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Discussion Starter · #1 ·
rebuilt 2001 4.0 followed the instructions for break in. 2500 RPMs for 10 minutes let cool completely and then 2500 RPMs for 10 minutes. Using Royal purple break in oil, question is how long would you leave in the break in oil when would you change it, 200 hundred miles or 500 miles or later
 

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2000 Jeep Wrangler Sahara 4.0L 5spd Money pit Green
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How deep did the rebuild go?

And what does the RP site tell you about the oil?
 

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The furthest I’ve driven with break-in oil is about 10 miles. But I’m overly cautious...

Edit: Then I switch to the oil I plan to use long term, then at 50 more, then 500 or so. After that, I’m back to 3000 intervals.
 

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Discussion Starter · #4 ·
The rebuild went very well thank you. Here's what I did block bored 30 over let the Machine Shop order pistons and rings to match their Bore. Remanufactured crankshaft with matching bearings, new t u p y head valve rockers lifters push rods Etc. I put in a stage 1 performance camshaft kit bike legs part number CBE - 24 - cam1. Supposedly this did not need anything changed on the computer it is a very mild upgrade. Melling high-volume oil pump. Pretty much everything is new. I followed the break-in procedure from the cam shaft company and all went well. However I have noticed it has a very rough idle RPMs die down to around 300 or so when in gear and when not in gear. Does not do it when it is cold. I know the first thing I should look for is a vacuum leak and I will do that tomorrow. I know all vacuum lines are hooked up but I could have a split in a line. The one thing that puzzles me on this motor is the cam position sensor. I did not mark it when I took it out would not have done any good anyway since the block went to the Machine Shop. I followed the Haynes manual and another Jeep 4L manual when installing. The motor runs very smooth everywhere except idle. I did read somewhere that you need to take these things to a dealer and have the timing reset but I do not know that that applies to my motor, I think that may just be for older Motors. If anyone knows any different please let me know and tomorrow we'll look for vacuum leaks. And I will go on the Royal Purple website and see what they say about oil change with the break-in oil.
 

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Discussion Starter · #5 ·
My voice recognition is a mind of his own or I don't speak clearly lol the above post it should say camshaft by clegg's LOL
 

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2000 Jeep Wrangler Sahara 4.0L 5spd Money pit Green
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( makes my Jasper grey look boring considering how much I spent)
If you drop a lot of coin doing a rebuild, IMO you should replace just a few more things.....

I skipped the painting step...... but I replaced everything from the radiator to the clutch......everything is new/ or remanufacture except the intake manifold, throttle body, starter, valve cover, OPDA and the cam position sensor......all the sensors.....MAP, TPS, IAC replaced also.

Have you or did you clean the intake manifold runners and the throttle body?
How old are your O2 sensors?
I would think that if you had a vacuum leak your idle would be too high.

You might want to read about seating the piston rings,
 

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Discussion Starter · #8 ·
Yes I did clean the hell out of the intake runners throttle body even exhaust manifolds I cleaned everything it does have a new radiator new radiator cap new thermostat automatic transmission so no clutch to worry about. all the O2 sensors need replacing they have since I bought the Jeep but where I live there is no emission inspection safety only.
 

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... the O2 sensors need replacing they have since I bought the Jeep but where I live there is no emission inspection safety only.
Replace them if they are bad. They sense air/fuel ratio and can retard performance if malfunctioning. Use NTK/NGK sensors.
 

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That's a nice looking motor. I have put a few engines together and after that break-ins I always changed the oil and filter. You'll have break in lube from the cam and assembly lubes/grease mixed in the oil at that point that should come out.
 
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