Cracked Exhaust Manifolds
Discussion
Opinions required chaps.
I have more than one crack in both exhaust manifolds, and whilst not absolutely critical to get the car on the road, it is certainly important if I want to ensure the cars maximum performance.
Also I understand that extended use of the car with cracked manifolds can cause the Lambda sensor to get more oxidised/encourages build up, and that increases problems with fuelling further causing issues.
So, do I:
1. Get the cracks welded at a cost somewhere between £500-£1000 depending on who quotes me. The main risk being the manifolds will be susceptible to re-cracking. Can both be done without removing the engine?
2. Replace the manifolds with standard performance stainless versions. Cost of the manifolds is c. £750+VAT. Add to that labour to replace, which I understand would be an engine out job?
3. Replace the manifolds with ACT high peformance stainless versions. Cost of the manifolds is c. £1000+VAT. Add the labour & engine out I assume? Are there other performance alternatives?
So, has anyone else had experience of any of the above options, and indications of overall costs for the complete job? Can anyone on here representing any of the independents do a quality job for me at a reasonable price? If I decide to replace the manifolds, I think it makes sense to spend the extra £250 on the performance versions.
My cerb is a 4.5 and has the cross-linked decat sports exhaust setup.
Cheers
Mike
I have more than one crack in both exhaust manifolds, and whilst not absolutely critical to get the car on the road, it is certainly important if I want to ensure the cars maximum performance.
Also I understand that extended use of the car with cracked manifolds can cause the Lambda sensor to get more oxidised/encourages build up, and that increases problems with fuelling further causing issues.
So, do I:
1. Get the cracks welded at a cost somewhere between £500-£1000 depending on who quotes me. The main risk being the manifolds will be susceptible to re-cracking. Can both be done without removing the engine?
2. Replace the manifolds with standard performance stainless versions. Cost of the manifolds is c. £750+VAT. Add to that labour to replace, which I understand would be an engine out job?
3. Replace the manifolds with ACT high peformance stainless versions. Cost of the manifolds is c. £1000+VAT. Add the labour & engine out I assume? Are there other performance alternatives?
So, has anyone else had experience of any of the above options, and indications of overall costs for the complete job? Can anyone on here representing any of the independents do a quality job for me at a reasonable price? If I decide to replace the manifolds, I think it makes sense to spend the extra £250 on the performance versions.
My cerb is a 4.5 and has the cross-linked decat sports exhaust setup.
Cheers
Mike
Sooooo.....if the manifolds can be removed & replaced without taking the engine out, is this a relatively simple job I could do myself?
I'm pretty handy with a spanner, and mechanically sound - I'm quite happy getting stuck into the suspension & mounts/bushes etc, but generally leave the engine mechanicals to the professionals.
If replacing the manifolds just requires removal of a few large components to enable the engine to be adjusted on its mounts to ease their removal, then I'd have a crack. Additionally, where are the Lambda sensors mounted? Are these in the engine exhaust ports, or within the manifold itself?
I'm pretty handy with a spanner, and mechanically sound - I'm quite happy getting stuck into the suspension & mounts/bushes etc, but generally leave the engine mechanicals to the professionals.
If replacing the manifolds just requires removal of a few large components to enable the engine to be adjusted on its mounts to ease their removal, then I'd have a crack. Additionally, where are the Lambda sensors mounted? Are these in the engine exhaust ports, or within the manifold itself?
mickydoo said:
Sooooo.....if the manifolds can be removed & replaced without taking the engine out, is this a relatively simple job I could do myself?
I'm pretty handy with a spanner, and mechanically sound - I'm quite happy getting stuck into the suspension & mounts/bushes etc, but generally leave the engine mechanicals to the professionals.
If replacing the manifolds just requires removal of a few large components to enable the engine to be adjusted on its mounts to ease their removal, then I'd have a crack. Additionally, where are the Lambda sensors mounted? Are these in the engine exhaust ports, or within the manifold itself?
The lamda's are about half way down the manifolds there are plugs that sit around the top of the gear box area. I would think that unplugging them would be enough to get the manifold out but correct me if wrong please. I too have cracked one's but unsure what route to go yet will keep an eye here. I'm pretty handy with a spanner, and mechanically sound - I'm quite happy getting stuck into the suspension & mounts/bushes etc, but generally leave the engine mechanicals to the professionals.
If replacing the manifolds just requires removal of a few large components to enable the engine to be adjusted on its mounts to ease their removal, then I'd have a crack. Additionally, where are the Lambda sensors mounted? Are these in the engine exhaust ports, or within the manifold itself?
The ACT performance items come in sections so engine removal is not required.
However the kit may cause problems to the lambdas anyway due to silicon required to seal them. That said I believe they are now sold with gaskets which should make the install easier. I still needed to have braces made to make mine fit. Fortunately my fitter did it for a fixed price.
However the kit may cause problems to the lambdas anyway due to silicon required to seal them. That said I believe they are now sold with gaskets which should make the install easier. I still needed to have braces made to make mine fit. Fortunately my fitter did it for a fixed price.
mickydoo said:
If replacing the manifolds just requires removal of a few large components to enable the engine to be adjusted on its mounts to ease their removal, then I'd have a crack. Additionally, where are the Lambda sensors mounted? Are these in the engine exhaust ports, or within the manifold itself?
Even with the engine free to move around the engine bay I found it really awkward, you definitely need a patient helper. However Andy at APM was adamant that the passenger side could be removed reasonably easily with the engine jacked to one side, but he warned that the drivers side was more difficult but doable.The lambdas are right at the far end of the downpipe.
i did the passenger side one when mine cracked.
it was fiddly but not too hard.
air box off
water rail off
water header tank off - to give some space
battery out
disconnected from the cat
undid the manifold studs - after soaking them for a few days in pentrating oil!!
once loose, you can drop it down and get easy access to take out the lambda
then a load of wiggling and twisting and out it came.
only lost a couple of knuckles!!
welding up is fairly straightforward.
I read up on the best welding techniques and filler wire and it recommended Mig with a special wire for steel/SS welding.
touch wood - it's been ok since.
drivers side does look tighter, but still do able
it was fiddly but not too hard.
air box off
water rail off
water header tank off - to give some space
battery out
disconnected from the cat
undid the manifold studs - after soaking them for a few days in pentrating oil!!
once loose, you can drop it down and get easy access to take out the lambda
then a load of wiggling and twisting and out it came.
only lost a couple of knuckles!!
welding up is fairly straightforward.
I read up on the best welding techniques and filler wire and it recommended Mig with a special wire for steel/SS welding.
touch wood - it's been ok since.
drivers side does look tighter, but still do able
I recently had a chat with an excellent indy specialist on this very subject.
My manifolds also have some cracks that will eventually need attention.
Advice given was as follows :-
ACT high performance (£1000+) manifolds make plug changes impossible without manifold removal. They are also a nightmare to seal due to the quantity of joints.
ACT standard type (£700) replacement manifolds are no better for flow than the originals as they are copies of that design. So apart from looking pretty there are no performance benefits.
The original manifolds can be removed and rewelded at a cost of about £300 labour to remove and refit plus additional £50 for subcontract welding. £350 total.
My opinion is that the repair/reweld of original manifolds is the most cost effective option and the one I'll be following. Looking at the difference between the £50 welding and £700 new options to me this makes sense.
Labour would obviously be the same for either option.
My manifolds also have some cracks that will eventually need attention.
Advice given was as follows :-
ACT high performance (£1000+) manifolds make plug changes impossible without manifold removal. They are also a nightmare to seal due to the quantity of joints.
ACT standard type (£700) replacement manifolds are no better for flow than the originals as they are copies of that design. So apart from looking pretty there are no performance benefits.
The original manifolds can be removed and rewelded at a cost of about £300 labour to remove and refit plus additional £50 for subcontract welding. £350 total.
My opinion is that the repair/reweld of original manifolds is the most cost effective option and the one I'll be following. Looking at the difference between the £50 welding and £700 new options to me this makes sense.
Labour would obviously be the same for either option.
From my understanding and web images the ACT high performance manifold design gives an equal pipe length per cylinder before the pipes join. To achieve this it some pipework goes up higher and masks access to the spark plugs. Therefore, the only means of changing them is to remove or as least unbolt before changing the plug.
The manifolds are sealed to the head with a gasket but where the original manifolds are a single piece per side the ACT items are in more than one piece per side. It is the connection of these piece to each other that are apparently the problem as you have to use paste and not a gasketted connection.
Hopefully someone on here will have a photo of the manifolds installed on the engine.
This should then either explain all or confirm that I've got the wrong end of the stick again!
The manifolds are sealed to the head with a gasket but where the original manifolds are a single piece per side the ACT items are in more than one piece per side. It is the connection of these piece to each other that are apparently the problem as you have to use paste and not a gasketted connection.
Hopefully someone on here will have a photo of the manifolds installed on the engine.
This should then either explain all or confirm that I've got the wrong end of the stick again!
Passenger side come out dead easy. Although I have the water rails off. But they come off easy. Engine mounts are easy enough. The drivers side took some manoeuvring and moving the engine but come out. I've now wrapped mine not ready to put them on yet as I've got other things to do but it's not a hard job.
That picture of the ACT manifold clearly shows a set of gaskets. I'll have a look tomorrow and see what it looks like on mine.
There have been problems with the sealing onto the secondary pipe, i think mine needed to be faced a bit if I remember correctly or maybe there was a gasket made to go in there, again I'll have a look tomorrow.
There have been problems with the sealing onto the secondary pipe, i think mine needed to be faced a bit if I remember correctly or maybe there was a gasket made to go in there, again I'll have a look tomorrow.
Nickccc said:
That picture of the ACT manifold clearly shows a set of gaskets. I'll have a look tomorrow and see what it looks like on mine.
There have been problems with the sealing onto the secondary pipe, i think mine needed to be faced a bit if I remember correctly or maybe there was a gasket made to go in there, again I'll have a look tomorrow.
Sorry if I wasn't clear, I was referring to the standard manifolds not specifically the ACT ones. However if sealant works on the standard ones is there any reason it wouldn't work on those as wellThere have been problems with the sealing onto the secondary pipe, i think mine needed to be faced a bit if I remember correctly or maybe there was a gasket made to go in there, again I'll have a look tomorrow.
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