Knocking noise with engine under load

[William Sevier]

I have a 1984 Ford Bronco 2 that recently developed a slight knocking noise or popping noise, anyhow something of the sort while the engine is under load, doesn’t do it in neutral all the way through the throttle at a stop it has smooth engine noise, just has the noise when you apply throttle in any gear, but once you are at cruising speed you don’t hear it just under moderate to heavy acceleration. What should I look at? Kind of stumped on this.

Topic

[William Sevier]

Well, I have a huge carbon deposit problem thanks to the previous owner’s complete neglect. This is what’s causing the knocking, just all the deposits causing issues, along with the carburetor not being adjusted properly caused some of it, its not as bad now, I’ve started dumping a little bit of ATF into the carb and it seems to be cleaning things out slowly.

[college man]

Try a dose of sea foam.

[jay]

that year bronco I think had a 2.8 with solid lifters and adjustable valves,they could be quite noisy.

[William Sevier]

I’m planning on trying the seafoam here this weekend. Yes, it has the 2.8L V6 engine. I know about the lifters and such but its not the lifters making the noise, they rattle, but this is a knocking noise only during acceleration, the lifters rattle all the time LOL.

[EricTheCarGuy]

Noises are impossible to track down without hearing them. That said, if it’s under load perhaps you have an EGR issue. EGR helps prevent detonation and preignition under load and if it’s not functioning properly it MIGHT cause the engine to make noise. It could also be a mechanical issue such as a worn out bearing or something like that. I suppose the first step is to see if you can track down where it’s coming from. You already have half the battle won by knowing WHEN the noise occurs. Keep us posted on your progress.

[William Sevier]

[quote=”EricTheCarGuy” post=57288]Noises are impossible to track down without hearing them. That said, if it’s under load perhaps you have an EGR issue. EGR helps prevent detonation and preignition under load and if it’s not functioning properly it MIGHT cause the engine to make noise. It could also be a mechanical issue such as a worn out bearing or something like that. I suppose the first step is to see if you can track down where it’s coming from. You already have half the battle won by knowing WHEN the noise occurs. Keep us posted on your progress.

http://www.youtube.com/watch?v=6mpNRJ7m-c8%5B/quote%5D

Update to the diagnosis. My EGR valve has been disconnected since shortly after purchase due to it won’t run at all if it is connected. The knocking started about a month ago, it ran just fine without the knock for about 2-1/2 months, so it surly isn’t EGR related. The only thing I could think of is something related to the carburetor, if I adjust the carburetor just right it doesn’t knock under load anymore but the idle at that point is just too high. If it was a bearing I wouldn’t think the noise would go away with a carburetor adjustment, so I’m thinking it has to do with fuel/air mix, possibly a vacuum leak somewhere is the only thing I can figure out.

Will update more if I figure anything else out.

Thanks,
Bill

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