Interesting noises under the hood - air leaks etc

[888]

It's finally warm enough to have the windows open so last night when I got out of the D350, I heard what sounded like air exhausting from under the hood after I shut the truck off, it went on for maybe 5 seconds. It seemed like it was coming from somewhere near the brake booster valve but I couldn't figure out what it was after cycling it a few times so I got my oldest son to help. 20 year old ears are better than 53 year old ears, and all that.

We ruled out a few things and eventually he determined that there was a supply of air coming between two of the six "towers" on top of the cylinder head, actually between the 4th and 5th back, and that air stopped at the same time the noise stopped. I had him start it while I checked it and determined he was right.

He went on his way and I pulled the "Dodge Cummins" plate off of the top of the engine over the towers to be sure that the tower bolts were all tight (they were) and the gaskets were all good (they were). I found that I was missing a 10mm hex head bolt on a drivers side bracket that holds the rear injection lines in place on top of the head. There was a small matching soot mark on the bottom of the "Cummins plate" above the hole. Hmmmm.

The bolt was gone so I replaced it (had to use a clamp to realign the bracket with the tapped hole) and the air supply from that location stopped. That had to be some sort of improvement, I would think. The truck seems peppier but it might have just been due to the 40 mph winds from yesterday dying down.

However, the noise at shutoff did not stop, and in fact lasted a little longer before tapering off to silence. Since I had more time to find it, I determined the noise seemed to be coming from the cone filter on the end of the aftermarket intake. Turbo spooling down, maybe? Maybe this is normal and I never heard it because I always had a stock airbox?

So anyway, moral of the story is to periodically check around the top of the engine to be sure those bolts are all there.

And if anyone has input on this air noise from the intake, that would be great. Since I have some more daylight, I just determined that the exhaust manifold gasket on cylinder one appears to be leaking. Those bolts look like fun, a lot of PB Blaster and time, any other suggestions?

Here's the engine bay and intake, cone filter is on the end. Not my choice of arrangements but it came this way and I don;t have the stock stuff to undo it.



TIA

Joe

[DodgeFreak]

you might have blown the gasket for the air intake plenum, if the bolt was out and was leaking there. Get soapy water and spray it down and try to find the air leak that way.

[888]

you might have blown the gasket for the air intake plenum, if the bolt was out and was leaking there. Get soapy water and spray it down and try to find the air leak that way.

Thanks for the reply. The Cummins trucks I've owned have given me so little trouble I'm not sure what the intake plenum is. I'm assuming it's under the surface where the bolt hole was opened and venting?

[DodgeFreak]

I'm not exactly sure that's what you'd call it I guess. But its the plate where the intake horn bolts on to. It has a bunch of bolts holding it down with a gasket under it. If you are wanting a stock air box and tubing let me know I would trade you for yours since you can't receive pm's or get on the classifieds email me at zamason3@hotmail.com if you are interested.

[PToombs]

Nothing wrong with an ASA filter setup! What you're hearing is the turbo spooling down, it's normal. You may hear it more because of the air filter. Those "towers" are the valve covers.
On the manifold, lots of blaster, and you may need heat to loosen them up some. I used a harbor freight air wrench, it was enough to rattle the bolts and turn them but not enough ass to break them off. My rear one I heated and tried and it wouldn't move. I walked away for a couple hours and played with my kids and when it started to rain I came back to cover the truck up, and decided to try it again. The last bolt turned right out after it cooled.
Check the #1 and 6 ports, and see if it looks like the manifold has shrunk and the bolts are bent looking before you pull it off. If they are, you should replace the manifold. There are quite a few choices out there now, so shop around and see what you like.

[888]

Nothing wrong with an ASA filter setup! What you're hearing is the turbo spooling down, it's normal. You may hear it more because of the air filter. Those "towers" are the valve covers.
On the manifold, lots of blaster, and you may need heat to loosen them up some. I used a harbor freight air wrench, it was enough to rattle the bolts and turn them but not enough ass to break them off. My rear one I heated and tried and it wouldn't move. I walked away for a couple hours and played with my kids and when it started to rain I came back to cover the truck up, and decided to try it again. The last bolt turned right out after it cooled.
Check the #1 and 6 ports, and see if it looks like the manifold has shrunk and the bolts are bent looking before you pull it off. If they are, you should replace the manifold. There are quite a few choices out there now, so shop around and see what you like.

Thanks for the reply. I have a MAC impact but was planning on trying a bar and pipe initially to work them back and forth just so I didn't break them off. PB Blaster has been the only thing to pull apart rusty Ohio Volkswagens in junkyards (even tried Aerokroil and Silikroil) so that's what I typically use.

I have a MAPP torch and a regular torch, typically save the MAPP for serious stuff. I was thinking of trying to back the bolts out with the engine hot after a few soakings with PB. I only have cylinder #1 in need of a new gasket so I was going to try to loosen 1 and 2 and sneak the gasket into 1 rather than tempt fate on all the bolts.

So the manifolds tend to draw in towards the center? That makes 1 and 6 harder to remove? Maybe that's my problem.

I would consider replacing the bolts but I've rarely found new bolts that are as good as the originals, once they are cleaned up. Seems like everything is made in China.

On the ASA, what you can't see is that I have what appears to be a K&N type oiled cone filter on the end of the intake and I've heard the oiled filters can load the turbo vanes and run them out of balance, this is fairly common on the VW TDI sites where nothing but OEM paper filters are recommended. Not true?

Joe

[cmann250]

On the ASA, what you can't see is that I have what appears to be a K&N type oiled cone filter on the end of the intake and I've heard the oiled filters can load the turbo vanes and run them out of balance, this is fairly common on the VW TDI sites where nothing but OEM paper filters are recommended. Not true?

I'm a big fan of large dry filters. If some engineer at Cummins was willing to let millions of dollars worth of warranty work hang on a paper filter, I feel safe following suit. A while ago, I attended an oil analysis seminar and the expert (Schaffer's salesman, take it with a grain of salt) was dead convinced that an oiled filter was the single worst thing for a turbocharged engine.

Some like them, some hate them. I think there's plenty of evidence that there are better options out there.

[PToombs]

I prefer the dry type myself. I've heard that the K&N filters suck dirt thru them on the turbo diesels, so I stay right away from them.

[DodgeFreak]

I believe the oiled filters are fine....As long as you keep them clean and properly oiled....I think that's the biggest problem is they are higher maintenance, and often get over looked. I haven't personally ran one on a turbo'd engine but my cousin has and haven't seen any negative effects towards the turbo. I will say this also though I have seen where it would suck the oil off the filter and it would show on the turbo from various trucks I've delt with.

[888]

[
I'm a big fan of large dry filters. If some engineer at Cummins was willing to let millions of dollars worth of warranty work hang on a paper filter, I feel safe following suit. A while ago, I attended an oil analysis seminar and the expert (Schaffer's salesman, take it with a grain of salt) was dead convinced that an oiled filter was the single worst thing for a turbocharged engine.

Some like them, some hate them. I think there's plenty of evidence that there are better options out there.

Can you give an example of a better option and why it is better? Performance, mpg, other? I'm not against changing to something else, I just am curious what is the best change and what I can expect out of it.

[888]

I believe the oiled filters are fine....As long as you keep them clean and properly oiled....I think that's the biggest problem is they are higher maintenance, and often get over looked. I haven't personally ran one on a turbo'd engine but my cousin has and haven't seen any negative effects towards the turbo. I will say this also though I have seen where it would suck the oil off the filter and it would show on the turbo from various trucks I've delt with.

I assume this is oiled like a K&N or AFE, it's pink like a K&N and probably needs cleaning. I ran an AFE on my departed 92 CTD 5 speed for 5 years and never had any problems, the guy before me ran one for 5 previous years, it had maybe 275k on it. But I never looked at the turbo closely, it just ran and ran and ran.

[cmann250]

Can you give an example of a better option and why it is better? Performance, mpg, other? I'm not against changing to something else, I just am curious what is the best change and what I can expect out of it.

Everything I have seen says a dry filter will filter better. It's not a performance or mpg thing, it's a piece of mind thing to me.

Have I ever seen or heard of an engine failing from an oiled filter? No. It's like a Fleetguard vs. Fram oil filter thing. I've just seen a lot of data that says oiled filters let a lot of dirt through. It's just one of those things that I like to do "by the book" because my luck is so bad.

[888]

Everything I have seen says a dry filter will filter better. It's not a performance or mpg thing, it's a piece of mind thing to me.

Have I ever seen or heard of an engine failing from an oiled filter? No. It's like a Fleetguard vs. Fram oil filter thing. I've just seen a lot of data that says oiled filters let a lot of dirt through. It's just one of those things that I like to do "by the book" because my luck is so bad.

Got it. I know all about the Fram versus Fleetguard thing. I saw my last Fleetguard oil filter was made in Mexico instead of the USA, BTW.

I've seen a K&N drop in really wake an engine up and I've seen them not make much of a difference. The oil on the turbo thing is something I've seen people swear happens and others have never seen it so it's just a matter of how you want to play it.

I did see a reference on another site to using the paper based BHAF AKA the NAPA 2790 (I think thats the number but I do know it's $81!!!) on the end of the factory intake tube. My ASA setup is too long in the tube area to get that 2790 into the corner of the fender and I don't want to cut it down.

I do have a source for parts so I'm probably going to get a used OEM intake tube and see what I can do to get a paper filter on there. In the meantime, I know I need to clean the ASA mounted filter, I have AFE and K&N oiling kits, I just need to see exactly what brand I've got installed.

Thanks

[RCCUMMINS89]

Yea... don't buy things from NAPA unless you want to pay too much... that 2790 "BHAF" retails for $56.99. Personally it is the ONLY filter I will run. I've had my filters dripping wet/muddy and the inside of the filter is brand new. I've never seen a single thing get through them, included dust. I've never even been able to rub dust off my turbo blades, which on factory filters I have.

[888]

Yea... don't buy things from NAPA unless you want to pay too much... that 2790 "BHAF" retails for $56.99. Personally it is the ONLY filter I will run. I've had my filters dripping wet/muddy and the inside of the filter is brand new. I've never seen a single thing get through them, included dust. I've never even been able to rub dust off my turbo blades, which on factory filters I have.

Where did you find it for $56.99?

Thanks