Please help with engine noise!!!

[mrussell]

I have a 99 sub that now has 150000 miles. Auto with 3.42 gears. It has been well taken care of and does little heavy towing. New parts include vibration dampner, injectors, IP at 100000 mi.

Made a funny erratic metalic sound at Idle, most prevelant on passenger side. Would not do it when cold, but will do it as it warms up. Thought that it was the bearing in the alt or vac pump. Removed the belt, started engine, and still there!

HMMMMM No direct source for the sound could be identified, but on numerous pieces of advice, felt that it was likely the torque converter (or possibly the flywheel). Ordered a new torque converter and replaced. Surprise, same noise still there! i,e, wasted 1,000$ for unneeded part!!!!!

Now It has gone to a diesel specialist, they have done injector cutout test, and several others and can find no cause for the noise. 200$ later - still no idea what is causing it.

It is metalic sounding, and is irregular in nature, sometimes rather consistant, sometimes in and out. Like I said, most prevelant from passenger wheel well or underneath. It has gone from barely audible to detectable from 50 feet away on passenger side. Last mechanics advice is to keep driving it..... I feel uneasy doing this as I was hoping to get many more miles from this before major expenses. I have already flushed @1200$ for christmas into this for no gain. I hope some of you have some suggestions.

[Mark Rinker]

Since the sound comes from the passenger wheelwell, it sounds like either a cylinder/rod on that side, as a crank bearing would be audible from either side. Could it be something simple like a starter bendix not completely disengaging? Thats near the passenger side wheelwell...

If it is an engine meltdown in progress, is the truck worth repowering? 7-8K will put a brand new longblock under the hood - and there aren't any other diesel Suburban options yet. Sounds like you have lots of good accessories to bolt to it already. A new GM-8 turbo might be a good idea during the swap.

Sorry to hear of your troubles. Personally, I'd drive it, but not far from home.

[chickenhunterbob]

turbocharger compressor wheel beginning to contact the housing?

Just a WAG, but obviously very difficult to diagnose noises on a computer.

[mrussell]

I have pulled the intake hose off the turbo and checked for contact/slop. It appears ok. The most puzzling (and maybe the most telling to the right person) is that it does not make the noise on startup (cold). I would think if it were the bendix, it would be worse at startup. No signs of any dragging on flywheel during torque converter install.

This thing is making me miss my dodge/cummins 285,000k on it when I sold it and it ran as good if not better than new.... BTW I have put nearly 100,000 mi on this since I purchased it, mostly highway non towing miles.

[john8662]

Does the sound go away just after a little bit of an increase of RPM?

This scenario does sound familiar tho, lots of 6.5's have irregular clacking that's usually heard from that side. Some reflashed PCM's offer a slight increase in RPM and the noise isn't heard any more (96 6.5 tahoe I had).

A sound recording from a stationary point would be helpfull in troubleshooting this noise, we'll know whether it's the normal or something more severe.

J

[mrussell]

I can not tell if it goes away as the noise of the engine overwhelms it. It does not sound like any engine noise that I have heard of though. It sounds like foreign metalic rattling of some sort. Similar to an anoying exaust rattle? I have also replaced motor mounts recently.

[john8662]

I've heard 6.5's make several "metallic" sounding noises, they all differ.

Do you have a method to record this sound?

Could save you some bucks!

Engine mounts bad will cause vibrations to be felt in the cab.

Check ALL Your injection lines for any places where they might contact a bracket nearby or anything close, they cause knocking noises when they pulse and contact something. Usually the heater line (off the crossover).

J

[redbird2]

Have you checked the heat sheild on the stater and the starter brace. something I ran across recently was a bad exhaust insulator in the rear of the truck it metal sound was telegraphing forward amlost pulled my hair out until I found it thank god its gone I was tired of this guy bring it back to the shop. good luck.

[Bnave95]

Try probing with a steh a scope, how ever it's spelled:D
Would think if it's that bad then this would work.

[Mark Rinker]

How many miles on injectors? I'd run some good injector cleaner through as well - possibly its a back knock from a dirty injector on that side.

[Bnave95]

Injectors good Ideal though he said they did a cut out test. How is that done?
Injector sticking open? That would be interesting!
This statement
"It has gone from barely audible to detectable from 50 feet away on passenger side."
This would seem to be a high pitch noise or a really bad rapping,hammer sound.
Should we question the oil? Type,brand, oil psi range? Cold,hot?
When the noise it at it's worse,does it effect the way the Eng. is running.
Valve train issues.

[mrussell]

supposedly they checked it with a stethascope. There have been numerous people look at it. The injectors were new and installed @40,000 mi ago.
The oil was changed during the last round of tests, no difference. Oil pressure constant (up to 50 to 60 psi cold)and appears ok. I have run PS fuel addative through it quite regularly. I am used to diesels, presently have this thing, a vw tdi and a boat with twin volvo tamd 31. Previously had a dodge cummins. The noise has more of a rattle to it than a hammering. It is detectable above the engine noise, but not by alot. It is metalic, almost like or similar to exaust rattle? Difference being is that it most definately seems to be coming from the engine somewhere? Some say the front, some say the oil pump area but there is no definite source. I know this seems strange! I will try to record it.

There seems to be no performance/smoking issues at all other than it is smoking a good bit at start up. I have been going through glow plugs lately, installed a set of Quick heats that went bad real fast. Then replaced glow plug controler. Smoke could be due to more bad plugs (also it is quite cold here) but once it has gone away (5 to 10 seconds) it never re appears.

I am not used to a diesel with a timing chain. Somehow they tested it at the diesel shop and felt that it was not overly loose. Is there something in there that could make a rattling type noise? However, it does make a good bit of noise running with the oil fill cap off, but it is constant and consistant. How difficult and what would the cost be to replace this? As far as the cut out test, they said that they could do that through the computer, made sense to me with the electronic control, anyone know?

I will check the starter and heat sheild, too bad it is so hard to get off, could remove it while running. I will also check the fuel lines.

Thanks for your help so far. Hopefully someone at some point has had something like this (and it was not engine failure!)

[mrussell]

I just checked it after only letting it warm up very little. The sound is somewhat audible from under hood, a little more so from the fender well and is distinctly heard from underneath. Could it be the oil pump? It gives no signs of oil problem.....

It is 4x4. What is the best way to go about getting a look at the bottom end of this thing to see if oil pump or bearing cap/block? Is it best to pull motor or drop 4wd or is this not necessary? Any pitfalls to look out for? Also, how would one go about cheking the oil pump? is it a gear type? I am going crazy with this thing, I just have a bad feeling that it is going to be major?

[joed]

Have you checked the turbo heat shield (covers the top back portion of the turbo)?

May dad's 95 truck has a metallic noise on the turbo side - can only really hear when it's warmed up. I think this is beacause the noise on a colder engine from advanced timing, etc. drowns it out.

Joe.

[john8662]

I just checked it after only letting it warm up very little. The sound is somewhat audible from under hood, a little more so from the fender well and is distinctly heard from underneath. Could it be the oil pump? It gives no signs of oil problem.....

It is 4x4. What is the best way to go about getting a look at the bottom end of this thing to see if oil pump or bearing cap/block? Is it best to pull motor or drop 4wd or is this not necessary? Any pitfalls to look out for? Also, how would one go about cheking the oil pump? is it a gear type? I am going crazy with this thing, I just have a bad feeling that it is going to be major?


Not the oil pump, they're plenty quiet.

You can remove the pan on the engine installed in the vehicle, but let's not concentrate on digging into the engine until the noise is heard.

As mentioned a lot of higher miles 6.5 (100k plus) have an odd clacking noise as I call it that is intermittant. This may be the noise you're hearing. If it's more serious, then dropping the pan might make sense. If the oil psi is good, it's probably not bearings.

A few things I can think of that would contribute would be loose wrist pin bushings, which you can't determine from underneath.

J

[JTodd]

I would get a mechanics stethoscope and find the source. There are also variants that have a solid probe that you can hold against a metal part to hear if it is being hit or moved by something else. If the sound is that audible you should be able to figure out the source. Using the steth or a hose or something will help determining the direction from which the noise is coming, (many times a noise heard up front is something like the resonance of the exhaust), then the source.

For reference, you said metallic. Is it a grinding, a banging, a rattle or what? My car has a bad timing chain tensioner that gives it just enough slack at idle to hear it 'slap' a little. I don't think it would be this, but just trying to understand the noise. Is it deep and resonating or tinny and tapping?

For those that know, what does it sound like when an injector fires out of sequence? Could there be a cross over of injector lines?

[rabt]

Broken plastic rocker arm retainer?

[mrussell]

what is the plastic rocker arm retainer? is it a bushing, what would I be looking for?

[john8662]

Valve train problems would likely cause the engine to run rough.

If a rocker arm retainer clip (button) had broken, the rocker would have slid off to the side and that pushrod wouldn't be depressed. The engine would have a miss to it.

From the description here, the engine seems to run fine, other than a noise present.

[rustyk]

I had a gaso boat engine with something similar - drove me nuts - I finally deduced it had to be wrist pin slop or piston slap. I agree with john8662 -it could be the former - which is what it was in the boat.

[TAG]

If this noise is a higher pitched metallic clanging or rattle type sound , coming from turbo side of engine after warm up, i wouldnt worry too much. My 95 pu has made this noise from the day i bought it with 92,000 mi on it. It now has 220,000 mi on it & i just installed a penninsular 18:1 7,000 miles ago, didnt change the noise at all. Hope this eases your mind a bit.

[Robyn]

Hello

Try using a gloved left hand and place it firmly on the back of the turbo heat shield. (Metal cover over the turbo)
If you are standing at the right side of the rig leaning over the fender this will be easy. Placing your hand on the heat shield and pressing should stop or at least dampen the noise if its what I think it is.

If I understand correctly you recently had new injectors put it the truck??

The injectors can and do make a very audible noise as they operate.
Also you can have a helper rev the engine while you listen out front, have them rev it to about 2500 and abruptly let off the throttle.
The engine should be quiet as it coasts down and then the noise will resume as the fuel comes back on at idle.

High mile injectors tend not to do it as much.

If this is the case it is the injectors.
The metal heat shield acts like an amplifier, by reving the engine and chopping the throttle the injectors receive no fuel during the decel and will not click


In 93 I passed on buying a new dually because of the noise and bought a different truck instead that did not have it.
A few years later I learned what the noise was.

If this turns out to be the case, welcome to the world of the clicky little 6.5
My freshly rebuild 6.5 did it and it was sooooooooooooo anoying
I finally bolted a little 1/4" X 1" X 2" piece of lead to the shield to dampen the noise.

Bottom line, if this is the deal, just drive it and ignore it as it is perfectly normal, or bolt a damper on the shield.

Having not heard your noise makes it hard, BUT there is one other noise that can occur.
The heater feed tube that connects to the cross over can vibrate agains the plastic engine cover.(If you still have it toss it)

When this occurs the noise will telegraph right into the cab and is terribly anoying.

Maybe???????

Hope this helps

Robyn

[65TD]

Yep,

Drive it like you stole it. Don't go into the engine looking for it. You won't find it in there.

[DA BIG ONE]

I've had a metallic sound since I installed a Flowmaster x-over pipe which seems more pronounced on pass side.

I'm still not use to the uneven firing sound of motor.