Still trying to figure out Ticking & knocking Sound

[Macrow]

So this is the issue that I am having currently I recently swapped motor's from my 95 Pathfinder with another 95 pathfinder. The 95 XE V6 VG30E 3.0 L 4WD Pathfinder I took the motor from was built in July of 94 & I put it into a 95 XE V6 VG30E 3.0 L 4WD Pathfinder that was built in May of 94. Swap went great other then oil dipstick getting stuck which we have currently removed & have new one in & working properly we have no leaks from any of the fluids at all which is great. The problem however that I am having now is when I start up the Pathfinder you can here a slight ticking sound which turns to a knocking sound which is all coming from the passenger side back towards the Firewall & the down pipe of the exhaust. The sound will stay there for a few minutes or so after first starting the engine up. Once it has run briefly & you begin to drive you can hear the ticking/knocking sound while barely accelerating when you let off the gas the sound goes away. You can also hear the sound very clearly when in park while lightly pushing down on the gas pedal. Now after you drive it for about 10 minutes or so this ticking/knocking sound begins to fluctuate all over from loud to not so loud the longer you drive it which then it almost goes completely away.

 

So here is my question at times it sounds like it could be a lifter going bad & other times it sounds like could be something coming from the exhaust. Has anybody else had this same problem at all & if so what was the outcome of this.

Also are there any good methods of testing that can be done to find out what is causing this sound. I do know in the FSM it mentions a few tests you can do but just not sure where to begin with them or if there are any other ways to test for what this could be caused by. Any input & help would be greatly appreciated thanks in advance.

[PathyAndTheJets]

Sounds like an exhaust leak to me, you could get a mechanic's stethoscope to narrow down whether or not its coming from the head.

 

Look for any blackening on the exhaust, that'll point to a leak in that area.

[SpecialWarr]

I have to agree with PathyAndTheJets... my first thought was the exhaust hitting something during warm-up. My exhaust wasn't welded perfectly ( my bad, I did the welding) and taps lightly on the fuel tank bash plate at times but with a broken exhaust hanger being replaced with a bolt that's not a surprise. I suspect a good look under the truck while it's running with all 4 wheels chocked and the e-brake on you should be able to find it; it is loud so you will want a set of ear plugs to filter out the noise and hone in on the problem area. I suspect that the exhaust is a tap-tap-tapping it's way through somewhere.

[k9sar]

if you don't have a stethoscope, there are a couple of other options. You can use a length of tubing, sticking one end in/against your ear and 'probing' the other end around the engine/exhaust to 'hear' the leak or source of the noise. Second, if you think it may be internal, take a length of brazing rod (or any other fairly thin rigid rod) and hold the end against the bottom of an empty veggie or soup can (think of the old string & cup phone systems as kids). Touch the free end of the rod at various places on the head, exhaust, etc and you should be able to isolate where the sound is coming from.

[Brad251]

My 88 has a cracked manifold on the pass side And it has that sound. Its hard to tell because of the heat shield. I would almost bet that's what it is. But what they said about a stethoscope is correct. They're pretty cheap. Would be worth it.

 

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[adamzan]

Rev the engine up while under the hood, if it sounds like a snapping sound more than a ticking, it's the manifolds. They will be louder under load. Lifters will go with the speed of the motor.

[Macrow]

Awesome thanks for the input & tips guys I do have a stethoscope & got the problem resolved with the knocking sound. Turned out that there was a nut missing off one of the studs in the manifold my guess is just rattled loose from not being tightened all the way. There is still a mild ticking sound coming from under the hood in that same spot which we are thinking is coming from a lifter still but not 100% on that though. Again thanks for the help & hopefully now will be able to take it up to the woods on Sunday to the plane crash up in Lyons, CO.

[Slartibartfast]

If the manifold was loose, the gasket could've burned away where it was leaking, explaining the lingering noise. A friend of mine installed an exhaust gasket backwards on his Blazer, and when we pulled it out again, part of it was burned down to the perforated metal core stuff.