Disco 2 Blowing exhaust manifold, again. Probably need new cylinder head; what am I looking at?

2001 Discovery 2 TD5

I had problems with a warped exhaust manifold previously, got it replaced, and it came loose again - this time throwing a stud altogether. In trying to replace the stud, the garage discovered the remnants of an old stud in the bottom of the hole, along with part of a drill bit. Trying to get it out they broke their bit, which is also now stuck in there too. They ended up tapping a new hole, and enlarging the one in the manifold to bolt it in. Seemed to work, until this past week when I'm getting the same squeal as before.

I've not been able to take a look just yet, as it was only while away over the weekend that I became sure of what I was hearing - but it's been getting worse as we drove back home. So I guess the first question is what might I be able to do about it?

But the main question is that if it's gone again in the same place I'm likely going to need a new head; and I have little idea what that entails either in terms of parts or labour. Obviously a replacement head; hoping to get a second hand one off ebay, head gasket kit, exhaust manifold gasket kit, new studs and bolts. Anything else? What's the labour like for a professional doing it? What sort of price would be fair? I'm on a pretty limited budget, so could really do without this in the first place; but I need to work out how to cover it all.

I'm guessing you have a TD5?

JUKE179r said:

I'm guessing you have a TD5?

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Yes indeed, added that. Thanks.

You may find that a new manifold is the solution. I bought one from ebay then had it skimmed flat and slotted the webs between the ports, works fine now.
Have you done any kind of tuning to the engine?
That usually causes excessive exhaust heat and warps the manifold then it wont seal.

raywin said:

You may find that a new manifold is the solution. I bought one from ebay then had it skimmed flat and slotted the webs between the ports, works fine now.
Have you done any kind of tuning to the engine?
That usually causes excessive exhaust heat and warps the manifold then it wont seal.

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Its been remapped, yeah.

The problem is bolting the new manifold to the botched head, otherwise I'd assume you'd be right.

If its tapped out to a larger size then could be ok with a new stud, if the manifold is not flat you will never get it to seal even with a new head you will just repeat the story, they just hold for a short time then either snap the stud, or just pull it out of the head. Would be worth trying to fix it first, especially as heads are not easy to find (beware of SH ones where the injector pocket is cracked) new one is about £1300 gasket and bolts etc will be just over £100, labour will vary depending on where you take it.

raywin said:

If its tapped out to a larger size then could be ok with a new stud, if the manifold is not flat you will never get it to seal even with a new head you will just repeat the story, they just hold for a short time then either snap the stud, or just pull it out of the head. Would be worth trying to fix it first, especially as heads are not easy to find (beware of SH ones where the injector pocket is cracked) new one is about £1300 gasket and bolts etc will be just over £100, labour will vary depending on where you take it.

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No, its a brand new hole in the head, separate to the one with stuff stuck at the bottom.

Do you subscribe to the theory that an already warped manifold is less likely to warp again/further if I just get its face skimmed?

I can't afford a brand new head at those prices, but I was wary about the SH ones. I've found a place does reconditioned ones for £440 or so. But even that is a stretch for my budget.

Naf623 said:

No, its a brand new hole in the head, separate to the one with stuff stuck at the bottom.

Do you subscribe to the theory that an already warped manifold is less likely to warp again/further if I just get its face skimmed?

I can't afford a brand new head at those prices, but I was wary about the SH ones. I've found a place does reconditioned ones for £440 or so. But even that is a stretch for my budget.

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Yes I belive that when they have warped if you mount them correctly in a milling machine and skim accross the faces then they are not so prone to warping more, when I took mine off it was certaimnly distorted, I bought an old one which had some distortion and a mate of mine skimed it and cut slots in the webbing between the ports, this allows it to "flex" very slightly and absorb the force, it was done about 4 years ago and its been fine, certainly much cheaper option and worth a go.
By the way mine had a piggyback type tuning chip fitted, I took it off shortly after I bought it.

raywin said:

Yes I belive that when they have warped if you mount them correctly in a milling machine and skim accross the faces then they are not so prone to warping more, when I took mine off it was certaimnly distorted, I bought an old one which had some distortion and a mate of mine skimed it and cut slots in the webbing between the ports, this allows it to "flex" very slightly and absorb the force, it was done about 4 years ago and its been fine, certainly much cheaper option and worth a go.
By the way mine had a piggyback type tuning chip fitted, I took it off shortly after I bought it.

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Then fingers crossed if I start with just getting this one refaced I can get away with refitting it and it'll be fine. Presumably I'd want to replace the manifold gasket against the head in that case - should I also be replacing the one between the manifold and the turbo while I'm at it?

Naf623 said:

Then fingers crossed if I start with just getting this one refaced I can get away with refitting it and it'll be fine. Presumably I'd want to replace the manifold gasket against the head in that case - should I also be replacing the one between the manifold and the turbo while I'm at it?

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Certainly the manifold to head.
Manifold to turbo is a good idea they are not expensive , but I got away with it, dont try to overtighten the nuts on the studs you might shear them.
Some people de web them totaly like this : https://www.ebay.co.uk/itm/DISCOVER...225908?hash=item4d9f5e18f4:g:qQ4AAOSwFTVdNEsX

raywin said:

Certainly the manifold to head.
Manifold to turbo is a good idea they are not expensive , but I got away with it, dont try to overtighten the nuts on the studs you might shear them.

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Who is your mate who refaced yours? I'm also in North Yorkshire.

Naf623 said:

Who is your mate who refaced yours? I'm also in North Yorkshire.

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It was someone who I used to work with but he lived south of manchester.

raywin said:

It was someone who I used to work with but he lived south of manchester.

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Ah, shame haha. I'll find somewhere.

Are machine shops so hard to find? Like many I suppose I use a bunch who I have used every now and then over the years. Only prob was "we only do cast on Fridays" so i have to assume Ally is what they do most of the time now. Once refaced, I think especially if you cut through the webs, that it should be OK. Am fascinated by how you are getting around the original hole which has been so jiggered. I was prepared to offer advice like "get an ally welder to fill the old but emptied out hole, then drill and thread it" But this looks a bit "after the fact" now. Any way best of luck sounds horrible and I only just missed a similar scenario myself two years ago.
Also, drill out the holes in the manifold as follows, to 2 and 4 ports, .5 to 1mm, to 1 and 5 ports 1 to 1.5 mm. Again this gives the manifold just a tiny bit of "wiggle" room. Anyway, 2 years later it is still all sound and is still working, and I didn't even slot the webs. There is a school of thought that once the manifold has warped, it won't warp no more. But the skim cost £60 as it was so far out of flat the guy had to keep repositioning the cutter.
Would love to see a photo or two of the problematic hole and the solution to it.

Stanleysteamer said:

Are machine shops so hard to find? Like many I suppose I use a bunch who I have used every now and then over the years. Only prob was "we only do cast on Fridays" so i have to assume Ally is what they do most of the time now. Once refaced, I think especially if you cut through the webs, that it should be OK. Am fascinated by how you are getting around the original hole which has been so jiggered. I was prepared to offer advice like "get an ally welder to fill the old but emptied out hole, then drill and thread it" But this looks a bit "after the fact" now. Any way best of luck sounds horrible and I only just missed a similar scenario myself two years ago.
Also, drill out the holes in the manifold as follows, to 2 and 4 ports, .5 to 1mm, to 1 and 5 ports 1 to 1.5 mm. Again this gives the manifold just a tiny bit of "wiggle" room. Anyway, 2 years later it is still all sound and is still working, and I didn't even slot the webs. There is a school of thought that once the manifold has warped, it won't warp no more. But the skim cost £60 as it was so far out of flat the guy had to keep repositioning the cutter.
Would love to see a photo or two of the problematic hole and the solution to it.

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Well I can only find one which I could cycle to, and only two others within about a half hour drive if I was to hire something else to get me there and back. In a city like York I did think there would be more and easier to get to.

You can sort of see in the image that the lower right is a bolt not a nut on a strut, and that its not through the middle of the original hole. I also seems to have stripped some of the threads, as it now turns easily by hand, so I guess I'll be driving without a working turbo for the foreseeable. Improved fuel economy, though, so silver linings lol.

Naf623 said:

Well I can only find one which I could cycle to, and only two others within about a half hour drive if I was to hire something else to get me there and back. In a city like York I did think there would be more and easier to get to.

You can sort of see in the image that the lower right is a bolt not a nut on a strut, and that its not through the middle of the original hole. I also seems to have stripped some of the threads, as it now turns easily by hand, so I guess I'll be driving without a working turbo for the foreseeable. Improved fuel economy, though, so silver linings lol.

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Have you ever used a helicoil insert? May be possible to put a thread insert in there and use a new stud. Studs are much better than bolts in this application because you dont apply any stress until all the threads in the head are engaged.
Just a possibility.

raywin said:

Have you ever used a helicoil insert? May be possible to put a thread insert in there and use a new stud. Studs are much better than bolts in this application because you dont apply any stress until all the threads in the head are engaged.
Just a possibility.

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The issue remains the stuff stuck in the bottom of the original hole that they couldn't get out

How wary would people be of any of these?

https://www.ebay.co.uk/itm/Land-Rov...Defender-years-1998-2002-HRC2880/193105546202
https://www.ebay.co.uk/itm/Land-Rov...scovery-Defender-years-1998-2002/233028874625
https://www.ebay.co.uk/itm/LAND-ROV...0P-TESTED-CYLINDER-HEAD-COMPLETE/123920511393
https://www.ebay.co.uk/itm/Land-Rov...a=1&pg=2047675&_trksid=p2047675.c100009.m1982

I feel for you buddy. I don't live near York (though I was born in Hull!) so I did some searching came up with this https://www.google.com/search?ei=xJ...hUKEwj-6d2HudHlAhX9TBUIHQK_CJEQ4dUDCAs&uact=5
Don't suppose there is anything there you haven't already found but there you go. The manifold isn't too heavy so you should be able to take it to the plce you can bike to.
That's the easy half of the problem.
I have been racking my brains trying to think how to help you with the other problem, how you can clear the mess out of the bottom of the hole in the head. I wondered if you could manage to weld a bit of threaded bar onto the mess at the bottom of the hole and then twist it anti-clockwise, using a couple or three nuts locked together on the bar to unwind whatever is in the head. The heat of welding might loosen whetever the mess is.
If not...when I did mine I bought some LEFT hand drill bits which tend to wind out anything they drill into, obviously you need to use a drill set to reverse. I'd go very slowly and gently with the one that only just fits into the hole withdrawing frequently, and lubricating like mad to stop any further snapping off incidents. Once the "mess" at the bottom of the hole looks smooth, I'd then use the dip in the middle of the "mess" to help centre another left hand drillbit a bit smaller and drill down into it, hoping to make sufficient of a hole to then screw an "easy out bolt extractor" into it and hopefully pull the crud out with it. You may have to keep going smaller and smaller to make any headway, and this in itself brings the risks of it being easier to snap a thinner bit.
If you buy this kit, be aware both the left-hand drill bits and the easy-outs are WELL weird sizes. But if you persist, and this could well take ages, I think you might be able to wiggle stuff out. Once you have a clean hole then drill a proper hole, tap it and then drill out the manifold hole to match. Making it a fraction bigger. You can then use a bit of threaded bar to match or a long bolt the end of which you then cut off to make a stud. This is really similar to what I had to do only mine was on the front-most hole. You can use washers to spread the load when you put the nut on the home made stud. Or maybe you will be able to get a purpose made stud of the right size.
I am also hoping a professional head work specialist will jump on and give you advice. There are also several YouTube videos although they may not be too much help in your particular case.
If all this fails, you could get the head off and present it to a machine shop who have better tools than hand held who may well be able to sort it out, then helicoil it or whatever.
The VERY best of luck. It would be a shame to have to replace a head just for one dodgy hole.

Stanleysteamer said:

I feel for you buddy. I don't live near York (though I was born in Hull!) so I did some searching came up with this https://www.google.com/search?ei=xJ...hUKEwj-6d2HudHlAhX9TBUIHQK_CJEQ4dUDCAs&uact=5
Don't suppose there is anything there you haven't already found but there you go. The manifold isn't too heavy so you should be able to take it to the plce you can bike to.... et.al..

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Its bloody heavy enough lmao, but yes fair point.

I was literally searching "machine shop", guess it pays to be more specific lol. One of those places opens early and is an easy detour on my way to work. I'll drop in for a chat in the morning; thanks!!