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Don’t worry, this isn’t a “what’s this MJ worth” post....mostly. I found a second MJ that would work well for my plans to take it camping/overlanding. 87, 4.0, auto, 4wd, long bed. It’s clean, interior is nice-ish, little rust, no clear coat, straight body (except for the rear quarter). It’s one of the nicer ones in the area and a decent price if it was running well...it’s not. 
 

Pretty good amount of blow-by, coolant overflow bottle bubbling (head gasket?), air filter 100% SOAKED in oil, engine dies with any load on it. So...

 

1) How much $ would you take off if the engine needs to be rebuilt/replaced (I can do either)?

 

2) It’s at a dealer (mostly nice classic European cars), any negations techniques to convince him it’s worth less? He gave the typical “needs a tune up” BS and can maybe sell it to another sucker who won’t recognize the engine issues.

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See if they would let you pull up the carpet to check the floors. I guarantee there is rust, more rust than the dealership figures. You could also see if it has a Dana 35 or a Dana 44 rear axle. A Dana 44 will add some value (or a Dana 35 will reduce value, depending on how you look at it) You could point out that the visor on there means that holes have been drilled in the roof, which can lead to water leaks. 

 

What is the price if you don't mind me asking?

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Price is $4500. Figure I could have gotten it for $3750ish if engine was in good shape. Sure beats the rust buckets I’ve seen lately for $3k-4. It needs a rear bumper and grille. I’d likely wrap it. 
 

I pulled the rubber mat/insulation. There is a little rust on the floors; driver side feels solid but the passenger is soft in some spots with a few small holes at the seat mount. Appears to be coming from inside (cowl vent or blower seal based on small puddle after rain). It’s a FL truck.  
 

I definitely thought that about the visor...kind of taking a chance on that but I don’t see any other rust or body work. 
 

It’s a D35, but I have a built 9” I’ll probably put under it. 
 

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$4500 asking seems steep to me. It will need the floorboard frame caps removed, new pans, and the caps re-installed. Engine may be salvageable but it sounds like it may need a fair amount of work. This might be one you let sit and come back after a month or two and offer 2.5-3k. Especially being that it is a 1987 and not a 1991 or 1992 where you get less desirable stuff under the truck. 

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If the air filter is soaked in oil then it likely is not getting enough air when under load.  Trying it without the filter or substituting a clean one would help narrow that down.

The expansion bottle gurgling may just mean there is air in the system.  Does it gurgle while running or after shut off.  My closed system stopped gurgling after I got all of the leaks fixed in the system.  That said, the rust looks pretty severe and a great deal more is likely hidden.  That and suspected engine issues would make me very hesitant to go much over 2K.  I would definitely want a pre-purchase evaluation at requested price.

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As far as negotiations. The fact that it is not their bread and butter of vehicles is a plus for you. You know far more about what you are looking at then they do. Might try the "Leave a price and phone number" tactic. If they want it off the lot they will let it go for whatever they have in it.

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2 minutes ago, rokinn said:

If the air filter is soaked in oil then it likely is not getting enough air when under load.  Trying it without the filter or substituting a clean one would help narrow that down.

The expansion bottle gurgling may just mean there is air in the system.  Does it gurgle while running or after shut off.  My closed system stopped gurgling after I got all of the leaks fixed in the system.  That said, the rust looks pretty severe and a great deal more is likely hidden.  That and suspected engine issues would make me very hesitant to go much over 2K.  I would definitely want a pre-purchase evaluation at requested price.

I should have mentioned, I test drove it with no air filter. The CCV tube was in bad shape and the idle was rough...it improved when the CCV tube was connected properly....why would that be???

 

Expansion tank bubbled when running only; coolant was VERY slightly brown...or just old. 
 

I checked all the normal rust spots and didn’t see any concerns. I’d much rather have floorboard rust coming from the inside than outside.  

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1 minute ago, Torq_Shep said:

As far as negotiations. The fact that it is not their bread and butter of vehicles is a plus for you. You know far more about what you are looking at then they do. Might try the "Leave a price and phone number" tactic. If they want it off the lot they will let it go for whatever they have in it.

That’s a good idea, thanks! He also hasn’t advertised it in any of the normal places, so probably isn’t getting much interest. Of course he “knows the market and what these things are worth” :sad2:

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10 minutes ago, Torq_Shep said:

$4500 asking seems steep to me. It will need the floorboard frame caps removed, new pans, and the caps re-installed. Engine may be salvageable but it sounds like it may need a fair amount of work. This might be one you let sit and come back after a month or two and offer 2.5-3k. Especially being that it is a 1987 and not a 1991 or 1992 where you get less desirable stuff under the truck. 

$2.5k was my thought. That seems to be a typical asking price for crappy MJs around here. And this one with some engine attention could be better than decent. 

 

I’m also tainted by the good price I recently got on my mint-ish ‘88!

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Sorry for the barrage of posts in a row...

 

In the absence of a way to check compression, what would you guys consider “too much” blow-by?

 

Oil cap removed, there is visible smoke that is pumping out at a decently high rate. How’s that for subjective?

 

Either way, it’s more than I’ve ever seen on a good-running 4.0.

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14 minutes ago, Tentrax_Brent said:

That’s a good idea, thanks! He also hasn’t advertised it in any of the normal places, so probably isn’t getting much interest. Of course he “knows the market and what these things are worth” :sad2:

Being willing to sit on things always brings better deals. Also your other truck is SWEET.

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14 minutes ago, 89 MJ said:

If that truck were up here in the rust belt, I think that $2,500 would still be a little high. 

Really? That’s good input!! It would be cool if we could compile a database of sale prices on Comanches based on region. Sort of like the charts that BaT has for different vehicles. Hmmm 🤔

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29 minutes ago, Tentrax_Brent said:

Really? That’s good input!! It would be cool if we could compile a database of sale prices on Comanches based on region. Sort of like the charts that BaT has for different vehicles. Hmmm 🤔

@Torq_Shepstarted one. When I got my truck, it was nicer than the one you pictured. I got it for $1500 and was offered $3000 the next day. And it is the shortbed, which is more desirable. 

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Crankcase vent system sucks air from the filter box to through the crankcase to the intake manifold. A disconnected line between the vent and crankcase is a vacuum leak, so hooking it back up can correct that. The disconnected (or blocked) line can also push crankcase gasses to the filter, which will soak down the filter with oil. How soaked the filter is will depend on how bad the blowby is and the age of the filter.

”Too much” blowby is subjective. All engines will have some, even new. Some will say so long as it’s not using “too much” oil (again subjective) it’s fine. In my mind it’s excessive if the CCV is in working condition but it’s still pushing combustion gasses to the filter, i.e. the system is operating beyond capacity. Others will tell you to pull it off and run a catch can or just a drip tube for the excessive gasses.

 

As a point of reference, my 2.5 has enough air moving out of the fill cap I can’t add oil with the engine running, but it doesn’t oil down it’s filter. Compression isn’t ideal at 110-130psi across all cylinders IIRC, and it does use some oil, about a quart and a half between ~3000mile changes. Yet it still makes enough power for climbing hills in the Rockies so I’m not concerned about it.

 

I’d expect you’d only be able to knock off at what it would cost a shop to R&R the engine with one from a junkyard. Call it $1500 at the most.

 

Be careful picking up a second MJ. Either the first will get jealous and start throwing fits for attention, or else the damn things will start breeding.

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1 hour ago, gogmorgo said:

Crankcase vent system sucks air from the filter box to through the crankcase to the intake manifold. A disconnected line between the vent and crankcase is a vacuum leak, so hooking it back up can correct that. The disconnected (or blocked) line can also push crankcase gasses to the filter, which will soak down the filter with oil. How soaked the filter is will depend on how bad the blowby is and the age of the filter.

”Too much” blowby is subjective. All engines will have some, even new. Some will say so long as it’s not using “too much” oil (again subjective) it’s fine. In my mind it’s excessive if the CCV is in working condition but it’s still pushing combustion gasses to the filter, i.e. the system is operating beyond capacity. Others will tell you to pull it off and run a catch can or just a drip tube for the excessive gasses.

 

As a point of reference, my 2.5 has enough air moving out of the fill cap I can’t add oil with the engine running, but it doesn’t oil down it’s filter. Compression isn’t ideal at 110-130psi across all cylinders IIRC, and it does use some oil, about a quart and a half between ~3000mile changes. Yet it still makes enough power for climbing hills in the Rockies so I’m not concerned about it.

 

I’d expect you’d only be able to knock off at what it would cost a shop to R&R the engine with one from a junkyard. Call it $1500 at the most.

 

Be careful picking up a second MJ. Either the first will get jealous and start throwing fits for attention, or else the damn things will start breeding.

The CCV tube from the valve cover to air box was definitely pumping fumes and smoke into the air box, so it sounds like a bad CCV valve or way too much blow-by? The air filter was completely saturated with oil. 
 

$1500 sounds like a reasonable deduction to me. I’ll see if he minds me checking compression, though I’m still concerned about the head gasket. 
 

Thanks for the multi-MJ warning! My YJ is already starting to get worried...
 

 

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1 hour ago, 89 MJ said:

@Torq_Shepstarted one. When I got my truck, it was nicer than the one you pictured. I got it for $1500 and was offered $3000 the next day. And it is the shortbed, which is more desirable. 

Oh man, this is what most $1500 Comanches look like around here...

 

https://www.facebook.com/marketplace/item/733085310622982/

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12 minutes ago, Tentrax_Brent said:

The CCV tube from the valve cover to air box was definitely pumping fumes and smoke into the air box, so it sounds like a bad CCV valve or way too much blow-by? The air filter was completely saturated with oil. 
 

$1500 sounds like a reasonable deduction to me. I’ll see if he minds me checking compression, though I’m still concerned about the head gasket. 
 

Thanks for the multi-MJ warning! My YJ is already starting to get worried...
 

 

The CCV “valves” are really just open hose barbs. There’s two ports on the valve cover. One should be a relatively small diameter line that goes to a port on the intake manifold. The other is larger diameter and goes to the filter box. Higher vacuum in the manifold (downstream of the throttle plate) pulls the clean air through the system. The system should be free-flowing, but is susceptible to leaks. If it’s all intact, a new filter is cheap and would tell you pretty quick if it’s still spitting oil. 

I wouldn’t necessarily correct it for the salesman, but if there’s obvious problems it may be a simple fix, and you might still get good life out of the engine.

If there is excess combustion gas bypassing the rings, the oil will turn dark pretty quickly. It’ll also likely take on a gassy or burnt smell. Most used car dealers would change the oil after taking in the vehicle, so this could be a tell.

 

Frankly though I’m surprised they let you poke around that much at all. But it does make it look to them like you want the vehicle as opposed to being on the fence about it and you’re just trying to find something to talk the price down which may weaken your bargaining position. Especially since it seems to me like that’s the case. 
 

Also, the floor pans rust out from the top. If there’s rust below there’s rust above. The rockers and cab corners won’t be far behind.

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1 hour ago, gogmorgo said:

The CCV “valves” are really just open hose barbs. There’s two ports on the valve cover. One should be a relatively small diameter line that goes to a port on the intake manifold. The other is larger diameter and goes to the filter box. Higher vacuum in the manifold (downstream of the throttle plate) pulls the clean air through the system. The system should be free-flowing, but is susceptible to leaks. If it’s all intact, a new filter is cheap and would tell you pretty quick if it’s still spitting oil. 

I wouldn’t necessarily correct it for the salesman, but if there’s obvious problems it may be a simple fix, and you might still get good life out of the engine.

If there is excess combustion gas bypassing the rings, the oil will turn dark pretty quickly. It’ll also likely take on a gassy or burnt smell. Most used car dealers would change the oil after taking in the vehicle, so this could be a tell.

 

Frankly though I’m surprised they let you poke around that much at all. But it does make it look to them like you want the vehicle as opposed to being on the fence about it and you’re just trying to find something to talk the price down which may weaken your bargaining position. Especially since it seems to me like that’s the case. 
 

Also, the floor pans rust out from the top. If there’s rust below there’s rust above. The rockers and cab corners won’t be far behind.

Thanks for the education on the CCV system 👍🏼
 

So currently here are the symptoms that may suggest the most serious engine issues:

 

1) High volume of smoke/air coming out of the oil fill cap and CCV hose going to the air box when running. The smoke is visible and fairly high velocity.

 

2) Gas smell and “thin” feeling oil on the dipstick.

 

3) “Bubbling” in the overflow bottle...but after comparing to my running 88 4.0, this may just be coolant pouring into the overflow bottle. I’m still learning about the Renix engine differences, all my previous Jeeps have had HO engines with an open coolant system. 
 

4) Engine dies with more than about 10% throttle while driving. Since the fuel pump and filter were recently replaced, I’m thinking this might be vacuum related. 
 

Any thoughts on numbers 1 and 2? Seems to point to ring issues and lack of compression...but also could be related to the Jeep not being operated much the past several years. 

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Gas smell in the oil definitely isn’t good. Best case scenario it’s a recent condition, and mostly brought on from only ne run enough to move it around the lot. Running excessively rich leads to gas condensing on cylinder walls, washing the oil off. This causes lubrication problems that lead to ring sealing issues, eventually cylinder wall and piston damage if left long enough. An engine only ever run cold will do this, but once it’s been run up to termperature it should burn/boil off the gas in the oil.

 

I suspect #4 is another symptom of what’s causing #2. #1 could easily be a result of prolonged #2. Without much to go off, I have no insight to guess down #3, but it may also be a result of some other issues, or simply cooling system neglect... it could also just be the result of an improperly bled cooling system. 
 

With this info it’s easy enough to make a case that it needs far more than “just a tune up”. For less than $50 in parts and a 1/2 hour labour for their “tune up” (only consumables in the engine are ignition parts) the dealer’s foolish not to have already done it. No one’s going to spend that coin on a truck that barely drives. 

 

I’d say it needs the time spent  to run through the tips at cruiser54.com before we can go much further with diagnostics, but for the time being I’d say your best bet to get a better deal on the truck is to make an offer you think is consistent with the truck having a blown motor, then leave your phone number and walk away, as was already suggested.

 

I really doubt anyone is going to pay the asking price for a truck that barely runs, unless they manage to find someone with deep pockets planning an LS swap or something of that nature, which doesn’t sound like their typical sort of customer.

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Looks like no rear bumper, dings on the rear quarters, peeling clear coat, missing grille, excessive tire wear on the inside edge of the front tires, hacked up battery cables, no battery tie down (safety item there). I bet they took it on trade cheap.

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Thanks everyone, I really appreciate all the input!! Excellent points all around, especially the fact that no “normal” person will buy a truck that is not running well...and it will probably sit a while as-is at that price. 
 

I’ll probably throw a low offer down, see if it sticks, and keep looking!!

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