Hey guys. I've had this knock problem with my ram since I picked it up back in the winter ( I knew about it when I bought it). Anyway, its with the number one cylinder. I compression tested that cylinder and it came up 112Psi I believe which I hear is normal for a truck this age. The wires, plugs, cap and rotor are all new, as well as the injector on this cylinder. The knock/ tick is so intermittent and random though. Last week I disconnected the injector wire and plug wire from this cylinder, went and fired up the truck, and the knock went away. I really don't know where to go from this, as I said it made the tick with the old set of plugs/wires, and the new ones too. The only check engine light I have is for a bad 02 sensor, but this knock occurs even when the truck is running closed loop.

 

you have a bad rod bearing on that cylinder. you should be able to fix by pulling the oil pan. dont drive it for to long or it will get worse and you will have to get a crank kit. which will invole pulling the whole crak shaft out. and geting over sized bearing.

 

'healthy' psi for the 4th stroke of a standard compression test
on a 1995 Magnum 5.2 V8 cylinder is about
145 psi dry
165 psi wet due to a tablespoon of motor oil poured thru the sparkplug hole

it is true the official Dodge FSM manual says only 100 psi
but that is generally thought to be way too low in the real world

if you get a replacement O2 sensor
try to find one of the NTK made sensors
rather than the Bosch

if you have a knock on cylinder #1
pull the valve cover on that side
and look for a broken spring or bad rocker arm
.... which is a much cheaper fix

if you want to diagnose further without
pulling the valve cover or dropping the oil pan
read up on this 'dynamic'
or running compression test procedure:

http://misterfixit.com/dyncompr.htm

this plus your dry versus wet psi reading
can give you a good idea if the problem
is due to a valve or rocker arm
instead of worn piston rings

you might also ask around to see if any friends
have a 'leak down air tester'
like this


http://www.area51groupllc.com/produc...products_id/30

1994 to 1995 Magnum v8s have an EGR system
that tends to get vacuum line leaks to the "modulating valve"
or have the valve seat of the actual EGR 'pintle' corode away
so put that on your check list.
With no EGR in the mid throttle range the programmed ignition timing
will cause pinging noises.

To see if this is the case you could fill up with 95 octane
Sunoco premium gasoline
and if the noise goes away on cylinder 1
it is EGR or carbon deposit related
rather than mechanical in origin

good luck

 

Hmm... I suppose I will have to do a little more in depth investigating. I thought I could rule a few things out because its intermittent, does not increase or decrease in proportion to engine RPM.... so it isn't frequent enough to be something mechanical ( or so I assumed ) bc now that the plug wire is disconnected the noise went away haha... I thought if it were valves / rockers the noise would be there whether that cylinder was getting spark or not?? As for the bearings suggestion... would this be a consistent noise?

 

I had a niose like that in a ford I had and it was a cracked header , just a very small crack will be louder when the engine is cold but when it heats up the noise goes away. Get you a short piece of water hose and put it to your ear and the other end in the area where you think the noise is comming from and see if you can narro it down to spot the area its comming from JMHO

 

I bought another distributor cap and rotor so I'm going to install them and see what happens. For now I just unhooked the injector and plug on that cylinder.

 

a broken heat shield on a catalytic converter caused an unknown noise that took several days to diagnose on my 1995 Ram

there are additional heat shields in the engine compartment on the firewall and above the exhaust manifolds that could cause noises

if the noise does not change with engine rpm
that is a clue to look outside the engine

 

Only problem is the noise isn't present with the #1 plug wire and injector disconnected

 

plug the wires back in and use something solid or a stethloscope and listen to wear the sound is loudest and go from there

 

this week
Home Depot stores have two 'flexible snake LED lighted Boroscopes'
on sale
one from Milwaukee $250 with a bonus lithium battery drill driver
and
one from Rigid $200 with various end of snake attachments

these devices allow you to see inside valve covers
and through the sparkplug hole into combustion chambers
without taking the engine apart

i have not yet made it to a Home Depot store to check them out more thoroughly,
but if either looks good I might buy one,
especially if either Milwaukee or Rigid company
makes extensions for the snake length,
which among other things
allows you to look down sewer pipes for intruding roots,
a trick that if caught early enough
can save hundreds/thousands of $ in plumbing emergency costs

professionally for me
it would also allow me to look up into roof bolt drill holes
at the rock strata layers,
which can be life or death matters