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Author Topic: 4.2L motor prob.  (Read 2121 times)

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4Play

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4.2L motor prob.
« on: January 18, 2007, 05:14:12 PM »
Well this week I was hunting a noise in the front of my jeep and replaced the clutch fan, water pump and timing chain and got her put back together; and it still makes the noise  It is kind of a knocking, only after it heats up, and only at about 1800 RPM.  I am thinking the motor has had it.  Any ideas.  Just replace it with a used one change all my good and new parts over?  Would a 4.0 block work, put my manifold on, and keep the new holley on.  Damn jeep runs perfect except that noise.  Expensive to rebuild I am assuming.  Just built a place in Airdrie and moving in Jan. 30 so a V-8 conversion is out for a few months till the garage is equipped with at least a bench and lights and some bills are payed....  Any thoughts or ideas.  Thanks.

Mike
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Offline calltrex

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Re: 4.2L motor prob.
« Reply #1 on: January 18, 2007, 06:17:49 PM »
Quote from: "4Play"
Well this week I was hunting a noise in the front of my jeep and replaced the clutch fan, water pump and timing chain and got her put back together; and it still makes it.  It is kind of a knocking, only after it heats up, and only at about 1800 RPM.  I am thinking the motor has had it.  Any ideas.  Just replace it with a used one, and change all my good, new, parts over.  Would a 4.0 block work, put my manifold on, and keep the new holley on.  Damn jeep runs perfect except that noise.  Expensive to rebuild I am assuming.  Just built a place in Airdrie and moving in Jan. 30 so a V-8 conversion is out for a few months till the garage is equipped with at least a bench and lights.  Any thoughts or ideas.  Thanks.

Mike


The teeth on timing gear break. Have plastic teeth. When i stripped my engine down there was like 3 chunks of plastic missing and some others crack.

You may have checked it or not already.

Theres pics of the timing gear in the project section under 88YJ that i built. Then u can see.
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.....(@)___JEEP_(__@)
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.../""""/........J
../""""/=(=)___....../""""/
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4Play

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4.2L motor prob.
« Reply #2 on: January 18, 2007, 11:59:47 PM »
When I replaced the timing gears, the old gears were all intacked.  Just a very stretched chain.  The noise is usually gone on the highway, but when in the city it does sound bad (much like the rattle of a chain) passing 1700 RPM or so.
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CJ-7

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4.2L motor prob.
« Reply #3 on: January 19, 2007, 09:49:36 AM »
actually the rebuild for the 4.2 is not as expensive as you would think. If you do it yourself and get rid of the labor. I did mine last winter. Firebolt has good deals on kits (i think they are called celtis now)
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4Play

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4.2L motor prob.
« Reply #4 on: January 19, 2007, 10:23:28 AM »
Quote from: "CJ-7"
actually the rebuild for the 4.2 is not as expensive as you would think. If you do it yourself and get rid of the labor. I did mine last winter. Firebolt has good deals on kits (i think they are called celtis now)


Couldn't find celtis in the phone book.  Just called firebolt and for a rebuild, crank to cylinder head; $1750 + GST
And they don't sell rebuild kits.
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Offline BlackYJ

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4.2L motor prob.
« Reply #5 on: January 19, 2007, 10:26:26 AM »
Thats not too bad of a price.  Does that include machining?
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'95 YJ with a few mods

4Play

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4.2L motor prob.
« Reply #6 on: January 19, 2007, 11:00:28 AM »
Quote from: "BlackYJ"
Thats not too bad of a price.  Does that include machining?

I didn't even ask them.  Cant afford near that right now...!  I would rather do a V8 swap for that kinda money!
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Offline stroker sahara

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4.2L motor prob.
« Reply #7 on: January 19, 2007, 05:47:03 PM »
Personally, if it has good oil psi, doesn't get hot, or make horendous noise, I would run 'er 'til she blows :)  Everyone has a different opinion as to what is noisy. Have you done a compression test? Is it noisy under load/coasting...?
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If you want to run with the big dogs you have to be able to pee in the tall grass.


1989 YJ SOA, 36" SX, 4.6 Stroker...

4Play

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4.2L motor prob.
« Reply #8 on: January 20, 2007, 12:33:26 AM »
Quote from: "stroker sahara"
Personally, if it has good oil psi, doesn't get hot, or make horendous noise, I would run 'er 'til she blows :)  Everyone has a different opinion as to what is noisy. Have you done a compression test? Is it noisy under load/coasting...?


It is to loud to drive. No compression test.  It is noisey under load.  When coasting it pretty much goes away.  Very loud when warmed up and at a certain idle.  My mechanic just suggests throughing a used one in for the time being and replace all gaskets and put a header on.  keep a $500 budget and rebuild mine on the side.  Just seems weird that it still has power and I thought it was a well running strong truck, with a suddenly loud spot!!!!
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wrenchead99

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4.2L motor prob.
« Reply #9 on: January 20, 2007, 10:19:13 AM »
try something out in left field...run it without any belts on it (ps, etc.).  In my years as a mechanic I've run into belt driven accessories that make an engine sound really bad.  Just my two cents worth.  also. does the noise change whether or not you step on the clutch?  could be a bad thrust bearing on the crank.
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gsxtacy

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4.2L motor prob.
« Reply #10 on: January 20, 2007, 03:08:47 PM »
cracked manifold??
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CJ-7

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4.2L motor prob.
« Reply #11 on: January 20, 2007, 05:51:58 PM »
Canadian-Ron
  on this site has a good 4.2  engine in the "Jeep stuff for sale" section.

Just thought I'd let you know

Also ...............  I made a mistake on the engine rebuild kit

I got it from ...........  Canadian Hi-performance discount

they are in prince george..............Gaskets and bearings only costed me 221.90$

I got the pistons and rings from firebolt  (and the machining)
All the smaller stuff ie. Water pump, gel battery, fuel pump   from napa

And the motor craft 2100 carb from BOWNESS AUTO  ( wicked guys!!!)

Autowreakers for the HEI  ingition conversion ...see here http://www.4x4wire.com/jeep/tech/electrical/hei02/
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4Play

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4.2L motor prob.
« Reply #12 on: January 20, 2007, 07:03:56 PM »
Quote from: "CJ-7"
Canadian-Ron
  on this site has a good 4.2  engine in the "Jeep stuff for sale" section.

Just thought I'd let you know

Also ...............  I made a mistake on the engine rebuild kit

I got it from ...........  Canadian Hi-performance discount

they are in prince george..............Gaskets and bearings only costed me 221.90$

I got the pistons and rings from firebolt  (and the machining)
All the smaller stuff ie. Water pump, gel battery, fuel pump   from napa

And the motor craft 2100 carb from BOWNESS AUTO  ( wicked guys!!!)

Autowreakers for the HEI  ingition conversion ...see here http://www.4x4wire.com/jeep/tech/electrical/hei02/


What do you think you spent on the entire rebuid doing it yourself?  And as far as CanadianRon, I have already PM'ed him!
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CJ-7

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4.2L motor prob.
« Reply #13 on: January 21, 2007, 12:03:07 AM »
I think with all the extras i spent about 800$-900$  including the 75$ core for the 4.2

Ohh yeah  the timing chain and gears were from firebolt as well


   .............. i had a 4 cyl in my CJ before
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Offline XJwrencher

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4.2L motor prob.
« Reply #14 on: January 21, 2007, 08:44:57 AM »
bad cam button??
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94 XJ with tires and sausage to make it go off roading
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