Name that engine noise...Please help! - Page 2 - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #11 of (permalink) Old 09-24-2003, 03:44 PM
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Re: Name that engine noise...Please help!

Oh and one more thing! You say you put a new distributor in it right!!! Are you sure its timed right, that can cause an engine to diesel and spark knock. Usually when it's in that area it kinda gives a spitting cough sputter when you shut it off!! Just another thought!!!!
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post #12 of (permalink) Old 10-05-2003, 06:05 PM Thread Starter
 
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Re: Name that engine noise...Please help!

Well I thought I was on the right track there with exhaust leak at the manifold. Went thru the trouble of pulling the intake and exhaust manifold to put in a gasket. For the archives, I got a Fel-Pro MS90949 manifold gasket set ($22) that comes with the 2 manifold gaskets (exhaust and intake) and a rubber o-ring like gasket and roundish paper gasket. I have no idea what the o-ring and round gasket were for so I didn't use them. Anyway, all in all the job wasn't too bad notwithstanding the 2 broken manifold bolts. One came out easy with the screw extractor, on the other I broke my screw extractor in the broken bolt [img]images/graemlins/cussing.gif[/img]. (Also, for what it's worth, there is no exhaust manifold gasket there from the factory...just metal to metal. There was an intake gasket there though.) Put it all back together minus the one exhaust manifold bolt, and guess what? The sound...chit, chit, chit... is still there. Oh well. Chaulk it up as a "been there, done that" experience. My Jeep buddy laughed at me and said "I told you so". "That noise is just the sound of a high mileage 258." I don't know, maybe he's right. But I'm not giving in just yet. When I get some time again, I'm probably gonna pop the valve cover and check the upper valve train for a broken spring or some valve abnormality. I'll also investigate the other leads by checking my plugs and timing again.

Mike
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post #13 of (permalink) Old 10-05-2003, 06:45 PM
 
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Re: Name that engine noise...Please help!

This may sound silly but just what size gears are you running and what is your tire size?
What I'm getting at is luging. If you are running to tall of gears with to tall of tires [img]images/graemlins/cool.gif[/img], 3;07 and say 32" tire and do a lot of driving you can lug a motor down and not even know it, but over time the piston slap that occurs doing this will tell on a motor. It's possible to crack or even break the piston skit off below the wrist pin and still operate normal but you get a high rpm knock due to piston wabble. I have seen this happen on lots of road queens, (not saying you have one) when I was a heavy line mech for Jeep years ago.

[img]images/graemlins/blush.gif[/img] I even had it happen to a Jeep owned. tall gears and tall tires and using 5th gear on the highway did it in over time. pulled the pan one day hand found all the skirt from #5 piston in the pan.

This is just another option on the noise and may not have anything to do with yours. [img]images/graemlins/grin.gif[/img]
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post #14 of (permalink) Old 10-05-2003, 08:48 PM Thread Starter
 
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Re: Name that engine noise...Please help!

Interesting. I'm running 30" tall tires with stock gearing...which I'm not even sure what mine are. I believe my rear is Dana 35c. But not sure of the gears. Stock tire height was 28" if I recall correctly. And I do do alot of 5th gear highway driving, but never really noticed the motor lugging.

No offense taken to the road queen mock. It's true anyway. I bought the Jeep years ago for the snow we get up here in NJ and it just eventually became my daily driver.
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post #15 of (permalink) Old 10-26-2003, 06:33 PM Thread Starter
 
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Re: Name that engine noise...Please help!

Well I finally got around to looking at some of the other leads suggested. Pulled the valve cover. The springs, rockers and pushrods all look good so I don't think that was the noise source.

Checked the timing and it was off a bit. Maybe it's just me, but adjusting the timing in this carbed 258 is a PITA. Anyway, I reset it to factory specs (9 deg BTDC at 1600 rpm) and the motor ran like crap. Idled real low and rough and didn't pull past 3000 rpm. So I reset it to where it runs and idles better...9 deg BTDC at about 1000 rpm. Either way the noise was still there.

Went snooping around some more with my mechanics stethascope, and long behold, I swear the noise is coming from the fuel pump on the side of the engine. Replaced it with a new one and the darn thing still makes a racket. Is every one's mechanical fuel pump this noisy?

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post #16 of (permalink) Old 10-26-2003, 07:38 PM
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Re: Name that engine noise...Please help!

Can you run it by either gravity feed or electric fuel pump with the pump removed?
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post #17 of (permalink) Old 10-27-2003, 10:18 AM Thread Starter
 
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Re: Name that engine noise...Please help!

Well I'd like to run it in the garage with the pump removed to see if the noise goes away completely. A gravity feed system should do the trick for that. I'd do that first before I invested in an electric pump setup. I guess I'd need to do a search on it also since I don't think I'm ingenious enough to figure out which electric pump to get and how to wire it up safely and properly.
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post #18 of (permalink) Old 10-27-2003, 10:39 AM
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Re: Name that engine noise...Please help!

When you're at a yard sale and see a outboard motor tank for sale, pick it up if it's cheap. You can use it as a portable fuel tank and all you do is squeeze the bulb once in a while to keep the carb fed.
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post #19 of (permalink) Old 10-27-2003, 10:55 AM Thread Starter
 
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Re: Name that engine noise...Please help!

I'm beginning to think the worn cam that Leve indicated may be it. Specifically the lobe that drives the fuel pump. That might explain why the new pump still exhibits the same noise.
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post #20 of (permalink) Old 11-03-2003, 05:07 PM Thread Starter
 
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Re: Name that engine noise...Please help!

Well I removed the fuel pump, covered the hole in the side of the block and gravity fed some fuel to the carb via an old coffee can. Noise is gone! I'm convinced now that the chit-chit-chit I was trying to describe in my first message is the fuel pump. As indicated above, I replaced the pump with a new one and the noise remains. I assume the cam lobe that drives the pump lever is worn and above a certain RPM (about 1500) the "slapping" of the lever against the cam is causing the noise. Damn it's annoying...like tinnitus (which I have by the way).

Time to start a new thread about possibly wiring in an electric fuel pump.
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