Omega Owners Forum
Chat Area => General Discussion Area => Topic started by: Marks DTM Calib on 01 February 2007, 12:20:19
-
For all those with a later (post 96/97) V6 which has the additional VAC tank mounted on the set of trumpets just in front of the alternator.
Here is something to try.....
The vac tank has two pipes, a feed and an output, the fed is the one on the right or bottom (or at least should be) which connects to a large rubber elbow piece.......
Here is the test I would like you to try.....
Follow the pipe from the vac tank feed to the rear of the engine bay where it connects to the brake servo pipe (normally via a T piece).
Disconnect the pipe here and suck on it, place your tongue over the pipe and check it holds vaccum.......
Reconnect the pipe and now remove the output from the vac tank (you can do this at the front multiram solenoid if its easier).....does it hiss for a short period or not?
I suspect it will take a few days to get some responses but, there is a good reason behind this question.....which could help your economy, low rpm acceleration.....and all for under a fiver...
-
Interesting, you could get to try it on 2 cars tonight! ;)
-
Interesting, you could get to try it on 2 cars tonight! ;)
Alas, M_DTM won't be testing that on mine tonight :'( ;)
-
Interesting, you could get to try it on 2 cars tonight! ;)
Alas, M_DTM won't be testing that on mine tonight :'( ;)
And mines only a 4 pot .....so i carnt contribute :(
-
if its the fault i think it is the quick easy fix is a one way valve fitted in line from a windscreen washer system takes 2 mins to plug in and cures all the vacuum leakage!!
Omegatoy
-
Will try and do the test at the weekend :)
-
Go on then M_DTM, I'll let you test it on mine tomorrow...
-
Checked mine today, yes to holding vac and yes to hissing.
-
Err, uhmm, no comment ::)
But it does hiss now... :y
-
So what's the script? If it holds vac and hisses does that mean all is OK?
-
So what's the script? If it holds vac and hisses does that mean all is OK?
;)
-
The vac tank has a one way valve.....if this is now a two way valve and you give it some gun at below 4000rpm....the vac dissappears (very little inlet vaccum at wide throttle openings) and the multiram cuts out making it flat until 4000rpm is reached.....
More noticeable on a manual but, also impacts the autos to....
-
Holds vacuum ok at reseroir supply, but no hiss at front multiram. Both my multirams worked last time i checked operation on the driveway though.
-
Holds vacuum ok at reseroir supply, but no hiss at front multiram. Both my multirams worked last time i checked operation on the driveway though.
In which case your one way valve is knackered.....this will not be noticeable under the usual test conditions because you only blip the trottle..
What you need is a one way air valve as used on aquariums (about 2 quid delivered on ebay) and insert it into the vac line (in the correct direction!) and the jobs a good un....much better low down torque under normal driving conditions....
-
It does indeed make a small, but noticible difference....
And M_DTM, IOU a 1 way valve... ...I forgot...
-
OK. Will report back when i've done it.
-
[In which case your one way valve is knackered.....this will not be noticeable under the usual test conditions because you only blip the throttle..
What you need is a one way air valve as used on aquariums (about 2 quid delivered on ebay) and insert it into the vac line (in the correct direction!) and the jobs a good un....much better low down torque under normal driving conditions....
OK, blond moment coming on, put the new one way valve between the servo and reservoir, or between the reservoir and the first multiram?
-
Between the servo and reservoir....then repeat the original test and you should get the hiss...if you dont you might have fitted the valve the wrong way round.
-
Just ordered some valves from ebay. 2 types, one has a mechanical spring, the other doesn't. As i will get a total of 5 valves for £3 not a big cost, but will be interesting to see if one type has more of a restriction than the other. All findings will be reported back, and there will be some valves going spare i should think.
-
Any chance of some piccy's ???
ta
;D
-
OK. As soon as the valve s turn up and it isn't throwing it down with rain. :(
-
Really just looking for an 'X marks the spot' type pic so I can give the same mod a go. ;)
-
Have you done the test?
Note, the results should actualy show an additional failure as 'The Boys' was not working.....but I fixed it there and then.
-
Just went out and had a wee explore, and finally found what I take to be the vacuum tank in front of the alternator. Oblongish black plastic box with rounded corners, about the size of a 20 pack of ciggy's? Two microbore plastic in/outputs on the engine side.
Traced one back to the T piece at the servo. Disconnected at the T piece but not enough space to get my big gob close enough to suck on the pipe! Took it off at the other end instead (vacuum tank) then sucked. Air, with a strong tang of 97 RON, but no vacuum.....
Connected it back up and started the car, ran it for a few minutes then stopped it again.
Went to do the other check and found this....
(http://i83.photobucket.com/albums/j298/hotel21/vacuumpipes.jpg)
Looks like it should be connected between the plastic tang to the top and what I take to be the multiram actuator in the centre of the next piccy...
(http://i83.photobucket.com/albums/j298/hotel21/vacuumpipes002.jpg)
Is this meant to be a push fit, glued in place or what? Anyone confirm, please?
thanks.
B
-
Just voted that mine didn't hiss, as it was faulty before you fixed it...
-
Just went out and had a wee explore, and finally found what I take to be the vacuum tank in front of the alternator. Oblongish black plastic box with rounded corners, about the size of a 20 pack of ciggy's? Two microbore plastic in/outputs on the engine side.
That is the Vac tank....
Traced one back to the T piece at the servo. Disconnected at the T piece but not enough space to get my big gob close enough to suck on the pipe! Took it off at the other end instead (vacuum tank) then sucked. Air, with a strong tang of 97 RON, but no vacuum.....
Thats no surprise....your sucking gunk out of the plenum that way round, if the hose is to short then disconnect it from the T-piece on the servo pipe, locate where it runs across the passenger side head and pull it through so you get a better length...
Connected it back up and started the car, ran it for a few minutes then stopped it again.
Went to do the other check and found this....
Looks like it should be connected between the plastic tang to the top and what I take to be the multiram actuator in the centre of the next piccy...
Is this meant to be a push fit, glued in place or what? Anyone confirm, please?
thanks.
B
That has been bodged I would say....the top connector to the multiram solenoid is plastic normaly.....you might be able to re-insert it with a bit of glue around the side to hold it stable but, I would look for a replacement (there are three of these on V6 Omegas so should be easy to source!) as a longer term solution.
As a general question....does the engine feel flat below 4000rpm and then suddenly take off?
-
Mark - I wouldn't say flat exactly, but there is probably a little less poke than I would perhaps expect or would like. It certainly lifts circa 4 - 4.5 k revs though.
-
Hi my 'meega is a '96-'97 model and i know its got a take off on vac servo pipe so will be checking this at the weekend. :y
But would this explain when i use a light to medium throttle from standing start nose lift well and pulls fairly well, but when i want to pull out of a junction in the dry ( so t/c not needed) and give it some wide throttle almost to the floor the car feels really well flat it climbs to 3-4000 ish then picks up well. I haven't had to do this often but a bit suprising when it happens :-/
-
Yes it could well do....full throttle equals almost zero vaccum....
-
:y :y :y
-
Ok. One type of valve arrived today, a packet of 3 :y. One was much less restrictive than the rest so used that one. Connected as described, then repeated test - ta dah! Hissing when pipe removed from multiram :y. Will be going out soon so will see how the car respondes and will report back.
(http://i104.photobucket.com/albums/m168/niffler21/Omega%20pics/DSCF1750.jpg)
-
I think "Perkier" would sum up the improvement. Nice one Mark. Top man :y
-
I was out and about this morning, definate improvement in performance :y so much so that when following another car on a short overtake we went so fast i almost ran into the back of him - wasn't expecting her to pull so well :)
-
Excellent news and thanks for the feedback....top job.....and nice and cheap to.
-
My engine had 2 flatspots between tickover and just over 4000 rpm where there was a definate howl and surge.This has been getting gradually more pronounced. I did the check and could'nt hear the snake,so found a non-return valve which a friend had laying on his workshop floor.Its 6mm so had to reduce it down to 4mm with a couple of adapters and Bobs your Auntie.
Flats spots appear to have gone :o and the throttle response seems alot better. No surge at 4000 rpm now either just smooth. :y
-
c/o Mark.
It didn't (I think someone suspected it might not)
It does now - thanks Mark :y
-
I can confirm that the initial pickup, esp WOT from standing start is much. much better.
-
No hiss from mine, put the valve in and it seems better. Will have a better idea after another test run. Top idea Mark :y