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Alan L's Avatar
 
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pop off valve noise

When I am standing over the engine and blip the throttle open the pop off valve is making a loud clacking noise - that I can feel in the housing. Should it be doing this. Even with small blips eg +500rpm this happens.
Also, should I be able to get on to boost with the car not under load, at 3000 rpm +
Thanks
Alan
Old 12-06-2007, 08:44 PM
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If I recall, they wear and there's no rubber to soften the clack any more. It should not do this.
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Andy Glass
'86 930 Kokeln IC, K27-7200, SC cams, GHL headers, Fabspeed muffler, Short R&P , misc other mistakes made...
Old 12-06-2007, 09:14 PM
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You have to rebuild your BOV with new gaskets. Quite easy. Here's the info:

Changing 930 dump-gaskets, pictures galore

No, you cannot build any boost w/o load. It will just rev!

Cheers!
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Old 12-06-2007, 10:29 PM
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Great post and pics Goran, thanks. I just put all that stuff back on yesterday - for about the 5th time. Now I have to take it off again. But I'm an expert at it now. Grrrr.
What is that bit across the top of your air plate. I don't have one. In the parts list it is called a stop. But in the manuals I have there is no mention of it, and nothing about setting any clearances etc. So what does it do?
Thanks
Alan
Old 12-06-2007, 10:49 PM
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I believe there was a kill-switch in the bridge across the flapper that shuts off the fuel pumps when engine isn't turning...don't remember really

About BOV, you might try to make those gaskets yourself as they are kinda hard to find. I ordered mine from a dealer. They were cheap, though.
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Old 12-07-2007, 12:47 AM
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Bump stop

BeepBeep, the bridge across the top of the air metering plate is a stop to arrest back lash if your car should backfire. The kill switch is integrated into the upper cast body of the metering assy.
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'77 930 turbo Garretson I/C 1 BAR spring, (2) '82 Triumph Bonneville Royal Wedding Edition
Past rides: '74 914 1.9 liter twin plugged track car, '83 928S, '87 924S, '75 911S w '78 ROW 3.0, '72 911T, '70 911T and various other insignificant domestic examples. Happiness is a grey tailpipe! Turbo lag......it's worth the wait!
Old 12-07-2007, 08:53 AM
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About BOV, you might try to make those gaskets yourself as they are kinda hard to find. I ordered mine from a dealer. They were cheap, though.[/QUOTE]

Pelican don't seem to have them listed - hopefully there is enough material left to see what they are made of.

930 Turbo - I like your choice of m/cycle. I had a Silver Jubilee and 79 Special.
Sold them both to buy my first SC.

Alan
Old 12-07-2007, 11:14 AM
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930 Turbo: thanx! I never peered into CIS longer than I had to!

Alan L
Hmm...I believe you will find just few dried out/blackened pieces which won't tell you much. The gaskets were white and quite hard. Consistency was like "rubberball".

Speaking about tre-cylinder oil-leaking motorcycles, the one to be had is Laverda Mirage or 3C (with 180-deg crank)
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Old 12-07-2007, 11:49 AM
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Goran, I am a bit puzzled. Pulled mine apart just now. It is a bit different. At the flange end with the tube, it had a piece of black spongy stuff that looked like it may have been a seat for the spring head tube. Is this the bit I'm trying to get?
At the piston bottom end I just have a big thick rubber pad blanking the whole end off. The base of the piston is not contacting the other housing end - so what am I looking for for gaskets?
I can only assume the clunk noise is the spring head end hitting the flange with the tube?
Thank you for your time.
Alan
Yes Triumphs did leak - unless you took a lot of care. Even then they tried - but some casting eras were better than others.
Old 12-07-2007, 12:10 PM
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Gaskets are white rings that are seated in grooves on each endplate of BOV. One is removed from the base and other is mounted in place on picture. Yours might be "enchanced" by previous owner? One base plate is "pressurized" and other one is just blanked off. Cylinder slides back and forward and blanks and opens ported holes in cylinder.



Gaskets are nr.7. Part nr.3 slides in the bore and hits the gaskets. On liftoff, vacuum pulls back 3 and let's air from intermediate throttle go past the port back into turbo again.

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Last edited by beepbeep; 12-07-2007 at 12:22 PM..
Old 12-07-2007, 12:16 PM
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This is what I have - pic. In order of assembly. So I assume the rubber pad is substitute for gasket. In which case the clunking noise must be the spring tube end hitting the cap - the bit with the soggy rubber thing?
Alan
Old 12-07-2007, 12:39 PM
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Your back plate doesn't seem to have recessed groove where O-ring should seat so it's possible that you have some other version of BOV where back plate doesn't have O-ring but a rubber pad.

That part of tube doesn't live as hard life as the one with O-ring (piston is accellerated by spring), so O-ring is probably chewed by piston hitting it. I suggest replacing both with some sort of hard rubber. Clunking sound comes probably from piston hitting the O-ring. As you can see, pistons has chewed trough O-ring gasket and divided it into two rings. If you compare your pic to mine, you'll see that inner part of gasket has separated on your BOV and piston is making metal-to-metal contact.
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Last edited by beepbeep; 12-07-2007 at 01:02 PM..
Old 12-07-2007, 01:00 PM
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Quote:
Originally Posted by beepbeep View Post
. As you can see, pistons has chewed trough O-ring gasket and divided it into two rings. If you compare your pic to mine, you'll see that inner part of gasket has separated on your BOV and piston is making metal-to-metal contact.
So you think there was originally one ring, and the piston has chopped it off into smaller one? I thought the small one looked like it sat under the spring tube - it fits about right. But that leaves the piston with nothing to seat on - so you could be right. It fits neatly inside the larger ring. It is a very neat slice tho if this is the case. The inner edge of the ring in the end plate is very clean. Does your system have anything for the spring tube to seat on, or is it normally metal-metal?
Alan
Old 12-07-2007, 01:24 PM
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Yes, I believe piston chopped off inner piece of that ring. I only had two gaskets in my BOV. PET doesn't mention 3:rd gasket either. Just change both and you're good to go.
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Old 12-07-2007, 02:48 PM
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