Oil-Bath Air-Filter conversion to dry

[45Dougal]

When I first bought my HJ45, I ordered a bunch of service parts including a paper air filter element Champion CAF100209R.
It wasn't until I pulled the top off the housing that I realised my mistake - glaring back at me was an oily mess of metal mesh in the form of an oil-bath filter.
Great for desert use, and no element to replace, but somewhat dirty, heavy, and so I'm led to believe; quite restrictive.

Now that I finally have time and space, the housing is on the bench, and it's my intention to convert it to use the dry element, and clean it up.

The outer housing appears to be common to both wet and dry filters, but the wet filter has an additional liner spot-welded inside both the top and bottom parts.

My intention is to drill out the welds and remove the oil bucket.

 

[45Dougal]

The first thing was to clean it up with Jizer and a stiff brush, and measure that everything will fit together as I hope..
So far it looks OK.

Next job is to drill out those welds in the coming days...
Unfortunately, the centre stud is welded inside the oil bucket, so that will need cutting out and rewelding in place once it's removed.
Hopefully my drilling is accurate enough to avoid the need to weld up a load of holes afterwards.

 

[45Dougal]

Ok, got the kids into bed and decided to press on with it..
Straight in with a 10mm drill bit seemed to work best.
The lower part is now three parts.
I only broke through the outer casing in two places, but tbf they will all benefit from a spot of weld to thicken up what is left anyway.

 

[Chamba]

Love that you're doing this: I've been pondering exactly the same thing with my oil bath to install a K&N.

 

[charliemeyer007]

My 72 came to me in 82 with a big paper element. In say 84 I put in the oiled foam unit from Man-a-fre. Well in summer of 2025 the foam more or less wore out. I think Manny doesn't make it anymore. So on Amoron I bought a big sheet of oil foam $20, its about twice as thick as the old foam 1" vs 0.5. I had to cut it to fit. I hot glued and sewed the seams to fit over the metal form - oiled it up with filter foam oil also from Amoron. Should be the last filter I ever need.

Back when Mt. Saint Helens blew up, a friend was in Lewiston. He had to drive 300 miles home. I think he said he had to clean his manny foam filter 6 times to get out of the ash. I'm sure a paper element would have fallen apart beating it on the side of the road that many times. Enough gas in the tank and a spare quart of oil or two is cheap fixing. Rubber gloves is a nice option.

 

[45Dougal]

Yea

My 72 came to me in 82 with a big paper element. In say 84 I put in the oiled foam unit from Man-a-fre. Well in summer of 2025 the foam more or less wore out. I think Manny doesn't make it anymore. So on Amoron I bought a big sheet of oil foam $20, its about twice as thick as the old foam 1" vs 0.5. I had to cut it to fit. I hot glued and sewed the seams to fit over the metal form - oiled it up with filter foam oil also from Amoron. Should be the last filter I ever need.

Back when Mt. Saint Helens blew up, a friend was in Lewiston. He had to drive 300 miles home. I think he said he had to clean his manny foam filter 6 times to get out of the ash. I'm sure a paper element would have fallen apart beating it on the side of the road that many times. Enough gas in the tank and a spare quart of oil or two is cheap fixing. Rubber gloves is a nice option.

Yea I definitely like the oil bath as a concept, and its very much in line with the go-anywhere nature of the beast, but my puny 1-H coupled with a heavy steel aftermarket body means i really benefit from even the promise of an extra horsepower

 

[45Dougal]

I found a pic of how the dry housing should look inside, and I'm missing the inner ring that holds the filter central..
I'll have the fab something up and weld in place.

 

[45Dougal]

I repeated the process of drilling out the welds on the top cover and removed the inner ring.
There are plenty of them, but they're not so big as the ones in the base, and are easily drilled out with a 7mm bit.

 

[45Dougal]

The centre stud arrangement with the oil level marker is too large to fit inside the dry filter and needs trimming down. It's pretty thin and easily cut with a pair of snips.
I then bent up a ring to fit around it from a bit of scrap steel, and mocked it up in the casing.

 

[45Dougal]

Maybe I'll get around to welding it over the weekend if i get a minute..
In the mean time, I'm still on the lookout for information on the correct housing colour.
AI tells me that early special export models were fitted with a grey filter housing, and thats in line with the base colour on mine- anyone ever seen another one in grey, or know what years it covered?

 

[rainingagain]

Honestly, that looks like primer to me. I have never seen one other than black but I'm a newb compared to some of the old dogs here, and since this is an HJ45, hmmm...

I have to say it, this is mad lad thing to do but I love it - the effort compared to just getting a later model air cleaner pales in comparison. It's like converting a generator to an alternator using the same housing - it still looks like a generator. Very cool!

 

[45Dougal]

Honestly, that looks like primer to me. I have never seen one other than black but I'm a newb compared to some of the old dogs here, and since this is an HJ45, hmmm...

I have to say it, this is mad lad thing to do but I love it - the effort compared to just getting a later model air cleaner pales in comparison. It's like converting a generator to an alternator using the same housing - it still looks like a generator. Very cool!

J40 was never sold in the UK, so finding parts is like looking for hens teeth.
I bought my heater while on holiday in florida, but that's not happening again until at least 2029 by current reckoning, plus, its sitting right there in front of me so why not

 

[rkymtnflyfisher]

@HUNTER3DAN


Weren't we recently talking about this as an option on your rig?

 

[HUNTER3DAN]

@HUNTER3DAN


Weren't we recently talking about this as an option on your rig?

Ya I tossed it around. But got lucky and was able to get my hands on one that was restorable. My air cleaner is back to 100% now.

 

[45Dougal]

All welded in to place and a rattle can coat of primer.
Welding up the drilled-out spot Weld holes in the washer-thin base was especially fun for a novice welder (so ignore the pigeon sh1t) - this was definitely the hardest part of the conversion.

Finished in black and filter installed with a homemade seal for now.

Looking good in the engine bay, but not bolted into place yet (the head is about to part company with the block).

 

[ToyotaDyna]

I love my oil bath filter on on BJ40, I just rinse the filter out in parafin or diesel and the housing, re-fill and I´m good to go!

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[45Dougal]

I love my oil bath filter on on BJ40, I just rinse the filter out in parafin or diesel and the housing, re-fill and I´m good to go!

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Yea each to his own. I'll report back if there's any noticeable change in performance. I'm carrying so much extra weight with the coach built steel rear body, that my puny H needs anything it can get.
I'm also trying to shed weight as i go, and so far I've lost around 25kg in the aftermarket side steps, and I'm hoping for another 30kg from the tow bar and about the same from the roof rack...

 

[65swb45]

The gasket to seal the filter to the housing is still available from Toyota. They used it on the FJ62 as well, which is one of the reasons it’s still available.

When I had my HJ45, I discovered that Toyota had snuck in a top secret prototype feature called the EHWS (Early Hill Warning System) that would slow the truck down a 1/4 mile before it got to any incline!