Knock and crunch from front of engine

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
On my drive home from work I started hearing some strange noises coming from the front end.... almost like gravel being spit up under the hood.

Upon closer inspection I notice an inconsistent but rhythmic knock coming from the front of the engine with an occasional "crunch". Reminds me of dropping gravel down a pipe almost.

I pulled the belt and spun every accessory. No noise to speak of from the idler or tensioner pulleys. PS pump seemed fine, AC was smooth and noiseless.

The water pump was done by me(duralast) less than 30k miles ago yet it has a slight bearing noise to it - if I had a wheel bearing making this noise without a load on it I'd say it's bad. But that doesn't explain the rhythmic knock. I did notice the occasional "crunch" when I spun the water pump though. It also sort of reminds me of a "water hammer" noise as small water bubbles work their way out of plumbing.

I started the car with no accessories and had no knock or crunch - although I notice that I had what felt like an occasional miss, probably a different issue at this point however.

So... stupid question - probably the water pump, right?
If I hadn't done the diagnostics I just did, I'd be worried about a cam bearing or bits and pieces getting caught in the timing gear/chain.
 

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
mrphoenix80 said:
Sounds like you on the right track to me. Try to see if any up, down, left, or right movement.

No movement to speak of when I took the belt off. Trying to wiggle it by hand and it moves almost imperceivably - like "spindle style" new wheel bearings will have a few thousands "wiggle" at the wheel edge. Running the truck without the belt yielded no noise. I'm convinced it's an accessory - and the way they mount makes me suspect that the water pump is the only thing that could make this noise and have the noise seem to come from the block. Is it possible for pieces of the impeller to break off and be bounced around inside the cavity? I swear that's what it sounds like. The sound almost disappears when driving if you let off the gas or if you rev high enough. Under slight load it's real bad, and at idle in park it's bad.
 

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
The noise has virtually disappeared, and I've done nothing to it. I'm starting to develop a "miss", but I think that's unrelated.
 

Mechanicman

Member
Mar 15, 2013
2
Noises from engine's don't virtually disappear, not in my experiences. And a miss from your engine, that just occurs , I'm sure is related.


I am having the same issue. A loud rapping but not a constant noise, like a rod bearing would. I have narrowed the noise to the timing chain cover area.

Never have I worked on this new style engine before, I attempted to inspect the timing chain, by removing the front cover.......

What a miserable engine to work on! ( I bought the Haynes Manual, it helped a little)

To remove the timing cover, you have to remove the oil pan ( the sump tube is connected to the front cover).

To remove the oil pan you have to remove the split differentials which are bolted to the oil pan ( and could possibly be seized in the oil pan) and the rack and pinion.

In fear of not wanting to break the oil pan, I removed the engine, which made disassemble a breeze.

After removing the oil pan, and finally the front cover..... I was hoping something, was going to fall out.

The only thing I could possibly see making the rapping noise, is the timing chain tensioner.

As I rotate the engine (on a stand) the tensioner collapses ( from about 3/8" extension) and knocks ( when it bottoms out) almost every half revolution.

To my knowledge that would be created by the pre load of the valve springs, but the the tensioner is bottoming out.

I have seen similar tensioners in the pontiac quad 4, 2.3L and in the Lumina 3.4L

Both of those styles were spring loaded, and you have to watch were the pieces go on disassemble, when it flies apart! lol

This 4.2L tensioner to me, seems weak and doesn't ratchet, maybe they have redesigned it, I'm not sure.

Does anyone have the information on how this tensioner works?

I would also like to know the timing mark for the crankshaft, which way is it supposed to point? Up or down? From the manual it says every 7th link is marked black.

So I assume, as long as the crankshaft/ camshaft timing marks are lined up with a black link, it's timed???

Any help will be much appreciated.
 

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
Well - now I've got a valvey diesely noise at part throttle. At about 2800 rpm it disappears. Strange. I'm going to pull the CPASV tomorrow and check it.
 

Phantom

Member
Jun 17, 2012
277
Mechanicman said:
Noises from engine's don't virtually disappear, not in my experiences. And a miss from your engine, that just occurs , I'm sure is related.


I am having the same issue. A loud rapping but not a constant noise, like a rod bearing would. I have narrowed the noise to the timing chain cover area.

We had a noise similar to this when the water pump went. at first i thought it was in the timing chain cover. but then i took the belt off and you could wiggle the water pump up and down a little. It sounded like i had marbles in the timing chain area. I believe that Voymom has a video on it. I believe that the thread was dont tell me its a rocker but im not positive.
 

Mechanicman

Member
Mar 15, 2013
2
I had just replaced the water pump thinking that was the noise....being loose and all. But that didn't change the noise.
 

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
So, I was waiting for the water pump to OBVIOUSLY fail (leak). I got my wish (or so I thought) this Friday past. Noticed droplets forming on the rear window as I drove to/from work. I decided to change the water pump. After removing the water pump, I found that the fitting for my transmission cooler return line had come loose right above the frame rail on the left side. It was ATF all over my windshield, side of car, and garage floor that I'd been smelling/seeing. The rearward line had been replaced at a Ford dealership and the flair on the line was incorrect - too long - and wouldn't seat into the coupling. I removed the coupling's o-ring, drilled down a bit, reassembled and it was perfect. I had the water pump replaced under warranty at Autozone. The one I received last year must've been bad out of the box because when I installed it, I had this horrible "whoosh" noise when I accelerated. This new one is so much quieter. So, noise went away, and found/fixed a tranny leak. It also appears (probably placebo effect) that my mileage went up by 2 mpg. The bearing in the old water pump was so worn that the impeller was contacting the block - WOW.
 

TequilaWarrior

Original poster
Member
Dec 5, 2011
576
Central Pennsylvania
BONUS!!!!

Confirmed it today - since I installed the new water pump, my mpg has gone up by 2! I managed 18.4 mpg over 300 miles today. I've never made this trip with one tank of gas, ever. Totally stoked.
 

Forum Statistics

Threads
23,321
Posts
637,914
Members
18,526
Latest member
GODSBROOKS

Members Online