| Author | Message | ||
     David Gore Moderator Username: david_gore Post Number: 2100 Registered: 4-2003 |
Help please - I know the accumulators are usually tested by checking the internal gas pressure but I need to know the typical number of "pump downs" that can achieved before the warning light is activated. I have checked the "Black Spur" as covered in another thread using the pump down test as I did not have access to a pressure gauge and would like to compare the result with that achieved in a fully charged system. Thank you in advance if you can provide this information. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1565 Registered: 6-2006 |
60 plus is ok. Some late cars cam be double that or more. Some years have shims in the brake pressure switches which bring them on earlier. If there is any air in the brake lines it will reduce the number of pumps. The more air the less pumps it will take. Hope this is what you are after. Cheers, Paul. | ||
| David Gore Moderator Username: david_gore Post Number: 2103 Registered: 4-2003 |
Hi Paul, Thank you for this information - exactly what I needed having no experience with mineral oil systems. My pump down tests gave results varying from 14 to 18 brake pedal pumps so past neglect rears its head in the brake area as well. Looks like accumulator replacement is another early expense to be included in the list of things to do - I would see this replacement as essential preventative maintenance as I suspect the diaphragm may have stretched permanently due to the low gas pressure. I trust Vladimir will see this thread in the next day or so. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1568 Registered: 6-2006 |
Dave, also try a physical pump down test. Very slight slope with plenty of space in front of the car. Car in neutral. Engine off. Ignition on. In neutral. Hand on key ready to start engine. Pump the pedal until the car rolls and you have no brakes. Start engine to restore brakes or you will never stop it!!! It's surprising how much the lights vary from actual reserve. (I'm sure you grasp the importance of being ready to start the engine . . But detailed instructions are for the less experienced.) | ||
| Christian S. Hansen Grand Master Username: enquiring_mind Post Number: 307 Registered: 4-2015 |
Paul... ...might add a 4"x4" timber about 3 feet (2 feet for the faint of heart?) in front of the front wheels as a "bump" to catch the car? | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1569 Registered: 6-2006 |
When I had our workshop in Hythe Road London. There was a railway bridge with the road scooped out under it to get the height clearances. It formed a perfect bowl for showing customers the importance of accumulator reserve. Occasionally you would get an owner that maintained that there was no problem at all with his brakes even though the reserve was down to zero. Of course as long as the engine is running there will not be a problem. I used to get them to do the pump test there (compete safety) and once the car was completely unstoppable they were eager for new accumulators. I guess that sometimes actions do speak louder than words. | ||
| David Gore Moderator Username: david_gore Post Number: 2105 Registered: 4-2003 |
Paul, Unfortunately the car could not be driven as it is unregistered and was hemmed in by other cars in the showroom. By the time I got to the brake system test, I was already convinced the car was a potential "money pit" compounded by a very poor quality repaint that would require a complete strip-back and repaint to return it to an acceptable appearance. The battery was also suspect and I would not have chanced a probable "failure to start" at a time when absolute reliability was essential for peace of mind........ Also the damage bill for the number of expensive cars in close proximity would have been a substantial deterrent. Discretion is the better part of valour in situations like this. |
