DOHC B6 Information

[reddragon]

Yeah, I block that one off on my setups too. That is the pipe that has led to a lot of B6T drivers thinking that they blew their turbo, when actually they just had blow by that blew oil into the turbo from the valve cover.

Is this the vent location, the hole on underside of alternator mount?

[Dragonhealer]

^ no, that's one of the fixture holes for machining the block. Look just to the rear of the alternator, 18mm pipe sticking out horizontally, that is the block vent which is blanked off with a rubber cap in USD Miata

[Advancedynamix]

The bung on the oil pan is the return port for oil to drain into the pan from the separator.

[reddragon]

The block pictured doesn't seem to have it. I also have a B6T block which does have it, so I know the area it should be. The hole I mention in above photo, it is different between the two blocks. On the B6T, that hole is just a hole. The one pictured, it is much deeper, it's more like a tunnel than a hole. After an inch, it bends 90 degrees and goes into the block - I can poke a six inch piece of wire in it. I believe its a B6ZE block, but it's a factory FWD version out of an Australian Ford Laser.

If I was to blow air into that hole, and feel it vent out through oil pan pipe or cam cover holes, could it be used as a vent?

[Advancedynamix]

Here, you can see the block vent bung. It's just below and to the right of where the oil filter mounts.
This block is a b6ze from a Japanese importer. It is identical to the b6t block in every way. The b6d Capri blocks are also identical here in the U.S.
The only b6 DOHC block that doesn't have this port is the late generation block from an MX3 here in the U.S., but that engine may have come in other cars in Australia. The head is different as well on that engine. There are extra oil return ports in the block and head.

[reddragon]

Is the distributer on the late gen MX3 mounted to the exhaust side of head?

[Advancedynamix]

Yes. It's similar to the B5 DOHC. We didn't get the B5DE here in the U.S., but my assumption is that the MX3 engine is just a 1.6 version of that engine. It's the predecessor to the Z series engines and is an evolution engine between the 2. Here in the U.S. it's very rare, as it only came in a few years of the base model mx3.

[reddragon]

It's probably safe to assume that is what I'm working with. Over here they also came in 1994 - 1998 KJ/KL lasers, and probably mazda 323.

Wikipedia suggests Columbia or Venezuela to source these in the Northern Hemisphere. Well, perhaps not quite Northern Hemisphere, but it's still just a road trip. .

[Advancedynamix]

They are common enough to find here locally, just not as common as the earlier style engine.
The head design is superior to the early b6d head, but the intake manifold on the mx3 is too bulky to easily fit in a Festiva with the stock engine location. Also, the lack of a block vent port is a downside, though the added oil return passages make up of some of the issue. Nothing beats a nice big block vent.
For some reason, modern automotive engineers have ditched block ventilation in an attempt at "cleaner burning" engines. This makes no sense to me, as a well ventilated block aids in ring seal and reduces leaks in worn engines. The engines I've built with proper air oil separators run better and use less oil. I think this is a case of follow the leader without question.
In the early part of this century, we saw many examples of engines (particularly turbo/supercharged engines) with oil consumption issues that were directly related to the PCV system on these modern engines. Several manufacturers, including Toyota and Mazda, have had continuous ring sealing issues which have led to heavy oil consumption as low as 50k miles. It's pretty easy to see why, when you know the basics of ring design and function and you take a close look at the restrictive crankcase ventilation on these engines.
The fight for "low emission" often seems like it's counterproductive when you look at the big picture.

[reddragon]

I'm still curious as to why the fixture/machining hole (tunnel) under the alternator mount would be different between blocks. Will see if I can get a hold of an inspection camera and explore it further.

The intake manifold twists away from the front of motor, so probably suits a RHD vehicle better due to helping with brake booster/master cylinder clearance.

[ryanprins13]

They are common enough to find here locally, just not as common as the earlier style engine.
The head design is superior to the early b6d head, but the intake manifold on the mx3 is too bulky to easily fit in a Festiva with the stock engine location. Also, the lack of a block vent port is a downside, though the added oil return passages make up of some of the issue. Nothing beats a nice big block vent.
For some reason, modern automotive engineers have ditched block ventilation in an attempt at "cleaner burning" engines. This makes no sense to me, as a well ventilated block aids in ring seal and reduces leaks in worn engines. The engines I've built with proper air oil separators run better and use less oil. I think this is a case of follow the leader without question.
In the early part of this century, we saw many examples of engines (particularly turbo/supercharged engines) with oil consumption issues that were directly related to the PCV system on these modern engines. Several manufacturers, including Toyota and Mazda, have had continuous ring sealing issues which have led to heavy oil consumption as low as 50k miles. It's pretty easy to see why, when you know the basics of ring design and function and you take a close look at the restrictive crankcase ventilation on these engines.
The fight for "low emission" often seems like it's counterproductive when you look at the big picture.

All they care about it what it puts out for emissions in their rating test and what their computer analysis says the fuel mileage will be. Doesnt matter what the car does after even 1000 miles to them as far as that goes.
With the block vent- is there anywhere you can drill and tap one in nicely on a b3 or this b6 block that doesnt have one?

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[Advancedynamix]

I can't say for sure. I'd look for a boss to drill through. It should be an area that's reinforced.

[reddragon]

So I put a camera into yesterday's hole. It leads through to what seems to be a decent sized chamber, but chamber is sealed, does not vent. I can see a plug of some sort in there though, which if removed, may allow it to vent, or leak, or something. Either way, I'm still curious.

[Advancedynamix]

So I put a camera into yesterday's hole. It leads through to what seems to be a decent sized chamber, but chamber is sealed, does not vent. I can see a plug of some sort in there though, which if removed, may allow it to vent, or leak, or something. Either way, I'm still curious.

I'm pretty sure the cavity that you have found is a space behind the unsealed portion of the oil pump. The plug you are seeing is plugging the oil galley from the pump to the oil filter. You don't want to vent that. Lol

[ryanprins13]

I'm pretty sure the cavity that you have found is a space behind the unsealed portion of the oil pump. The plug you are seeing is plugging the oil galley from the pump to the oil filter. You don't want to vent that. Lol

The catch can may have a hard time with that?

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