take a guess at odd engine noise?

-
jefframin

jefframin

http://www.jefframin.org
Joined
May 23, 2004
Messages
25
Reaction score
5
Hi folks.

I know this is almost impossible to diagnosis, but I have a ticking/tapping noise at idle that I'd be interested in hearing guesses about. It's a 340, rebuilt 15 years ago. Only has about 4000 miles on it.

I don't think the noise is new (didn't just suddenly occur), but may be getting worse over time. It seems to be emanating from the right side of the engine, but cannot say for sure. Maybe every other revolution. At warm idle (7-800 RPM), it's quite noticeable. At 1000 RPM it's less noticeable, and by 1200 RPM I can't hear it at all.

Any ideas? Thanks.
 
Last edited:
Got the same noise... but mine will go away or lessen on occasion....using a stethescope has been no help.

I will be following this .
 
Right side (passenger side) front or rear ? Does it have a mechanical fuel pump, had one with a broken spring make a rattle noise as it was bouncing off the cam.
 
brian6pac said:
Right side (passenger side) front or rear ? Does it have a mechanical fuel pump, had one with a broken spring make a rattle noise as it was bouncing off the cam.
Click to expand...

Yes, mechanical fuel pump. I don't think noise is from the fuel pump, but can't guarantee it.

Wouldn't such a situation cause other problems?
 
Pour a quart of marvel mystery oil in it and run it. If the ticking goes away it was a stuck lifter.
 
brian6pac said:
wouldn't that be once per 2 revolutions

a wrist pin is faster knock
Click to expand...

Yep, but it could also be confused with once for a lot of people I think.
Had a guy once tell me he could specifically hear the number one cylinder each time it fired because there was a miss and he thought the space in the sound meant the firing order was gone through and it was starting over (as in 18436572,,,18436572)
I had a heck of a time explaining that what he was hearing was 184365,2 (as in 7 wasn't firing) and that was the gap he was hearing.

How much patience does it take to explain that to someone without laughing at them or getting annoyed?:D
 
SO help me understand.... as the statement about 'only when in neutral' does not quite make sense. If you are stopped, and are in the car, and you push in the clutch, and engage any gear, the tapping/clicking stops?
 
nm9stheham said:
SO help me understand.... as the statement about 'only when in neutral' does not quite make sense. If you are stopped, and are in the car, and you push in the clutch, and engage any gear, the tapping/clicking stops?
Click to expand...

I meant when the car is idling. Whether it is actually in neutral or the clutch is depressed does not matter.
 
TrailBeast said:
Yep, but it could also be confused with once for a lot of people I think.
Click to expand...

Yes, I am definitely estimating things here - I didn't use a stop watch and count the number of taps/ticks. I can definitely say it's not once per revolution.
brian6pac said:
wouldn't that be once per 2 revolutions

a wrist pin is faster knock
Click to expand...

My apologies - I meant once every 2 revolutions (at least, that's my estimate). Original post has been corrected.
 
kiss said:
Pour a quart of marvel mystery oil in it and run it. If the ticking goes away it was a stuck lifter.
Click to expand...

I'm willing to try something like this before taking it to a shop...how many miles can I run the engine with the MMO in it? Within how many miles should I expect a change?
 
What 4-speed?
The O/Ds have a floating cluster pin, that is supposed to eliminate cluster rattle. Whenever the engine is running and the clutch is not depressed, the maindrive is spinning, and so is the cluster and every other gear inside that box. If the engine is not dead-smooth then the crank is continuously changing speeds. And so is the maindrive and everything else in the box. That is an easy recipe for geartrain rattle. Gear-oil is supposed to suppress that rattle. What oil are you running?
I have to admit, that I doubt your issue is in the tranny.I'm just a post-*****,lol.
But, I have heard alternators make random noises and belts too. Even cam-walk. Certain motorcycles are well known to bounce the cam from one end to the other. Randomly. A timing chain in a chevy can make that racket too. But a Mopar can have really loose chain, and it won't touch the chaincase. Although I have taken some apart that showed evidence of something slapping the case inside there,lol.I've also seen rocker arms slapping a loose baffle in the valve cover.And of course the most common one is an exhaust leak. Or a heatstove. Or a heatriser valve
 
I'd try the MMO first; if it does anything, it will do in pretty quickly. (I personally would start with a pint only.) The sticking lifter or lifter with a bad check valve are good possibilities and common causes for such noise.

Also, run your hands near and all around the exhaust manifolds on that side, trying to feel for any puffs of exhaust gases, being careful with the hot parts and belts. Exhaust leaks can make an almost tapping sound, and will often change with idle RPM.
 
Update - in my case, it was an exhaust leak. The gasket had failed.

Happily, an inexpensive problem to fix.
 
You must log in or register to reply here.
-

Back
Top