Help, Loud engine noise!
 

Alright, I have a 1985 gmc 4x4 305/7004/208np. I now have a noise that ive spent 2 weeks trying to find and can NOT find it for the life of me. So first i thought it was my alternator bearing so i just bought a 140 amp alternator, put it in and noise is still there. Its a hard noise to describe, almost like a loud chatter,chirping but realllllllly loud when pulling a hill. makes the noise 75% of the time now. only time it doesn't is when traveling on dead flat road and or down hill.I had taken the alternator belt off to see if it was those 3 pullys, still there. Messed with the power steering and doesn't see, to be that either. I'm completely stumped, Ive listen to so many videos an cant really see to find it. Please help. Oh and the belts are newer too.


- Jake

Re: Help, Loud engine noise!
 

Take a look at your engine's flexplate. It sounds like it is cracked. I had this happen on a couple of trucks, so I replaced the flexplate with a heavy duty plate and solved the issue. The noise comes from the torque converter ballooning out when you spin it up to speed. The convertor will spread axially and cause the flexplate to crack.

Re: Help, Loud engine noise!
 

Definitely sounds like something tied to your drive train if the noise gets worse when the motor is under a load.

I chased a noise under the hood once. I replaced everything and it was still there. It ended up figuring out that it was the fan clutch. You might check that. They will wobble and chatter when they start to go bad. Grab your fan and see if the fan & shaft wobble any when trying to move it up and down.

Re: Help, Loud engine noise!
 

can you hear it through the exhaust. you can also use a tube to listen at different parts

Re: Help, Loud engine noise!
 

Alright funny you say that, this morning for ****s and giggles before i left in it for work i spread down the power steering V belt and pulleys. Got in the truck and drove the noise wasn't there. Peddle to the floor going up hill. it returned when I left work this evening. But its a relief to know its not internal. Now, after reading your post i'm bout to head out side and see if i can wiggle around the fan at all. If that checks out okay, I'm thinking maybe its the pulleys or one of the 3 or just a ****ty belt, which is surprising considering its from napa. What are your thoughts?

Re: Help, Loud engine noise!
 

I can not, but I'll have to use the tube in the future!!!!

Re: Help, Loud engine noise!
 

If you sprayed the belts and the noise no longer existed then I would say it has to do with your belts. They can make a racket if worn or not inline with the pulleys correctly. Have you tried tightening your power steering belt? Are you sure its the correct one?

Re: Help, Loud engine noise!
 

Just checked the fan and there is a lil amount of play in it, but to be completely honest the belts a the correct size, so id say yes there correct one, but the power steering side v belts seems 3x's more rigid than the alternator side v belt, and yes I have a few times now, I have the Power Steering belt pretty much as tight as I could get it. bout a 1/2 inch of play up and down. If I let it be any less, the belt squeals like a pig with the slightest turn. Now as for the pulley alignment, I dont know how to Correctly check that, by eye it looks good and straight.

Re: Help, Loud engine noise!
 

After taking a second look at it, when I grab the fan clutch to see if it has any play. I noticed when it moves, it's also moving the water pump pulley... what does that mean? Anyone?

-Jake

Re: Help, Loud engine noise!
 

It means you probably found your noise. My truck was making some noises from the front last fall and when I grabbed the fan the water pump pulley was moving. Easy fix.

Re: Help, Loud engine noise!
 

What would you say I have to replace then? New fan and pulley?

Re: Help, Loud engine noise!
 

Sounds like a water pump. Tighten the bolt on the fan and pulley and if they are tight and the pulley still moves it's the pump bearing.

Re: Help, Loud engine noise!
 

Pulled the truck round back at school and found the play in the bearing, new high flow pump and a belt on the way, hah never replace, just upgrade. I'll see what happens.


Thanks for all the help guys!:metal:

-Jake

Re: Help, Loud engine noise!
 

well, replaced the water pump, the old one indeed had a bad bearing. Noise is STILL there. insane. all new belts best i could get on summit racing, new alternator, and new water pump... idk what to do next, pretty damn confused.

Anyone any suggestions??????

thanks again, Jake

Re: Help, Loud engine noise!
 

maybe a video of the noise would help

Re: Help, Loud engine noise!
 

I would if my phone wasn't also all broke :banghead: But, I can describe it. in neutral i can rev it all i want and it will never make the noise, going down a hill or coasting at any speed no noise. But, pulling a hill or any sorta real acceleration i get the noise. The noise reminds me of a few things hah, a mason jar with nuts and bots in it rattling around, dieing pigs, its a real aggressive sound, just watched a YouTube video of a power steering pump with a bad bearing that sounded similar... but I'm honestly stumped, i drive the truck 40-50 miles to school and back ever day with this noise. its been about 3 weeks now and what ever it is hasn't let go. As i said before some belt conditioning helps for a mile or so. Not sure if any of that helps

Re: Help, Loud engine noise!
 

My power steering pump SQUEALS like a pig when i really get to turnin. I'm redoing all my steering this summer as my new 11" lift has taken it's toll already... Ram assist here i come!

Re: Help, Loud engine noise!
 

If belt dressing helps then it is in your belt system. Maybe you have the wrong pulley configuration. Or one is out of alignment. Saw a bent steering pump bracket do this to a guy for years til he figured it out when he switched out the engine.
Although the symptoms sound a bit like the tranny. Why would it make the sound when pulling on a hill?

Re: Help, Loud engine noise!
 

Have you tried the belt dressing several times and everytime the noise stops? To me it definitely sounds drive train related. I'm thinking tranny now. Maybe your timing chain has got slack in it? Are either of your motor mounts broke? If so your motor could be pulling up on one side when under a load. The motor mount might be rattling when lifted a little (just a thought).

Re: Help, Loud engine noise!
 

After looking at the truck all day and romping it around at school found out that the noise is coming from the transfer case. I thought it was the belts because it made less noise when the engine was cold so as it warmed up I thought it was the belt conditioner wearing off when really it was just getting warm. But, I'm not at a loss guess I should starting looking for a new 208 transfer case

Re: Help, Loud engine noise!
 

probably not, but does it still has the cathalyc converter? if its from the tc by the sound it makes put your figer in the oil to see if its silver

Re: Help, Loud engine noise!
 

Cats are long gone, but right in the oil drain plug?

Re: Help, Loud engine noise!
 

take the fill plug out on the tc and put your small finger in and look at the oil if there is still some left, if it sounds like loose shrapnel rolling in there maybe youll see it in the oil color. also put the tc in neutral and shift all the transmission gears maybe youll hear it

Re: Help, Loud engine noise!
 

Alright, I'll have to do that in the morning. Thanks for all of the responses. Also the noise is almost like a high pitch chirping, along with a bad loose sounding bearing. That's the best way to describe it after hearing it for my self out side the truck. I just dont understand how nothing has broke after a continuous month with this noise, and just how loud and bad it sounds. its louder than my my radio turned up. its insane.
Thanks again.
-Jake

Re: Help, Loud engine noise!
 

After trying the belt dressing a few times, it indeed has nothing to do with my belts. oh well a new alternator and water pump isnt a bad thing. But now im thinking transfercase. and how would i check my engine mounts??

Re: Help, Loud engine noise!
 

To check your mount id visually inspect it then have somebody load the engine up. Generally a motor mount will make a clunking sound and itll feel alittle sluggish.

Re: Help, Loud engine noise!
 

Sounds pretty good, and I started to look at it and think about it. And I have a flex pipe that runs right up close behind the transfer case, it's actually woarn down the fins a half inch but not has a quarter inch gap. Now that im thinking about it I bet I have a bad motor mount that is clanking and the engine is torquing and chattering off the T case. Just a hope! Hah

Re: Help, Loud engine noise!
 

Best way to check for a bad motor mount yourself is to open the hood and with the truck running. Put it into gear and act as if your going to power brake your truck. While your doing this look through the gap between your hood and cowl. Don't be afraid to give it the gas because you trying to duplicate the same torque when your driving. If your mount is broke the engine will lift up on one side in drive. If it doesn't then try to power brake your truck in reverse to check the other mount.

Its pretty easy to figure it out once you see the motor try and climb out from under the hood, lol.

Re: Help, Loud engine noise!
 

Hahah I like how easy that sounds to check it. Drive one way reverse the other

Re: Help, Loud engine noise!
 

As much as that motor mount made sense... I have my thoughts that it's not that.It's really going down hill.... Burning through gas and oil. And oil is coming out the breather in the valve cover. A lot of power loss I was going up at hill at 55 put the pedal to the floor went know where the motor sounded louder but no rpm or mph increase. May be the end of the old girl.

Re: Help, Loud engine noise!
 

On one of your posts you said it sounds like a mason jar with nuts and bots in it rattling around. Could it be pinging or detonating? Under a load like going uphill is when this happens most. Maybe your timing is too far advanced or you got a realy bad batch of gas.....both of these could cause that type of sound.

Re: Help, Loud engine noise!
 

Maybe he just needs to downshift?

Re: Help, Loud engine noise!
 

It sounds silly but check your flywheel cover. My dads came loose on time and it started rattling around and made alot of noise. Its just something simple to check

Re: Help, Loud engine noise!
 

I did say it sounds like that, but I will say it sounds like loose rocker arms almost, but, it doesn't make the noise in neutral at all. I can rev it all I want no noise. Also I'll add the noise isn't there when the engine is cold, or the part in which the noise is coming from, I have a long drive home from work and all of it is mostly down hill. I noticed if I am coasting a lot and then have to pull a hill the noise isn't there and then comes back pretty soon. I texted taking a video of it but you can't hear it over the engine. At 1100 rpms is when it starts and at 2000rpms you can hear it over the radio turned all the way up. I've never been so stumped in my life

Re: Help, Loud engine noise!
 

I was going to take it off today and check the flywheel itself to see if it's bent or cracked

Re: Help, Loud engine noise!
 

It's a auto, but I wish that was the problem! Haha

Re: Help, Loud engine noise!
 

It's a auto, but I wish that was the problem! Haha

Re: Help, Loud engine noise!
 

When it starts making noise does the truck still run okay? Does it start missing and lose power at all? Does your drivetain shudder at all?

Re: Help, Loud engine noise!
 

It might be looseing power idk if it does I don't notice it, I try to baby the truck never really going above 2k rpms.and It shifts fine and sounds good

Re: Help, Loud engine noise!
 

Well everyone I found the noise. I had a spark knock due to the distributor being waaaay advanced, THANKS everyone for all the help.!