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pigdog

how to seperate manifold from block?

Question

Ok I removed the brass nuts with a minimum of cuss words, now I'm trying to separate the exhaust mainfold from the block.

Do I need to remove the studs to get the manifold off or is there a trick to getting off without breaking the studs?

Thanks-Chris

Ferret 00 EC 55

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Hello Chris

Sorry to not answer your immediate question, but coincidentally I've spent the day removing the silencer and associated tubes on my ferret. (and opening out two 1/2" AF spanners in the process) Not only is the rear box blown, but the manifold gaskets have blown too.

Do you have any advice to removing the manifold nuts from the studs? I've soaked mine in penetrating oil but they don't seem to be moving... I'm worried about breaking the studs.

Cheers

Matt

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Chris and Matt,

 

Do not try removing the studs, they will likely break and access to drill them out is not good. To get the manifold away from the block I suggest you be very patient and gentle easy it away a bit at a time with an old and thin flat blade screwdriver. Do no lever, just use it as a wedge, tapping it in one end then the other, knock the manifold back on, then ease off again using plenty of penetrating fluid. I am speaking from long time experience on these engines.

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Matt, as far as getting the nuts off I used lots of Kroil. I drove the ferret yesterday in the hope of expanding the nuts on the studs. Then I sprayed the Kroil penetrating oil on the studs before the engine cooled off, but not when it was still hot. I also tapped lightly on the manifold and let it soak overnight. The problem is the brass 9/16 nuts didnt exactly fit the wrench. On those I used a 15mm open end. also I wire brushed the end of the studs. I must have got lucky they didnt cause too much trouble. The Kroil really is great stuff if you can get it there. I'm then using a tummbler to clean up the rusted parts.

Richard,

I'll try the wedge method, and soak it again overnight with Kroil.

Thanks-Chris

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Mine is exactly the same. I've bought some new gaskets from Banisters.

 

How is the rest of your exhaust? My silencer is blown in the usual place, I was hoping to repair it but upon removal I have found that it's FULL of rust. The baffles appear to have totally disintegrated. I was hoping not to have to buy a repro because of the cost :embarrassed:

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The rest of my exhaust is ok I believe. My ferret came with a set of replacement manifold gaskets. I only had to get the hull ones. At least there you have better access to parts. I cant imagine the postage of shipping an exhaust stateside. Any luck getting the brass nuts off? I'll be trying my manifold again today.

-Chris

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Hello Chris

 

Yes, success. Looks like the soaking in penetrating oil has done the trick, I have managed to remove all the brass nuts. However I think some of them have stripped, the studs are heavily corroded and I think some, or all will need to be replaced. How essential is it to use brass nuts? Could steel be used?

 

Cheers

 

Matt

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Hello Chris

 

Yes, success. Looks like the soaking in penetrating oil has done the trick, I have managed to remove all the brass nuts. However I think some of them have stripped, the studs are heavily corroded and I think some, or all will need to be replaced. How essential is it to use brass nuts? Could steel be used?

 

 

 

 

Brass nuts are used so that they can be removed, if you use steel nuts and they sieze, then as sure as anything you would snap a stud trying to remove a nut.

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when at last you do manage to remove the manifolds, use loads of copperslip when you put nuts back on new or old, (always try and use new nuts, brass if possible, ...but in all my years of working on engines of all sorts, I've never had a steel nut sieze, after having used copperslip on them...)

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The benefit of the existing fasteners is that, unlike a normal nut, they incorporate a shaft presenting the nut faces near to the end of the stud. This makes it more accesible to various spanners that might be used.

 

You could get around this by cutting some tube to make spacers. But then the length of engagement of the stud thread is greatly reduced. On occasions where I have graunched the faces of the fastener I have carefully recreated the flats by filing. Doing so that it will engage with a smaller sized spanner. If your are using a box spanner this will make it much easier to engage the head as the lower part of the manifold gives only slight clearance.

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when at last you do manage to remove the manifolds, use loads of copperslip when you put nuts back on new or old, (always try and use new nuts, brass if possible, ...but in all my years of working on engines of all sorts, I've never had a steel nut sieze, after having used copperslip on them...)

 

Or even better Bostik 'Never Seize' available in 980C, 1400C or nuclear grade. We always used the standard grade on Mitsubishi Evo turbo studs and never had any problems.

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Well round 2 goes to the ferret. I spent all day yesterday trying to separate the manifold, but no luck. The problem is the inner bolts are a tight fit whereas the outer 2 have wider holes. I can get it about 1/3 away from the block. The problem is trying to evenly wedge it away. Will be trying again today.

If the studs are steel and the nuts are brass, dont the two different metals cause corosion? I forgot the word used for it.

-Chris

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If the studs are steel and the nuts are brass, dont the two different metals cause corosion? I forgot the word used for it.

 

 

Chris,

 

That does not happen with brass, hence the use of brass nuts, it was once a common practise on manifolds.

 

There is a possibility that coolant had seeped along the stud threads, they are tapped straight in the water jacket, and rusted the studs, I have come across them eaten away on occasions. If you can move the manifold out as far as you say, then flood the studs and holes with the penetrating fluid you use, and knock it back on and try again, back and forth, as I said before, patience is the thing here. If your studs are in good order and only need a die nut to reclaim them, then you do not want to break one, because that will give you one problem you did not want.

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Richard,

Ive been doing as you recommended. Using a screwdiver as a wedge and tapping it in and then hammering the manifold back on. I did it all day, back and forth and been soaking it with the Kroil. The studs are rusted, but arent too bad I think. I just hope the screw driver isnt wrecking the mating surfaces, tho I am going slow and carefull. I didnt know that brass dosent corrode. I'll keep trying.

-Chris

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I just hope the screw driver isnt wrecking the mating surfaces, tho I am going slow and carefull.

 

Chris,

 

The manifold might want facing anyhow, if it has been blowing, also check for bowing, with a straight edge. There are two types of gasket, one is a stainless steel shim type, the other is a thicker composite type, I prefer to use the thicker ones.

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not trying to be picky but: brass has a anodic index of 0.40 v, low alloy steel a index of 0.85 v in a outdoor environment the ideal would be a anodic index of 0.15 v or less so dissimilar / galvanic corrosion can occur . paul.:cool2:

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not trying to be picky but: brass has a anodic index of 0.40 v, low alloy steel a index of 0.85 v in a outdoor environment the ideal would be a anodic index of 0.15 v or less so dissimilar / galvanic corrosion can occur . paul.:cool2:

 

Been reading Wiki have we ? :coffee:

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boring stuff i had to learn whilst doing my civil aviation authority licenses .paul.:cool2:

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boring stuff i had to learn whilst doing my civil aviation authority licenses .paul.:cool2:

 

 

In the context of what we are discussing here, you can be assured that there is no issues with brass nuts and steel studs reacting, that is why Rolls Royce chose to use that combination.

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i was replying to your statement that galvanic corrosion does not occur between bras and steel it does .:cool2:

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Chris,

 

The manifold might want facing anyhow, if it has been blowing, also check for bowing, with a straight edge. There are two types of gasket, one is a stainless steel shim type, the other is a thicker composite type, I prefer to use the thicker ones.

 

SUCCESS! I finally got if off! tapping it from the bottom out then tapping in back on. There was just enough wiggle to go back and forth. I'll check it next with a straightedge. I have the thicker gaskets that seem to be a sandwich of an inner ( asbestos)? and outer metal/copper layer. I also need to check the tappets and replace the gaskets there. What manual has that info? I thought I have all of them but havent found it yet.

Thanks for the wedge secret.

-Chris

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