Noise coming from remanufactured 351w

[Godwick]

So... Long story short, I finally saved up the money to pull the trigger on a remanufactured engine. Went 1996 roller block from Tristar engines out of WI due to good online reputation and the guys are good on the phone.

This (2nd) engine they sent and I installed (first looked like hell and they made good and sent another) has been running fine (save for some distributor trouble for about 500 miles. Occasionally I get this noise:

https://youtu.be/7SkbCBA9VQg

Called Tristar about 5 months ago and they told me to change the oil and see if it came back. It came back.

It comes and goes. No loss of oil pressure when it happens. Can happen hot or cold. Thinking maybe loose rocker? Dunno. Open to speculation. Pulling cover tomorrow to check and see if all is tight.

Thoughts?


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[DirtDonk]

Well, it's not subtle, that's for sure!
Just for you-know-whats and giggles, try checking all the front pulleys and tighten the belts a little.

I know it sounds farfetched, but a local customer here had a similar noise (a bit deeper, but still close) and I gave him all the dire situation possibilities and that he should definitely have it checked out before driving it any more.
Well, they tightened the belts and it went away!

I still say it sounded like the death throws of a failing engine, but the noise has not come back since. And that was more than two years ago now!

Anyway, worth a shot. And it's free...
Unless it doesn't pan out that is. Then it could get expensive after all.

Good luck.
Oh, and his noise didn't sound like it was coming from the front accessories either. Sounded internal. Still could have been and tightening the belts just put some English on things enough to change the dynamics inside. But that's just too easy an answer.
And stranger things have happened with Broncos.%)

Paul

 

[tirewater]

Odd it didn't seem to increase with rpm.

If it's not front accessory related, I'd pull off the valve cover and see if something is loose rattling around in there.

 

[DirtDonk]

What he said. Not sure why, but rockers pulling out and pushrods getting bent or dislodged is a fairly common thing with some rebuilds.

Paul

 

[Godwick]

Cool. Thank guys. I'll tighten accessories and pull the cover tomorrow. Will report back. If it is a bent pushrod, is there a way to tell without yanking the head?


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[blubuckaroo]

Sounds like a rocker hitting the valve cover.

 

[SHX669]

Rockers hitting the "vent/oil splash baffle " in the valve covers { I couldn't use those} valve covers on my "83 351W} or maybe the cooling fins on the alternator hitting the mounting bracket.

 

[Apogee]

I would remove the accessory belts...less noise, less wind, etc. That would remove several variables from the equation that have nothing to do with the engine manufacturer.

Are you running press-in rocker arm studs or did you convert to screw-in? It could be a lot of things, but most that involve a pushrod, rocker arm, or rocker arm stud would generally result in a miss, rough idle, etc. My 351W randomly removed a stud on start up one day and it instantly dropped 50 RPM on the idle, picked up a stumble and some clickity-clack valve train noise...but not quite like what you have.

 

[AZ73]

Rockers hitting the "vent/oil splash baffle " in the valve covers { I couldn't use those} valve covers on my "83 351W} or maybe the cooling fins on the alternator hitting the mounting bracket.

X2. I couldn't run those valve covers with my rockers. They hit the baffle for the breather. I had to run a taller cover. Do you have the same noise on the other side?

 

[Apogee]

I run the Bronco script valve covers on my '86-ish 351W with Comp Cams chromoly roller rockers. They're slightly lower profile than most of the aluminum ones I've ever used on other engines, and I haven't had any interference issues. That said, the engine has what I believe is just a typical lower-lift RV cam, so I'm sure that helps.

 

[DirtDonk]

...If it is a bent pushrod, is there a way to tell without yanking the head?

No need to remove the heads. At the worst you'd have to loosen a rocker arm to remove and check a pushrod.
Some will be detectable right in place, if the valve is closed and you can easily spin the pushrod with your fingers. You would be able to see a larger bend at least.
And if there is one that's already loose, then you definitely have to look deeper into any of those.

Paul

 

[Godwick]

X2. I couldn't run those valve covers with my rockers. They hit the baffle for the breather. I had to run a taller cover. Do you have the same noise on the other side?

The noise is intermittent, otherwise I'd think you were right about it hitting. It's only occasional, and on one side. We'll see what's what when I get home tonight.

Is it too much to ask for to go fast? %)

 

[Timmy390]

You sure it's coming from up top and not from the bottom.....as in oil pan as in loose oil pump pickup tube or pump mounting bolts loose? What is the oil pressure? My 96 351W pops 55-60psi

Tim

 

[blubuckaroo]

What's really odd is it keeps the same rhythm when the engine speeds up.
Maybe an issue with the clutch arm or throwout bearing. Maybe the clutch return spring is missing?
Does the sound stop when you push the clutch pedal in?

 

[Godwick]

Clutch doesn't affect it. It does increase with the engine too, that video didn't really capture it well. Thanks all for the tips. Got a new twist today, but don't think it's related.
Engine started running rough out of the blue. Sounded a bit like the engine was missing so I went to touch the dist cap and got a prompt shock. Should note that the original noise was not occurring when this was happening. Killed the engine and pulled the cap. Saw a little burn mark. Think this could cause the misfiring?

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[Godwick]

Weird thing though was I pulled two wires off the cap while it was running and it didn't seem to affect the engine (was running rough anyway).


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[DirtDonk]

Is it just the lighting of the pic, or are the different terminals in different conditions on that cap? The one on the bottom looks practically new, but the ones in the shade look darker and more scored than the clean one.

Paul

 

[dave67fd]

You could also try to isolate the noise a bit better by using a 3ft or so piece of small diam. tubing to your ear as a stethoscope. You can also remove the breather and place the tubing near/in the hole.

As mentioned disconnect your belts to eliminate your accesories. Although it doesn't sound like it, make sure your exhaust is tight and not leaking. It can slightly mimic lifter noise.

 

[Godwick]

Is it just the lighting of the pic, or are the different terminals in different conditions on that cap? The one on the bottom looks practically new, but the ones in the shade look darker and more scored than the clean one.

Paul

That is just the sunlight hitting it. They all look about the same. Not sure about the burn mark, but the shock coupled with the burn and running rough are making me think I might just replace cap and wires.

Pulling valve cover today - will report on what I find.
Thanks again, all for the assist.

 

[SHX669]

Two more guesses ; something hitting the water pump impeller and if you have a mechanical fuel pump { i couldn't quite tell } a bolt that is too long contacting the fuel pump cam lever .