| Author | Message | ||
     Chris Browne Experienced User Username: chrisb Post Number: 14 Registered: 2-2010 |
Hello everyone. I have recently removed the header tank from my 1979 Shadow 2 for refurbishment. I noticed when I first took it off that it rattled when I shook it and found that the steam valve was able to move in its housing whilst the cover plate was still screwed down. I assumed that the O ring had probably hardened so replaced it but the steam valve is still a loose fit once the cover plate is replaced. I have since refitted the header tank and flushed and refilled the cooling system. I now find that after a run, I have lost about half a litre of coolant. There is no sign of any visible leak so I assume the coolant is being vented from the overflow pipe. Am I right in thinking that if the steam valve is a loose fit in its housing, the system cannot pressurise properly and coolant may be escaping past the steam valve rather than being contained by it until a critical temperature is reached and the valve opens? Is the solution to fit a second sealing ring beneath the valve to ensure that it is a tight fit once the cover plate is tightened. Any thoughts would be appreciated. Kind regards, Chris | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 639 Registered: 6-2006 |
Hi Chris, it should be a tight fit. Can't imagine why it should be loose. When you say o'ring - it should be a flat section rubber seal. Regards, Paul. | ||
| Chris Browne Experienced User Username: chrisb Post Number: 15 Registered: 2-2010 |
Hi Paul, Yes, I meant to describe it as a flat rubber seal rather than an O ring - it is the correct part. I seem to remember reading a reference somewhere that sometimes additional thickness has to be added to the seal to make it a good fit. Is that something you have come across before? Also, am I right to assume that the system will not be operating at the correct pressure if the steam valve is not properly seated? Thanks in advance, Kind regards, Chris | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 641 Registered: 6-2006 |
Sorry, not come across that before. I can't picture it loose either. Unless the seal is too thin or the . . . . nope can't see what else. Does the valve look complete? right way up? If it's not sealing it can not pressurise. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1269 Registered: 4-2003 |
Chris are you sure that you have the right valve? And when you say it is loose is it loose sideways or vertically? With the valve out is the rattle still there (baffles have come loose on some). Are you sure it is not pressurising? Try running the over flow pipe to a plastic bottle the latter tied appropriately and see how much comes out. If you fill the system to the brim natural expansion will force some out through the valve. Finally is the cap seal in good condition and the lip of the screwdown cap not chipped? | ||
| Chris Browne Experienced User Username: chrisb Post Number: 16 Registered: 2-2010 |
Hi Paul and Bill. Thank you both for your quick replies. To answer your points - the valve is an OE part, is complete and is fitted the right way up.It is loose vertically in that the cover plate does not seem to clamp it down when it is tightened. The valve locates in its rubber seal correctly so does not move about horizontally. The filler cap is in good condition with no chips to the sealing lip. I have replaced the filler cap sealing ring. The temperature gauge has always read normal incidentally, the car has never overheated. I am beginning to think that someone in the past may have fitted the wrong valve. I know that the factory fitted two sizes, large and small, but only the small one has been available for a long time and the small one, in any case, would have been correct for a late model Shadow 2. I shall do some more investigating (head scratching) as although the car is running fine, I do like things to be as they should. Is that obsessive, compulsive disorder or Rolls-Royceitis?! Kind regards, Chris |
