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Topic Review (Newest First)
03-07-2010 11:25 PM
kilgoretrout844 The only time my torque wrench comes out is on critical engine parts, and certain suspension. I have never even heard of people useing a torque wrench on spark plugs before, cant be a bad idea I guess but overkill if you ask me. I work in the automotive field and can tell you the torque wrench could probably see more use than it does in the shops, but like said above time is money and all that. But this is a tune up...snug em down
03-07-2010 11:16 PM
rrich Drain plug? I guess you missed the whole point.

Do what you want.
03-07-2010 11:11 PM
s3nt3nc3d
Quote:
Originally Posted by rrich View Post
No, it's not really critical. Up to 5% or so power isn't important if you aren't looking for every littly pony.
Passing smog may not be important either. The higher emissions might be just enough to fail, but a new cat can usually cover it up enough.
A little better gas mileage isn't important either.

Sure, you can live your life "getting away" with things.

I've found it's never wrong to do things right "the first time."
I'm not saying it's the right way to do things...but I can tell you half the shops around here don't use torque wrenches (which is why I do most of my own work when it's something I can handle...they tend to use impact wrenches and overtorque everything they touch). These are all "professional auto shops"...some are chains, some are mom & pop places. Every one I've been in has operated the same way though. Impact wrenches are faster...torque wrenches take time and time is money.

I can also tell you that my old Dodge Dakota was rated at 14 city/19 highway (Source: Side-by-Side Comparison). It consistently got that until I changed my oil, oil filter, spark plugs, wires, distributor cap and rotor, and O2 sensors...all without the use of a torque wrench. I then began to get approximately 16 city (usually closer to 17) and no less than 20 highway (got 24 multiple times). Used the same gas as always (not to mention most gas stations are switching TO gas with ethanol added and not FROM it). Yeah, my mileage increased considerably. All without the use of a torque wrench.

Does that mean it's going to work on every vehicle I own...of course not. But I don't think it's NEARLY as crucial on everyday vehicles as you make it out to be. Does it hurt? Not hardly...but unless I'm working on something crucial, I'm not going to go pick up/borrow a torque wrench. Those things ain't cheap.

Just curious for the rest of the members here... how many of you utilize a torque wrench religiously while working on your Jeep? How many of the shops you take your stuff to utilize them religiously? How many utilize impact wrenches/air ratchets?

But thanks rrich...when somebody asks how to get better gas mileage in their Jeep, I'll be sure to recommend that they buy a torque wrench and make sure their oil pan drain plug is torqued properly because they could gain up to 5% more power.
03-07-2010 10:14 PM
rrich No, it's not really critical. Up to 5% or so power isn't important if you aren't looking for every littly pony.
Passing smog may not be important either. The higher emissions might be just enough to fail, but a new cat can usually cover it up enough.
A little better gas mileage isn't important either.

Sure, you can live your life "getting away" with things.

I've found it's never wrong to do things right "the first time."
03-07-2010 02:12 PM
Jerry Bransford
Quote:
Originally Posted by koz555 View Post
thanks guys, jerry i bought the ap985 spark plugs, do i have to worry about the gap on the plugs or are they already set to the correct gap? also im having trouble finding the brass rotor, i found brass connections on the distributor cap.. will it make a difference if i dont use brass on the rotor? just having problems finding it and auto zone keeps ordering the wrong one with out the brass and i need my jeep up and running by tommorrow morning.. thanks ahead of time guys,,
You can run an aluminum tipped rotor with the brass distributor, no worries. You should not have to worry about gapping those AP985 plugs to the required .035, the spark plug manufacturers are really pretty good about pre-gapping them to the right gap for the application. I haven't had to set the gap on new plugs in years.
03-07-2010 12:45 PM
s3nt3nc3d Yeah...rrich, I realize it's important, but IMO, on certain things it's not crucial as long as you can get it in the general ballpark. It's also easy to know after you've overtorqued a few bolts where you stand as well... nothing worse than stripping out the threads on something in a location where it's gonna be a biatch to retap it.

The big thing is... most auto shops around here don't use torque wrenches on anything other than major engine components where the proper torque can mean the difference between your engine running properly or not running for long...if at all. Does that make it right? No. But I figure if they can usually get away with not using a torque wrench for brakes, spark plugs, wheels, suspension components, etc, etc, I think we're pretty safe using reasonable judgement when it comes to spark plugs and oil fill plugs. lol
03-07-2010 12:41 PM
koz555 thanks guys, jerry i bought the ap985 spark plugs, do i have to worry about the gap on the plugs or are they already set to the correct gap? also im having trouble finding the brass rotor, i found brass connections on the distributor cap.. will it make a difference if i dont use brass on the rotor? just having problems finding it and auto zone keeps ordering the wrong one with out the brass and i need my jeep up and running by tommorrow morning.. thanks ahead of time guys,,
03-07-2010 11:30 AM
Jerry Bransford I have several torque wrenches but I don't use either for spark plugs. Here's the secret... use a 3/8" drive ratchet wrench for spark plugs & you'll be able to get them tight enough without fear of getting them too tight like could easily be done with a 1/2" drive ratchet wrench. I get them pretty snug with the 3/8" drive ratchet wrench and know they've been installed with the right tightness.

As recommended above, just a touch of anti-seize on the spark plug threads is a good idea.

Same thing on the oil plug, it doesn't have to be super tight though I do use a 1/2" drive ratchet wrench there. I tighten it to just below one grunt's worth of tightness, making sure I threaded it in all the way by hand first so as to prevent cross-threading it like the monkeys at Jiffy Lube like to do.

P.S. A great spark plug for your '98 is an Autolite AP985 which will run well for pretty darned close to 100K miles. If you install new ignition wires, avoid the "low resistance" type wires. That low-resistance malarky is a marketing gimmick because of course low resistance does sound good. The truth is that factory wiring is more expensive to make because they purposely add resistance to it to cure several problems caused by low resistance wires when used in an ignition system. You can't beat OE ignition wiring, much of the aftermarket stuff is pure junk that pulls apart when you change your spark plugs the next time, not to mention that most (especially "low resistance") aftermarket ignition wiring sets add ignition noise you can hear on the radio.
03-07-2010 10:13 AM
rrich Using a torque wrench to proper tightness is important. Not just for the fact it can come loose or freeze in the hole.

First - always use a touch of anti-sieze on the threads. If you don't, your torque reading will show much higher that it really is - due to resistance of the threads dragging. Same for everything, always a light oil or something that will lubricate the clean new threads- your torque reading is to get clamping force correct. Even fresh Loc-tite is enough of a lube.
Picture tightening something with dirty or rusty threads - your reading is the thread's resistance, not the clamping. You could even tighten to spec and never have the parts touching!

On plugs with a gasket the gasket has to compress, on the tapered seat type the shell has to stretch a little to get the right sealing. Both require proper torquing.

Most of the time we put them in by hand ends up too loose. I do it all the time. Shame on me!

Now the motivation - torquing down to spec also turns the plug a little more - sometimes even 1/2 turn more. IF you are using the factory recommended plugs, that extra turning puts the ground electrode where it's not a detriment, and the spark is exposed to the most mixture to start a good fire - called Indexing.

The ground electrode in the wrong place actually creates a shadow for the spark. The flame fronts gets split into 2 fronts, then they collide after they get around the electrode. In some case it can cause inaudible ping - possibly causing damage.
And - it slows down the flame's propagation. (Picture lighting a BBQ by putting the match on the edge of the charcoal rather than the middle.) It takes the mixture a longer time to reach peak cylinder pressure. Those 2 factors can affect mileage and horsepower.

When the Champion guy showed me what happens with an internal camera and my tests on my dyno it really surprised me how much "Indexing" the plugs correctly does make a difference.

But, like everyone else, I rarely use a torque wrench too. Snug, plus a little!
03-07-2010 02:45 AM
s3nt3nc3d For stuff like that, I don't use a torque wrench... both don't require large amounts of torque so I typically just snug em up and then give a lil extra to ensure its tight. No need to crank em down hard... now for crucial stuff where tolerances are strict like when doing engine work or working on components that are crucial to your safety (suspension, brakes, etc)...that stuff I'd wanna use a torque wrench on. lol
03-07-2010 12:57 AM
nwjpr Just double checked and the manual says 27 for the plugs but that seems excessive to me. I would go with what it says on plug box (21 or 22) oil plug is 30 though.
03-07-2010 12:47 AM
koz555 ok thanks guys, i thought it was 22 on the spark plugs and 20 lbs on the oil plug.. i appreciate it.
03-07-2010 12:39 AM
nwjpr Spark plug torque is 21 ft lbs (should also say on the spark plug box). Oil plug is 30.
03-07-2010 12:31 AM
Wyominer Stu Olson has two good write-up's with pictures for the oil change ad spark plugs.
stu-offroad.com

Have fun, good luck!
03-06-2010 07:57 PM
koz555
tune up question

on a 98 sahara 4.0 , i was wondering how many lbs of torque is required on the spark plugs and oil plug as im doing a tune up tomorrow and dont have a owners manual? thanks ahead of time for the input

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