'Diesel rattle' in my 350...?

[7900_Blazer]

Not sure how to describe the 'rattle' I'm hearing coming from, I believe, the front of the engine at idle - not a consistent rattle. The rattle does not 'come and go'... but also is not consistent - so not something like rubbing as the engine turns....

Again, a bit of backstory... bought the truck from a guy in Denver - have replaced a ton of stuff getting it road-worth... the seller communicated it had a solid engine... with a torque cam upgrade.

After many months off work, I'm finally where I can drive it and the engine definitely has a 'rattle' in the front at idle. Kind of reminds me of a diesel rattle at idle, or maybe a really really bad water pump type rattle but the water pump spins freely and feels solid.

The truck has good oil pressure - 60+ when cold... never gets below 30 even when hot and at idle.

Thoughts?

 

[Captcorvette]

Does the truck have very old gasoline in it? Very low octane? When shutting the engine off does it die immediately or "diesel" a bit like it is trying to run then stop? Can you record the noise and send it in a file?

 

[7900_Blazer]

Does the truck have very old gasoline in it? Very low octane? When shutting the engine off does it die immediately or "diesel" a bit like it is trying to run then stop? Can you record the noise and send it in a file?

Thanks for your help.

Truck probably had some 'old' gas... but I put 10 gallons or so of premium in it the first time I was able to drive it a few miles as a test (4 days or so ago).

No, it doesn't 'diesel' when shutting off the engine.

Yes, I can grab a video this evening and post the link here.

 

[Matt69olds]

Fuel pump? Timing chain?? Is tgenoise constant, or will it come and go with engine speed? Take the belts off, is the noise still there? If so, it’s not a belt driven accessory.

Does the noise change shifting from park into gear? You said the noise appears to be coming from the front, a broken flywheel can make a funny rattling sound.

 

[Rusty Nail]

At idle...in gear? In park?
Does it change with engine rpm (ever) or no?

We're gonna need some pix of a 79 blazer pliz.

 

[PrairieDrifter]

Yup, front accessories or timing chain.

 

[7900_Blazer]

Here are two videos… the only difference is taking off the belt. Thanks @Matt69olds

#1: https://youtube.com/shorts/89g_78ldlgw?feature=share

#2: https://youtube.com/shorts/733GzhI8wkI?feature=share

 

[Rusty Nail]

Woah. What's the change between videos?
What belt? The water pump?

I thought "timing chain" at 0:04 and counted that sound 4 times before the first video ended. Faint at 07, 08, and 09. But that don't make no sense.

 

[PrairieDrifter]

Seems like water pump to me. Could also be the alt, spin those over by hand.

 

[Snoots]

Water pump.

 

[Jawzjeep]

If you haven't found it yet try putting a broom handle or a wood dowel against your ear then set the other end on the block in different places. CAREFULLY! It helps to narrow down the location.

 

[78C10BigTen]

Well what i see only leaves 2 choices.... water pump or alternator. Only 2 things not turning after belt was removed...

 

[SirRobyn0]

If you haven't found it yet try putting a broom handle or a wood dowel against your ear then set the other end on the block in different places. CAREFULLY! It helps to narrow down the location.

Yes you can also use a rubber hose, which will transmit the sound just fine, but won't get thrown at you if you hit something moving. Still need to be careful. Also I think it's likely to be the water pump as well.

 

[Jawzjeep]

Yes you can also use a rubber hose, which will transmit the sound just fine, but won't get thrown at you if you hit something moving. Still need to be careful. Also I think it's likely to be the water pump as well.

Yeah your right. Over been beat by a rubber hose though? Either way its hurts to not be careful.

 

[7900_Blazer]

Water-pump installed after work, 1st drive for it in years… no noise and ran pretty good.

thanks for everyone’s help!