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tapping under load

My 69 F250 /390 recently developed a tapping noise under load. The noise is similar to a fan hitting something. It won't do it in park, only when pulling a hill or similar load then fades away as the load lessens. It seems to have begun after installing a new starter and the noise may even come from that area but it doesn't make sense. If the starter were hitting the flywheel it would do it in park also I would think. The starter in in properly and mounted solidly. I'd appreciate any suggestions. It has me puzzled.
 

john112deere

caffeine junkie
Staff member
10,807
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central Vermont
Tapping under load...like it's pinging? Marbles in a coffee-can kinda noise?
 

SuperCab

Moderator
Staff member
10,068
547
Montana
My 69 F250 /390 recently developed a tapping noise under load. The noise is similar to a fan hitting something. It won't do it in park, only when pulling a hill or similar load then fades away as the load lessens. It seems to have begun after installing a new starter and the noise may even come from that area but it doesn't make sense. If the starter were hitting the flywheel it would do it in park also I would think. The starter in in properly and mounted solidly. I'd appreciate any suggestions. It has me puzzled.

Maybe not. The engine 'torques' under load, that is, it moves to one side under the force of the engine. it could be hitting then. IDK. Under load though, my first thought was the same as Ian's... pinging. Just changing the starter wouldnt do that though...
 
I find it kind of humorous how the OP made a thread about "Tapping under load" and his username is "69er"... :rofl: :p
 

73F100Shortbed

That's how we roll!
5,937
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NJ
Sounds like pinging to me from the description.

As for Conner's take on it well.... 'smiliedoh'
 

flareside_thunder

Florida Chapter member
7,812
246
Grab a timing light and check your timing. Too far advanced and cause spark knock which is a pinging sound. You didn't have to remove any exhaust parts to swap starters did you? Could also be an exhaust leak.
 
Maybe not. The engine 'torques' under load, that is, it moves to one side under the force of the engine. it could be hitting then. IDK. Under load though, my first thought was the same as Ian's... pinging. Just changing the starter wouldnt do that though...

Too much clearance for it to be hitting anything. The truck would really be rocking if it torqued enough for that.

What grade of fuel are you runnin and does your 390 have higher compression pistons than stock.

Nothing unusual or different about the engine or fuel.

I find it kind of humorous how the OP made a thread about "Tapping under load" and his username is "69er"...

:nono: :rofl:

Sounds like pinging to me from the description.

Possibly. Don't think so but not ruling it out.

Grab a timing light and check your timing. Too far advanced and cause spark knock which is a pinging sound. You didn't have to remove any exhaust parts to swap starters did you? Could also be an exhaust leak.

I'll check the timing. Too many are thinking pinging so it needs to be looked at. Just did a lot of work on the truck and the exhaust was part of it. Sounds better than it has in years. Good thought though.

Do you have a mechanical temp gauge to see if the temp rises when your tapping starts ?

Yes I do have but temperature doesn't seem to be part of it at all. Thanks for all the responses. It's much appreciated.
 

1985 Ford F-150

Country Boys Can Survive
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Tooele, Utah
What I meant by that is these old motors especially the ones that were built before they changed from leaded to unleaded fuel is that they ping when ya run em on 85 grade fuel try goin mid grade or even premium if you can. You can also get lead addative that ya dump in the tank and itll do the same thing as goin to a higher grade fuel. I ran it on my last 390 and it would ping incredebly bad if I didnt do one or the other. Exhaust leak is another possiblity but it would do it all the time and just get louder under a load.
EDIT: Just thought of another thing it might be. It could be a plug wire not on quite all the way that will make a kind of faint tickin sound. For the exhaust check the donut on the pipe where the manifold bolts to the pipe. Sometimes these will get loose if ya mess with the manifolds. Theres two bolts on each one and they need to be tightened up evenly in order for it to seat right.
 
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flareside_thunder

Florida Chapter member
7,812
246
Exhaust leaks happen also when the header/head gasket heats up or surfaces warp...I've heard truck run real nice when they're cooler but once they get worked and heated they leak(like mine it's drivin me nuckin futs)
 
What I meant by that is these old motors especially the ones that were built before they changed from leaded to unleaded fuel is that they ping when ya run em on 85 grade fuel try goin mid grade or even premium if you can.

Yes, I understood that. I used to use the additive years ago. I've been burning the same fuel for a long time without this problem so unless it's bad gas it doesn't seem likely. I've owned the truck for 24 years so it's not a new one to me. It is worth looking at though. I'll look at the wires again but had a pretty good look when I checked the timing.

The timing just needed a tweak to be dead on so that wasn't it.

Exhaust leaks happen also when the header/head gasket heats up or surfaces warp...I've heard truck run real nice when they're cooler but once they get worked and heated they leak(like mine it's drivin me nuckin futs)

Yep, that's been a problem here too. Last week I pulled both of them, replacing one that had a broken ear and another beginning to crack with a new manifold. Put new studs in both of them and replaced them using new bolts and donuts. I used hi temp sealant and left the gaskets out this time. Sounds great with no leaks, even at running temperature. Imagine all the exhaust going out the mufflers! :) I did the same on a Chevy 350 long ago and it never did leak again. A lot of the older motors didn't come out with gaskets.
 

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