Jump to content

Recommended Posts

So my Comanche has 310k miles on it. What I’m faced with is fixing the many oil leaks it has or to just replace the whole engine. I know the oil has been changed religiously for the past 250k Miles. And 200k of the 250k mikes I’ve owned it have been on the highway. The engine gets decent fuel economy for a 4.0 with 4wd and 31” tires 16-18mpg. However it dose have some blowby. It also feels like the low end power on the engine isn’t what it once was. What I’m not sure is if it’s worth resealing the engine without rebuilding it. Maybe I should just leave it and add oil? Hopefully you guys can point me in the right direction. 

Share this post


Link to post
Share on other sites

you need to determine the health of the engine using things like the compression and leakdown test.  :L:  butt-felt "power loss" can easily be the result of fuel delivery or sensor issues and blowby could just be a CCV system that isn't up to snuff.  also, 31" tires can suck the life out of any stock engine.  you need the gearing that goes with those tires. :L: 

Share this post


Link to post
Share on other sites

There are those who build and there are those who patch. 

 

You decide. 

 

 

Personally, I can't wait to build another. 

Share this post


Link to post
Share on other sites

Depends what the leak is. A valve cover gasket can make a huge mess everywhere. 

What's your budget?

Share this post


Link to post
Share on other sites

Yeah I would like to build it. However it’s my only vehicle so I will need to wait until I have a vacation if a rebuild is in the works. Or maybe throw a junkyard engine in for $250 and take my time rebuilding it. Either way I agree I need to do a compression test and leak down to see the health of the engine. And every oil seal/gasket aside from the front crank seal is leaking. 

Share this post


Link to post
Share on other sites

By blowby, do you mean you're getting alot of oil in the airbox?  If yes, you can swap a later model stamped steel valve cover on to help.  It doesn't really fix the blowby problem but it does fix the oil-getting-into-the-airbox issue.  It all but completely cured mine.  The internal baffling on the newer covers is at the top of the inside cover, while the older ones have "towers" inside that pull CCV from right on top of the valvetrain (and also the oil there).

Share this post


Link to post
Share on other sites

I have replaced the valve cover with a aftermarket one with the better gasket about 100k miles ago. The Ccv isn’t hooked up to the air box anymore but is a chrome breather that sits on top of the valve cover. 

Share this post


Link to post
Share on other sites
So my Comanche has 310k miles on it. What I’m faced with is fixing the many oil leaks it has or to just replace the whole engine. I know the oil has been changed religiously for the past 250k Miles. And 200k of the 250k mikes I’ve owned it have been on the highway. The engine gets decent fuel economy for a 4.0 with 4wd and 31” tires 16-18mpg. However it dose have some blowby. It also feels like the low end power on the engine isn’t what it once was. What I’m not sure is if it’s worth resealing the engine without rebuilding it. Maybe I should just leave it and add oil? Hopefully you guys can point me in the right direction. 
In my opinion the options are a low mileage 4.0 and reseal it before you put it in then crack the one you have now and see what would be needed to do a complete rebuild on that. Look to Titan engines for a kit. I got mine for around $375 included pistons and cam and lifters...Chuck Manis Performance is also a good source...

Sent from my LG-M210 using Tapatalk

Share this post


Link to post
Share on other sites
19 hours ago, Jeep Driver said:

There are those who build and there are those who patch. 

 

You decide. 

 

Personally, I can't wait to build another. 

 

You're so cool. I swing both ways.

 

Since you said it is your only vehicle and it is still driving, I would avoid pulling the motor twice. If your motor is okay, then you can just slap a bunch of new gaskets on it and drive it another 100k. If its in poor health, you can pull it out and rebuild it pretty cheaply so long as you can get away with avoiding machine work ($$$). Or you can get a used engine and rebuild it on a stand while you squeeze the last few miles out of your current engine.

Share this post


Link to post
Share on other sites
1 hour ago, Darren said:

 

You're so cool. I swing both ways.

 

Since you said it is your only vehicle and it is still driving, I would avoid pulling the motor twice. If your motor is okay, then you can just slap a bunch of new gaskets on it and drive it another 100k. If its in poor health, you can pull it out and rebuild it pretty cheaply so long as you can get away with avoiding machine work ($$$). Or you can get a used engine and rebuild it on a stand while you squeeze the last few miles out of your current engine.

 

I agree, buy one off craigslist or something and start gathering parts for that.

Share this post


Link to post
Share on other sites

Find a core to build. Keep driving what you've got until you get the core built. 

Share this post


Link to post
Share on other sites

Ok so I just got finished with a cold compression and leakdown test. 

1-134psi

2-137psi

3-133psi

4-129psi

5-136psi

6-133psi 

I put 90psi into each cylinder and they all dropped down to arround 80 psi. I could hear some air getting into the oil pan but nowhere else.

Dose anyone know what the factory spec for this engine is? 

Share this post


Link to post
Share on other sites
Ok so I just got finished with a cold compression and leakdown test. 
1-134psi
2-137psi
3-133psi
4-129psi
5-136psi
6-133psi 
I put 90psi into each cylinder and they all dropped down to arround 80 psi. I could hear some air getting into the oil pan but nowhere else.
Dose anyone know what the factory spec for this engine is? 
Not sure what we're working on but I believe 100 psi on compression is minimum. Did you block off everything attached to the intake? PCV? Other vacuum hoses?

Sent from my LG-M210 using Tapatalk

Share this post


Link to post
Share on other sites

my '88 is insanely jealous of those numbers!  :bowdown:

Share this post


Link to post
Share on other sites

Those numbers are a bit low, but still acceptable.  The big thing is the limited variation between them, which is good.

 

Did you pull all the plugs, wedge the throttle plate WFO and disable the fuel pump and ignition?  That's the only real way to do a proper test.  On the leak down test, make sure each cylinder is at BDC and no valves are partially open.  Losing 10 psi might be due to the crank rotating.  If the pressure falls but holds, you're good.

 

Id try a wet compression test next to see if the numbers got better.  Leak down test wet as well.

Share this post


Link to post
Share on other sites

Ok excellent thanks. And yes I had all the plugs pulled along with the fuel pump relay unplugged. And I made sure it was WOT. I plan on doing a hot compression test along with one with oil to see if the numbers change. 

 

 

Share this post


Link to post
Share on other sites

In a unrelated matter. I found a 1987 Cherokee Chief in the same color as my Comanche. However it has 35k original miles and is 2 hours away from me. It’s has spent the past 10 years in the garage. Original paint it even has the factory tires. That being said it needs tlc to be a good driver. As in sure everything rubber is dried out. The owner is reluctant to even sell it. What I’m wondering is what can I offer for it without insulting him but not overpaying for it because it matches my MJ. 

Share this post


Link to post
Share on other sites
1 hour ago, ComancheFan said:

In a unrelated matter. I found a 1987 Cherokee Chief in the same color as my Comanche. However it has 35k original miles and is 2 hours away from me. It’s has spent the past 10 years in the garage. Original paint it even has the factory tires. That being said it needs tlc to be a good driver. As in sure everything rubber is dried out. The owner is reluctant to even sell it. What I’m wondering is what can I offer for it without insulting him but not overpaying for it because it matches my MJ. 

Tell the seller you will have it towed and you will accept full responsibility and that you know what you are doing and you will go through the entire XJ for repairs.....convince him to sell it to you. $500 to $800 like yesterday. 

 

I have always said.......Time causes more wear than miles. Low miles does not impress me at all. And you are correct, every seal, bushing, line, hose, water pump, radiator, tires, shocks, fuel pump, fuel tank, entire brake system.........etc....

 

30-40 year old 0 mile cars do exist........now that impresses me, other wise...........

Share this post


Link to post
Share on other sites
21 hours ago, ComancheFan said:

Ok so I just got finished with a cold compression and leakdown test. 

1-134psi

2-137psi

3-133psi

4-129psi

5-136psi

6-133psi 

I put 90psi into each cylinder and they all dropped down to arround 80 psi. I could hear some air getting into the oil pan but nowhere else.

Dose anyone know what the factory spec for this engine is? 

150-160 IIRC........without looking it up. 

 

 

There are costs associated with resealing an engine that most guys either don't admit or they are cheap and do halfassed work. 

 

You are going to pull the pan for the RMS and pan gasket, are you going to replace the oil pump while you are there? If you have low idle psi you should replace it, virtually everyone here will state that 9psi at idle is acceptable, that's BS. 

 

You are going to pull the timing cover for new gasket and seal, do you replace the timing set? Why not? you have 300K, you should. 

The hub to your HB is worn and will destroy a new seal within the year, do you replace it? you should. 

 

If they have not been replaced recently you'll find that the heater hoses and rad hoses need to be replaced. 

 

You are going to pull the water pump, replace it. 

 

Coolant and oil and filter......plugs wires......etc.............PCV and related hoses.........cleaning materials.

 

Are you replacing the intake/exhaust gasket? what will you do when you find cracks in your exhaust manifold?

 

Serpentine belt, replace it?

 

 

 

There are guys who "just slap some gaskets on" and there are guys who properly go through an engine and do the job right.

 

Cleaning is time consuming.........clean clean clean. IMO that is a three day job and will cost around $400. 

 

And then you still have the blow-by to contend with. You may, as others have, as I attempted to do, contain or control blow-by, but you will never cure it. 

Share this post


Link to post
Share on other sites
2 hours ago, Jeep Driver said:

Tell the seller you will have it towed and you will accept full responsibility and that you know what you are doing and you will go through the entire XJ for repairs.....convince him to sell it to you. $500 to $800 like yesterday. 

 

I have always said.......Time causes more wear than miles. Low miles does not impress me at all. And you are correct, every seal, bushing, line, hose, water pump, radiator, tires, shocks, fuel pump, fuel tank, entire brake system.........etc....

 

30-40 year old 0 mile cars do exist........now that impresses me, other wise...........

Yeah the seller is out of touch with the value of it. I haven’t purchased one with that little mileage before so I’m not sure the value. He is asking $9500 for it. I was thinking $3000-4000 just because I would like to have a matching Cherokee Chief. So if I were to offer him $3000 it would be too much as far as the real value of the truck is? It’s a Florida rust free vehicle if that means anything. 

Share this post


Link to post
Share on other sites
20 minutes ago, ComancheFan said:

Yeah the seller is out of touch with the value of it. I haven’t purchased one with that little mileage before so I’m not sure the value. He is asking $9500 for it. I was thinking $3000-4000 just because I would like to have a matching Cherokee Chief. So if I were to offer him $3000 it would be too much as far as the real value of the truck is? It’s a Florida rust free vehicle if that means anything. 

It has still be sitting for 10 years.

 

Yes, he's out of touch. 

 

Guess I was under the impression that it was something of a 'barn find' covered in dust and rotted tires...etc....

Share this post


Link to post
Share on other sites
1 hour ago, Jeep Driver said:

It has still be sitting for 10 years.

 

Yes, he's out of touch. 

 

Guess I was under the impression that it was something of a 'barn find' covered in dust and rotted tires...etc....

It’s clean original paint well taken care of. But it’s only driven for Sunday drives and he hasn’t changed the tires brakes, radiator hoses etc. so there is a lot there and with age gaskets dry out aswell so there’s no telling what needs to be resealed. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...