deceleration noise.

[rgreen]

Hello everyone how is everybody? I have 09 prostar when I go over 50mph and let go of the accelerator my engine is making a noise like the engine brake is on (but the engine brake is not on) or it sound like something is grinding. It goes away with speed under 25 mph but this does not happen all the time. Only happen after truck been running for a few hrs driving.Has anybody ran into this problem before????

[Signature620]

When you say engine brake noise do you mean the brake rockers rattling or the actual exhaust noise?

[Running rough]

Clutch???

[rgreen]

it might be the brake rockers, how can I tell? I don't think it is the clutch the truck is automatic, when you go over 50 or so and take your foot of the accelerator the engine is making a wired noise like something grinding or rattling.

[Signature620]

Does it have the same noise when you come off of the engine brakes? The detent pockets in the valve rocker shafts wear out and the rockers can have a hard time staying in their neutral position. This allows them to knock back and forth between the cam and the exhaust valve - Creating a top end rattle constant with engine rpm. If this sounds like your issue, you can pull off the rocker cover and try to rock the engine brake rockers by hand to see how solid they lock into their neutral position.

[rgreen]

(09-27-2016 )Signature620 Wrote:  Does it have the same noise when you come off of the engine brakes? The detent pockets in the valve rocker shafts wear out and the rockers can have a hard time staying in their neutral position. This allows them to knock back and forth between the cam and the exhaust valve - Creating a top end rattle constant with engine rpm. If this sounds like your issue, you can pull off the rocker cover and try to rock the engine brake rockers by hand to see how solid they lock into their neutral position.

I never tried to put on the engine brakes to see if i have the same problem, I will try that tomorrow. Is it safe to drive????

[rgreen]

(09-27-2016 )rgreen Wrote:  

(09-27-2016 )Signature620 Wrote:  Does it have the same noise when you come off of the engine brakes? The detent pockets in the valve rocker shafts wear out and the rockers can have a hard time staying in their neutral position. This allows them to knock back and forth between the cam and the exhaust valve - Creating a top end rattle constant with engine rpm. If this sounds like your issue, you can pull off the rocker cover and try to rock the engine brake rockers by hand to see how solid they lock into their neutral position.

I never tried to put on the engine brakes to see if i have the same problem, I will try that tomorrow. Is it safe to drive????

When I put on the engine breaks it seems like it goes away but i have take the cover off this what i have found, How can i tell if the engine brakes rockers are out of adjustment

[rgreen]

(09-28-2016 )rgreen Wrote:  

(09-27-2016 )rgreen Wrote:  

(09-27-2016 )Signature620 Wrote:  Does it have the same noise when you come off of the engine brakes? The detent pockets in the valve rocker shafts wear out and the rockers can have a hard time staying in their neutral position. This allows them to knock back and forth between the cam and the exhaust valve - Creating a top end rattle constant with engine rpm. If this sounds like your issue, you can pull off the rocker cover and try to rock the engine brake rockers by hand to see how solid they lock into their neutral position.

I never tried to put on the engine brakes to see if i have the same problem, I will try that tomorrow. Is it safe to drive????

When I put on the engine breaks it seems like it goes away but i have take the cover off this what i have found, How can i tell if the engine brakes rockers are out of adjustment

[attachment=2008]

[Signature620]

Do you have much experience with this engine? This is a fairly involved task to walk through over the internet. If you don't have the necessary tools and knowledge, you should take it to someone with does.

EDIT: Just saw the photo...That roller is only just starting to go. What does the cam look like? If the cam is severely damaged it could be the source of your noise, but judging by the roller I'd guess it is not yet bad enough to make much sound.