Thump like sound, yes I've searched and nothing

[Nitesaber]

Thump like sound, VIDEO UPLOADED

So this is my first diesel so please be patient if I ask about certain acronyms or parts. So rescent work include oil change to amsoil(spare me your opinion please), new fuel filter, new fuel pump. The sound is almost exactly the same sound as when I purged the fuel through the pump for the first time. Same thump sound as if its dry trying to pull fuel. Sound is intermittent. If there, I can rev it up sound increases with RPM but quickly dwindles. Sometimes comes back. Is not after a particular point in power band or hot or cold or at a cold start or warmed up. Ran diesel kleen twice thinking clogged injector. Truck has slowly started to burn less and less fuel(i.e. When I gun it to pass less black smoke). Any ideas or suggestions on diagnosing? No metal was in oil when I changed, was actually extremely impressed with how clean it was.

I've purged system while running and fuel squirts out. I will say if I allow fuel to get low in my tank it is more prevalent. But why would this make sense?! I have literally sat at a fuel station and as I fill I have heard the sound dissipate.

Truck is a 1993 f350 ext cab custom flat bed 7.3l non turbo. E4od. Engine is a jasper crate with unknown mileage. The motor had gasoline ran through it before I got it and they replaced head gaskets, intake gasket, vale cover gaskets, etc. inspected heads and they looked damn near new they said. Certified diesel mechanic did all the work! Pressure tested fuel system and no issues. Trans is also rebuilt if it matters.

https://www.youtube.com/watch?v=oAJFAgtNV6w

 

[Nitesaber]

Just added a video. Bump, would like help please if possible! Thank you

 

[ironworker40]

Broken flex plate would be my first guess.

 

[Black dawg]

is the noise coming from the intake or exhaust? sounds like intake to me.

 

[Nitesaber]

Not sure. I know it's extremely prevalent at the front. It does have a slight sound in the exhaust as well. Well nothing like up front. With hood up its even louder. It's becoming more and more of an issue. If I wind it out it sometimes goes away and other times it doesn't. Very odd symptom but again this is my first diesel. Figured I should stick with something all mechanical before I go into a powerstroke or Cummins.

What makes you say flex plate? Starts up just fine so how would that cause an issue?

 

[Nitesaber]

If it helps it has the exact same sound as if the motor wasn't getting any fuel and you have the hose off going towards fuel distributor from the filter assembly. I put 32oz of diesel kleen in the tank again to see if it helps but nothing noticeable so far. Only had 8-10 gallons of fuel so figured it would be a heavier mix to break anything up inside injectors/pump/etc.

 

[icanfixall]

Sounds like a valve guide on the intake side has failed. Remove the intake air cleaner and run engine. If it is an intake guide you will hear much more noise. Only other issue I'm thinking is an injector sticking. You posted the sound can be intermittent at times. To test if an injector is faulty just loosen one injector at a time. See if the sound changes. If you "find the cylinder at fault please post back telling this board. Then more help can be suggested. BTW welcome to the forum.

 

[Hydro-idi]

Sounds like either a valve-guide problem or you lost a hydraulic lifter IMO. I would pop the valve covers off & take a look at all rockers. Press down on the top of each rocker where the pushrod meets rocker. They should all have tension and be very tight (shouldn't move). If one is loose, bingo you found your collapsed lifter and that's the problem.
If everything checks out ok, I would guess that you have a valve problem, most likely intake the way it sounds.

 

[riotwarrior]

Often referred to as huff out intake..caused by bad guide allows valve to not seat correctly and seal cylinder pressure so it whumps huffs thumps back out intake.

As said remove air filter assembly amd listen carefully.

Same can happen out exhaust....dont ask how I know...

JM7.3CW

 

[Nitesaber]

Well sounds like this is going to suck. The motor just had head gaskets replaced by a reputable mechanic. He inspected everything as he reinstalled it all and heads look extremely clean!!!! One had valve damage so he replaced that head with a rebuilt one. Maybe he overlooked lifters at the time. I'm hoping it's just an injector. If it is I'll just upgrade.

 

[icanfixall]

Sadly we had a member that had his heads rebuilt and installed a typ4 cam. The valves contacted the pistons. So the newly rebuilt engine came apart. Turned out to be weak original valve springs. They are supposed to be 110 lbs but his were 45 to 55 lbs.... Hell... Thats not enough to keep the lifters from pumping up and causing valve to piston contact. Many thought it was a bad cam grind but several were not going to acuse the cam. Problem is some "reputable shops" lie to you because time is money. It happens all to often.

 

[Nitesaber]

But this is a stock motor, I trust him, he'll when I bought the truck he spent 4 hours of his time chasing down a fuel issue when it was just something simple that we all overlooked. Replaced fuel pump and filter on his own dime. Stayed at a gas station until tow truck arrived. Etc. I'm not to worried about him doing time is money. What I'm worried about is he didn't think about more as to what caused the valve damage. He figured it was the gasoline that ran through the engine and caused it to happen.

And again it's very intermittent but becoming more prevalent. When I hear it, All I do is wind it out through a gear or two and it's gone. Obviously it comes back but it's odd. It's does it right off start up sometimes as well now. Same noise. I noticed a slight tick as well before it starts but I think it's just me listening to hard for an issue now.

 

[riotwarrior]

Well collectively we likely ha e seen heard and been there done that more than any 1 single reputable mechanic has or could in a lifetime.

 

[ironworker40]

I said flex plate for a couple of reasons
first im assuming motor was rebuilt and is okay and things can go wrong with even a new engine but that is a knocking sound to me
second back in the 90's a friend of mine had a 93 superduty tow truck that develoved a knock. We (me him and several other ford mechanics) assumed it was a crank bearing. When we pulled the motor we found a cracked flex plate. Truck started and ran fine. We replaced the flex plate and put the motor back in and it had no more noise.

Third i had gasoline run thru my 87 6.9. I siphoned the tank then filled it with diesel changed fuel filter and drove it pulling a Trailer with harleys back from sturgis 1800 miles the next day and it was fine. That truck is still on the road today and i sold it with 300000 miles on it in 2000

 

[icanfixall]

Tunning gas thru our idi at best will tuin an injector or injection pump. It wont cause rod knocks or bearing damage. Gas has no lubrication in it so what the diesel fuel lubes now is starved for lube. So things fail exponentially. Might want to try loosening an injector nut at the injectors and see where the noise is coming from. Do that and post back what you find for more help.