2.9 Bronco II engine noise sounds bad with AUDIO AND VIDEO!

[Tedybear]

Ok Campers.

I'm not sure what to make of this. So I'll post the youtube video and hope it works so we can figure this out--and how much downtime/repair it is going to take.



I removed the valve cover and the heat riser to check for exhaust leaks at the manifold and the pipe. We have a very minor leak at the flange--but nothing that would create this noise.

I didn't note anything odd when we ran the engine without the valve cover, but then again we couldn't run it more then a few moments due to the oil mess we created.

It sounds loudest under load. If I remove the spark plug wire at the rear left cylinder (It's the one passenger side rearmost.) The noise all but vanishes. (does it very faintly....but not anywhere near as bad) So I'm pretty convinced it's centering on that cylinder---but I've not a clue as what the issue could be? Currently it's off the road (parked) until we can determine what is going on.

Please look at and listen to the video. Any advice is very welcome. As mentioned before: The compression test was 180 and 170 for the entire engine. The other issue was running very poorly when stone cold--so we pulled the plugs--checked great. Compression tested good. Pulled the intake plenum and serviced the injectors. (cleaned and blew out the filter socks. Not sure if that solved the rough running when stone cold at this point.

Thanks in advance all. If this is going to run into a lot of time and $$? I'll probably wind up driving the truck to the family 'barn' and working at it in my spare time. We have it in a garage currently while the rental property is being redecorated (warmer to work in....but loosing it in a few weeks time)

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[ab_slack]

I can't see a video here.

 

[Tedybear]

I can't see a video here.

Odd. It's showing up on my screen in the post.

Let me grab the physical URL.

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[Tedybear]

http://www.youtube.com/watch?v=7RD9j6ki8Qc

I'm not sure why the video didn't work. But that's the direct URL to the video.

Thanks again to everyone!!

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[RonD]

If removing spark on a cylinder reduces the noise alot then it is either an exhaust leak on that port of the manifold
Or a rod bearing


Rod bearing knock noise is caused by the cylinder firing.
crank journal has just pulled rod/piston down after TDC, this leaves a slight gap at the top of the spun or elongated rod bearing, when cylinder fires it slaps rod to crank, metal to metal, and you get "the knock"

If cylinder is not firing then almost no knock could be heard over engine noise.

 

[Tedybear]

If removing spark on a cylinder reduces the noise alot then it is either an exhaust leak on that port of the manifold
Or a rod bearing


Rod bearing knock noise is caused by the cylinder firing.
crank journal has just pulled rod/piston down after TDC, this leaves a slight gap at the top of the spun or elongated rod bearing, when cylinder fires it slaps rod to crank, metal to metal, and you get "the knock"

If cylinder is not firing then almost no knock could be heard over engine noise.

I'm hopeful it's something that is easier to deal with then a bad rod bearing. Sad part is? This engine has a lot of rattles and knocks that have always been very 'minor' (As the tech at the local ford garage said--I have (or had) one of the quietest 2.9 engines that he has ever heard)

I'm going to drive it up to the barn at the parents place. This is clearly going to take a lot longer to resolve then the few weeks that I have to work with the actual garage. Plus the air compressor is up there. Provided I can get the darn thing to fire up? (The electric is very weak--It has a limited amp service) I'll pick up a leak down fitting or the kit and see what happens.

Best plan of action--(unless someone else has heard that exact noise before and can chime in with more info---PLEASE DO!! I need all the ideas I can get)

Drive it back to the barn where the compressor is. Pull the valve cover again and put that cylinder to TDC and hit it with compressed air. See where I get any leaks. I suppose it is very possible that the exhaust valve guide/seat may have an issue I've not found yet--and perhaps I'm hearing exhaust "Squirting" up and out of the valve guide? This just sounds more like exhaust then a bearing.... This is going to suck--as we replaced the heads with new ones from World Products when we purchased it.

Not sure why we would have such strong compression readings if that was the case? But clearly the ol' girl is feeling pretty bad.

Again, my thanks. Anyone else have ideas? Feel free to post 'em. I'm willing to take the time to get this right, as I have a connection to this ol' girl.

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[jhammel85]

Judging by the video, I would suspect a rod knock too

 

[RonD]

If you have the spark plug out of that cylinder rotate crank until cylinder gets to TDC and then go past TDC so piston is being pulled down by crank.
Put a wedge in fan belt to hold crank
Push down on the top of the piston, if it moves and you hear a metal clank noise..........rod bearing


You couldn't get that loud of a noise even if valve guide seal was missing, exhaust port is just too big and guide too small to push that much pressure out the guide.

 

[Tedybear]

I posted the youtube vid over to Eric the Car Guy early today. He's not 100% sure, but he stated it sounds like a good sized exhaust leak.

There is the flange leak--but the "Timing" of the leak is all wrong. I can hear the popping sound--but it's not at the same time as the "pulse" of the flange leak. (Besides--that would happen no matter which plug wire I pulled on that side.)


Best thing I can probably do at this point is the test Ron stated--and also do a cylinder leak down test. I'm wondering what the chances of an exhaust port crack into the valve cover area would be? The heavy blow by seems to also happen at the same time that "Pop" sound happens. The pop sound happens at the same time the "blow by" gasses seem to worsen out of the oil filler neck. And removing the spark from that cylinder? The blow by "Smoke" pulsation seems to vanish a great deal. (Still has some---but with the engine under slight load---the "Pop" happens..and we get almost a matched increase in the smoke show for an instant but only if I have spark on that cylinder.)

I think the only move forward would be to check that piston for slop. Then make plans on pulling the head and doing a complete inspection.

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