My jeep has developed a sputter over the last month and its getting more frequent. It sounds and feels like its going to stall like all cylanders are not firing. also i smell antifreeze but i dont see a leak. does this sound like antifreeze is getting into the piston causing it to sputter. i have recently added antifreeze caue it was low. both the resivore(empty) and the rad itself just a little low.

other notes if i rev the engine long enough it goes away. doesnt sputter first thing only if i drive a short distance shut it off and start it back up.

It looks to me like a gasket is leaking but i just know if it could be anything else before i get into tearing it down.

thanks
tom

Howdy Tom... If you can smell it then you can SEE IT! Small leaks cause engine failure if not attented to. Get a light and climb under her. You WILL be able to find the leak.
No the leak is not internal. Internal leaks 99.999% of the time allow compression to get into the coolant system and make the vehicle PUKE within 2 or 3 blocks of driving.
As for the "sputtering" please elaborate. Not enough information.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

thnaks jim, well thats good to know that its not internal...as for the sputter'n it like it wants to stall but doesnt. it could be in park drive doesnt matter. But when in drive its like it looses power, it'll kind of buck a bit, maybe chugg'n might be a better word to describe it. but it will go away if i wait it out or try rev up the engine. im thinking of doing a tune up to eliminate some stuff.

Have you changed your fuel filter recently????

Doesn't sound like tune up to me... Sounds like IAC or maybe maf or map.. I'd start by cleaning the iac and see what happens.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

I IAC (Idle Air Control) motor would only effect the speed of the idle. Usually sputtering is caused by miss fires, either random or sequential. If I understand what is going on, when the engine is left at slow speed for a while, it starts sputtering. If the engine is then rev'ed up it cleans up. There are 2 things that come to my mind; Dirty plugs, or dirty/leaky injectors.

An oil or carbon fowled plug will misfire when it is cold. If you rev it, it heats the plug up and puts a thermal load on it, temporarily cleaning it up.

A dirty/leaky injector will behave the same way. If it has a slow leak, it will leak all the fuel in the rail out; flooding the motor. When started, there may not be enough air flow to clear the flood. By reving it, the airflow is increased and the flood cleared. With the cylinder now running warm, it will run rich, but not misfire. A dirty injector is on the opposite side of the spectrum, but it's symptoms can be the same.

Considering how easy it is to remove plugs compared to injectors, I'd start there. Pull the plugs and inspect them. If you haven't replaced them in a while, spend the big $20 and throw some OEM plugs in it.

i'll take a closer look over the weekend and let you all know what i find.

If you suspect that the head gasket is blown, remove the spark plugs, use a pressure tester to pressurize the cooling system, wait a few munutes, and crank the engine over. If coolant is getting into the cylinders, it will spray out of the affected cylinder/s when you crank it over.

If you don't find coolant in the cylinders, check the compression, usually 120-140 PSI is normal.

'99 TJ's will set misfire code/s and set the check engine light on. Check for codes with a scan tool to find out where the problem is if the light is coming on. Some TJ's will allow you to pull codes by cycling the ignition key from Off to Run three times, leaving it in Run the last time. The codes will appear in the odometer. Misfire codes are in the P0300 range.

As Sunder wrote, replacing the spark plugs with factory type plugs is a good idea, and I would add that the cap, rotor and wire set should be changed if they are over 5 years old, or have over 60k miles on them. Any corrosion inside the wire connectors warrants immediate replacement. Lastly, the coil is a common source of failure, too. Having one in the Jeep as a trail spare is a good idea!

ok so i changed the plugs, wires, cap and rotor. didnt help. the sputter is still there. but i would like to add that it seems to happen when i come to a stop and try go again. it feels like im just tapping the gas pedal. no check engine light so i dont think its misfiring. so now i'm thinking its the injectors, is there a way to test each one or should i just replace them all? is there something else?

now on the anti-freeze leak. i think i found the general area. seems to be on the left side, the oil pan was all wet, the back part. so what i can see is it doesnt seem to be coming from the head gasket. it starts, from what i can tell, from the oil pan gasket or just above it. its dry from there up which doesnt make snce to me. but there is alot stuff in the way so i'm not 100% sure. any ideas?

one more thing i heard that the heads are prone to warping, is that true?

Oh and all the old plugs had normal ware.

Ok so now you know the leak is on the left side... Is left your left or my left?

What you need to think about is the fan blows the coolant backward. Also gravity plays it's part. Is either of the freeze plugs wet?
How far forward is there any coolant?
Have you went out at night with a light and layed under it? I have had much better luck looking at night than in the daytime.
You should be able to find the ONE DROP coming out of where the leak is.

The heads don't show warpage until they are taken off. The head bolts hold them straight. I always just put the warped ones back on the block and the head bolts tighten them up just the same as if they were straight.

In fact I haven't had a head in a shop in many years. If one has a burnt valve I just install a new one and lap it in. Then I put all new seals on the valves and install it.. Always works just fine.

Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />