Engine/Transmission (1998.5 - 2002) Cold Air Intake VS Stock

[leathermaneod]

Hey everyone,

My truck had an Airaid intake with a K&N filter when I bought it and I am debating about going back to the stock setup. I recently had some work done to the truck which included extending the crank case vent down by the axle. After getting the truck back I started seeing a lot more gas out of the vent than I had expected. I checked blow by out of the oil fill cap and it also had more than I liked, so I started reading. I ended up holding my thumb over the vent trying to see how much blow by I had. I held it for about 20 seconds and just as I was about to let it go I heard a pop and a hiss and had oil everywhere. I thought that the dipstick would pop and the gas would vent out the tube before anything broke, but I was very wrong. The tappet cover gasket blew out and I'm still not sure what else. I picked the truck up from my mechanic yesterday and it was still leaking. I'm really hoping its just the oil pan gasket but I don't know yet. I also had the blow by tested last week and was told it was within spec, so (even better) the whole thing is caused by me, once again, trying to fix something that isn't broke. This long story all leads to my question, are washable filters such as Airaid and K&N more likely to cause dusting and blow by? Is it best to just stick with stock? I don't know how long the current setup has been on there. The truck is at 250,000 and I am trying to make it last to at least 500,000 so I want to take the best care of it that I can.
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[RonaldLarson]

Hey everyone,

My truck had an Airaid intake with a K&N filter when I bought it and I am debating about going back to the stock setup. I recently had some work done to the truck which included extending the crank case vent down by the axle. After getting the truck back I started seeing a lot more gas out of the vent than I had expected. I checked blow by out of the oil fill cap and it also had more than I liked, so I started reading. I ended up holding my thumb over the vent trying to see how much blow by I had. I held it for about 20 seconds and just as I was about to let it go I heard a pop and a hiss and had oil everywhere. I thought that the dipstick would pop and the gas would vent out the tube before anything broke, but I was very wrong. The tappet cover gasket blew out and I'm still not sure what else. I picked the truck up from my mechanic yesterday and it was still leaking. I'm really hoping its just the oil pan gasket but I don't know yet. I also had the blow by tested last week and was told it was within spec, so (even better) the whole thing is caused by me, once again, trying to fix something that isn't broke. This long story all leads to my question, are washable filters such as Airaid and K&N more likely to cause dusting and blow by? Is it best to just stick with stock? I don't know how long the current setup has been on there. The truck is at 250,000 and I am trying to make it last to at least 500,000 so I want to take the best care of it that I can.
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First, get rid of that K&N filter. Countless posts have identified them as sub standard for dust. The stock filter with a foam prefilter (NAPA< DODGE< CUMMINS) as a part of the filter is what Cummins wanted us to use. Just as critical, use only Cummins or Mopar fuel and oil filters. That's what Cummins wants, to protect their magnificent engines.

 

[leathermaneod]

I am planning on switching to cummins oil filter and a baldwin fuel filter on the next change. As for the air filter, I have to buy either a stock setup or an aftermarket setup because when I bought the truck it didn't come with the stock setup, and I have not been able to find any filter that will fit on the Airaid intake other than the K&N because it is about 6 inches in diameter. I have been researching the S&B setup and it sounds like using their dry filter may actually be better than stock. Any thoughts?

 

[seafish]

WARNING--my bad, my post below refers to 3rd and 4th gen CAIs and the thicker 4" filter available for them…NOT sure at all if it applies to a second gen truck, which is what you are posting about, so while I won't delete it, take it with a LARGE grain of salt--


You are on the right track going back to the stock CAI and there use the updated, 4" thick Mopar filter in it. You can and should also do the "home depot" mod to it so it can flow a little more unrestricted but filtered air through it. The light modified stock box with the 4" filter in it sill easily support 500hp with excellent filtration and minimal cost.

Keep checking the classified ads and/or Craigslist auto parts ads for a 3rd gen CAI…they often come up for sale because people are going the other way like they did on your truck.

You CAN also fit a 6.7 CAI on it with very little modifications if you can't find a 5.9 CAI.

Heres a little reading---

https://www.turbodieselregister.com/threads/217248-Need-6-7L-Air-Filter-Box

 

[FCrowder]

It may not be blow by. The vacum pump exhaust is into the crankcase. If you have a broken vacum line it will smoke alot out the crankcase vent and build up alot of pressure in the crankcase.

Francis

 

[leathermaneod]

It may not be blow by. The vacum pump exhaust is into the crankcase. If you have a broken vacum line it will smoke alot out the crankcase vent and build up alot of pressure in the crankcase.

Francis

I have heard that about vacuum leaks, wouldn't I have problems with the HVAC controls in that situation? Also, does it hurt anything if a leaking vacuum line is causing extra gasses in the crank case as long as it is venting?

 

[leathermaneod]

WARNING--my bad, my post below refers to 3rd and 4th gen CAIs and the thicker 4" filter available for them…NOT sure at all if it applies to a second gen truck, which is what you are posting about, so while I won't delete it, take it with a LARGE grain of salt--


You are on the right track going back to the stock CAI and there use the updated, 4" thick Mopar filter in it. You can and should also do the "home depot" mod to it so it can flow a little more unrestricted but filtered air through it. The light modified stock box with the 4" filter in it sill easily support 500hp with excellent filtration and minimal cost.

Keep checking the classified ads and/or Craigslist auto parts ads for a 3rd gen CAI…they often come up for sale because people are going the other way like they did on your truck.

You CAN also fit a 6.7 CAI on it with very little modifications if you can't find a 5.9 CAI.

Heres a little reading---

https://www.turbodieselregister.com/threads/217248-Need-6-7L-Air-Filter-Box

What is the Home Depot mod?

 

[klcammie]

I agree get rid of the K&N. I went with a BHAF [big honking air filter]. Check out www.bighaf.com That is what I have now. If you go that route make sure to get the Outerwears prefilter. Mine has been it the truck for 3 years and is still good.

 

[JR]

There is a poor selection of air filtration on the 2nd gen trucks. All aftermarket "cold air intake" systems are only partial at best, drawing a mix of cold and hot engine bay air in. In my experiences the factory boxes are good for around 300 hp and is the best option if you are at or under that mark. You can cut some holes in the bottom of the box to increase air flow but then you are back to drawing in hot engine bay air.

I believe the best solution for the 2nd gens (and one I plan on doing if/when I ever need more air than my factory box is capable of) is to relocate the passenger side battery to the back corner of the engine bay where the factory air box sits. This would permit you to run a 6.7 factory air box which is capable of supporting quite a bit more hp, especially if you mod the factory box which is much more feasible in the location that it is compared to the 2nd gen trucks. A little bit of fabbing would be needed but used 6.7 OEM intakes are available all over the place for a fraction of the cost of an aftermarket system that will draw as much hot air as it will cold. Not to mention the OEM Fleetgaurd filters are of the best filtration on the market.

 

[leathermaneod]

There is a poor selection of air filtration on the 2nd gen trucks. All aftermarket "cold air intake" systems are only partial at best, drawing a mix of cold and hot engine bay air in. In my experiences the factory boxes are good for around 300 hp and is the best option if you are at or under that mark. You can cut some holes in the bottom of the box to increase air flow but then you are back to drawing in hot engine bay air.

I believe the best solution for the 2nd gens (and one I plan on doing if/when I ever need more air than my factory box is capable of) is to relocate the passenger side battery to the back corner of the engine bay where the factory air box sits. This would permit you to run a 6.7 factory air box which is capable of supporting quite a bit more hp, especially if you mod the factory box which is much more feasible in the location that it is compared to the 2nd gen trucks. A little bit of fabbing would be needed but used 6.7 OEM intakes are available all over the place for a fraction of the cost of an aftermarket system that will draw as much hot air as it will cold. Not to mention the OEM Fleetgaurd filters are of the best filtration on the market.

Unfortunately to go back to a stock set up I have to buy one because I bought the truck with this stupid airaid/k&n combo. So since I have to spend the money anyway I am debating between going back to stock or getting an S&B intake with dry filter

 

[JR]

Correct, you have to buy something and in terms of filtering efficiency AND a true cold air intake the OEM 6.7 intake is the best of both worlds. S&B offers good filtration but is not a true cold air intake on the 2nd gen trucks as it draws much of its air from the hot engine bay.

Just to clarify, my opinion is the OEM 2nd gen set up is the best and most economical choice if around the 300 HP mark or less. If above that the OEM 6.7 intake is the best choice as the box has higher CFM capabilities, excellent filtration and you can make a true cold air intake with it.

Both set ups can be had very reasonably on Craigslist or various classified ads on forums like here, CF, CompD, etc.

 

[leathermaneod]

Thanks for the info JR, I respect your opinion, however I can't justify all the work of the OEM 6.7 right now and I am somewhat worried about using the OEM 2nd Gen airbox. I have heard that as they wear they start leaking unfiltered air at the corners. For this reason I really like the idea of a round filter that covers the entire end of the tube. I have read a lot of good things about the S&B and if I get it I will be using the dry filter not the oiled one. So my final concern is if the S&B filters at least as well as a stock fleetguard? My other option is to us a BHAF but I'm not sure how to secure the filter in place or if I need a heat shield or not. I read that having an intercooler makes the hot air from the engine bay somewhat irrelevant?

 

[JR]

In some cases in hot climates and elevated engine bay temps I have heard of them warping over time. I've had 2 2nd gens, a 2000 with over 380k and my 98.5 with around 125k and not had an issue with either truck.

While an intercooler will help negate hot engine bay air it still can be detrimental, especially if you tow heavy. Slow speed high load driving is where you will suffer the effects of drawing in hot air the most. I was given a BHAF some time ago and ran it through the winter but as soon as the hot summer months came around I noticed a definite change in my IAT (intake air temperature) that I monitor with a Scan Gauge. Enough that i rwmoved it and went back to my OEM box. I think the BHAF are a bad idea in all but the coldest of weather. All one has to do is take a look at where ALL the OEMs draw their intake from to determine where it is the most beneficial. Nobody draws air from the engine bay, not Dodge, Ford, or GM. They are all drawn from the fender well and since 13+ Ram went a step further and developed a shutter system that draws in direct cold air weather permitting.

 

[leathermaneod]

Oh ok that makes sense, thanks for the replies. Now the only thing holding me back is my concern with the oem box drawing unfiltered air at the corners, I guess as log as it is in decent shape that is a moot point. Oh one other question, how are your egts with the oem air box?

 

[JR]

With 275 HP injectors and a Smarty on level 5 EGTs are very manageable. Just got back from towing 8k with another 500-700 lbs in the bed through the mountains of West Virginia. I have no problems maintaining 70 mph on 6-7% grades on the freeway. Grades on local roads easily reach 7-9%. If I was exceeding the OEM boxes CFM capabilities I would be drawing the filter minder down excessively which is something I've never done.

 

[leathermaneod]

With 275 HP injectors and a Smarty on level 5 EGTs are very manageable. Just got back from towing 8k with another 500-700 lbs in the bed through the mountains of West Virginia. I have no problems maintaining 70 mph on 6-7% grades on the freeway. Grades on local roads easily reach 7-9%. If I was exceeding the OEM boxes CFM capabilities I would be drawing the filter minder down excessively which is something I've never done.

Oh wow sounds like I should be fine then, my truck is mainly a daily driver, I have 75hp injectors but only because the last guy put them in because he towed a lot. I have a smarty but rarely use it. I try to baby the truck as I love it and want it to last forever lol

 

[JR]

Your injectors are hotter than mine, RV 275's are about the equivalent of 40HP. But if you don't use your Smarty we are probably pretty close in power.

 

[leathermaneod]

oh ok. I honestly don't know too much about injectors period and all I know about mine is what the last guy told me which is that the are 75hp. Thanks for all the info!

 

[JR]

Knowing now that you've got 75 HP injectors it does change things a little. If you don't plan on anymore power upgrades youd be fine with an OEM box. If you think you might go bigger in the future then you would probably be better off going with something other than the 2nd gen OEM intake.

 

[leathermaneod]

I don't have any plans for more power in the future. I think the truck can do all i need and more the way it is. I even contemplated going back to stock injectors just to take it easier on the engine. If I use the smarty it has incredible power so like I said I don't think Ill be doing anything else to make more lol