly would not be available in Australia but I am willing to import one and give it a try.
The only other possibility in my own thinking is the Bendix drive not returning fully at start-up touching the ring gear until it returns but to be honest that would sound a lot more of a dry metallic noise.
It is not a tick that lasts till warm up it is a rapid short rattle.
Any thought or experience would be greatly appreciated
The 2 possible causes are lifter drain back and or oil filter drain back with even dealers saying it is normal if jeep is let sit for over 24 hours and not to worry about it? Other mechanical advise online addressing this issue seems to be just don't rev it at start up.
I only change my oil about 10 weeks ago and I just noticed it again recently so I think I will start with just replacing the filter even though my most recent filter was a synthetic high quality performance non drain back costing me $28, I will soon see if there is oil in the filter or not when I take it off cold!
Apparently one cure is to use a bigger oil filter that holds more oil, I have read a few members mention the bigger filter but cant remember make and possibly would not be available in Australia but I am willing to import one and give it a try.
The only other possibility in my own thinking is the Bendix drive not returning fully at start-up touching the ring gear until it returns but to be honest that would sound a lot more of a dry metallic noise.
It is not a tick that lasts till warm up it is a rapid short rattle.
Any thought or experience would be greatly appreciated
Off the top of my head Wix 51515 is I believe a Ford filter that is considerably larger that fits. I ran then for a long time on my Golen stroker which had the 90 degree filter adapter mount thingy. Just eyeballing it I don't think it'll fit on my current (stock for a '98 block) setup and I just run whatever stock is. Do you have that mount adapter thing or does it just screw directly to the block?
Video of the noise would help, but I understand the challenge of catching it.
Video of the noise would help, but I understand the challenge of catching it.
Screws directly to the block horizontally, I couldn't get a new filter today so I will swap it during the week.
I watched a vid where the only way one guy could stop it on his JK was with a Mopar filter but I cant see that making much difference.
Maybe the filters are getting sludge particles keeping the anti drain back open a bit?
If it was pump low pressure I would expect it to rattle every time I let it sit for a day or 2 but there is no real consistency and the reason its hard to capture.
Managed to get a new filter late today, after leaving it sitting for 40 odd hours old filter only had around 1-1/2 tablespoons of oil so 3/4 to 1 fl oz only, I am sure it should have more, the filter element was wet with oil.
I think so, yeah. I just changed my oil the other day. Completely dry filter and no clackity clack. Didn't you say you were running thicker oil or some kind of additive or something? Did this noise happen before that?
No additive and it was the same with the 10w-30, the 10w-40 Magnatec semi I am running is a recommended replacement for 10w-30 conventional
one of the reasons for going slightly heavier was the occasional start up rattle same reason I tried an additive change or 2 before last, I have never actually experienced it in any other vehicle I have owned and you get the feeling the engine must be toast but it runs like a dream even on long trips.
The oil must be slowly draining back from somewhere else it would rattle on every overnight start not just the times it is left more than 24 hours.
It only started again 10 weeks into the latest oil and filter change, I might do an engine flush, I was avoiding a flush in case it made things worse.
Copy that.
I really think it's a lifter issue. There isn't a lot that doesn't "drain back" in the oiling system. Almost all of it winds up in the sump after sitting except for what's in the filter and the tiny tiny amounts stuck in the lifters. Now, having some in the filter let's it build pressure quicker which could effect things on start up, but I don't think that's causing your issue. If you look at how hydraulic lifters work, you can see how a failing/gummed up lifter could clack at start up until oil pressure forces it to work as normal.
Take a brand new lifter out of the box and push the plunger by hand. It pushes back from just the spring, but it's pretty easy. Soak that lifter in oil and actuate the plunger while submerged a couple of times, it gets pretty hard to push, and it stays that way for a long time as long as oil is in there. That's how they operate (correctly) in your motor. If something keeps them from holding oil like they should, they will clack at start up until oil pressure starts making them do their job.
I really think it's a lifter issue. There isn't a lot that doesn't "drain back" in the oiling system. Almost all of it winds up in the sump after sitting except for what's in the filter and the tiny tiny amounts stuck in the lifters. Now, having some in the filter let's it build pressure quicker which could effect things on start up, but I don't think that's causing your issue. If you look at how hydraulic lifters work, you can see how a failing/gummed up lifter could clack at start up until oil pressure forces it to work as normal.
Take a brand new lifter out of the box and push the plunger by hand. It pushes back from just the spring, but it's pretty easy. Soak that lifter in oil and actuate the plunger while submerged a couple of times, it gets pretty hard to push, and it stays that way for a long time as long as oil is in there. That's how they operate (correctly) in your motor. If something keeps them from holding oil like they should, they will clack at start up until oil pressure starts making them do their job.
Fishtaco it's time for me to change my oil this week and I'm going to use Valvoline Full Synthetic Advanced 10W-30 instead of my usual Valvoline or Castrol High Mileage blend. I do believe from your explanation I have the same 2 second startup rattle you have only difference being mine happens during cooler weather NEVER during the summer. I've read where using a heavier weight motor oil will not help loud lifters and a full synthetic oil may stop startup lifter clatter experienced only during cold temps. I don't consider temps in the 50's all that cold but my Jeep does?!
Let me know if your filter has any or much oil, its supposed to have a fair bit, My filter is usually quite full but I warm the engine before a change then let it cool a bit, this time I just changed the filter and didnt start it up and it was empty so the anti drain back cant be working?, I read everything I could find about this even really old jeep forum threads and it seems some of the cold start rattles were cured by using 5w-30 so the full synth may work for you but most couldn't find a cure and just lived with it, most used suggestion was leave your radio volume up when you start up and forget about it lol
Hope the oil works for you as I know how annoying and concerning it is.
You could try a hail Mary and run 50/50 cheap oil and ATF for 10m or more...ATF is thin oil with a lot of detergent. That might free up a sticky lifter...but as easy as the 4.0 is to take apart and fix right...I'd just start tearing it down...or ignore it until it breaks enough to really pinpoint the problem.
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