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Is my engine knocking or have I just lost my marbles

dbrannon79

dbrannon79

I'm getting there!
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Seguin, TX
Good morning fellas,

I have a curiosity where the old 6.5 engine has been making what I call a knocking sound only when at a higher rpm and without any load. Now as you all know I just replaced my harmonic balancer after finding it had separated, but this noise had been here as long as I can remember. I really never worried about it, just kept driving since there wasn't any noise at idle or while driving.

this was just a curiosity since lately I have been thinking more and more about pulling the engine and replacing all the gaskets, timing chain, oil pump, among other tedious things trying to make it last me another 50-100k miles without any issues.


Saturday after I got the HB replaced and running I revved it up in the driveway making sure nothing flew apart and of course all was fine. she runs and drives no different than before I had found the HB in the condition it was in. No more or less vibrations, sh just runs when I turn the key :)

The knocking noise I am hearing seems to have always been there, again I never gave it any attention since it wasn't a noise that was there all the time, only being able to hear it with rpm's above 2000 and only when sitting still with no load on the engine.

what my theory is that it's ether cam bearings or maybe one of the crank main webs has cracked fully though on the block and I am hearing the crack in the block flexing IDk I'm just guessing.

What I am thinking about is wondering if I should ditch the idea of pulling this engine to do a gasket refresh and start prepping the 6.2 that fell into my lap to go in. it has web cracks but was told it ran when it was pulled.


In all my years of working with engines (gassers) a noise like this is from a rod or main that has some wear on it but isn't that bad yet. usually some thick oil additive like a couple of quarts of Lucas oil treatment would take care of it and make it last a while longer, but this isn't something I want to just band-aid and keep going. I really want this truck to be dependable to drive long distance with the family when we decide to go somewhere.

I wanted to get yall's input with all the experience yall have with these 6.5 diesels
 
Can you post a video for the more knowledgeable to listen to?

Have you had the valve covers off?

Maybe check operating temp of each cylinder?

I'd be keeping my eye out for a low mileage 6.5 that you can use the engine out of.
Sometimes rust or wrecked can be bought cheap.
Sometimes a 6.5 can also be procured rather reasonably at an auction.
 
I can try to do a video. the noise isn't anything new. it's been like this for a good while and hasn't gotten any worse or better. that's the only reason I'm not too worried about it. still drives find and goes when I need to lol. Oil pressure is decent. cold startup at 40. warm idle at 20 or so and goes up to just under 40 when moving on the road.

I just want to weigh in all my options and opinions before I make the decision to pull it out to do a gasket refresh.
 
jrsavoie said:
Can you post a video for the more knowledgeable to listen to?

Have you had the valve covers off?

Maybe check operating temp of each cylinder?

I'd be keeping my eye out for a low mileage 6.5 that you can use the engine out of.
Sometimes rust or wrecked can be bought cheap.
Sometimes a 6.5 can also be procured rather reasonably at an auction.
Click to expand...


I have had the valve covers off a while back to replace the gaskets. didn't do anything else and should have replaced the rocker buttons but at the time hadn't learned about them. that is one of the things on the list to do if I do pull the engine to replace all the gaskets. it's starting to leak more oil that I noticed when I replaced the HB over the weekend. I had to add a quart of oil to top things off and I only have a little over 1000 miles into the current oil change. there is oil on the starter indicating the valve covers are leaking again. I know the pan is leaking too, that is one of the main reasons I want to pull it out. much easier to to the pan gasket with it out and on a stand!
 
Its an older rig and even if you dropped in a perfectly new engine: the trans, diff, electrical system, etc could still fail ya. So just have a free tow or two on your insurance policy is best suggested for that situation.

If you already have or are getting the 6.2 that is out- deal with it now and drive the 6.5.
Open the 6.2 pan looking for cracks, do a compression test on the engine stand, all that simple stuff while it is out. If you decide to do gaskets- that would be the time. If the 6.2 is in good looking condition- consider building it as the new engine and just run the 6.5 till she dies. Then drop in the 6.2.

If you find cracks in the 6.2, weak compression, etc. that makes it bad candidate:
Save $ and when you have a few grand, pull the 6.5 for rebuild. And install the 6.2 do drive on in the mean time. Start with checking for main web cracks. If cracked, my suggestion is button it up and leave as emergency back up. Search for another 6.5.

If it’s ok, tear it down for rebuilding while ya drive on the 6.2.
 
Will L. said:
Its an older rig and even if you dropped in a perfectly new engine: the trans, diff, electrical system, etc could still fail ya. So just have a free tow or two on your insurance policy is best suggested for that situation.

If you already have or are getting the 6.2 that is out- deal with it now and drive the 6.5.
Open the 6.2 pan looking for cracks, do a compression test on the engine stand, all that simple stuff while it is out. If you decide to do gaskets- that would be the time. If the 6.2 is in good looking condition- consider building it as the new engine and just run the 6.5 till she dies. Then drop in the 6.2.

If you find cracks in the 6.2, weak compression, etc. that makes it bad candidate:
Save $ and when you have a few grand, pull the 6.5 for rebuild. And install the 6.2 do drive on in the mean time. Start with checking for main web cracks. If cracked, my suggestion is button it up and leave as emergency back up. Search for another 6.5.

If it’s ok, tear it down for rebuilding while ya drive on the 6.2.
Click to expand...
I have done a minor inspection on the 6.2. there are some cracks in the main webs. I have not gone any further on it since other than putting it back together and left it on the stand. the only thing I found broken on it was the front crank pulley rubber had let loose and ate up the bolt heads. I figured that was why it was pulled thinking it was knocking LOL. it has a db2 on it as well as the turbo. only missing the starter for me to do a compression test.

So I would assume the best option would be to begin gathering parts and fixing up the 6.2 to go in then rather than pulling the original 6.5 for gaskets and whatnot
 
I brought this up since we normally plan out a summer family vacation trip to the coast each year. with me driving the truck every day really just putt-putting around and short trips to and from work, the last thing I want to happen is this thing fly apart on me when I'm 100+ miles away from home LOL
 
On the ‘94 Suburban my son gave me there are no knocks, but it does have a good amount of blow-by. It consumes oil, but is not leaking oil. My intention is to run it until it grenades, then I have the engine from the ‘95 that has 185K miles on it. It was a strong runner with slight blow-by. Between those two engines, it should see 500K miles. I will probably need to have the transmission rebuilt and I’m in the middle of rebuilding a transfer case for it.
 
Yeah, I remember wanting to strike a deal with you on the engine until funds became an issue. I guess life happens and seems to find it's way when there's money in the bank lol

Wonder if a better option would be to renew my loan and start looking for a better donor engine. then going ahead for the swap out.
 
I stumbled across a 98 1 ton dually with a 6.5 for parts on FB the other day, they only wanted $1,500 for it as a complete truck. 160 something miles on it, but the condition of the engine was unknown. I kinda steered away since I'm afraid I'd end up with another cracked block.

I think the wifee might let me renew a loan if I found a known good one but prices I've seen on rebuilt ones up in the 10k range, she'd be ready to collect on life insurance HAHA.
 
dbrannon79 said:
I stumbled across a 98 1 ton dually with a 6.5 for parts on FB the other day, they only wanted $1,500 for it as a complete truck. 160 something miles on it, but the condition of the engine was unknown. I kinda steered away since I'm afraid I'd end up with another cracked block.

I think the wifee might let me renew a loan if I found a known good one but prices I've seen on rebuilt ones up in the 10k range, she'd be ready to collect on life insurance HAHA.
Click to expand...
My neighbor has an 2005 LLY for sale for $5K. Probably has a tool storage bed on the back as that was their company. California truck, so no rust.
 
Maybe a cracked flex plate?

The cracks on the 6.2 will get worse and let go without warning anytime.

If you want the truck to keep running simply do as GM designed this disposable engine: get a new longblock. The stories of getting good take out engines like I did in the past are getting scarce. Last attempt I did with take out engines was a disaster.

Give the wife a choice: New Engine or New Pickup. Price a new pickup for her... It's an easy choice.
 
The flex plate was replaced not too terribly long ago, if it's not in the engine it would have to be in the converter or trans. I will do a video / audio of it tonight. if hearing it over my phone will do any justice.


New long block... who would be the best to get from and for the price. I might have to look at this and just bite the bullet. I see the local auto parts show them as a reman long block for around 5k. no pan or valve covers but complete with heads.
 
I'm always very leery of buying any reman unless it's from a very reputable source or it carries a very good guarantee.

I've had better luck with good used engines that I can hear run and drive.
I sold a good one a few years ago and still regret it.
Should have saved it.
A friend has the engine in his shed. I would have kept the whole truck.
 
Ok, Here is a video. it took me a couple of tries between my phone stopping the recording to incoming phone calls. but here it is.

funny thing is the engine is fully warm and I didn't hear it knocking! maybe it's the injectors and when it's cold? Idk, now I am scratching my head.

and yes I just discovered the new front seal is leaking. I guess I need to pull it all down and replace the seal again. not sure what I did wrong installing it. I will run it for a few days and see if it seals up, but I doubt it will.


 
You might pull the inner fender and turbo.
Crack the injection lines one at a time and see if the noise stops.
If it stops on one certain cylinder then swap around a couple of the injectors.
If the noise follows the injector then replace that injector.
If the noise subsides but returns on that cylinder with a different injector then suspect a rod bearing is getting ready to let loose.
If the noise gets louder with the cracked injection line then suspect a wrist pin or piston is going to flap out on Yuh.
If it has been making noise for this long chances are whatever itiz, might just stay there for long time now.
 
dbrannon79 said:
Ok, Here is a video. it took me a couple of tries between my phone stopping the recording to incoming phone calls. but here it is.

funny thing is the engine is fully warm and I didn't hear it knocking! maybe it's the injectors and when it's cold? Idk, now I am scratching my head.

and yes I just discovered the new front seal is leaking. I guess I need to pull it all down and replace the seal again. not sure what I did wrong installing it. I will run it for a few days and see if it seals up, but I doubt it will.


Click to expand...
Did You install some sealer on the HB side of the warsher and on the warsher side of the HB bolt ?
 
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