4.0 noises

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suthernoutlaw

NAXJA Forum User

Location

PassChristian, MS

• Jan 15, 2007

• #1

i put a 98 4.0 in my 91, it had 26k miles on it...bought as a rollover. my question is, does the change in weight of the oil affect the noises? i heard a little bottom end noise when i had 10w40 so this change i went 20w50. now i hear it more than before. should i run a lighter oil, i thought the heavier would be better.....

 

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90xj06

NAXJA Forum User

Location

Peabody, MA

• Jan 15, 2007

• #2

if it is cold out use a lighter oil thick oil may be to heavy to correctly flow through the system. not completely lubricating things.

 

CanMan

NAXJA Forum User

Location

Lake Tapps, WA

• Jan 15, 2007

• #3

Try 10w-30, and see if the noise is still there. If it is, you may have bigger problems than just the different viscosities of oil.

 

djblade311

NAXJA Member # 1474

NAXJA Member

Location

Mission Viejo

• Jan 15, 2007

• #4

if its knocking you should check the flexplate for cracks or loose bolts first. That is the cause of most knocking noises.

 

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suthernoutlaw

NAXJA Forum User

Location

PassChristian, MS

• Jan 15, 2007

• #5

it may be the flex plate, it sounds like a light knock, and its the same one off my last engine

 

XJPhoenix

NAXJA Forum User

Location

Guelph, Ontario, Canada

• Jan 15, 2007

• #6

Does it go away under load?

My 1991 XJ did the same thing; I thought I had a bad bearing or something getting ready to let loose on the bottom end of the engine. The knocking went away when I goosed the gas for a quick take-off. (I was mad, and gave it a shot out of frustration.) I pulled the inspection plate on the advice of my brother, and found all of the Torque Converter bolts were finger loose! I pulled them one at a time, cleaned them with a wire wheel, then re-installed them with red locktite.

I hope this is your problem...

 

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bwh0069

NAXJA Forum User

Location

N.C.

• Jan 16, 2007

• #7

Try looking on the right firewall. There you will find a duty cycle purge solenoid.It makes a terrible knocking noise when it gets some age on it.Really will fool you with its noise.

 

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suthernoutlaw

NAXJA Forum User

Location

PassChristian, MS

• Jan 17, 2007

• #8

what does the duty cycle purge solenoid look like? i looked around cant figure it out. thats the first time i ever heard of one.... i did find a vacuum line unplugged, starts way faster now.

 

Ecomike

NAXJA# 2091

NAXJA Member

Location

MilkyWay Galaxy

• Jan 18, 2007

• #9

With 26K miles on the engine, you need to be running 10W30 ( and I am assuming you are in the south from your name and not Canada where they are probably running something like 0W20) . Anything over 30 Weight is too thick for a new engine and will make it knock and ping. 26K is a new engine.