Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: terry paget on 26 August 2013, 20:33:17
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X84GNB 2000 2.5 petrol manual estate
Have finally got manifold off - thanks to all for help and advice.
I thought manifold was cracked, Chris Gixer thought fault was blown gasket. Either way it was noisy and getting noisier. Pictures follow. I think Chris was right, but I have also found a crack underneath the manifold. It looks as though there was a blow at the top and back of the manifold/gasket. I have bought a good manifold off e-bay. Clearly I need a new head to manifold gasket and a manifold to downpipe gasket. I do not think the head is 'burned'. Should I clean it with steel wool to make sure? The studs came out with the nuts on them. Should I buy new studs and nuts? Have you any more advice for me? I have not done this job before on a V6.
Pictures follow. First two are of manifold and gasket showing where blowing; third shows crack
[img http://"https://www.dropbox.com/s/cxys6v12aia38ob/DSCF2310.jpg"]http://[/img]
[img http://"https://www.dropbox.com/s/e7vrh28lo9ubymu/DSCF2313.jpg"][/img]
[img http://"https://www.dropbox.com/s/dvybgl3z6r8mahd/DSCF2315.jpg"][/img]
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Here's your pics mate ;)
(http://dl.dropbox.com/s/cxys6v12aia38ob/DSCF2310.jpg)
(http://dl.dropbox.com/s/e7vrh28lo9ubymu/DSCF2313.jpg)
(http://dl.dropbox.com/s/dvybgl3z6r8mahd/DSCF2315.jpg)
HTH ;)
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Its cracked and has also been blowing at the rear.
New gaskets.
New studs is dependent on how bad the old ones are, you should ensure the studs are in the head before fitting the manifold and then the nuts screw onto the studs, failure to do this could strip the threads in the alloy head.
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^wot he said. Definitely screw the studs into the head without the nuts on or you risk doing serious damage as Mark has said.
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All my studs came out either with the nuts attached or by removal after manifold was removed.
I was not in any hurry to do the job again so decided for the cost involved to by new stads and copper helicoiled nuts direct from VX.New genuine GM multilayer gasket and then torqued nuts up in the correct sequence and you should be fine.
I also bought new copper helicoiled nuts for the downpipe studes after giving the treads a good clean up with die set to be sure all would tighten up properly along with correct gasket for downpipe to manifold seal.
Other than that its just a matter of putting it all back together,although refitting is quicker as you now know the sequence and how to get at the bits .
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I hope you got a replacement manifold too........
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I have used 2 types of manifold gaskets .. both gm.. but only one is sheet metal .. which has a longer life..
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Would metal 3.2 gaskets be better? Don't know if they would fit..? Or indeed, is it worth fitting 3.2 manifolds? (If 3.0 un available maybe)
I was going to suggest welding the crack, but would the manifold distort in the process?
Defo blowing and cracked though. So we where both right :y
Sorry Terry. More questions than answers. I've experienced the symptoms, but not done the repair. :(
Interesting notes on the studs. :)
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Would metal 3.2 gaskets be better? Don't know if they would fit..? Or indeed, is it worth fitting 3.2 manifolds? (If 3.0 un available maybe)
I was going to suggest welding the crack, but would the manifold distort in the process?
Defo blowing and cracked though. So we where both right :y
Sorry Terry. More questions than answers. I've experienced the symptoms, but not done the repair. :(
Interesting notes on the studs. :)
Thanks for the thoughts Chris. My 3.2 does not has exhaust has recirculation, whereas the 2.5 has, so I presume the manifolds and gaskets are not interchangeable.
I have had cracks welded up on 2 litre Omegas only to have them crack again at the same places.
Yes, we were both right. That explains why it was so noisy.
AS you may have read on other threads, I have made hard work of this job. Access is so difficult on these V6 engines.I have yet to reassemble it. When I have done so I shall have a celebration.
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I have used 2 types of manifold gaskets .. both gm.. but only one is sheet metal .. which has a longer life..
Here the non metal multilayer part was superseeded as a spare in the mid 90's.....although for some stupid reason they kept fitting it at the factory!
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Would metal 3.2 gaskets be better? Don't know if they would fit..? Or indeed, is it worth fitting 3.2 manifolds? (If 3.0 un available maybe)
I was going to suggest welding the crack, but would the manifold distort in the process?
Defo blowing and cracked though. So we where both right :y
Sorry Terry. More questions than answers. I've experienced the symptoms, but not done the repair. :(
Interesting notes on the studs. :)
The 2.6/3.2 is a better manifold and should flow better to (it does fit) but the gaskets are not interchangeable.
Welding cast iron is an art form, not easy and you need to drilling the crack ends to stop spreading first (which many dont bother with)
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Since you only have one side off, there is no point putting on a 2.6/3.2 manifold because you will have an imbalance of course. You will also need to use a 2.5/3.0 gasket cos you'll have the SAI system.
If you were doing both sides, I'd say go for the 3.2 manifolds and gaskets and bin the SAI system and EGR valve completely.
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Got a pair of 3.2/2.6 manifolds here if you decide to bite the bullet , don't envy you though , manifolds are a nightmare! well done for getting this far :y
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Got a pair of 3.2/2.6 manifolds here if you decide to bite the bullet , don't envy you though , manifolds are a nightmare! well done for getting this far :y
Yeah, not a task I'd like to try with the engine in the car - so glad I did the conversion to 3.2 manifolds before the engine went in!
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Drivers side is not hard to do, three-four hour ish job
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as for crack in manifold---try Frost Restoration :y they do stuff for that----and it works--saves lots of p*****g about :y :y
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Would metal 3.2 gaskets be better? Don't know if they would fit..? Or indeed, is it worth fitting 3.2 manifolds? (If 3.0 un available maybe)
I was going to suggest welding the crack, but would the manifold distort in the process?
Defo blowing and cracked though. So we where both right :y
Sorry Terry. More questions than answers. I've experienced the symptoms, but not done the repair. :(
Interesting notes on the studs. :)
The 2.6/3.2 is a better manifold and should flow better to (it does fit) but the gaskets are not interchangeable.
Welding cast iron is an art form, not easy and you need to drilling the crack ends to stop spreading first (which many dont bother with)
...now you mention it, some of our older machines at work have exposed cast iron connecting rods. Which some gorilla broke.
The resulting bodge Weald looked like boiling pigeon poop pored over a red hot hob that had run like mercury. The repair didn't hold. None of the weld had penetrated, and none of the cast iron join had melted in any way. How it lasted as long as it did was beyond me.
Sorry Terry, bad idea. :(
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Can be done using specialist rods & specialist welder - probably easier to replace though ;)
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I have welded cast a few times but, it requires a high carbon rod and needs massive pre and post heat to prevent cracking.
If its a small non loaded part then drilling the cracks at each end followed by a spot weld and tap approach works well (create a small molten pool of metal and as it cools tap rapidly with a ball pein hammer to minimise stress in the joint)
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Since you only have one side off, there is no point putting on a 2.6/3.2 manifold because you will have an imbalance of course. You will also need to use a 2.5/3.0 gasket cos you'll have the SAI system.
If you were doing both sides, I'd say go for the 3.2 manifolds and gaskets and bin the SAI system and EGR valve completely.
how .. you can block EGR valve but cant disable it from the ECU.. only dbw ECUs dont have egr but they will require other setups.. as far as I know only in some astras it was possible to tell ecu you dont have egr :-\
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Correct Cem but you can make an EGR simulator circuit to repalce the valve with.
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Correct Cem but you can make an EGR simulator circuit to repalce the valve with.
I have done a "special design" ::) ;D may be you will remember ;D ;D :y
and upto now cant see any negative side effect :)
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But think of the benefits of replacing that heavy valve with three resistors, a diode and small relay ;D
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Make sure you add a new "o"ring to the shopping list for the coolant pipe that comes off of the back of the block. Only cheap and I wouldn't re-use the old one. :y
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Drivers side is not hard to do, three-four hour ish job
I see it's the driver's side that's already off - how long to do the passenger side? Easier or harder?
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Drivers side is not hard to do, three-four hour ish job
I see it's the driver's side that's already off - how long to do the passenger side? Easier or harder?
The hard thing about the passenger side is that all the work needs to be done whilst lying on your back
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Drivers side is not hard to do, three-four hour ish job
I see it's the driver's side that's already off - how long to do the passenger side? Easier or harder?
some may not agree, but if there is a lift handy I would take out the engine (instead of changing those seperately) and do many other jobs at the same time as those are old cars anyway.. :) so you wont need to work under the car over and over..
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Drivers side is not hard to do, three-four hour ish job
I see it's the driver's side that's already off - how long to do the passenger side? Easier or harder?
some may not agree, but if there is a lift handy I would take out the engine (instead of changing those seperately) and do many other jobs at the same time as those are old cars anyway.. :) so you wont need to work under the car over and over..
Yeah, engine comes out fairly easily once you get the radiators out. I only put the coolant one back and ditched the AC.
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as for crack in manifold---try Frost Restoration :y they do stuff for that----and it works--saves lots of p*****g about :y :y
The JB weld stuff?
Have you used it? Any good?
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Make sure you add a new "o"ring to the shopping list for the coolant pipe that comes off of the back of the block. Only cheap and I wouldn't re-use the old one. :y
Thanks. I did not know it was an O ring. The pipe was stuck on the head and took some prising off. It was a nightmare getting the screws off; goodness knows how I shall get them on again.
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Yeah, another GM engine designed for front wheel drive then bodged into rear wheel drive.
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as for crack in manifold---try Frost Restoration :y they do stuff for that----and it works--saves lots of p*****g about :y :y
The JB weld stuff?
Have you used it? Any good?
cannot remember name of the stuff--but wacked it on my migy manifold--job done :y :y
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as for crack in manifold---try Frost Restoration :y they do stuff for that----and it works--saves lots of p*****g about :y :y
The JB weld stuff?
Have you used it? Any good?
cannot remember name of the stuff--but wacked it on my migy manifold--job done :y :y
Is this JB weld some magic potion (epoxy, silicone?) that one can apply cold to a manifold crack that cures/sets to make a permanent repair?