For the I6 4.0 gurus...

I have a small problem... well to what I think could be a small problem, who knows could be the end of my engine. So here's my issue. This could happen after my first start of the day, engine being ICE cold, start it for lets say 10 seconds and shut it right down. It pings, it sounds alot like heat pings but however I know it's not there's now way anything can expand in that little time, I keep trying to trace the sound but can't get far it goes on for about 5 minutes after shut down. I can feel it a little bit in the rockers when the engine is off, oil pressure is perfect, no odd sounds while it's running, coolant looks good and no oil loss at all... does anyone know what could be causing this?? Alot of people never even heard of this before me.

I've driven 4 XJs and they all did this. Not loud, just a quiet tapping.

Really? mine never did this until the end of winter... huh... so I guess I should add it do the normal sound list now haha

mine does it before it gets warm...

wait I am confused..
when you say pinging.. are you talking about "pinging"
http://en.wikipedia.org/wiki/Engine_knocking

or are you talking about engine run on... http://en.wikipedia.org/wiki/Dieseling

or are you talking about the ticking that metal and things do when they heat up? tick tick tick tick...?

My first read of your post makes me think heat popping. which would point me right at your catalytic converter. they are usually the culprit for 'heat expansion' ticking and will heat up very quickly, especially if they are getting old and clogged, or if the catalyst has turned in the housing and is blocking air flow.
I would love to hear a recording of it....

My 2000 xj did it this past winter. It happens. I changed motor oil and added a duralube just to make sure and it went away but it's still no big deal, just annoying.

muduck18 said:

wait I am confused..
when you say pinging.. are you talking about "pinging"
http://en.wikipedia.org/wiki/Engine_knocking

or are you talking about engine run on... http://en.wikipedia.org/wiki/Dieseling

or are you talking about the ticking that metal and things do when they heat up? tick tick tick tick...?

My first read of your post makes me think heat popping. which would point me right at your catalytic converter. they are usually the culprit for 'heat expansion' ticking and will heat up very quickly, especially if they are getting old and clogged, or if the catalyst has turned in the housing and is blocking air flow.
I would love to hear a recording of it....

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I'll try to record it when I get off duty, but TECHNICALLY it sounds like really slow lifter tic, but remember this is while the engine is off, and cold. it will do it for about 5, 6 minutes after shut down. It could only be running for 10 seconds for the first start of the day and it will do it. Also Cat is brand new, it's definitely not dieseling, or heat pings, just slow ticks... and like I said if you stick your hand in the valve cover while it's off you can feel the tick via rockers... but I'm not positive it's coming from the top end I can just feel it better there.

sorry I did not see what year we are talking about here. Also Mine ticks too as the metal cools down. it could be that you have a hairline crack in a manifold or that a bolt/nut is contracting at a different rate or loose. After a few minutes the exhaust would have heat on it due to the combustion. The material is less than the block or the head so it would cool faster as well. I am just used to hearing it on all the rigs up here in Kodiak... even our brand new gvs do it. Some of our rigs have rattles in the exhaust until they warm up and its coming from the shield on the cat usually.

Stihl029 said:

sorry I did not see what year we are talking about here. Also Mine ticks too as the metal cools down. it could be that you have a hairline crack in a manifold or that a bolt/nut is contracting at a different rate or loose. After a few minutes the exhaust would have heat on it due to the combustion. The material is less than the block or the head so it would cool faster as well. I am just used to hearing it on all the rigs up here in Kodiak... even our brand new gvs do it. Some of our rigs have rattles in the exhaust until they warm up and its coming from the shield on the cat usually.

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Its a 95 sorry about that, yea that's heat ping your talking about. it's definitely not that. The engine can be cold as ice. start it for 6 seconds shut it off and it will do this slow ping/tic that sounds heavier that heat pings

I can't imagine any noise it makes when turned off would be cause for concern. All of the cherokees I have owned made enough weird noises at times to worry about when they were running:yap:. Only thing I can think ofthat isn't related to engine metal expansion would be lifter drain down or some sort of oil pressure bleed back.

Mine does it as well.

Justpunchit said:

I'll try to record it when I get off duty, but TECHNICALLY it sounds like really slow lifter tic, but remember this is while the engine is off, and cold. it will do it for about 5, 6 minutes after shut down. It could only be running for 10 seconds for the first start of the day and it will do it. Also Cat is brand new, it's definitely not dieseling, or heat pings, just slow ticks... and like I said if you stick your hand in the valve cover while it's off you can feel the tick via rockers... but I'm not positive it's coming from the top end I can just feel it better there.

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ok, that's what I thought,
and it sounds the same if it was run for 5 seconds or 3 hours?

it sounds like a slow release of "stored" energy? or like an electronic propulsion?...
My first guess would be the manifold or exhaust system. they do collect heat quickly and make those ticking sounds.
But it could also be a portion of your oil delivery? maybe oil draining from the valve cover back to the pan?
Vacuum system? is it the vacuum system letting go? (check this by moving your heating dials in the jeep to ac or heat, and move the temp back/forth. this will drain the vacuum canister and ensure that the system is drained then see if the ticking is still there.

Air conditioning/defrost. try running the engine like this but look to see if the climate control knob is in the ac/ or defrost (both run the A/C compressor and, if it leaks it could be releasing energy slowly)

well thats the end of my brain fart session for today.
Good luck to you, and it might be one to chalk up to "Cherokee"...

Justpunchit said:

Its a 95 sorry about that, yea that's heat ping your talking about. it's definitely not that. The engine can be cold as ice. start it for 6 seconds shut it off and it will do this slow ping/tic that sounds heavier that heat pings

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Mine did that too for a while. I'm not sure what changed, but it went away on its own. It definitely wasn't ticket as you could cause it by cranking the engine over without starting it.

The exhaust manifolds on these engines are pieces of exhaust pipe welded together. The make more noise than cast iron when expanding and contracting due to changes in temperature. Ignore it.

lawsoncl said:

Mine did that too for a while. I'm not sure what changed, but it went away on its own. It definitely wasn't ticket as you could cause it by cranking the engine over without starting it.

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IIRC I noted the same weird noise on a cold engine after a brief run for a minute or 2.

Mine makes so many scary noises, and has done so for so many miles (40,000, and up to 269,000 on the ODO) and years, I ignore them unless they are new!