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

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?

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

Regards

Col Tigwell

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..

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.)