4.0L is out, what should we do to it?

T

TJ's-TJ

TJ Enthusiast
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MA, USA
84k miles. What should I do to it prior to putting it back in?

Was thinking:
Front and rear main seals
Oil pump
Timing set
Harmonic balancer
Water pump
Valve cover & oil pan gaskets
Clean/Paint

Too much? Miss anything?

Thanks
 
Curious as to why it's out?

With that mileage, reseal anything leaking. New spark plugs. Serpentine belt. Maybe a new waterpump of you want to go all out. Stick it back in a drive it.
 
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I don't see Amy reason for the harmonic balancer, nor the oil pump, especially at that mileage. Timing chain isn't necessary yet, I replaced mine @ 140k, as it had a fair amount of play, but wasn't that bad either.
At the same time I replaced water pump, Thermostat, every gasket, seal, and rubber hose in the engine bay, along with degreasing everything, painted valve cover.
 
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Fyi, this is what the 140k chain looked like, also if You have a manual transmission, I suggest you replace the throw out bearing, I didn't, and ended up doing it 1000 miles later. Would have been so much easier when the body was off...
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20160528_152831.jpg
 
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If it was running good @ 84k, i would:

-replace all cooling system components
- replace fms and rms
- oil pan gasket
- freeze plugs
Harmonic balancer should be fine
The timing chain should be fine also, it's still young @ 84k
Check motor mounts
Throw out bearing if manual
 
Didn’t think of freeze plugs. Have people had issues with them?

I was more worried about the age of the harmonic balancer. Does the rubber degrade over time?
 
TJ's-TJ said:
Didn’t think of freeze plugs. Have people had issues with them?

I was more worried about the age of the harmonic balancer. Does the rubber degrade over time?
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Im curious why ppl are recommendin freeze plugs as well. They are a non issue here is CA, but the coolest it gets around here is in the 20s, I've always maintained proper anti freeze, some ppl run water only. As for the harmonic balancer, the only ppl I know that have replaced theirs had Hondas and the thing just fell off lol.
 
Jeepaholic said:
Im curious why ppl are recommendin freeze plugs as well. They are a non issue here is CA, but the coolest it gets around here is in the 20s, I've always maintained proper anti freeze, some ppl run water only. As for the harmonic balancer, the only ppl I know that have replaced theirs had Hondas and the thing just fell off lol.
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Freeze plugs have a bad name. They were never designed to protect the block from freezing. That is what antifreeze is for. The holes were the freeze plugs go are made during the casting process. But they do like to corrode and then you get a leak. If the look corroded change them. If not don't.
 
I had the freeze plug on the back of the cylinder head leak at 113,000 miles. I pulled the transmission to get to it about 2 months after i had it off to replace the clutch. Change them out while it's easy.
 
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If you do the freeze plugs, don't forget the one behind the flywheel. That's the one that started leaking on mine and I had to pull the trans to get to it. Good times.
 
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