Just spreading the word. If you're hearing a rattle/ knocking during cold starts on your p400 defender, your exhaust manifold bolts are broken. Unfortunately im seeing a lot of defenders with this issue. It's a job I do not recommend for a DIY person unless you have professional tools and a welder. I just got done doing this on our Defender where 6 out of the 13 bolts were broken. Took 3 days.
Why is this happening? The exhaust manifold bolts are made from inconel and are stretch to yield. After the the torquing process they only see about 15-17 ftlbs of torque. And unfortunately you can't tighten more as they just stretch without providing more clamping force. Inconel is great for high temperature but not great with vibrations. After some time of expansion and contraction due to the engine heat cycles, they break. And to add insult to injury, they are loctited with make extraction more difficult. Welding nuts to them seems to be the best method to remove them.

We are going to come up with new hardware for this but for the meantime. Replace with what's available. As soon. As you hear a rattle, get it done before you end up like us with half of your bolts broken which will only add to the labor.


Only way to see the broken bolts are by removing the heat shields around the manifold. The gasket has a heat shield intergrated to it making it difficult to see without removing the shields surrounding the manifold.

4 broken bolst on the left sife of the manifold/turbo. You can see the top one sitting on it's side

2 broken bolt on the right side

Its not pretty but it worked. Getting our mig gun in there was a bit of a challenge for some of the bolts. May be time to invest in a flexible gun.

 

This is interesting, what kind of sound does it make? I've only had my '23 for a couple months but it makes a heck of a lot of racket, and only on cold starts. I was thinking it sounded a little like heat shield clattering. I've only got 14,000 miles, could this be what I'm hearing?

 

it sounds exactly like the clip from this thread
https://landroverforums.com/forum/20...m_content=post

 

With the amount of labor cost involved in this,(I'm estimating a kidney and a left nut) and the complexity involved, I think it will spell the end of ownership for many affected folks. I know this issue is in my future.

When I looked at the shop manual for the P400 to just gain access to the bolts, I immediately said "nope". Not for me.

Seeing more and more of this in the forum now that we're coming up on 6 years into the L663.

 

Fascinating @Saltek Motorsports your contributions are appreciated immensely here.

Perhaps I shall proactively replace all mine with 31K miles on the Defender. Preventatively. I have no noises now.

In your opinion, is the replacement fairly straightforward if none of them have yet broken, and do-able at home ? I’m a decent tech, work on my cars & have all the tools, this should be cake if access is OK. Is access possible with disassembly? Remove, replace with new?

 

The job is pretty straight forward although the shop manual leaves out a few things, some one with experience working of other vehicles shouldnt have an issue doing this at home.
From what I can remember, tools that most diy dont have but you'll need are inverted torx, triple squares, a wiper arm puller, o2 sensor socket, dull 90 degree pick, a digital professional grade torque wrench that can do angle.
there's a bunch of coolant hoses but they fall into place so it'll be hard to confuse them. Disconnect the battery that way you dont risk erasing any adaptations from the throttle body or set codes from disconnecting sensors. Dont disconnect the supercharger. You can cut a zip tie that holds the 48v harness and just set the supercharger aside once removed from the mount. Use a hammer and pound a sacrificial bolt to for the supercharger mount to spread pressed-on nuts. (Similar to what you would find on some alternator or power steering pump on some vehicles)

 

I believe in you Gavin.

 

@Saltek Motorsports

Great info as always.

I'm curious if you happen to know how long the unbroken bolts are. I know I have one that came out. I pretty confident it's broken leaving its loctited end in the head, but I'm not 100% sure. Probably more than 1 bolt affected here but without a full disassembly I have no way to know.

No rattles or anything but I don't think I could stomach the butcher's bill for this one. I'd need to find a good shop.

 

I think I'd end up with a garage full of Defender parts if I took this task on. Getting to the bolts seems like a monumental job. As reference, my spark plugs took me all day and I really thought I'd bitten off more than I could chew. This makes that job look like a walk in the park.

Maybe after @nashvegas does his, he can pop up to WA and walk me through it.

Maybe Santa will bring me a welder and all the other tools I've never heard of.

 

It is 58.5mm long. Or about 2.3 inches.