Jeep Engine to Rebuild or Not to Rebuild - JeepForum.com

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post #1 of 32 Old 09-10-2009, 08:54 AM Thread Starter
booyia
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Jeep Engine to Rebuild or Not to Rebuild

1997 Jeep TJ with 185,000 miles needs a new engine.

The check engine light (or as my friend calls it the "hey idiot" light) has been glowing for the past 2-3 months. Took it to my non-regular mechanic and he nearly ripped his hair trying to figure it out. One cylinder seemed to have been the problem, changed wires, replaced fuel injectors, etc. Check engine light still on. Took Jeep back to my regular mechanic. He told me since the other guy made all the changes, all he could suggest was to run a compression test. Lo and behold the cylinder that was giving us a problem had a compression rate of 110 (btw, these numbers mean nothing to me) 2 of the other cylinders were at 125 and the rest were "normal". He said the engine is shot, said I have maybe 1-2 years left.

He also said the oil pan gasket needs replacing, but if the engine is going to be replaced he would not do that as it would be a waste of money for me to do it now.

My question's are as follows:

1. Financially is it worth replacing the engine? the car is paid off, has been a daily driver but with a baby on the way we are looking to get a different daily driver.

2. What is involved in replacing an engine? What's the usual ball park figure on cost?

3. I have seen some of the threads and links to Jasper Engines, and the prices seem reasonable, but I don't know if my mechanic can do this kind of job (he estimated a cost of about $3000 which sound excessive.

4. If I do an engine replacement might an engine swap (different engine, perhaps one with better gas mileage make sense)?

5. What are my other options? I've considered selling it as/is or parting it out and trying to make the best of a bad situation. I am not mechanically inclined so I can't make this my project Jeep however if I can justify the cost I would be willing to do this as i see some re manufactured Jeep engines come with as much as a 7 year warranty.

Thanks for any help, guidance and thoughts. I love my Jeep but couldn't justify paying $3000 to keep it going. If I can come up with a better option or solution I would appreciate it.

Also any Jeepers in the New York tri-state area who could/would recommend a mechanic that can do this job at a reasonable price I would be most thankful.

PS: Anyone in this area who wants to make some money this could be your project Jeep

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post #2 of 32 Old 09-10-2009, 09:17 AM
emev0l
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You have a couple options:

You can buy a used 4.0

You can buy a new 4.0

You can buy a new 4.7 stroker (4.0 stroked to a 4.7)

You can do a V8 swap (Dodge 5.7)

The V8 swap will cost quite a bit if you don't do all the work yourself, the 4.7 is only worth it if your looking for more power in your jeep, I would rather see you buy that than a new 4.0

Your cheapest and easiest choice would be a good used 4.0

It's honestly not very hard to replace a motor, it is time consuming if you haven't done it before.

You should be able to find a used 4.0 for $200-$500

You should also be able to find someone who will do the swap for under $1,000

The only other option would be to sell your jeep and buy another one.

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post #3 of 32 Old 09-10-2009, 09:21 AM
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What are all the compression numbers? Individual numbers don't mean as much as a comparison of all the numbers to each other......

There are a number of reasons why one cylinder could be low although 110 doesn't sound all that low. For instance, you could have one bad valve that is leaking and could be an easy repair. I wouldn't write off the engine just yet.....
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post #4 of 32 Old 09-10-2009, 09:29 AM
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My question to you is what apears to be wrong. Is he saying the rings are shot? Could your engine just need the head reworked and a valve job? Having the head reworked is a lot less money than a new engine. The fact that three cylinders are normal compression would make me think it is a head issue. Possibly just a head gasket issue. Does the engine use oil?
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post #5 of 32 Old 09-10-2009, 09:56 AM Thread Starter
booyia
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Thanks for the replies. Getting some good feedback here so far. I spoke to the mechanic and the only thing he said was he ran a compression test and 2 of the 6 cylinders came back low. The expected compression is 150 PSI, 4 cylinders were correct the other 2 were 110 and 125.

I honestly don't know what that means, but that was the most information I could get from him. I hope this helps clarify things.
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post #6 of 32 Old 09-10-2009, 10:42 AM
DevilDogDoc
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Sounds like the head gasket is blown between those two cylinders rather than the motor needing a rebuild.
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post #7 of 32 Old 09-10-2009, 11:10 AM
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The most likely causes are rings, valves, or head gasket. A good mechanic would be able to do a little more testing for you and determine what is causing the low compression on the two cylinders.

Quote:
Originally Posted by DevilDogDoc View Post
Sounds like the head gasket is blown between those two cylinders rather than the motor needing a rebuild.
If the two cylinders with low compression are next to each other you have a valid point. But unless I've missed something, he hasn't said anything that would identify which two cylinders have the low compression.

Keep in mind that free advice can frequently be worth less than you pay for it.
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post #8 of 32 Old 09-10-2009, 11:25 AM
lupinsea
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Even at $3000 it might be worth it.

If you were to buy another car for $3000 could you get one in as good a condition as your Jeep but with an engine that is new / freshly rebuilt?

I don't think so.


Seems a big question is . . . do you even want a Jeep anymore.


$3000 to will get you a new engine and let you keep it as a secondary vehicle, even if you get a different car now.

- Jay
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post #9 of 32 Old 09-10-2009, 11:34 AM
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Here's some stuff to help you narrow it down:

Blown Head Gasket?:

There are a few simple indicators you can check for with the engine cold and not running.

1. contaminated oil, it will have a milky appearance from the water mixing in the oil. 2. oil on the top of the coolant inside the radiator (if your vehicle has a remote header tank you may not get this) 3. have someone crank (remove the coil lead or disable the elcectronic ignition) the engine on the starter with the radiator cap or coolant jacket bleed hose/bolt removed, if the coolant pulses up and down or blows bubbles you could be in trouble.

If you find any of these symptoms move on to removing the spark plugs (lable the plugs and the leads as you remove them so you can put them back in the same place as you got them from) and again crank the engine on the starter, depending on how bad your head or gasket is gone you may get coolant or oil coming out of the plug holes. inspeection of the plugs will also reveal problems during combustion, if you have rusty flaky deposits on the plugs you may be burning off water and if you have a heavy carbon your burning oil.

depending on the severity of the leak (and how hard you want to look for it)

if you have any of the first 3 items listed (water in oil, oil in water or pulsing coolant but dont get any result from checking the plugs change the oil and water as appropriate then warm up the engine without the radiator cap on (or the bleeder hose/bolt) and watch for bubbles as the engine warms up. Put tha cap back on the cooling system and take the vehicle for a short drive or run the engine till the entire system is up to temperature and then check the oil for contamination.

Having these symtoms is not always indicitaive of a blown head gasket and usually if the gastket is gone there is going to be some warping of the head and or block of the engine.

There are a few other things that can give similar symptoms to the ones listed above 1. internal damage to water/oil galleries 2. damage to oil/water intercoolers if fitted 3. weakened hoses on the cooling system can cause pulsations in the coolant 4. leaking valve seals may drop oil into the chamebers 5. poorly bleed cooling systems or systems where there are high loops in the coolant jacket may have some bubbling.

I can't take credit for the abouve, found it on the intrawebz/
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post #10 of 32 Old 09-10-2009, 11:42 AM
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I would try this. May be carbon on the valves.

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post #11 of 32 Old 09-10-2009, 12:02 PM Thread Starter
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Thanks for all the advice and directions guys. I should also mention when I took the car in to check the "check engine" light, I had the mechanic do a once-over. Before he ran the compression test he did a once over on the car and also told me I would need to replace the oil-pan gasket. When he ran the compression test, he told me I should wait to do this after I decided what to do with the Jeep. I'm not sure if this changes the equation on which way I should go on the decision here.

As for keeping the Jeep, in an ideal world I would keep it and repair it. However $3000 is not feasible for a vehicle that does not get great gas mileage to begin with (as a daily driver). The $3000 would be a nice downpayment on a new vehicle (or certified pre-owned with attendant warranties). I love my Jeep and would hate to give it up, but I have a "mental idea" of how much I would be willing to spend on keeping it going and $3000 just seems wasteful. Not to mention parting this one out (full doors, half doors, sailcloth, hardtop, rack, etc) along with the $3000 I save would probably be closer to $5000.

That is why I am hopeful that some of the suggestions and possible alternative solutions may be in order.
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post #12 of 32 Old 09-10-2009, 12:30 PM
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Quote:
Originally Posted by emev0l View Post
You should be able to find a used 4.0 for $200-$500
You must be smokin the whole rock. If i could have found a 'good' used motor for that i would have been all over it. A 'good used one i have been finding are going for 800 and above

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post #13 of 32 Old 09-10-2009, 12:55 PM
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Quote:
Originally Posted by booyia View Post
Thanks for all the advice and directions guys. I should also mention when I took the car in to check the "check engine" light, I had the mechanic do a once-over. Before he ran the compression test he did a once over on the car and also told me I would need to replace the oil-pan gasket. When he ran the compression test, he told me I should wait to do this after I decided what to do with the Jeep. I'm not sure if this changes the equation on which way I should go on the decision here.

As for keeping the Jeep, in an ideal world I would keep it and repair it. However $3000 is not feasible for a vehicle that does not get great gas mileage to begin with (as a daily driver). The $3000 would be a nice downpayment on a new vehicle (or certified pre-owned with attendant warranties). I love my Jeep and would hate to give it up, but I have a "mental idea" of how much I would be willing to spend on keeping it going and $3000 just seems wasteful. Not to mention parting this one out (full doors, half doors, sailcloth, hardtop, rack, etc) along with the $3000 I save would probably be closer to $5000.

That is why I am hopeful that some of the suggestions and possible alternative solutions may be in order.

Ive changed oil pan gaskets on V8's before and the 4.0 oil pan is pretty accessible. It's not hard or expensive. Dont let that be a determining factor. Piece of cake.
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post #14 of 32 Old 09-10-2009, 12:56 PM
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Quote:
Originally Posted by 2000jeeper View Post
You must be smokin the whole rock. If i could have found a 'good' used motor for that i would have been all over it. A 'good used one i have been finding are going for 800 and above
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post #15 of 32 Old 09-10-2009, 02:00 PM
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Quote:
Originally Posted by 2000jeeper View Post
You must be smokin the whole rock. If i could have found a 'good' used motor for that i would have been all over it. A 'good used one i have been finding are going for 800 and above


I would think the person asking $800 for a 4.0 I6 would be the person smokin the rock.

When someone says $100-200 or even $500 for a motor, they are usually talking about a private seller.

If you have to ask a local yard for the motor, forget about it. They'll say $800 just like they would if you asked them for a D35 rear axle.
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