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Black smoke under acceleration and Knocking
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=90904
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Author:  Aaron198 [ Sat Jan 25, 2020 3:10 pm ]
Post subject:  Black smoke under acceleration and Knocking

Started having trouble with my 2005 Jeep Liberty CRD 2.8L Diesel today. Vehicle pours black smoke out of exhaust under acceleration and has begun knocking. Checked oil level when the problem arose and it was not low. Did some digging and found that the turbo has a fair amount of burnt oil covering it. Now when I start the car the engine knocks bad for a few seconds then smooths out to a less severe knocking. Any suggestions/ Diagnosis would be very helpful.

Author:  My66dodge [ Sat Jan 25, 2020 9:57 pm ]
Post subject:  Black smoke under acceleration and Knocking

Sounds like worn rockers... pull the hose from the intercooler to the intake on the drivers side and see if it’s popping or backfiring in the hose, sure sign of trashed rockers. I fixed 10 in the last year, very common in the 100k + miles from using the wrong oil or going too long on the oil change.

Here’s an example Of what it can sound like

https://m.youtube.com/watch?v=95x7NiozPB0

If it is worn rockers you had better find a shop or person who is familiar with these engines to fix it. So post your location and someone will guide you where to go. You can also go to Sasquatch to find a shop nearby who knows how to fix these Jeeps.


Sent from my iPhone using Tapatalk

Author:  TKB4 [ Sun Jan 26, 2020 8:16 am ]
Post subject:  Re: Black smoke under acceleration and Knocking

with the knocking the above is most likely the cause but it certainly doesn't hurt to check the boost hoses very carefully for cracks or loose clamps especially if they are original equiptment ones. That is the most common cause of black smoke on acceleration and a very easy and less expensive fix.

Author:  rankom [ Sun Jan 26, 2020 3:31 pm ]
Post subject:  Re: Black smoke under acceleration and Knocking

As suggested earlier above, rocker is most likely the problem. In addition to that, do you have check engine light on the dash? Any fault codes? Perhaps fuel pressure codes (p0093)? etc...

Author:  Jay ne Ohio [ Mon Jan 27, 2020 1:39 pm ]
Post subject:  Re: Black smoke under acceleration and Knocking

How many miles on the engine? Several possibilities:

1) Rocker failure. I've seen them worn out at 120k miles and I've seen them last 200k. It's possible that a glow plug tip broke off and caused interference in the cylinder which can break a rocker or two. Diagnosis is by examination of the rockers which requires removal of the valve cover (not an easy job). Check for other problems first.

2) Low boost. Can be caused by turbo failure, clamp failure, split intercooler hose, intercooler crack. Start by looking at the intercooler hoses and clamps. If not obvious, then remove them and check the bottom side of the hoses. Once the hose is removed, you can look into the outlet side of the turbo. Examine for damage to the turbo wheel or excessive play.

3) Timing belt slipped. If it only went one notch, then you may not have any rocker damage but will have a rough running engine. If it went more than one notch, you probably broke a couple rockers. You can check the timing with a kit containing the timing pins. You will need to rotate the engine by hand until the pins can be inserted into the cams. Then check to see if the crank pin lines up.

4) Dropped valve. Usually around 200k miles. Major damage that requires removal of the head at the minimum and possibly replacement of piston and liner.

Start with number 2. Then go to number 3. Then number 1. Hopefully you don't get to number 4.....

Author:  Gypsy62 [ Thu Sep 09, 2021 3:02 pm ]
Post subject:  Re: Black smoke under acceleration and Knocking

I'm having identical symptoms post-op so am jumping into this 1/2020 thread.

Did you ever resolve your problem??? And...?

Obviously, all these experienced voices are requesting more info, so towards tshooting your beast, questions:
- Do you know your Jeep's repair/maintenance history?
- Have the rockers been replaced?
- Have any valves been replaced?
- Has the timing belt been replaced?
- Have the glo plugs been replaced?
- ANY CODES???

You say that you're hearing abnormal "knocking" accompanying the throttle-on cloud. Imo, that points to either mechanical internals and/or timing.

Anyway, if you found the culprit please share.

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