'Whoof, whoof, whoof' -- air release under passenger side battery..

[Az4x4]

I'm new to the Dodge turbo diesel, so excuse my ignorance and bear with me on this. We bought an '03 Ram 2500 earlier this summer to pull our travel trailer with. The truck was well cared for, in great shape inside and out. From the day we got it we noticed a strange 'whoof, whoof, whoof' sound, always in a series of three, kinda like the truck was clearing it's throat. This comes from under the battery box on the passenger side of the truck, and there's a discharge of air associated with it. If it's a normal thing I won't worry about it. If it indicates a potential failure of some sort I'll get it fixed.

So far it's caused no problem. Once it 'whoofs' three times we don't hear it again until the next time we start the truck and take it for a spin. We spent 11 days pulling our trailer through Arizona to New Mexico, north through NM to northeastern Colorado, from Colorado north into Wyoming, then west across Wyoming into Utah, and finally back home to Arizona's Mogollon Rim country -- all without a problem of any sort.

The only thing that's gone 'wrong' since we bought the truck is that the cruise control has stopped engaging. The "Cruise" indicator lights up, but depressing the button to engage cruise mode no longer does anything. Not sure if this has anything to do with the occasional 'whoof, whoof, whoof' air discharge under the passenger side battery, or if it's entirely unrelated. What do you guys think?.. Any expert help or ideas would be appreciated..

 

[NIsaacs]

I recommend getting your valve lash adjusted, that sounds like an exhaust pulse out the intake. Have you checked your air filter? It might show some soot if it is a valve lash issue.

 

[Az4x4]

I recommend getting your valve lash adjusted, that sounds like an exhaust pulse out the intake. Have you checked your air filter? It might show some soot if it is a valve lash issue.

I changed the engine oil, installed a new oil filter, and checked the air filter prior to our recent trip. The air filter showed no soot and was clean enough to leave in place.

 

[B.G. Smith]

Does this occur only when towing? Isn't the air cleaner box behind the battery on that year model? bg

 

[Az4x4]

Does this occur only when towing? Isn't the air cleaner box behind the battery on that year model? bg

This occurs, one cycle of three 'whoofs' of air, shortly after I first start the truck, and generally a idle. Never hear it afterwards and not when towing.

The air cleaner box on my '03 Ram 2500 turbo diesel is forward of the passenger side battery at the front of the engine compartment.

In addition, when it does it's cycle of three 'whoofs', the engine slows with each 'whoof'..

 

[B.G. Smith]

do you have exhaust brake?

 

[Az4x4]

do you have exhaust brake?

Yes, there is an exhaust brake..

 

[seafish]

I believe that your 2003 still had a vacuum pump for the EB and IIRC its is mounted on the passenger side. Likely the diaphragms are going bad as they tend to do. Also old hoses will deteriorate and fail. There are rebuild kits available.

 

[Az4x4]

..I believe that your 2003 still had a vacuum pump for the EB and IIRC its is mounted on the passenger side..

Wish I had a service manual for my truck so I could look up these things.

..Likely the diaphragms are going bad as they tend to do. Also old hoses will deteriorate and fail. There are rebuild kits available..

I'll see what I can find out. I have to go to Show Low to find a good diesel mechanic, but I'll do that ASAP..

 

[Az4x4]

Wish I had a service manual for my truck so I could look up these things..

Found the manual in PDF form: http://www.ossh.com/dodge/03DRM.pdf

 

[Ozymandias]

The Aircon makes also a hissing sound from time to time in that corner of the engine bay.

 

[NIsaacs]

do you have exhaust brake?

B.G. is on to something here. Good chance your Exhaust brake is stuck on for a few seconds.

 

[TConver]

If it is a BD Exhaust brake, they cycle three times at start up to exercise the ram on the exhaust brake.

 

[Tuesdak]

Video of the truck doing the barking would help.

 

[Az4x4]

Video of the truck doing the barking would help.

I agree. I'll take a video late today and get it posted so you guys can see and hear what's happening..

 

[Az4x4]

Wondering also, is it best to leave the exhaust brake engaged all the time, or use it only when needed? I've read some who say leave it engaged, and others who say not to. I haven't left it engaged, but I will if someone can explain why that works best -- if it does..

 

[TConver]

Wondering also, is it best to leave the exhaust brake engaged all the time, or use it only when needed? I've read some who say leave it engaged, and others who say not to. I haven't left it engaged, but I will if someone can explain why that works best -- if it does..

Your three woosh noises are the exhaust brake exercising. I left mine engaged all the time, kept the mechanism moving free. It can carbon up and freeze otherwise.

 

[Az4x4]

Your three woosh noises are the exhaust brake exercising. I left mine engaged all the time, kept the mechanism moving free. It can carbon up and freeze otherwise.

I've read others who've said the same thing. I'll explore the issue a bit further before I decide, but I'm open to change if leaving it engaged makes sense. It's an interesting question in that it seems counter intuitive to have the exhaust brake continually engaged -- given that its purpose is to increase back pressure and slow the vehicle. But I've seen other things that seem counter intuitive until they're put into practice -- then they're not so counter intuitive after all.

 

[TConver]

I've read others who've said the same thing. I'll explore the issue a bit further before I decide, but I'm open to change if leaving it engaged makes sense. It's an interesting question in that it seems counter intuitive to have the exhaust brake continually engaged -- given that its purpose is to increase back pressure and slow the vehicle. But I've seen other things that seem counter intuitive until they're put into practice -- then they're not so counter intuitive after all.

It is not continually engaged. It is only engaging when you let off the throttle and the torque convertor is in lockup if you have an auto trans. Otherwise with an manual it will engage when you lift off the throttle.

If you do not believe me on the woosh, have some one else start it while you lean over the battery and look at the exhaust brake actuator cylinder. It will cycle three times. I am assuming it is a turbo mounted unit, if it is an inline mounted unit you may have to lay under the truck to see it. Also you need to buy the BD lubricant and keep it lubed per BD instructions.

 

[Az4x4]

It is not continually engaged. It is only engaging when you let off the throttle and the torque convertor is in lockup if you have an auto trans. Otherwise with an manual it will engage when you lift off the throttle.

If you do not believe me on the woosh, have some one else start it while you lean over the battery and look at the exhaust brake actuator cylinder. It will cycle three times. I am assuming it is a turbo mounted unit, if it is an inline mounted unit you may have to lay under the truck to see it. Also you need to buy the BD lubricant and keep it lubed per BD instructions.

I believe you. I lifted the hood, started the truck, then took a 20 second video of the engine running looking at the passenger side of the engine compartment and the exhaust brake actuator cylinder. It cycled, as you noted, three times shortly after the engine was started. Mystery solved and lesson learned. From now on, running an automatic transmission, I'll leave the exhaust brake engaged..

Here's a link to the video. For some reason I can't hear the 'whoosh' of the audio on it, although it's there in the original. But you can see the brake actuator cycling three times..

https://imgur.com/dnfGQuL