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Re: [Healeys] fuel in Brake Booster

To: Bob Spidell <bspidell@comcast.net>, Healey List <healeys@autox.team.net>
Subject: Re: [Healeys] fuel in Brake Booster
From: Price Lindsay <050.rpl@gmail.com>
Date: Wed, 30 Dec 2015 20:45:57 -0500
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
References: <E2EAE439-541D-429C-A4CF-2D16DE0597A5@gmail.com> <56847DC7.5020602@comcast.net>
Thanks Bob. I was wrong about the routing of hoses. The repair company is going 
to give me an in line check valve. Per your note, I should be OK. 

Price Lindsay



Sent from my iPhone

> On Dec 30, 2015, at 7:58 PM, Bob Spidell <bspidell@comcast.net> wrote:
> 
> Price,
> 
> I'm having trouble following your description because:
> 
> 1) there should not be a 'vacuum hose' going into the stock air filters.  
> That is actually a (slight) pressure hose for venting crankcase fumes back 
> into the induction system for combustion
> 
> 2) there IS a vacuum hose from the brake servo--with a check valve at the 
> servo or possibly fitted inline in the hose--and it should never be installed 
> anywhere but on the nipple on the intake manifold
> 
> 3) if you want to run a vacuum line from the crankcase to the intake manifold 
> you need to install a PCV valve inline
> 
> Anyway, the only possible way to get fuel in the servo is from the intake 
> system downstream of the carburettors; if 2 cylinders were not/mis-firing 
> that unburned fuel would end up in the crankcase and oil (and possibly some 
> evaporated back into the induction system). So, yes, some fuel could get into 
> the servo via the vacuum line on the manifold, but if it was more than a 
> trace your engine would likely be flooded out.
> 
> I'm not sure what the servo rebuilder was talking about (unless you talked to 
> the tech that did the rebuild he could have been blowing smoke).  There is no 
> 'baffle' in the servo; the large air/vacuum piston has a rubber/leather seal 
> around the perimeter, and this can get brittle contributing to poor operation 
> of the servo.  The typical failure mechanism--the one resulting in brake 
> fluid being drawn into the air/vacuum cylinder--is the aging and 
> embrittlement of the 'gland seal,' a small, circular rubber seal that seals 
> the shaft of the air/vacuum piston; on one side is manifold vacuum and on the 
> other is the brake fluid in the servo's 'master' cylinder.
> 
> If all your hoses, etc. are connected properly to their proper locations I 
> would not worry about getting fuel in the rebuilt servo.
> 
> Bob
> 
> 
> 
>> On 12/30/2015 3:07 PM, R. Price Lindsay wrote:
>> Listers -
>> 
>> A couple of weeks ago my brakes were acting funny.  It turned out that all 
>> of the fluid was out of the brake/clutch reservoir.  I sent the brake servo 
>> into be repaired at the suggestion of the list.  I just talked to the 
>> rebuilder and he said the baffle in the servo was swollen because of a large 
>> amount of fuel present in the booster.  He mentioned this is not unusual 
>> with TR6â??s.  I guess this can cause the servo to fail and  draw the brake 
>> fluid into the servo.
>> 
>> Now that the servo is fixed, I donâ??t want a repeat the problem and am 
>> searching for a cause for the presence of fuel.  A few months ago I was 
>> having a problem with fuel starvation.  It turned out to be a pinched fuel 
>> line.  During my long search I made a number of changes including installing 
>> a new distributor cap and wires.  Somehow I switched a couple of wires and 
>> could not get a spark in cylinders 5 & 6.  I found the problem after quite a 
>> bit of trying to get the car to run smoothly and driving it for 20 - 30 
>> miles.  Also, maybe a contributing factor or maybe not, a year or two ago I 
>> moved the vacuum hose to the induction manifold because I installed air 
>> cleaners without a connection point for the vacuum hose. (Before the fuel 
>> starvation issue I reinstalled the original air cleaners and moved the 
>> vacuum hose back up to the air rear cleaner.)
>> 
>> Now for my question: Could the presence of fuel in the brake booster have 
>> been caused when I was not getting spark and not burning fuel in 5 & 6?  
>> Could the unspent fuel have been sucked into the servo through the induction 
>> manifold a while ago, or through the air cleaners recently?
>> 
>> Thank you so much for your collective thoughts.
>> 
>> Price Lindsay
>> 67 BJ8
> 
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