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Discussion Starter #1
So the topic of this has come up in a few threads over recent months and weeks and most people would have seen OldMav's comments about the size of the standard breather being way too small. I've had this in mind for months now since the first time I read one of Pete's ramblings on the subject. I've had the Provent for ages and like most been guilty of running it with the reduction fittings to get down from the 1" Provent fittings to the breather outlet of 1/2"/12mm. In my case the machined aluminium fittings you can find on ebay, for others the cheap Bunnings garden sprinkler fittings etc. Obviously this was a quick and easy solution, and ignorance is bliss. Guilty as charged.

So recently I finally got my hands on a cheap rocker cover so I could get a look at the breather without disabling my engine for any period of time. Can you believe some people, or at least one close by, want $200 for 1 rocker cover. Finally got one from WA of all places for $40.

So for those that have not seen under the rocker cover, or more correctly the breather, this is the gasket. Note the 3 round holes are the fixing holes and the 2 ovals are the breathing passages. The roughly 10mm hole in the middle I have no idea about. It corresponds over a small about 3mm hole in the breather and cover so I don't really know what's it's function is but obviously has something to do with the chambering and operation of the standard breather. @OldMav can probably explain if anyone really wants to know.

Note that the gasket has 2 ovals as does the rocker cover but in close up you can see an outline of a third oval. Also note the ovals in the gaskets are bigger than the breather so the original path is pretty small. The cross sectional area of the ovals in the gasket are actually pretty close to the cross sectional area of a 25mm circle.
 

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Discussion Starter #2
So with all that in mind here is my solution.

First I've drawn up a new base plate based on the original design. Initially I was going to have the 3 large ovals and the big middle hole but all these stop starts cost money on a water jet (and no doubt laser), so I've decided to just open the whole area up in the base and then enlarge whatever way I like in the rocker cover.

In the first pic you will see the base plate I had cut, the 3" tube for the body about 60mm long, the perforated sheet to ensure the "filter" doesn't drop into the engine, the stainless steel scrubber as a "filter/scrubber" of sorts, the lid and the 1" hole tail/barb.

Second pic shows the perforated ally sheet at a guard and the third the stainless scrubber. It's quite unlikely the scrubber would fall out or through and in my experience of using these for muffler packing they don't tend to have any bits that fall off ramdomly when handling so it is unlikely they would cause any issues.

The fourth and fifth pics just show my little home (at work) made pressing jig for putting some detail into the lid so it didn't look so plain. It's just a combo of unused disks from other jobs with a bit of 25mm bar as a former to give a bit of a hump into the lid. It's not just for decoration though that hump is a critical aspect of the design to remove the oil from suspension and return it back to the rocker in a controlled manner ;) That, or I'm just OCD and didn't like the look of a flat lid.
 

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this is on my list. i just havent been able to find 1" alloy fittings to weld up onto a tube. nor looked very hard to find some stainless mesh to hold some steel wool inside the breather part.
As you can see i havent put much effort into it yet haha.
 

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Discussion Starter #4
So then it's just a matter of tacking it all together in order then welding it up. The base gets tacked in position, the perf dropped in, the scrubber stuffed in and the lid tacked on. The perf just sits in there and is slightly domed to tension slightly i suppose. The scrubber is about 4/5ths of a $2.00 scrubber from a commercial food supply place. If you haven't seen these before they are neat, they are like a big spring donut all coiled up. You can open the centre up and they are just like a donut, when used for mufflers you just stretch them open and slide over the baffle like sock or donut. Mmmmmm donuts. The scrubber is fairly tightly packed but not crazy so it will hold the perf in place and it breathes quite easily. I could breath through it with ease for any length of time as an example.

I actually borrowed a little home made weld positioner off a mate to have a crack at welding this up because I saw the other day he had one and I've never tried one. Not really needed to do this but what the heck. This one is a wiper motor with an adjustable home made step down transformer, a washing machine pulley by the looks, a basic shaft and the turntable believe it or not is a go kart cylinder head and the shaft was threaded to the spark plug hole.
 

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Discussion Starter #6
But then i remembered my old router was still at work and had a bull nose bit in it still. So...
a bit of router-milling and a bit of sanding and blending and scotchbriting and we have the finished article. Pointing over roughly to where the vacuum tanks originally sat as this is where my Provent is fitted.

I'm not sure what it's cost me yet as I don't have the cost of getting the base cut. The scrubber is cheap, the hose tail is surprisingly cheap, I had some perf sheet, the lid is a bit of scrap. The tube and base will be the dearest bits because I had to buy a metre of tube as we don't use that size at work and although we use the water jet cutters a lot, the base will still cost me trade price, although I won't cop a set up cost because I've supplied my own CAD file and am friendly enough that they do the job when they have other material the same to do so I don't pay set up.

Still though not a particularly dear project if you can source some scrap and weld it up yourself because you can if you have a bit of skill and geometry skills cut a useable base plate out by hand if you have to. Even as a one off I like to do it right even for a few extra bucks because I have access and can't help myself (literally can't stop myself).
 

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i bought some what i thought was 1" barbs but turns out they were only like 7/8" or something so im back to the drawing board but everything else is easy. 3" hole saw will make the base out of 10mm i have at home. 3" cooler pipe cut to length and a 2mm cap is easy to cut out with the plasma.
all i need is the barb, the perf thingo and some staino wool.....
so bunnings you say has these 1" barbs?
 

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GQ Dual Cab. TD42Ti with fruit.
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Interesting. Your pictures just reminded me of the old Holden red motor breather cap!
 

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This was my solution,

Rocker Cover 1.jpg
Rocker Cover 2.jpg

I had access to a lot of Chev 6.5 diesel engines and found the turbo version had the right size outlet for my needs.

810dEV9H6nL._SL1500_.jpg


I cut off the section needed from the Chevy, cut the area neede off the Nissan Cover leaving the internal baffles in place and Tig Welded the Chevy section with its Steel Wool Mat in place.


Seems to work for me.
 

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GU IV 4.2
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Good write up mate and finished product looks good. Good solution to the problem of incorrect hose sizing
 

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GQ Dual Cab. TD42Ti with fruit.
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This is on my list to do as well, next time I have these pieces off. My thoughts were simply to weld something on to it too.
 

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Discussion Starter #12
i bought some what i thought was 1" barbs but turns out they were only like 7/8" or something so im back to the drawing board but everything else is easy. 3" hole saw will make the base out of 10mm i have at home. 3" cooler pipe cut to length and a 2mm cap is easy to cut out with the plasma.
all i need is the barb, the perf thingo and some staino wool.....
so bunnings you say has these 1" barbs?
No bunnings have the ghetto plastic barbs. I got that one off ebay.
 

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Brilliant Fester!
Top effort, well done, thanks for posting 馃憤
 

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Im doing, or more like having one very similar made up at the moment. A couple of things to note that ive come across. Not sure about the gq but my gu has an air con pipe running about 80mm directly above the breather so even though the raised breather would fit, i think there would be some issues fitting the rocker cover with the new breather fitted and since it has to be bolted on from inside the rocker cover it can not be fitted after the rocker cover is fitted. I also had issues with the bottom being too thin and could not enough thread to tighten the bolts properly. My solution which will be happening shortly is to split it in two pieces and have an aluminium vband clamp welded into the middle to join the 2 sections so that i can keep the bottom section of the breather low and of similar height to the standard breather so that the rocker cover is able to be fitted. Also this will allow me to put bolts right through with a lock nut so that there will be no issue of the bolts ever falling out. Thirdly my rocker cover which is gu factory turbo actually has 3 holes already in it, so all that has to be done on mine is punch a 3rd hole in the gasket.
 

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Discussion Starter #15 (Edited)
Im doing, or more like having one very similar made up at the moment. A couple of things to note that ive come across. Not sure about the gq but my gu has an air con pipe running about 80mm directly above the breather so even though the raised breather would fit, i think there would be some issues fitting the rocker cover with the new breather fitted

Yes this might be an issue but I think with the air con pipe unclipped and rolling the cover in a bit it should fit. You can always make one a bit shorter but obviously the further away you get the outlet from the entry the better.

and since it has to be bolted on from inside the rocker cover it can not be fitted after the rocker cover is fitted. I also had issues with the bottom being too thin and could not enough thread to tighten the bolts properly.

In my example the base is 10mm thick so the amount of thread will actually be more than what's in the factory breather. If yours was too thin then you must have been using very thin sheet for the base. Even a 6mm ally base would have plenty of thread to tap as a 6mm nut is only about that thickness. My other idea was stainless in which case I was going to use 3mm for the base and weld some nuts inside.

My solution which will be happening shortly is to split it in two pieces and have an aluminium vband clamp welded into the middle to join the 2 sections so that i can keep the bottom section of the breather low and of similar height to the standard breather so that the rocker cover is able to be fitted.

I think a V band clamp is over complicating it a bit and I'd be careful as I've seen some V bands that don't seal up perfectly until they get some decent heat and expand. A Tri Clover would be a better clamp with a proper seal between the halves. If you are trying to keep it low profile, how high do you envisage it as there would not be a lot of room for v band components and a 1" hose tail in a low profile side.

Also this will allow me to put bolts right through with a lock nut so that there will be no issue of the bolts ever falling out.

I would not panic about bolts falling out of any design if there is sufficient thread (only needs about 6mm and they can be locktite'd for piece of mind. Don't forge the engine is full of bolts already including the standard breather arrangement now.

Thirdly my rocker cover which is gu factory turbo actually has 3 holes already in it, so all that has to be done on mine is punch a 3rd hole in the gasket.
That is interesting in regards the factory turbo breather, although mine is turbo the rocker I got to measure up from was in fact a silver top cover and it does only have the 2 holes in the cover and I just rechecked the breather and it too only has the 2 holes so obviously there would be a part number difference between the engines or somewhere along the line Nissan superceded and started using the 3 holes. Like I said the gasket actually has an impression for the third hole. I've added pics of what the silver top cover components look like.

Don't forget for anyone wanting to do this you don't have to have the fancy cut out in the base, you only have to do what will match your rocker cover. Obviously if you have the 3 ovals in your rocker and that's all you want to use you will have to cut similar holes but the reason I did the cut out I have is I can then do nearly anything within that cut out. If you wanted to do one like benos said then a hole saw will cut you a base reasonably easily and a corresponding round hole in the middle from another holesaw will do the job as you can drill the same size hole in the rocker cover. It won't matter than the original holes are partially covered by the new base as long as you have a big enough hole to breath properly. The only tricky bit will be cutting through the rocker cover skin but not the inner skin. You can see if you cut out the hole in the middle to match the mark from the gasket and then just joined the holes you would have a reasonable opening. You just don't want to leave any really small slithers of material hanging in case over time there is a chance they could fatigue and break off, as there is a chance they could fall back arouond the skin into the rocker area. Also remember to clean out the rocker cover really well if you are cutting or grinding on it because grit and swarf between the 2 skins could work their way back into the rocker area.

Really I wouldn't even bother with the original (or new gasket) I would just use some suitable RTV sealant. Also a 6mm base will be more than enough thread to tap and reliably hold. In reality even a 3mm steel base tapped would hold a thread if locktited in and you didn't overdo tighten it, remember it only has to seal and RTV will take care of that. (However that is not my recommendation) The only issue with a thinner base depending on your cut out size is warpage when it's welded and keeping the base as flat as possible, especially if you weld nuts inside. (For the record flange nuts are really good for welding in somewhere to use as captive nuts.This is where the ally is easy as it can easily be filed and sanded flat if it has pulled a bit.

Not a dig at you Dirty just clarifying some info for anyone wanting to tackle their own.

Admittedly I haven't tried fitting mine yet as I don't want to pull the intercooler just to do this till I have other things to do and when I do I want to paint the rocker cover.
 

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Very nice work festerGU, nice that the older TD motors at least had this breather as a separate unit not built inside the rocker cover. I'm waiting to see what skegs comes up with on the ZD rocker cover.
 

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As you know the TD42T engine was not used only in patrols. they are used in busses, forklifts and small trucks in Asia. I dont know when but later TD's did have 3 hole rocker covers but the gasket always blocked of the hole facing the breather outlet for obvious reason (for the uneducated, too reduce the shortest path to allow oil to separate from air, a tiny bit more effective.) The idea for me came from the CabStar Which had a highmount turbo and the breather was somewhat larger with 19mm outlet, it is babbled as well, and faces the inlet manifold.

Off subject a bit, but what interested me and my real passion in this engine was to acquire and fit the oil filter assembly, the pic's attached tells the story. Oh yeah forgot the other serious interest was the very much larger flywheel clutch and pressure plate. For those that don't see the difference The flywheel face is outside the ring gear and the pressure plate is a man side assembly. It was in the days when high clamp pressure pressure plates were difficult to find, until i found a Mcloud Racing assembly.

Edit and forgot again and another interest it has a very much larger harmonic balance and i thing it is a fluid damper as well not confirmed but look suspicious.
 

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The fabricator i got to make mine had a mind of his own. I asked him to cut and use the original base flange and when i returned to pick it up he had scrapped that idea as he said he couldnt weld to it so he made a flange of his own accord which was too thin. As far as the fitment is concerned on mine, i dont think it will fit but happy to be proven wrong. To salvage this breather that i have already had made and paid for, i have no choice but to open it up and put mounting bolts right through, so i thought i may as address the fitment issue as well appears that it would be quite difficult to fit the rocker cover at best. It will also allow me to go as high as Petes original suggestion which was 70mm i think. I went 50mm so that i had some chance it may fit. If it doesnt seal perfectly i will use a tiny bit of copper rtv on the flange. I will be using this on my dump vband as well as that had a small exhaust leak that i found apon removal. The idea was to have a low bottom section so that the rocker cover fitment would be no harder than standard. The upper section with the outlet will be much taller and can be fitted easily once the rocker cover is on. It may look ugly, not really sure, but it will definately fit and be functional. There is also one other small advantage of being able to rotate the outlet infinately to which ever position best suits your install. Im definately not saying there is not a better way of doing it, this was just my solution to salvage the money i have already spent and improve a few potential fitment issues. The fabricator i used did have a few issues following the instructions i gave him but ultimately i ended up with something that will work with a bit of further development.
 

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As you know the TD42T engine was not used only in patrols. they are used in busses, forklifts and small trucks in Asia. I dont know when but later TD's did have 3 hole rocker covers but the gasket always blocked of the hole facing the breather outlet for obvious reason (for the uneducated, too reduce the shortest path to allow oil to separate from air, a tiny bit more effective.) The idea for me came from the CabStar Which had a highmount turbo and the breather was somewhat larger with 19mm outlet, it is babbled as well, and faces the inlet manifold.

Off subject a bit, but what interested me and my real passion in this engine was to acquire and fit the oil filter assembly, the pic's attached tells the story. Oh yeah forgot the other serious interest was the very much larger flywheel clutch and pressure plate. For those that don't see the difference The flywheel face is outside the ring gear and the pressure plate is a man side assembly. It was in the days when high clamp pressure pressure plates were difficult to find, until i found a Mcloud Racing assembly.

Edit and forgot again and another interest it has a very much larger harmonic balance and i thing it is a fluid damper as well not confirmed but look suspicious.
Hey Pete, does this mean we should leave one hole blocked off, Or will the steel wool be good enough to separate the oil so that we can take advantage of that extra hole?
 
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