Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Webby the Bear on 01 November 2014, 14:31:23
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Afternoon guys,
So, did as Mark suggested and disconnected the brake servo pipe, blocked it off and ran the engine. Vac leak hissing did NOT disappear. So vac leak narrowed down to sandwich plate gaskets, inlet to plenum o rings and top hat / breather bridge o rings.
So with it blocked off I got my ears right down to the breather bridge and sure enough even though I've replaced the top hat gasket it was really loud from that area.
Sprayed carb cleaner under the breather bridge but no ''sucking'' noises so I'm thinking it's a small leak and not allowing the carb cleaner in; but big enough to make the hissing during car running.
Pulled breather bridge off and as I forgot to take photos i'll try and describe what I found...
The ''hole'' in the plenum where the breather bridge fits in to is all ''jagged'' and the paint of the plenum peeling off :o so I think I need to either get a cheap replacement plenum or repair mine. How on earth can I repair this to make the hole ever so slightly smaller to help seal this up? initial thoughts are peeling off old paint and spraying some high temp caliper paint or something.
thoughts?
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Firstly, stop with that carb cleaner trick. If the leak is big enough for that to work, you should be able to locate by ear. However, remember that carb cleaner completely buggers up any rubber seal.
IME, the tophat fits nicely (assuming nobody has coated it in carb cleaner ;D), so may just be a case of repairing plenum. 2.5 plenums should be plentiful from any breaker :-\
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Thanks Jaime. So I am right in thinking that I could still have a vac leak without the carb cleaner working?
And yes I will stop it ;D
So replacement best :y
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Have you compared the sound of yours against the sound of another similar 2.5 engine? There's an element of done sucking noise with the plenums anyway.
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I haven't Chris, no. However it's odd that there's a distinct hissing from the breather bridge / top hat area.
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BigG mite have spare plenum , i had one of the actuators off it .. Dont know if it was 2.5 plenum though :-\
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BigG mite have spare plenum , i had one of the actuators off it .. Dont know if it was 2.5 plenum though :-\
Weighed two in about 4weeks ago,along with heads,and condensers.
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BigG mite have spare plenum , i had one of the actuators off it .. Dont know if it was 2.5 plenum though :-\
Weighed two in about 4weeks ago,along with heads,and condensers.
No worries mate... i'll see if RobG can help; if not i'll pop up a wanted ad :y
Out of interest, is there no way of sealing it up i.e. a repair that folk can think of? :-\
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A ring of black goo outside the hole... The rough edges are nowt to worry about... :y
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A ring of black goo outside the hole... The rough edges are nowt to worry about... :y
Exactly what I was thinking Al, obviously ensuring none gets in to the pin holes on the breather bridge :y
For best results let it dry for a while?
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I would put it on the flat top surface of the plenum about 5mm from the hole...
Bare in mind that the breather bridge will sound like it's hissing when the engine is running as there is air moving through it ::)
So don't be surprised if goo changes nowt...
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I would put it on the flat top surface of the plenum about 5mm from the hole...
Bare in mind that the breather bridge will sound like it's hissing when the engine is running as there is air moving through it ::)
So don't be surprised if goo changes nowt...
:y :y :y
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Serek mite have plenum :)
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Thanks BG.
I'll try the black goo first and then see if I need to replace :y
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Got a complete 2.5 plenum here,but not sure if they differ from PFL to FL as this one was from a 1998 so has the throttle cable mounts etc.
Not just round the corner though from you
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As you know Webby, I'm having leaking issues too ( ::) )
Now I'm back off my hols, tonight i get to play again. My prob is I think I've found the leak (just by having the engine off and blowing into various pipes, and listening for hisses) I've narrowed it down to the vacuum reservoir next to the pollen filter. Unfortunately I can find no way of getting the thing off to properly 'ram' on the rubber elbow.
Block the outlet on the reservoir with finger = no wheeze
Block off the hose, blow into other end = no wheeze
Push the hose back on, apparently 'good n tight' = wheeze back again.
So I say that's a bad seal. Tried replacing the rubber elbow for a better one. Still the same. Sorry to be hijacking your thread, by the way! My point being, of course. I know your pain, and hope both our leaking improves soon :y
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You have a nice holiday mate?
You need to remove the scuttle to get at that rear vac resevoir :)
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That's already off mate :y
Can't see any torx or anything. Strange :(
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And you still cant get to it? Can you see it at all?
Throw up a piccie
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Sadly no ability to get a pic yet (at work. They make me come in five days a week, the sods!)
Yes, can see it perfectly clearly, felt around the brackets where the other vacuum reservoirs have their studs, and it seems to be smooth. So weird! There'll be some difficult to see studs or something I'm sure, but I'm just not seeing it. :-[
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Sadly no ability to get a pic yet (at work. They make me come in five days a week, the sods!)
Yes, can see it perfectly clearly, felt around the brackets where the other vacuum reservoirs have their studs, and it seems to be smooth. So weird! There'll be some difficult to see studs or something I'm sure, but I'm just not seeing it. :-[
Do you have to remove it to check it? Can you not just pull vac pipes off and listen for hissing like with the front ones? Then look at removing it if you think its fekked? :)
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Yeah, that's what I've done, good fellow :)
Blew into one of the pipes, there was a hiss from that area. So disconnected one, and held my finger over the disconnected pipe, blew into again - no hiss, so not leaking from that pipe.
Ok, so disconnect the other pipe, reconnect the original pipe, seal the remaining hole at the reservoir with my finger, then blow again = the noise goes.
Reconnect the 2nd pipe, blow again = hiss again.
as a final check, disconnect 2nd pipe, blo into other end = no hiss, so not leaking from 2nd pipe.
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Sorry, realised I've hijacked your thread :D To return things back to you, last night, as my top hat was torn, I refitted it, but using a spare (also torn) I chopped off the 'extra' thus leaving just an o-ring shape. I warmed this in warm water, then stretched this over the whole top hat assembly, then refitted the breather bridge. So I have one seal in place (with a tear) and one past it, 'at the base'... No idea if this has actually done anything positive or not, but it's theoretically sealed the breather bridge. Of course a handy o-ring from your o-ring set will do the job as good/better, but I didn't have any handy o-rings present, only two torn top hat seals :D
Hope this is sorting things, anyway!
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The vac res on the heater assembly is plastic welded on, you wont shift it easily.
As for the breather bridge top hat, with the correct seal correctly fitted (I know how you like to bodge the wrong seals on Webby :y) the seal seals against the machined hole and not any where near the top of the plenum
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That machined hole is in the top of the plenum......... or have i missed something ??? ;D
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Thanks Mark.. just did my little bodge (have I been hanging round Webby too much?) to try and stop any air that would be weeping past the damaged top hat seal actually leaving the plenum, as I was literally kicking my heels with nothing to do, due to not having a spare seal. Good to knwo the seal does have a critical function... here's hoping this tiny leak is the cause of Webbys (and my) woes!!! :y
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Also I think Mark was referring to my bodge, as the seal sits inside the hole, against the machined surface, not on the rough cast top surface - where my modified o-ring sits. :y
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ok got ya. to be fair to me i have an OE ''top hat'' in there
its hell frauds o rings ive fitted to the TB..... Bodge? perhaps. Does it work better than the brand new OE ones. Hell yeah :y
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Hehe, Yeah, don't worry, not knocking you, my good man. I certainly don't mind putting genuine Vx o-rings etc.. when they're literally pence, less that £2 each etc.. but there's lots of 'buy brand new genuine GM nothing else will doooo' attitude on here, which, to be honest isn't always economical. Again, not knocking those who do. We've all got our preferences and budgets. Some cars are daily drivers, doing 15k a year, other may only do 500miles between MoTs, in which case a cheap-n-cheerful part that'll 'only' last 10,000 miles will last them 20 years... and so on...
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Exactly! And no offence taken btw ;)
Thing is if they failed shortly after..... i'd take the ten mins to put them back. no biggy. but the OE ones were not working for me. i replaced them and now i have no vac leak. simplez :y
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Just because I'm tired and thick sometimes - where did you fit the halfrauds o-rings? Is that the two pipes that go into the throttle body? :)
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Just because I'm tired and thick sometimes - where did you fit the halfrauds o-rings? Is that the two pipes that go into the throttle body? :)
Correct :)
I played about with the fitment of various sizes and finally selected some ones that were about the same diameter as the OE ones but just slightly thicker :)
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Exactly! And no offence taken btw ;)
Thing is if they failed shortly after..... i'd take the ten mins to put them back. no biggy. but the OE ones were not working for me. i replaced them and now i have no vac leak. simplez :y
The question you need to ask is why weren't the correct o rings working.......as you have addressed the symptom......but what is the cause.... :y
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Exactly! And no offence taken btw ;)
Thing is if they failed shortly after..... i'd take the ten mins to put them back. no biggy. but the OE ones were not working for me. i replaced them and now i have no vac leak. simplez :y
The question you need to ask is why weren't the correct o rings working.......as you have addressed the symptom......but what is the cause.... :y
Fair point Mark.
I merely put it down to Vx making rubbish parts that need amending ;D
..........i'll get back in my cave with my angle grinder ;D
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Exactly! And no offence taken btw ;)
Thing is if they failed shortly after..... i'd take the ten mins to put them back. no biggy. but the OE ones were not working for me. i replaced them and now i have no vac leak. simplez :y
The question you need to ask is why weren't the correct o rings working.......as you have addressed the symptom......but what is the cause.... :y
Fair point Mark.
I merely put it down to Vx making rubbish parts that need amending ;D
..........i'll get back in my cave with my angle grinder ;D
;D ;D
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Just because I'm tired and thick sometimes - where did you fit the halfrauds o-rings? Is that the two pipes that go into the throttle body? :)
O rings in TB ??? ??? ???
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Exactly! And no offence taken btw ;)
Thing is if they failed shortly after..... i'd take the ten mins to put them back. no biggy. but the OE ones were not working for me. i replaced them and now i have no vac leak. simplez :y
The question you need to ask is why weren't the correct o rings working.......as you have addressed the symptom......but what is the cause.... :y
Fair point Mark.
I merely put it down to Vx making rubbish parts that need amending ;D
..........i'll get back in my cave with my angle grinder ;D
Lol, sadly the engine designers will be considerably better paid, trained, more experienced and qualified than you or I in such design items so they generally get it right. I suspect the V6 engine has been produced in numbers of between 250-500K units and its an issue not been seen before....... ;D :D :y
Do be aware with the setup that the hole in the throttle where the breather bridge tubes go taper in to grip the O rings.
Can you get a pic of the plenum top with throttle assembly fitted and breather bridge removed?
Anyway, where have you been lucky enough to find a cave with power!
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Oh of course, i completely agree. but ive experienced shite parts from vx before. thats no reflection on the designers i presume.
mines all back together now but i will take a pic when its al apart again.... seems to be apart more often than not ::)
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Yup. Sadly the Accountants will always have an input in the design of anything, even a Bugatti Veyron... (admittedly in that case not much of an input! :y )