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A different kind of problem with Weber carb... air cleaner getting rained on due to hood vents, what to do? UPDATE: problem solved! (see latest post)


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Finally got everything parts, money, and time wise together to get my Weber 32/36 carburetor on. Had some issues with timing, tuning, and throttle cable, got them all sorted out thanks to Google and "search" on this forum and a couple of other forums. But now I have a different problem I figured might happen, but was hoping wouldn't... due to the hood vents my air filter is getting wet in the rain. Had a hard rain yesterday while the truck was parked in the driveway, and the filter was soaked. literally soaked, also the PCV hose had some water in it. So I am pretty sure I have water in my oil now. I took the filter off and brought it in, routed the hose downward, stuffed a rag in the top of the carb, and covered it all with a plastic bag. I can cover it with a bag during the times when I am not driving, but eventually I will get caught in the rain while driving, also it snows here sometimes in the winter. And no, I cannot weld, and really don't want to weld up the vents, and do not want to modify the ugly filter housing that was on it factory, besides, the top of it was rusted from it getting wet over the years. Anyone else have this issue? Anyone come up with a real permanent solution? I don't even know which years Datsun used the hood vents on the 720 other than 1980. Or if it was done on other models.

 

 

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UPDATE: Problem solved. Thanks everyone for your suggestions. See my last posts for solution.

Edited by JoeCool
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Water can't get into your oil through the PCV valve. It sucks inward to the intake. If there was water in the pipe this is normal condensation that would be in the engine that the PCV valve is working to eliminate. (it would be much worse without the PCV)

 

I think those wraps are for exposed engines like on open wheel or roadsters, hot rods, when not using the engine to keep weather off them.

 

Put a plastic sandwich bag under the louvers with duct tape for the winter... well you get the idea.

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No, not the PCV valve hose, that is run to the intake manifold. I am talking about the PCV breather coming out through the valve cover. Then again, it loops down like a U. So may not have any water in the oil, I dunno. Still raining today.

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See if you can find a 1983-86 hood from another 720, they don't have any holes at all in the hood, and will bolt right on.

As for getting a little/small amount of water in the oil, it will likely not hurt it, and it will evaporate when the engine warms up and get sucked out through the PCV valve, a lot of water in the oil, change the oil and filter.

The 1981/82 hoods will also work, but they have these tacky plastic things on them, but maybe you will like them, I don't like them, they look tacky to me.

A 1982 hood.

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You could also weld them up like this guy did in his thread, it's on page 1.

http://community.ratsun.net/topic/64040-720zx-time-to-finish-it/

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You want to affix a collection container of sorts. Like a shallow Tupperware but durable. Fiberglass would be great. Then attach it under the vent with a drain hose running forward to a point that it can drip freely. Permanent solution without welding.

 

Welding up the hole is much better.

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Weld um up.. i owned a 1980 back in the late 80s also so i can say for a fact the water will build up on top of og stock air cleaner enough to get into carb if not driven every day.. So on my sons,, we just went ahead and welded them..


 

 

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Or get a newer style hood without vents.

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Buying another hood or welding up the vents just is not an option I want to consider. I love the look of the heat extraction vents, plus I think with the vent over half the filter it puts air into my filter for MORE POWER! (maybe? Or I might just THINK so because I hear the suction when all barrels are wide open?) I guess I may get the K&N drywrap later this week and do this while it's parked and weather calls for rain (yes, that is a Food Lion grocery bag!):

 

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I guess later on I may make a sliding cover?

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A buddy of mine had an old 720 he used as a beater, and he worried about water getting into the engine if he left the truck parked outside and unused for a long period of time- which was basically 95% of the time with this truck. He made a small sort-of scoop- just a little wedge shaped thing he bent out of aluminum sheet. Think of a small hood scoop, only on the underside of the hood and with the opening facing to the firewall. He made it just long enough to clear the back edge of the air filter housing, so rain would just run off the end and onto the ground underneath the truck. I don't remember how he attached it,  I think he used emblem tape, but I'm thinking Velco might work if you want to make it removable.

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Maybe seal your floorboards up perfectly and put a funnel under each vent with a hose that drains onto the floor... That way when you are stranded on a deserted island you will have plenty of water and won't have to resort to drinking your own urine.

 

It's a thought.

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Maybe you can find some piece of plastic trim that will cover the hole that can be screwed or bolted down somehow for the winter months that can be taken off, something tacky like the 81/82 hood trim pieces, it would give you something to talk about when people ask there function.

Other than that I would just find a small hood scoop for each side pointed towards the rear so it still lets the air out, it might even suck it out if installed properly. :)

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Ace is the place.They have magnetic sheets used to close off forced air furnace registers in certain rooms.Throw it on and it'll stay until you just peel it off.

Dude, you are a genius! They fit like a glove, and a cheap solution as well! THANKS! I bought two, so may as well cover the one over the valve cover too since I went through the trouble to polish and paint it. Will keep the overnight dew off as well, which with the temps dropping into the 40's recently, has been happening.

 

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I am going to put them to the test tomorrow when I drive to work and get up to 65mph, but I am certain they will stay put.

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Wow!! you could replace that open air cleaner with a closed piece. You get to much water dripping into your carb draining into a intake port you'll hydro lock your motor and likely bust a piston or bend a rod or both. Another option is a plastic cover with double sided tape around it's perimeter. That should seal it until drier weather. Didn't those vents come with a under cover vent drain to prevent this? I can't imagine Nissan designing those vent completely exposing the air cleaner like that.

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DatsunMike always tells me this.

 

 

Glad it worked.

 

Well, even though it wasn't raining, I drove to work today with the magnetic covers on, stayed put up to speeds of 70mph. Hosed the hood down with water this afternoon, not a drop leaked underneath... AWESOME!  :thumbup: 

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Well, even though it wasn't raining, I drove to work today with the magnetic covers on, stayed put up to speeds of 70mph. Hosed the hood down with water this afternoon, not a drop leaked underneath... AWESOME!  :thumbup:

I figured.There is a slow moving layer of air over the hood called"the boundry layer"It is slow moving(as opposed to the air further away for the vehicle)THis is also why most Ram Air systems(sans a couple) are a joke.

 

NWB-your "hydro-lock" scenario has about as much odds of happening as me winning the Powerball lottery.

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