Ok, 400,000

[Wayne Sihler]

The Ol,96 has turned over 400,000 miles,,so now what? Motor still uses no oil between changes(3000) oil pressure at speed 50 and at idle(hot)20 psi-factory guage,
Yes it has valve train noise,Vacuum at idle is 15>17 inches with a little needle flutter.
Nothing inside engine has been changed,valve cover never been off in the 360,000 that I have had it.
How long can they go ?
Even though motor is still good the plan is to replace with a Jasper Class 1 next week....just for piece of mind. I hope replacement will last as long.......

 

[md21722]

Run it another 100,000 and re-evaluate.

What's the compression?

Maybe pull the head and have a valve job done. And change the lifters.

Mine has 323,000 and compression was 145-161. No ridge on the cylinder walls when the head came off.

Valve cover gasket was original also, but the valve cover had been off once before.

 

[94xjsport94]

I'd do a valve job and keep it going. Thats awesome.

 

[Jesse_Hallum]

How long can it go? As long as you wish.

Why change anything? You're obviously taking very good care of your horse. Be proud of your commitment and stay the course. Few enjoy membership in the 400k club.

 

[Dest]

Why replace a known working engine with a Jasper?

 

[cal]

The replacement won't last anywhere near as long. It seems like people running mass rebuild motors get less than 100K out of them and they fall apart. Nobody put it together the way the factory did.

I see no reason not to keep running yours...

 

[JeepNoob]

Vacuum seems a bit low to me and an engine textbook I have confirms. Should be 17-21 on a healthy engine idling at sea level with 1 in/Hg subtracted for every 1,000 foot increase. A fluttering needle also isn't good, but it could be anything from a valve sticking to an ignition problem. You might be able to look around the internet and find some charts on interpreting vacuum gauge flutter, would be hard for me to say without more info. FWIW, I think some people out there have 4.0's with 500 or 600K miles on them.

 

[8Mud]

If it ain't broke don't fix it. One of my basic axioms. Some people equate new with better. It may or may not be better, that is yet to be proven. New and improved is way to often, flawed and unproven.

 

[winterbeater]

The numbers are with the old motor. If you are worried about it, you could drop the oil pan and retorque the mains and rods.

 

[Wayne Sihler]

The motor is down on power,a stiff head wind will cause the trans to shift out of OD.There is almost no throttle response,when in cruise,the slightest grade will cause a down shift.
I live in a valley ,so any way out is up hill and mountains to climb east and west.These mountain roads are twisty,while not the Rockies,they are short and steep,heavy throttle is required to maintain 45 mph,and the temp rises to un-healthy areas.
Then the age....how long are the rings and timing set really going to last? and at my age I,m too old to walk the interstate at night.
There are many reasons to keep it going .But time to do that ,I don,t have,so a one shot replacement is what it gets.

 

[Demonoid369]

The motor is down on power,a stiff head wind will cause the trans to shift out of OD.There is almost no throttle response,when in cruise,the slightest grade will cause a down shift.
I live in a valley ,so any way out is up hill and mountains to climb east and west.These mountain roads are twisty,while not the Rockies,they are short and steep,heavy throttle is required to maintain 45 mph,and the temp rises to un-healthy areas.
Then the age....how long are the rings and timing set really going to last? and at my age I,m too old to walk the interstate at night.
There are many reasons to keep it going .But time to do that ,I don,t have,so a one shot replacement is what it gets.

Doesn't sound like a motor issue, sounds like a gear issue as your profile shows your running 33" on 4.10 gears. Flat level ground and 4.10 will do well but if you're doing hills then 4.56 or 4,88 would have been better. Don't Blame the motor for down shifting, Blame the improper gearing

 

[md21722]

A blockage in the exhaust, plugged catalytic converter, will cause low power and increased rubbing tenps.
Weak Fan clutch and poor airflow through radiator would cause higher running.

It may be low compression of the engine or it could be something else.

I would try to figure it out before dumping in a different engine.

 

[Wayne Sihler]

Doesn't sound like a motor issue, sounds like a gear issue as your profile shows your running 33" on 4.10 gears. Flat level ground and 4.10 will do well but if you're doing hills then 4.56 or 4,88 would have been better. Don't Blame the motor for down shifting, Blame the improper gearing

Yes,the gears are an issue,but with the amount of highway vs offroad,the highway wins.2500 rpm at 70 is better than 3000+ in the long run.

 

[Wayne Sihler]

A blockage in the exhaust, plugged catalytic converter, will cause low power and increased rubbing tenps.
Weak Fan clutch and poor airflow through radiator would cause higher running.

It may be low compression of the engine or it could be something else.

I would try to figure it out before dumping in a different engine.

Cat and exhaust system are fresh.Fan clutch is new and rad is clean.The winch does block some air flow. But engine is weak.
We may do a compression test before removal.

 

[Demonoid369]

Well it looks like none of what we say matters as you have your mind set on this motor being weak and not willing to fix the other parts.

 

[Demonoid369]

Yes,the gears are an issue,but with the amount of highway vs offroad,the highway wins.2500 rpm at 70 is better than 3000+ in the long run.

Doesn't look like 3000+ at 70 mph and using 4.56 on 33" tires

 

[md21722]

I took his post to see how others at 400,000 were doing and just sanity checked some of the common pitfalls. I'd probably pull the head for inspection before changing out the motor. If the bottom end looks good it may just need valve work. Jasper engines are spotty.

 

[poorboy87]

Put a timing chain in it and keep it running. Chains stretch, as it goes it slowly retards the timing. Mines doing it at 275k 3.55 and 31s.
I honestly think you would be surprised.

Keep that ol girl alive. Few have made it that far.

 

[GregGA]

Absolutely keep the one you have and do whatever preventative work needs to be done. Who wants to worry about a slapped together reman.Go for 500k.

 

[boncrshr]

Put a timing chain in it and keep it running. Chains stretch, as it goes it slowly retards the timing. Mines doing it at 275k 3.55 and 31s.
I honestly think you would be surprised.

Keep that ol girl alive. Few have made it that far.

I have been wondering about that. I am approaching 300K and it seems a little sluggish all of a sudden. Does it wake these older engines up noticeably?