Fuel Pump Ticking noise?

[Jonlopes]

Ok I have spent the day trying to figure out the knock on my truck. After eliminating a couple of things I started the motor and used an 18" screwdriver to try and listen for the noise. I listened to the heads and valve covers, nothing. Oil pan nothing, engine block I did not hear anything.

Fuel pump, there was a definite tick that to my ears sounded like it was timed exactly with the knocking noise my other ear was hearing.

The noise through the screw driver was quieter than the knock but it was definitely there. Does this sound correct seeing as how a screwdriver is not meant to me an audio device or (assuming it is the source of the knock) should it have been louder because sounds travel through solids faster than air?


If you are interested here is a video where you can hear the knocking. click on the link below and click on the picture of the engine.

http://dadgummit.smugmug.com/Cars/Random-forum-uploads

[7tee]

It sure sounds like rocker arm but a way to test the fuel pump rod is to remove the pump from the block (this will allow the rod to slide down) then start the motor. If the knock is gone then it's likely the rod (it should measure 5 3/4" long). If it's not then I would check the valve lash adjustment or at the timing chain. I hope this gives you some other ideas...

[geezer#99]

An easier way than a screwdriver is a long wood broom handle.
Stick one end behind your ear lobe.
You'll narrow it down better that way.
Sounds like a lifter or exhaust leak.

[Jonlopes]

Originally Posted by 7tee

It sure sounds like rocker arm but a way to test the fuel pump rod is to remove the pump from the block (this will allow the rod to slide down) then start the motor. If the knock is gone then it's likely the rod (it should measure 5 3/4" long). If it's not then I would check the valve lash adjustment or at the timing chain. I hope this gives you some other ideas...

I can do that. How long will the truck run without a fuel pump? From cold it takes 10-20 seconds for the motor to settle down before I can hear the knocking.

[CST10]

I had the same noise awhile back. It was the fuel pump return spring had broken and didn't keep the lever against the cam. It still ran but had that noise. When you take it off. Work the lever on the pump and see if it's nousy.

[Fitz]

Originally Posted by Jonlopes

Ok I have spent the day trying to figure out the knock on my truck. After eliminating a couple of things I started the motor and used an 18" screwdriver to try and listen for the noise. I listened to the heads and valve covers, nothing. Oil pan nothing, engine block I did not hear anything.

Fuel pump, there was a definite tick that to my ears sounded like it was timed exactly with the knocking noise my other ear was hearing.

The noise through the screw driver was quieter than the knock but it was definitely there. Does this sound correct seeing as how a screwdriver is not meant to me an audio device or (assuming it is the source of the knock) should it have been louder because sounds travel through solids faster than air?

If you are interested here is a video where you can hear the knocking. click on the link below and click on the picture of the engine.

http://dadgummit.smugmug.com/Cars/Random-forum-uploads

The Screwdriver acts just like a stethoscope which is is a contact audio device with a diaphragm which transmits air pressure changes to your ear. The screwdriver transmits mechanical pressure changes directly to your skull and the three small bones in the middle ear. Same effect. The speed of sound is about 740 MPH so the short difference in distance or speed between your skull and screwdriver tip or air to your ear is so short it is indiscernable.

As shown in the cutaway, the fuel pump is driven off the camshaft so, what you have is either a lifter or the pump operating rod, eccentric, or the pump itself. Warm the engine, and drop the pump. That will only take a minute or two so the engine won't have time to cool. get someone to start the truck for you and listen again. If the noise is still there it will be a lifter on one of the two front cylinders on the right bank. If it went away, check rod and eccentric on the pump. I'm betting on a bad pump. Good luck.

[sleepertruck72]

I had that exact sound on my engine...found fuel pump pushrod return spring broken in 2 pieces...

[Jonlopes]

I warmed the engine, stopped it and pulled the pump off of the engine and the rod slid down. I started the engine and the knock knock is still there just as loud as before so it is not the fuel pump.

I am going to have to find a shop that is competent to do internal engine work, does anyone know of one in north Orange county, CA? Someone that can be trusted?

[Boog]

Well thats too bad. I had hopes it was the pump.

[White70C20]

I wonder if that could be what my knocking noise is. I'll be starting my truck on Monday so I'll see if it sounds similar. I sure hope so. I lifter, fuel pump, or exhaust leak would be SO much better than a spun rod bearing!

[7tee]

By not truly knowing how much had been done to the engine before me, I waved the machine costs and rebuild parts and still having an old block theory plus down time having to wait and opted for a "new" long block crate motor. Man this thing is sweet and the cost is not much more if any, than a total rebuild. Hopefully you'll not need either one...

[Jonlopes]

So I have checked everything I can with my ability and the tools I have in my garage. Does anyone have a shop they can recommend in the OC Area who is good and honest?

[leuggy]

just listened to your video of the knocking noise i had the same thing turned out to be connecting rod bearings shot on mine i'm going for a crate motor



Blaine

[Jonlopes]

Originally Posted by leuggy

just listened to your video of the knocking noise i had the same thing turned out to be connecting rod bearings shot on mine i'm going for a crate motor



Blaine

My oil pressure is exactly where it should be though. about 30 at idle and 60-70 while driving, I have read that with a bad or spun bearing the oil pressure drops pretty low at idle. Also using the (maybe not so accurate) 18" screw driver I did not hear any noises that matched the knock when I pressed it against the oil pan block area down below which is where I imagine the sound would come from if that was the issue. Or in other words I really really hope it is not a rod or main bearing but I am not sure.


Man, I just looked at crate motors and for a big block it will cost like $5-6000++ for new or $3-4000 for remanufactured. That is just too much, I cannot afford to have that much in this truck I will part it out before I go that far. I purchased this truck (with no knocking) partially because the motor was rebuilt 10 years and 40,000 miles ago.