Every once in a while my engine will have a faint sound like a Cummins at low speeds (like in a parking lot) when cold. Its pretty awesome to me, so I was wondering, does this happen to anyone else? Should I be worried or just kinda let it go and let it sound like a boss? It has the stock exhaust, somewhat leaky. I know they can sound like a tractor when the exhaust is taken off because of the way the engine is designed, but it sounds like a quiet non-turboed Cummins. Gotta love the straight 6

Sounds like what youre describing is a misfire on one or more cylinders...

Nope, its not that. Its a very faint sound, but noticeable. Every cylinder fires fine, not a tick in the engine. Except for the usual 4.0 noises. Runs like a champ and never lets me down. I'm just curious if anyone else ever noticed this.

I should probably add it makes the noise more under a light acceleration at low speeds. Like 5-10mph.

Mine sounds like a diesel at low speed to but i have a half arsed side exit from the previous owner and my buddies sounds like it at idle but he has a stack

If you aren't having fun with knocking check out your pulleys. If I recall correctly the 89 doesn't have a tensioner pulley so have a listen to your power steering pump and water pump.

Also, you're right that sounding like a Cummins is a problem... Detroit Diesel or go home! :P

Well, "terminal pinging", (diesel sound to me), is mentioned with the knock sensor here > http://www.lunghd.com/Tech_Articles/...iagnostics.htm It doesn't mention a test. I hear you can "rap" on it with something and the engine should change as the Renix ECU retards the timing. Guess people have had problems with a loose bracket somewhere rattling and messing up their timing, (retarding it which won't cause pinging).

Also if you put premium in it and it stops, you probably could suspect the sensor or it's wires. (On my 90 the wires going down to the lower sensors grounded on the heat shield).

All my pulleys are fine, just replaced the water pump also. And it's not a pinging or knocking sound like anything went wrong, its just the sound of the engine. I've heard pinging before and it's not that. It sounds like its just the compression of the engine or somethin. Not anything harmful. And like I said, it's only when the engine is cold and when driving at low speeds. It would ping constantly if the knock sensor went. It's a very faint sound and is only really noticeable in the cab.

Piston slap was common in these engines when cold. More of a clock/clock sound than like a lifter tick or a rod knock. Reduces or goes away when warm.

If it turns out to be multiple slight lifter ticks combined, a crankcase flush or oil brand change can help, along with MMO.

Gotta ask. What brand of oil filter are you using?

That could be it. I was thinkin that. My dirtbike kinda does the same thing when cold, so it gave me the idea. I use super tech oil and the fram filter that everyone complains about. I never had a problem with fram though, and I just heard that they were bad for the engine not too long ago. Next oil change I'll get somethin better. It's got 233k on it, so everything is pretty worn down already so I'm not too worried about the filter. As long as its lubricated I'm happy. The sound does go away when warm.

Well, you should be worried about the filter. With that many miles on it, how many more "dry starts" do you think that engine needs to finish it off?

If it were mine, I'd change just the filter to a Wix or Napa Gold right now. Don't worry about losing much oil from the filter cuz there will be very little in it. That's courtesy of Fram's crappy design and quality.

Yeah, I should probably do that. It sucks being low on cash though. How much is the Napa Gold? I think the Wix is around $20.

$20? Try $6 to $8. Versus, of course, to keep twisting the knife in the back of an already tired engine that's ticking. That won't be cheap.

Damn, really? I must have read it wrong somewhere. Looks like I'm goin out to get a new filter this week. Do they sell the Wix at Advance Auto?

They have purolator PureOne filters at advance which are made by wix