Running without air filters on AD41B engines -- Risk ???

[westhunt22]

I have AD41B engines with the later style plastic air filter housings and filters. I'm getting some blow by, which coats the filters. First, I don't understand how that oil is getting into the filter housings, since it seems to be coming in from outside, and there is NO blow by hose going to the filter housings. And I've removed the filters and looked at the air side turbo impellers, and they are clean on both engines -- no oil). During recent trouble shooting of low power, I removed the filters, which needed changing, and ran the engines under load (i.e., took the boat out into the river an ran it). Performed MUCH stronger. I'm getting about 100 hours on the engines before the filters start affecting performance, and Volvo filters are stupidly expensive.
So, that begs the questions: If I remove the filters, but leave the filter housings in place, am I risking engine damage? The filter housings have slots in them, but not big enough to allow any large items (plastic bag, etc.) to get in, and the air in the bilge is quite clean. So, the filters are only catching blow by.
A follow up question: Has anyone found a different filter system -- K&N, etc... that would be higher capacity, and/or has washable filters or dry filters that I could substitute for the Volvos ?? (I'd be leery of oil soaked washable filters like the K&N, because of the likelihood of sucking the oil into the air side of the turbos).

Thanks for any help. And please remember -- these are diesels, not gas.

 

[westhunt22]

Re: Running without air filters on AD41B engines -- Risk ???

I have AD41B engines with the later style plastic air filter housings and filters. I'm getting some blow by, which coats the filters. First, I don't understand how that oil is getting into the filter housings, since it seems to be coming in from outside, and there is NO blow by hose going to the filter housings. And I've removed the filters and looked at the air side turbo impellers, and they are clean on both engines -- no oil). During recent trouble shooting of low power, I removed the filters, which needed changing, and ran the engines under load (i.e., took the boat out into the river an ran it). Performed MUCH stronger. I'm getting about 100 hours on the engines before the filters start affecting performance, and Volvo filters are stupidly expensive.
So, that begs the questions: If I remove the filters, but leave the filter housings in place, am I risking engine damage? The filter housings have slots in them, but not big enough to allow any large items (plastic bag, etc.) to get in, and the air in the bilge is quite clean. So, the filters are only catching blow by.
A follow up question: Has anyone found a different filter system -- K&N, etc... that would be higher capacity, and/or has washable filters or dry filters that I could substitute for the Volvos ?? (I'd be leery of oil soaked washable filters like the K&N, because of the likelihood of sucking the oil into the air side of the turbos).

Thanks for any help. And please remember -- these are diesels, not gas.

OK, I think I'll answer one of my own questions. After thinking through it, I will be reinstalling the filters. Otherwise, the blow by oil will end up in the air side of the turbo, and find it's way into the aftercoolers, inevitably plugging them in the future.
I'd still like to know if others have found a different filter system that has more capacity......

 

[JPfisher]

Re: Running without air filters on AD41B engines -- Risk ???

OK, I think I'll answer one of my own questions. After thinking through it, I will be reinstalling the filters. Otherwise, the blow by oil will end up in the air side of the turbo, and find it's way into the aftercoolers, inevitably plugging them in the future.
I'd still like to know if others have found a different filter system that has more capacity......

Sounds like you need to install an airsep system they are available thru raccor. The work like a Pcv system on a gas engine but are designed to run on diesels. They will keep your filters clean and keep you engin room clean. Most commercial marine diesel opt for intake silencers because absence of dust in marine environment. But not all boats are in a dust free environment 100 percent of the time. Pony up the dough and get the new filters and an airsep system

 

[westhunt22]

Re: Running without air filters on AD41B engines -- Risk ???

I agree -- In fact, I did some research on them, and have emailed the Airsep people to find out which system will fit. Thanks for the input. I'll contact Racor.

J.

 

[EricR]

Re: Running without air filters on AD41B engines -- Risk ???

Walker Airseps are NOT made by Racor. Racor produces a system that does the same thing called the Crank Vent system. Both the Airsep and Crank vent are good products in my experience. Airsep is made by Walker Engineering.

 

[stepphen]

Re: Running without air filters on AD41B engines -- Risk ???

I do not have your engine but know a little about diesels.
If you are getting oil on the intake side of your air filter it is coming from the only source of oil smog that must be coming from your engine crankcase... I doubt if it is caused by someone smoking nearby > I suspect you have worn rings. How about doing a compression test.

Good luck. stephen

A quick test would be to see if there is a high positive pressure inside your crankcase. Oil fill opening will give you a spot to check. But beware the hot oil or spray may shoot out under pressure and spray the Captain and the engine room. DANGER Oil fill cap is another test point. Caution also required.

 

[westhunt22]

Re: Running without air filters on AD41B engines -- Risk ???

I do not have your engine but know a little about diesels.
If you are getting oil on the intake side of your air filter it is coming from the only source of oil smog that must be coming from your engine crankcase... I doubt if it is caused by someone smoking nearby > I suspect you have worn rings. How about doing a compression test.

Good luck. stephen

A quick test would be to see if there is a high positive pressure inside your crankcase. Oil fill opening will give you a spot to check. But beware the hot oil or spray may shoot out under pressure and spray the Captain and the engine room. DANGER Oil fill cap is another test point. Caution also required.

Just a quick follow up -- For some reason, the Volvo Penta folks didn't put crankase breather filters on their engines. They just ran a hose from the crankcase vent outlet to the edge of the air filter housing. So any blow by would end up in the air filter! A nice way to speed up the plugging of the air filters, which they are very proud of. So, I removed the hoses, and installed K&N crankcase vent filters. I have very little blow by (just the typical amount for the AD41's), so I expect the vent filters to last at least one season, and the air filters should last a long time.
I also discovered an exhaust leak in the flange between the exhaust side and the air side of the turbo, on one engine. So exhaust fumes (with the famous AD41 smoke) were getting sucked into the air side of the turbos. Filters were only lasting about 50 hours. I think I'm "good to go" now !!! Thanks for all your help.

 

[Don S]

Re: Running without air filters on AD41B engines -- Risk ???

They just ran a hose from the crankcase vent outlet to the edge of the air filter housing. So any blow by would end up in the air filter!

I think if you will look at where the breather hose mounts to the air filter housing cover, that it's inside the element. So any oily blow by will not go through the filter element.

 

[westhunt22]

Re: Running without air filters on AD41B engines -- Risk ???

Actually, the vent hoses do not connect to the air filter housings. They "stub off" at the outside edge of the filter housings, so the discharge is into the open - no fittings on the end, just an open hose. So any blow by is sucked through the slots in the air filter housing, and passes through the filter element. I get the black blow by deposits on the air filters.
There is an earlier metal air filter housing, mostly on the "A" and earlier "B" engines, that may have the connections you described.

 

[K-2]

Re: Running without air filters on AD41B engines -- Risk ???

I converted my twin AQAD41A's to after market filters.
I got reducing silicone 90's here:
Intercooler Pipe Fabrication - Silicone Intake Systems Auto Parts and found filters like this :
http://img.alibaba.com/img/pb/219/899/582/582899219_914.jpg
I got the filters at Oreillys auto parts, they were cheap, not K&N brand.
I think my turbo housing was 2.5" OD, so I went with a 2.5" X 3" reducing 90 then another reducing 90 from 3" to 4"
I needed the 2 90's to position the air filter where I wanted it. I wish I remembered the brand of filters, the boat is in Alaska right now and I am not. They are like a K&N but they do not use oil and you can clean them.
I got all the hardware and 4 - 4" ID filters,(2 spares) for the price of 2 Volvo OEM filters.

OOPS!! I just noted the date on this original post.

 

[westhunt22]

Re: Running without air filters on AD41B engines -- Risk ???

Thanks for the reply -- the original posting is pretty old, but the issue is not. I've had some interesting times with the engines, and have made some modifications. I replaced the hoses leading from the crankcase vents with K&N vent filters, and have done some research on air filter replacements. The ones you are using look like the ones I'm going to go with. I think yours are similar to the Walker Airsep filters, which don't use oil. Walker is also proud of their filters, so I will definitely be visiting Oreilly's ! I measured the intake flanges to my turbos, and they are 3", so I'll go with 3" 90's leading to the new filters.
Thanks for the info !!:yo::yo:

 

[K-2]

Re: Running without air filters on AD41B engines -- Risk ???

My crank case vents were already modified when I got the boat.
When I had both outdrives gone through the mechanic was in my engine room looking at the tilt motors.
He was happy to see that the crank case vents had already been modified.