Got a weird tapping sound today from the motor today. Never heard it before haven't driven much recently either. Only when accelerating, idles fine. I did some quick googling people saying it could be en exhaust leak? At first I thought it was my air cleaner cause I got it spaced up because of my HEI but I held it and it was still happening. It could be from the driver side but I may be wrong.

Oil pressure ~50
Temp ~ 185
Idles ~950-1100 (My truck doesn't really like idling lower)
Oil changed less than 100 miles ago


2 videos posted below:



Thanks guys!

 

To find an exhaust leak squirt some ATF down the carburetor. You also could have a loose flywheel. Does it get louder if you put it in drive and power brake it ? Hopefully it is not a lower end problem.

 

A tapping noise could be loose rockers or a collapsed lifter. I had rocker nuts backing off. I sure hope its something simple.

 

I'll take my valve covers off tomorrow and check, but I did have them off about 100 miles ago and my rockers all seemed fine.

What do I check for after squirting the ATF? Whether the sound is still there or fluid leaking? I'll try putting it in Drive tomorrow and rev it to see if I still hear it. The sound feels like its coming from the top not really something near the trans.

The only thing I did change, a day ago, is I lowered the truck a bit, so I put shorter coils in the front and moved the springs up using the DJM kit. I bought 6 degree shims but didn't put them in yet. I thought I might have drive shaft issues but it seemed fine (I only drove it a few miles), but once again this can't be the problem because I'm having this issue when my truck isn't moving.

 

Sounds like a bad lifter or a bent rod.

 

Yeah, that is not an exhaust leak. Something that spins. Check accessories first (by taking belts off). If still there, you need to start disassembly.

Chris

 

Okay some updates. I took off the belts, air cleaner, etc. Tried to hold different things down, no luck so it's definitely internal. Sound seems like it's even on both sides, it doesn't louder on one side of the valve covers at least hard for me to tell.

I have low oil, it was barely touching the dip stick, I literally have probably driven less than 100 miles since my last oil change and I definitely have no leaks which means I am burning it. This probably explains the tapping sound, but now I obviously have other core issues.

Truck: 302 with a c4 auto, holley 750 4160 carb (its too big everyone told me already)

History of my vehicle: The guy that I bought it from told me that when he bought the truck that owner had rebuilt the 302 in order to go racing. So he said the truck has about 5000 miles on it after rebuild. When I got the truck it was not tuned well, timing was off, choke had no power so it was running rich, valve cover leaks. I know the vehicle has roller cam and when I pulled the valve covers a long time ago the rockers paint looked worn? Maybe a junkyard rebuild? I'm not too familiar with the internals still learning.

I swapped the plugs, wires, set the timing, put power to the choke and adjusted the carb, new valve cover gaskets, new valve covers. I did a compression test about a month ago only dry it was between 109-119 on all cylinders (I feel like this is low). I will run another test tomorrow, dry and wet, and see what I find. I have white smoke coming of my exhausts at times, after I drive it around the block it usually stops (doesn't matter whether its hot or cold out) and exhausts smell like fuel until i drive it around the block

I run 10w-30 conventional and I also recently saw a video about Engine Restore from ProjectFarm on youtube. It seemed to work for him but I will do a compression test first to see the results. I will top off the oil and post an update with the compression results.

 

Sounds like a bearing knock to me. Definitely not an exhaust leak. The only other thing I've heard that sounds close to that is a cracked flex plate or loose torque converter nuts. That's the easiest thing to check, and can sound like bad bearings.

 

Some Updates for you guys - did a compression test - results posted below. Took photos of my spark plugs all posted below, some had dried oil residue past the threads.

Format: Cylinder - Dry : Wet

1 - 111 : 120
2 - 126 : 113
3 - 113 : 105
4 - 119 : 108
5 - 107 : 124
6 - 113 : 119
7 - 115 : 139
8 - 124 : 116

I thought when squirting oil you could only go up in compression but I have no idea what these results mean. I did cylinder 2 twice again after noticing the drop and got 111 (no squirt) and then 113 with a squirt of oil, note that this was directly after the first wet - so results may be off.
Vacuum was reading about 15 at 14 degrees timing, I brought that to 13 degrees and then adjusted my air/fuel mixture screws to get vacuum up to 17.

After doing my compression test I let the truck run for about 20 minutes and the metallic noise pretty much stopped. It was extremely minimal and would only be able to hear it slightly at 3500+ rpm. Then I let the motor cool down for an hour started her up again to pull her in the garage and the full on metallic sound came back. No idea what to make of it it was 54 degrees all day.

So confused. I just want to drive my truck haha. Appreciate all the help guys.

 

This is something internal, as posted before. Tear it down. Pull the intake and heads and start there. Or just pull the motor and put it on a stand.

Don't be intimidated by pulling the motor. First, drain radiator and remove. Remove battery. Remove headlights and buckets. Take horn relay, starter solenoid and voltage regulator off sheet metal, leaving wiring connected. Undo ALL wiring from inner fenders and snake back the headlight connectors (marker lights disconnect).

Leave hood on.

Get at least 2 friends that can lift. Take off 12 bolts - 3 horizontal bolts running just behind hood hinges (not the ones on the firewall), 1 bolt in underside of fender and one holding inner fender to isolator that goes to firewall (just above frame), and 1 on the core support. Repeat for other side, 12 bolts total. Lift finders, core support, grill, hood and inner fenders off as one unit.

Set aside.

Now pulling your motor does not look so daunting or back breaking. You will most likely find something in the bottom end of engine, but regardless you will want to pull it to work on it. Just way easier...