RE: Breather hose, oil

From: Dave_Clement-LDC009@email.mot.com
Date: Fri Jul 12 1996 - 08:45:00 EDT


To: CringB@smtp.nvg.com@INTERNET; dakota@csclub0.cs.fredonia.edu@INTERNET
From: Clement_D on Fri, Jul 12, 1996 8:50 AM
Subject: RE: Breather hose, oil

From: CringB@smtp.nvg.com@INTERNET on Fri, Jul 12, 1996 8:16 AM

>The breather is connected to low pressure by being connected to the air
>filter housing. This is the preferred method of venting the crankcase
>pressure as it helps to suck the high pressure out of the cranckcase. I
>have actually heard of some racers going as far as hooking the breather
>vent hose to the exhaust, very low pressure. This brings the crankcase
>pressure down lower, increasing engine performance and putting less
>pressure on seals(it can actually suck oil out of the crankcase). My
>opinion I don't think it would hurt anything leaving the breather open to
>atmospheric pressure, but you are probably decreasing your engine
>performance, very very slightly.

Your statements are only true for and engine that does not have a PCV valve.
On PCV engines the breather hose attached to the air filter housing is to
allow air back into the engine. The PCV plumbing is what controls crankcase
pressure.

>Now, for a question for everyone. In the dakota owners manual, they
>recommend using only 10w-30 oil and suggest not using any heavy
>weights. I run synthetic oil and have been considering running 5w-50 or
>20w-50 to increase my oil pressure. Anyone else running higher
>viscosity oils? My oil pressure seems a bit lower than normal, about 1/8
>to 1/4 on the gauge, I have been told synthetic oils tend to have lower
>pressure because they flow better; higher velocity thus lower pressure.
>I have a 91 dakota with a V-8 with 76,000 miles its always had synthetic
>oil so I wouldn't think it is worn out. Any opinions?

I use 10w-30 conventional in my 89 v6 Dakota and get a mid-scale reading on
the pressure gauge. I have also had several failures of the oil pressure
sender on my CC vehicles so I would not put much faith in the actual reading
on the gauge. If you are concerned about oil pressure get your hands on a
mechanical gauge and plumb it in and get some real readings.

I use Mobil 1 synthetic in my turbo Daytonas and have seen no difference in
oil pressure readings when the ambient temperature is in the 50-80 degree
range. When the engine is hot the synthetics maintain a higher oil pressure
because their viscosity changes less when they get hot. When it is real cold,
 20's or lower, the intial oil pressure with the synthetic comes up faster
than with conventional but I can't really say that I have noticed a
difference in the pressure reading once everything has stabilized.

Dave Clement
89 4x4 LE
 



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