Graham Harris Posted August 29, 2015 Report Share Posted August 29, 2015 I have been suspicious of my vacuum unit for some time thinking it may have a hole in it. I took it off a month or so ago and pushed the diaphragm in to see if i could get it to hold suction. When i pushed it in liquid came out the vacuum tube, after a few more pushes a lot more came out and it was petrol. I cleaned it out and put it back together and today i took it off again and it was the same, about a desert spoon full of petrol, how can that be? Any one come across this before? Regards Graham Quote Link to post Share on other sites
Don Elliott Posted August 29, 2015 Report Share Posted August 29, 2015 The normal way of testing a vacuum unit (in a TR3A at least), is to take it off and the suck on one end. If there is a leak or a pin-hole in the diaphram, it has to be changed. For a few years, I doubted the original vacuum unit on my 1958 TR3A, but I never found any liquid in it. And the suction seemed to be OK. But I had "The Distributor Doctor" rebuild mine (maybe he replaced it) and since then my TR3A has started and run fine. The only way petrol can get into the unit is via the fitting and small tube that connects the vacuum unit to the bottom of the front carb. Quote Link to post Share on other sites
Fireman049 Posted August 29, 2015 Report Share Posted August 29, 2015 (edited) . Edited September 20, 2015 by Fireman049 Quote Link to post Share on other sites
Graham Harris Posted August 30, 2015 Author Report Share Posted August 30, 2015 Thanks Tom PM sent Graham Quote Link to post Share on other sites
CliveG Posted August 30, 2015 Report Share Posted August 30, 2015 There appears to be conflicting advice on the need for a flame trap. This was posted by JohnJervis a few weeks ago:- "I have been in contact with Frank Bontenbal of Albertronic BV regarding 123 distributor issues and here is the response regarding the expansion chamber/flame trap:- "The sensor in the ignition is a sealed, this means there is no mixture flowing through the ignition (via the vacuum pipe).Sometimes we recommend an expansion chamber, this is not to keep mixture away from the ignition.This chamber is to stabilize a much fluctuating vacuum value.This happens sometimes when the vacuum connection is made close to the inlet of the engine, or in case of a very short manifold."" I have fitted one to be on the safe side, but it would appear that it may not actually be necessary. Quote Link to post Share on other sites
Fireman049 Posted August 30, 2015 Report Share Posted August 30, 2015 (edited) . Edited September 20, 2015 by Fireman049 Quote Link to post Share on other sites
Graham Harris Posted August 31, 2015 Author Report Share Posted August 31, 2015 I think i have answered my own question, i connected a tube to the vacuum pipe but the unit in a bucket of water and gave it a blow. Bubbles came out the spring end so it's into the trash department. Thanks all Graham Quote Link to post Share on other sites
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