Double air filter in Patrol.....necessary or not?

Submitted: Friday, Nov 21, 2003 at 23:07
ThreadID: 8673 Views:2343 Replies:4 FollowUps:5
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I am working in Kenworth Truck. Every truck they manufactured with only one paper air element. Some of them have 2 air intake with 2 snorkel but still air pass one air filter on each side.
My question is.... such expensive machine which probabaly built for the toughest condition still using only one air filter
Is it really necessary for GQ TD42 use 2 air filter?

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Reply By: mrdesmo - Saturday, Nov 22, 2003 at 05:00

Saturday, Nov 22, 2003 at 05:00
How many Kenworth trucks do you see on the dirt or working in dusty situations?
What are the service intervals for a Kenworths air filters?
I would assume the road trains you see on the Tanami etc or dump trucks would have beefed up filters though?
AnswerID: 38078

Reply By: herkman - Saturday, Nov 22, 2003 at 06:53

Saturday, Nov 22, 2003 at 06:53
A varity of Donaldson type filter assemblies are fitted to Kenworth, and in actual fact most heavy trucks.

The second filter, is not there really to clean the air durring normal operations, but are there as a safety filter.

Donaldson and other similiar type filters, are changed on condition, and there is a resriction device fitted, which shows what the restriction level is at, some are mounted on the outside of the filter casing, and some send the signal to the cabin.

In trucking applications, Donaldson filters can be washed in a tub, with their applicable cleaner, but have to be dry before they can be re installed. Washing and or overloading of the filter, can cause them to spilt, usually on the inside side of the pleats. This can be seen by putting a lamp up inside the filter, and any pleat damage can then be seen. Generally the wider the pleats the greater the risk of pleat damage. Donaldson also recommend that filters be shanged yearly, inspite of how many times they have been washed.

The purpose of the inner filter, is to act as a safety filter, because they are smaller, there is less risk of them spilting.

Now what I do not know, is whether 4WD types can be washed, I suspect on principals Nissan etc would say NO!

The Donaldson paper is a special type of paper called Duralife 11, and as they have a patent on it, I doubt if any one elses, comes up to theirf quality.

Removing the inner filter, is not really a good idea, it will take very little dirt to "Dust" your engine, which means a total rebuild. Bear in mind that the OEM, reaaly does not want extra costs built in, unless there is a requirement.

Hope this helps in your decision making


Col Tigwell
AnswerID: 38083

Reply By: Truckster (Vic) - Saturday, Nov 22, 2003 at 10:38

Saturday, Nov 22, 2003 at 10:38
In Bayswater?? used to work there myself.. which dept you in?

Anyway Im running one filter in my GQ,bleepthe precleaner box off, its restrictive.

Up to you, but no you dont really need it. If your heading into the desert etc, possibly I would..
AnswerID: 38090

Follow Up By: pathfinder - Tuesday, Nov 25, 2003 at 13:21

Tuesday, Nov 25, 2003 at 13:21
if you're heading into the desert, just slip on the snorkel head foam sock...very easy to clean regularly
FollowupID: 27870

Follow Up By: Truckster (Vic) - Tuesday, Nov 25, 2003 at 13:42

Tuesday, Nov 25, 2003 at 13:42
Snorkel SOcks, not recommended for Turbo cars ..

but then again depends what day of the week it is doesnt it, and who you talk to, you never seem to get the same answer from different staff at the same store... SOme only seem interested in the sale... Commission is a deadly thing to honesty.
FollowupID: 27873

Follow Up By: pathfinder - Tuesday, Nov 25, 2003 at 13:48

Tuesday, Nov 25, 2003 at 13:48
yep, I agree if they're not serviced properly/allowed to dry out, there is a possibility of foam flaking off and getting caught in turbine fins. The advantage of the snorkel head sock (as opposed to internal full snorkel sock) is that they are used just on a temporary basis in dusty conditions and are very accessible so servicing is not a problem...
FollowupID: 27874

Follow Up By: Truckster (Vic) - Tuesday, Nov 25, 2003 at 14:23

Tuesday, Nov 25, 2003 at 14:23
Not the flaking issue, its the restrictiveness issue..
FollowupID: 27878

Follow Up By: pathfinder - Tuesday, Nov 25, 2003 at 14:44

Tuesday, Nov 25, 2003 at 14:44
haven't actually noticed much performance/economy diff with foam vs any case, the snorkel head sock is only in place during dusty periods where dust clogging the main filter would definitely reduce performance anyway...
FollowupID: 27880

Reply By: David N. - Sunday, Nov 23, 2003 at 17:44

Sunday, Nov 23, 2003 at 17:44
Truckster is correct.
I removed the Pre-filter from my Patrol 12 years ago and the improvement was immediate and very noticeable. Less black smoke, more power.
Diesels need LOTS of air, any restriction is bad news.
One filter will work just fine, as long as you maintain it properly.
(You could always chuck the prefilter back in if you were doing some serious dirt roads.)
AnswerID: 38196

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