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General Forums => The Mess Hall => Topic started by: Bigboi on March 09, 2014, 06:40:48 AM
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Hi everyone, ive got a 98 dakota 2.5
just bored and rebuilt my 2.5 like 2,000 miles ago, i swapped out a 2.5 TB for the 4.0 TB and i didnt notice much of a mileage difference, but ive been having to drive back n forth about 37 miles each way on a highway and i am chugging gas and im only doing about 75mph
about April of 2013 i went to tampa, FL and riverview, FL from north Orlando, FL and it only consumed about 1/2 a tank of gas, but now im using about $10 for about 40 miles, im gonna check it out today, i may consider throwing on the 2.5 TB and see if that makes a difference
any input is greatly appreciated
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When you used the 4.0l tb, you did transfer the sensors from the 2.5l tb?
IIRC when you swap in the 4.0l tb and use the 2.5l sensors, you also require to swap out the injectors as well.
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calculate your exact mpg, it's hard to tell where you're at by approximating in $ or 1/2 tanks. Fill up, note the odo, drive around and fill up again, substract your initial odo reading from the new one and divide the result by the gallons you just put in.
my YJ does about 15mpg on a good day but i don't baby it. at 75mph in your case (since is not lifted or big tires) all hwy i would think it should be around 16-18mpg (just guessing here), if you drop another 10mph should get another 2mpg, something like that.
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Also check your O2 sensor and vacuum lines; both could kill your MPG rather quickly...
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At 75mph that 2.5 is under a pretty good strain. I would not expect it to get good mileage. My '01 Wrangler will get just over 20mpg at a steady 65 but will drop to maybe 16-17 at 75mph. Wind resistance kills you the faster you drive.
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At 75mph that 2.5 is under a pretty good strain. I would not expect it to get good mileage. My '01 Wrangler will get just over 20mpg at a steady 65 but will drop to maybe 16-17 at 75mph. Wind resistance kills you the faster you drive.
Yup, at 75 mph it's a struggle. I've mentioned it over in the MPG thread.
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Yup, at 75 mph it's a struggle. I've mentioned it over in the MPG thread.
before the bore and TB, i drove 260 highway miles on less than a half a tank @ no less than 75mph, i was at 85 for most of the way, i know theres no way i can find out my mpg that day, But i put $40 in that day and i came back home with a lil bit over a half a tank
I am starting to have top end noise from this head i put in a few months ago, so i may just use some valve lapping compound so Cyl #3 and #4 seal up like new again, then slap on my original head
but my truck has always ran Rich, could it be from a bad cat? i am getting a P0420 code but both my NGK o2 sensors are new, i was also told my fuel sync could be off by a few and not cause a code, i was told id need a DRB tool to scan and adjust the fuel sync, i dont know anyone with this tool and ive looked it up and its Expensive so i aint buying it
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What you have a 36 gal tank. I've never gotten 260 miles from mine on a full tank.
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What you have a 36 gal tank. I've never gotten 260 miles from mine on a full tank.
i should have a 12 gallon tank, $40-45 is about all i can fit in it
I... Believe my exhaust isnt sealing right due to one of the studs for the exhaust bolts missing, which would cause all kind of issues with the 1st o2 sensor but i am not 100% certain, i do know i am gettng a crap load of ticking, whether its related due to the nut for the exhaust missing or due to valve springs/rocker arms/tappets i am not sure at the moment but i am gonna buy some valve lapping compound and refresh my original head because it just has a little build up on the valves which caused #3 and #4 to misfire, my bottom end is fine, so i will be pulling the head off again here soon
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i should have a 12 gallon tank, $40-45 is about all i can fit in it
I... Believe my exhaust isnt sealing right due to one of the studs for the exhaust bolts missing, which would cause all kind of issues with the 1st o2 sensor but i am not 100% certain, i do know i am gettng a crap load of ticking, whether its related due to the nut for the exhaust missing or due to valve springs/rocker arms/tappets i am not sure at the moment but i am gonna buy some valve lapping compound and refresh my original head because it just has a little build up on the valves which caused #3 and #4 to misfire, my bottom end is fine, so i will be pulling the head off again here soon
The stock tank should be 15 gallons just like with the Jeeps.
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The stock tank should be 15 gallons just like with the Jeeps.
ive ran it all the way down to just below the red line on the guage and ive never been able to fit 15 gallons thats for certain, but according to Edmunds.com its:
1998 dodge dakota 2.5 4 cylinder 5 speed
Fuel type: gas
Fuel type: regular unleaded
Fuel tank capacity: 15.0 gal.
Range in miles (cty/hwy): 270.0/345.0 mi.
EPA mileage est. (cty/hwy): 18/23 mpg
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why don't you just calculate the mpg in a normal fashion, 6gal for 260miles gives you 43mpg, so you're obviously off by a large margin, I mean not even close. Even if you go with 7.5 gallons (15 gal tank) you're at 34, unless you push it won't be anywhere near that. Eyeballing the tank level gauge is really a bad way to calculate it - mine gets about 70mpg if I go by the first 1/4 of the tank according to the gauge.
1. fill the tank, reset the trip odo
2. drive some 100 miles or more (just to make it as accurate as possible, the less you drive the more margin of error)
3. fill the tank again, read the odo
4. divide the odo reading to the gallons you just put in (and include the numbers following the decimal point on the pump display).
EDIT:
official mpg numbers for '98 Dakota 2.5L 2wd
18mpg City
23mpg Hwy
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After towing a trailer today with a decent size load for the 2.5, i have to say im absolutely sure that theres an exhaust leak before the 1st o2 sensor where the header seals to the head, me and the machinist both missed the fact that theres a stud broken off on the head for the 1st bolt to the exhaust, but like i said im just gonna reuse my original head after i clean up the valves so #3 and #4 seal like new again
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i popped my hood to take a look and sure enough, 3 bolts were missing from my intake/exhaust, ive heard this is a common problem with this engine, so how do i avoid this issue again? use some kind of thread locker??
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i popped my hood to take a look and sure enough, 3 bolts were missing from my intake/exhaust, ive heard this is a common problem with this engine, so how do i avoid this issue again? use some kind of thread locker??
The front and rear-most bolts are actually studs and commonly break. Chrysler makes a replacement kit that is less likely to break.
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Uhhm, waatt???? Both of my heads have bolts for the intake/exhaust and is also shown this way in the FSM, theres 1 stud for the middle and thats all there is for studs on my original head, while the one i pulled had ALL bolts
if theres some kinda illustration/pics u can show me that would be Awesome....
i have a nice tick going on and i dont think its gasket related, tick gets louder under load
With these lifters, in my experience, i buy em from the store, prime em by hand with oil, i can press the inside all the way in No problem, with ALL of the ones ive pulled (Even newer ones with low miles) they have been locked up and i cant press the middle down as i did before installing them, Is this normal?
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With these lifters, in my experience, i buy em from the store, prime em by hand with oil, i can press the inside all the way in No problem, with ALL of the ones ive pulled (Even newer ones with low miles) they have been locked up and i cant press the middle down as i did before installing them, Is this normal?
yes, they bleed very slowly if you put like 100lbs of pressure on them, (and that means they work as expected, otherwise you have a tick).
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yes, they bleed very slowly if you put like 100lbs of pressure on them, (and that means they work as expected, otherwise you have a tick).
then i am going to get some compound and clean up my valves on my original head and reinstall it, idk if the valve job caused the tick, but its from the top end, as long as the bottom end has 0 problems ill be happy (no need to fully disassemble the engine) the head is easy to swap out
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then i am going to get some compound and clean up my valves on my original head and reinstall it, idk if the valve job caused the tick, but its from the top end, as long as the bottom end has 0 problems ill be happy (no need to fully disassemble the engine) the head is easy to swap out
the tick is most likely from your exhaust manifold.
EDIT: i suggest at least get a grind on the valves if you're not going to do the seats, otherwise you'll just make the groove deeper and will be back where you started shortly. Imo if your current head is fine (take a compression test) just leave it alone (unless you have broken studs/bolts you can't take out with it installed)
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the tick is most likely from your exhaust manifold.
EDIT: i suggest at least get a grind on the valves if you're not going to do the seats, otherwise you'll just make the groove deeper and will be back where you started shortly. Imo if your current head is fine (take a compression test) just leave it alone (unless you have broken studs/bolts you can't take out with it installed)
the front most bolt is broken off in the head which goes through the exhaust, it doesnt seem impossible, just seems like it would be a PITA to tap it and rethread it with the head in place, but i may be wrong
EDIT: Do you think running the engine with the loose bolts damaged the exhaust manifold causing the tick? because i never heard this tick before, but then again i should retap the bolt hole before replacing the gasket
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I always bleed the lifters with them installed, and use an adapter to turn the oil pump with the distributor removed. It will prime them all the way up the pushrod tubes without turning the engine over.
And anytime you replace a lifter or cam, throw some break-in additive in there with a good zinc content.
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EDIT: Do you think running the engine with the loose bolts damaged the exhaust manifold causing the tick? because i never heard this tick before, but then again i should retap the bolt hole before replacing the gasket
i don't know if that's the only tick you have but it's known with our engines that a broken bolt causes a noise which is sometimes mistaken with a lifter tick. I had the rear most broken and it was a pita to get it drilled and chase the thread, it was making a tick like noise.
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i don't know if that's the only tick you have but it's known with our engines that a broken bolt causes a noise which is sometimes mistaken with a lifter tick. I had the rear most broken and it was a pita to get it drilled and chase the thread, it was making a tick like noise.
the front most exhaust bolt is broken off, mechanic friend suggested something called "Easy out" (I think) that i can get from like home depot or lowes
would the FSM have the bolt specifications so i could look as to which bit i need to pull the broken bolt?
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EZ-Out's are a good way to make a job 1000x more difficult. Typically what happens is that you drill the bolt then when you insert the EZ-Out, it smapps off leaving a hardened steel slug in it's place.
If you can get down there, use a reverse cut drill bit. Start small and besure to center tap it. If you're lucky you'll the bolt will unscrew itself. Depending on where it broke you might be able to just unscrew it or get vice grips on it once the manifolds are off. If not you can work you way up in drill size and slowly eat the bolt up from inside. Once it gets to a certain point it will usually unthread as long as you drilled straight and didn't hit the threads.
You can see the threaded studs here. The only problem I have is that they sometimes back out, threads and all, which isn't even a problem.
(http://img.photobucket.com/albums/v239/quick_seven/ExhaustManifold100.jpg)
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the fordward most threaded stud on the cylinder head in the picture u posted is the one which is broken off inside of the head, it has nothing to grip, its broken below the head surface
theres no threaded studs on the head i just put on my engine, just bolts, my original head has the top middle threaded stud and thats it
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the fordward most threaded stud on the cylinder head in the picture u posted is the one which is broken off inside of the head, it has nothing to grip, its broken below the head surface
theres no threaded studs on the head i just put on my engine, just bolts, my original head has the top middle threaded stud and thats it
Someone's changed them then. If the hot tanked the head then they removed all of the bolts and studs anyway.
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they are 3/8 coarse thread
I drilled and tapped in the center and used a drill stop on the bit to know how much to go in (measured another hole prior to that). I started with a center punch, then a center drill to spot it and then went with a small bit and tried to keep it centered and leveled. Went higher and checked each time (don't go larger bit than the minor diameter, i was probably lower than that in the end), i was off the center by .020 or so and at some point i was able to see the tip of the threads with a mirror on one side, i got a small screwdriver in and was able to unscrew what was left in there, took like 2 hours for the bolt itself (not counting the manifolds and such), pain in the rear
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well i know that one of the valves was worn the hell down, no doubt it needed a valve job...
i hope the loud ass tick is exhaust gasket related
if the manifold gasket is leaking wouldnt that cause the 1st o2 sensors readings to be off causing a difference in the fuel mix?
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if the manifold gasket is leaking wouldnt that cause the 1st o2 sensors readings to be off causing a difference in the fuel mix?
i doubt that would make a big difference unless the hole is large (like a crack in the manifold that's open).