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Assortment Of Questions Regarding My 2.5L


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I am still in the process understanding my comanche that I have owned for about 7 months now, learning things through this site here and there.  Right now I am in the middle of replacing my water pump due to having over heating problems.  After I get my truck to working conditions I am just wondering a few things about my vehicle.  Everything is stock.

 

From this post : http://comancheclub.com/topic/28409-engine-tranny-and-axle-ratios/?hl=axle+ratio

 

I am guessing that the axle I have is the Dana 35 and it has a gear ratio of 4.56.  Can someone validate this and also explain to me what this means? and kind of explain in layman's terms what the performance of my truck is compared to other comanches, like the power, and speed.  I have 235/75r15 tires on.  Its the 2.5l with the AW4 automatic. 

 

Also, I have acquired a drawtite receiver hitch and I am wondering how it will do pulling a bass tracker that weighs about 1200 - 1500lbs.  Will it drive alright? or should I not even attempt it? or should extra upgraded measures make this safe?

 

And the last question is that I have manual steering and this summer I would love to put in power steering. What work and what parts at what cost would this be to add power steering? is it easy to do?

 

Thank you for your time, I apologize if I come of as amateur.  I'm new to working on vehicles.

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I'm assuming based on your signature it's an '88?  The 2.5L with AW4 is somewhat rare.  I imagine it will feel somewhat underpowered.  You are probably correct with your guess of 4.56 gears.  A Dana 35 looks like this:

cover_dana35c.jpg

 

As far as power steering, you'd need the pump and all the mounting brackets, the steering box, hydraulic lines and the correct length serpentine belt.  Best to find a donor at the junkyard.  XJ's, MJ's, YJ's with the 2.5 all should work.

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2.5L automatics after '86 are quite rare. You have one of the slowest drivetrain configurations offered throughout the model range, but it's enough to get the truck moving at least. The 4.0 Comanches had impressive performance for their day and still hold their own, but the 2.5 was and still is perfectly usable. For an '80s 4 cylinder engine, it's very strong.

 

The AW4 is a reliable transmission with the 4.0's torque and the 2.5 is substantially weaker, so unless the transmission has been abused (more on that later), you probably won't have to worry about it.

 

Nothing is guaranteed but you likely have 4.56 gears. This means that for every rotation of the wheels, your driveshaft (after being multiplied by the transmission's ratio) must rotate 4.56 times. This means that the engine must rev more for a given speed, but it also multiplies the engine's torque and allows the engine to reach its peak power quicker. This was done to compensate for the relative weakness of the 2.5L engine coupled to an automatic transmission - the downside is that the engine will be running at high RPM on the highway, reducing fuel economy. Lower (numerically higher) gear ratios make the throttle feel more responsive and "quicker", also.

 

235/75/15 is probably the most common "stock" tire size now. That's 29" in diameter.

 

A 1500lb trailer isn't very heavy but at the very least you want to have an auxiliary transmission cooler. There are a number of these out there and they're all fairly decent. Heat is what destroys automatic transmissions so it's a very worthwhile investment. Otherwise, make sure everything is in order mechanically and be very careful. Someone with more experience than I do with the 2.5 (and towing in general) would know more about how it handles when pulling a load.

 

Comanche receiver hitches are quite rare and very coveted by us Comanche people.

 

If you have any questions, please ask. Don't be embarrassed. Us weird truck people like explaining this sort of stuff. Also, post pics. Lots of pics. :thumbsup:

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The 2.5 with an auto should be up to the task of pulling 1500lbs. I've loaded that (and more) in the bed of my 2.5/AX4 with little issue. It does feel sluggish, what with the 3.55 gears in mine and 31's, but it isn't as bad as you think. I wholeheartedly agree with the tranny cooler, and I'd also throw on an electric fan set up to free up some power. Other than that, love the 2.5 for what it is. 

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I would not assume the gear ratio......lots of things could have been changed in 26 years.......even the tag that should be there could be wrong as to what is inside......be sure .....and at the same time do some maintainance.....jack up your rear and put it on stands....put a pan under your rearend and take off the diff cover and drain the fluid....your ratio will be stamped on your ring gear...cover back on and new gear oil....$10 worth of maintainance and no more guessing  :thumbsup:

 

 

FYI mine is a 2.5 AX5 with 4.11's amd I run 31" tires.....I have pulled many trailers.....had to downshift on the inclines but we made it. . :MJ 1: .

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I would not assume the gear ratio......lots of things could have been changed in 26 years.......even the tag that should be there could be wrong as to what is inside......be sure .....and at the same time do some maintainance.....jack up your rear and put it on stands....put a pan under your rearend and take off the diff cover and drain the fluid....your ratio will be stamped on your ring gear...cover back on and new gear oil....$10 worth of maintainance and no more guessing  :thumbsup:

 

 

FYI mine is a 2.5 AX5 with 4.11's amd I run 31" tires.....I have pulled many trailers.....had to downshift on the inclines but we made it. . :MJ 1: .

 

This is good advice. Never assume something just because a data sheet says so. Jeeps of this era (it got better after '87, though) were very much thrown together from the parts bin with no real rhyme or reason. Verify things yourself, and chances are the diff needs new oil anyway :thumbsup: It's hard to mess up a gear oil change too so it's a good way to become more familiar with how your truck works without getting into danger.

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Thanks all for the info and tips. I have a summer with plenty of afternoon and weekend time. So I plan to do a lot of maintenance to get my truck in tip top shape. This weekend I now plan to change the oil in my differential and then finalize what my gears actually are. And also gonna pull my water pump and check it hoping that's the cause of my recent over heating. I'll probably have questions regarding that soon enough lol. And with the towing when my truck is running well I'll test it out and get back. The lakes I plan to go to are just about 15 minutes away. No long trips while towing so donno if getting an auxillary cooler will be necessary. But if you all advise it. I'll definitely look into it.

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Welcome to the site. There are a few of us 4cyl freaks here so don't be afraid to ask questions. In mine there was a dummy pulley in the place of the power steering pump. I couldn't find a stock pump with a resevior or pulley so a trip to the junkyard to get a complete setup would be best. I had to make a resevior from seething else work and found a new pulley through Mopar restoration parts at the dealer. You'll need a gear too and this is a good time to get a better one than stock. Do some research here about upgrade power steering boxes and you'll be all set. Another great 4cyl reference is www.4bangerjp.com for performance upgrade ideas. Good luck and keep us updated

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Well thank you and thats good to know.  Ill consider myself a 4 cylc freak, it is all I got lol.  This weekend after pay day, ill be ordering a water pump, and begin replacing that, gonna replace the valve cover gasket had a slight oil leak, and gonna replace the oil in my axle.  Just picked up some an hour ago.  Got lots of plans this weekend and once I get the required maintenance done Ill start looking into the upgrades like power steering. and will be doing the research then.   Thanks so much for the help

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BTW, I have a strong suspicion that the P/S system on my 6 banger 94 ZJ drops into my 87 2.5 Comanche. I'll know for sure when I swap in a '96 P/S pump and bracket into the ZJ.

I have the complete 4.0l powersteering set up from a 94 XJ on my 2.5l,bolted right up.

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BTW, I have a strong suspicion that the P/S system on my 6 banger 94 ZJ drops into my 87 2.5 Comanche. I'll know for sure when I swap in a '96 P/S pump and bracket into the ZJ.

I have the complete 4.0l powersteering set up from a 94 XJ on my 2.5l,bolted right up.

 

Nice! Am I to assume that the ZJ and XJ set up is the same?

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Havent looked at one in a while but I think they interchange.

 

Only issue with the 4.0l pump is the reservoir, it may interfere with the stock air box. I don't have any of the stock stuff on mine so I can't confirm but it looks like they would interfere with each other.

 

Originally I had a 2.5l pump with a reservoir from a BMW, it started having problems so I swapped in a 4.0l one I had laying around and its been that way ever since.

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The 2.5 version has a remote resevior and the 4.0 has one built to the pump. The airbox may be an issue. I found that the stock resevior from a Dodge Journey has the right sized fittings for the stock Comanche 2.5 pump return and supply hoses. I made a custom bracket to mount it. I also removed my airbox and install a "cold" air intake at the same time, so plenty of room to mount stuff after that.

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Just pulled my water pump this afternoon, it didnt seem like there was anything wrong with it, but I hope that there is because I have no clue what else could be causing my overheating problem.  Just ordered another pump so should have everything back on next week.  if it doesnt fix it i don't know what it could be.  I'm so impatient and want to get it back up and running to add the things I want to it.

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Have you changed the thermostat? You should do that when you do a water pump anyways. Also flush through the radiator with a garden hose to make sure it has flow. Do you still have the fan shroud on? The stock fan needs a shroud to direct all the air through the radiator too.

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Yeah I have replaced the thermostat and still overheated.  I checked the tstat first with hot water to see it working properly.   I will do the radiator flushing when I get a chance, do i just take a fully running hose to the top and all should be running out the bottom with out it over flowing the top?  and Yes the fan shroud has been on the whole time.  Thanks for the help and suggestions

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I considered maybe a head gasket but wouldnt that mean Id see evidence with oil and coolant mixing?  and how do I know if I have a bad fan clutch?  Ill definitely just get back after Ive replaced my water pump.  and see if that does the trick

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If you have plans both the replace and water pump and to install power steering, plan ahead. It was possible to get the 2.5L with power steering either with multiple vee belts, or with a single serpentine belt. This is important, because the serpentine belt spins the water pump in the opposite direction.

 

Yes, there are TWO water pump part numbers, one for vee belts and one for serpentine belts. Externally they look the same and you can install the wrong one without ever knowing it -- except that it won't circulate coolant, and you'll have a constant overheating problem.

 

Get your power steering setup squared away and choose compatible parts.

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I do plan to get power steering eventually. I just want to get my truck in operation as quick as possible.  Ill do the power steering upgrade later this summer.  And as for replacing the water pump, I made sure I ordered the correct one.  I had to get the reverse rotating one, I have a single serpentine belt. 

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