The following turned out to be a bit of an epic tale. I apologise for the length of my tome!

When I bought my car in 2013 I was told 'Buy a new throttle body coolant hose - they should be regarded as a maintenance item'. So I duly bought the hose, chucked it in the spare wheel well and promptly forgot about it. Twelve years and 120,000km later the hose finally burst, luckily only 500 metres from home.

The first thing I realised was that, in 2013, I had forgotten to purchase new manifold gaskets. No problem, that would only add a bit of time for delivery.

So I duly looked up the manual and was somewhat surprised by the first instruction 'Remove the wiper arms'. No problem, off I set on my task. All went well until it came time to loosen the manifold bolts. The front two pairs of bolts came out very easily, and came out looking like new. The next pair back were a little reluctant to release and came out somewhat corroded. The fourth pair were scarily tight and I had to work them back and forth a bit to get them to release and they came out quite corroded. The rearmost pair of bolts simply refused to come loose. I tried every trick I knew of - back and forth many, many times, impact on top, impact driver, prayer....In the end the inevitable happened and the two bolts sheared off. Between them, because they cant in towards each other, they acted as very effective dowels, preventing me from lifting the manifold.

The bolt on the right hand side broke off about a centimetre above the block. I thought I could drill it down to the level of the block. Good in theory, but my power drill was too bulky to line up the bit to go into the bolt hole in the manifold. I could perhaps have used a right angle drill adaptor, but I don't have one and have never used one so I would have been a bit twitchy about learning on the job, so to speak. In the end I found, in amongst the tools I had inherited off my father, a little 3/8 inch electric drill which tucked in under the firewall beautifully. (So much for 'Why do you insist on keeping that old junk of your Dad's?'). So, bolt number one was out of the way, but the manifold still wouldn't lift.

The left hand side bolt sheered off just below the head, so it was a 95mm long spike sticking out of the block.


On this side there was absolutely no way of fitting a power tool of any description in front of the firewall. My only option was to get hold of a long drill bit which would just clear the front of the firewall. I tried a 280mm long multi-material bit with carbide tips, but the tips almost immediately chipped off. This is my attempt to use this bit and you can see I 3D printed a little guide to help me get the drilling angle about right.


Given that the carbide-tip drill bit failed, I decided to extend a high-speed steel bit. This is what I ended up making. It is a 160mm long, 8mm bit and I put a 120mm extension onto it.

This drill bit worked very well but, despite my best efforts, I ran off line. That is the challenge of drilling a hard, steel bolt out of a soft, aluminium housing! Nevertheless, I managed to cut sufficient material out of the bolt that I could now lift the manifold. Here is how the bolt ended up:


Once the manifold was off the motor I was able to soak the stub of the left hand bolt with penetrating oil and ultimately a pair of vice grips proved up to the task of gripping it so that I could unscrew it out of the motor. I used JB Weld to repair the manifold where the drill had drifted off line. Dealing with the remains of the right hand bolt, however, proved a different matter altogether. In the first instance I tried to use an 'Ezy-out' to remove the remains of the bolt. This proved a bit of a disaster. The Ezy-out caused the bolt to basically 'explode' inside the aluminium, damaging the surrounding material to a depth of almost a centimetre. Such was the damage that it wasn't really an option to use an 8mm helicoil (I tried and failed), so I decided to install a larger bolt using a 10 x 1.25mm helicoil. My next challenge was, how do I ensure I get the 10.2mm helicoil pilot hole in the right place, and at the correct angle? I was able to measure the centre-to-centre distances and offsets from the other bolt holes in the manifold and engine block and from those I designed a pair of drill guides that I could 3d print. Into these I pressed lengths of aluminium tubing to ensure the drill bits remained true to angle. This is the configuration of the guides. One hole accepts a bolt which is screwed into the adjoining manifold mounting hole, and the second hole accepts the drill bit:


One guide accepted an 8mm bit and I used it with my little power-drill to generate a preliminary pilot hole. I followed this up with the 10.2mm bit. The latter was too large diameter for my Dad's little machine, so I had to use a decidedly unconventional technique, which took me ages but worked a treat:

I had no trouble tapping the thread for the new 10x1.25 helicoil and the thread ended up true to angle and in exactly the right place.


The final step was to drill out the corresponding hole in the manifold with a 7/16 inch drill (a bit over 11mm) to accept the larger, M10 bolt with appropriate clearance. This is what the larger bolt looks like in the manifold:


This is a mere summary of what has been a very stressful six weeks. I have left out some of the more spectacular disasters I had along the way. There were times when I really thought I may not get that manifold back onto the motor with ten bolts holding it in place. But I am glad to report that the beast is finally running once more AND THE NEW HOSE LOOKS MUCH BETTER THAN THIS!:

 

Replaced my coolant valley hose last winter on the 4.0. Luckily I didn’t have to remove the wipers and my bolts weren’t completely seized. Still the thermostat housing and almost every bolt on the intake was a battle. The ptsd had gone away until I read your post. Thanks for reminding me of the things we’re willing to endure to keep these beasts rolling.

 

The PTSD effect you mention was very real for me. I had also intended, while the car was up on ramps, to change the figure-eight seal under the oil filter housing. But it has long M8 bolts too and shearing off one of those would represent a whole new world of woe. In the end I decided to regard the slight oil weep as an 'Integrated Underbody Rust Prevention System' - i.e. I chickened out.

 

While I was reading your thread I kept thinking: "Whatcha doin' ?"
Half-way thru your thread I finally saw the word, that should have been at the very beginning of your thread: "PENETRATION OIL"!
Maybe, if you had used that from the onset, you'd 've saved yourself a few weeks of trouble...
But at least you were able to dig yourself out of the hole, that you dug for yourself...

 

I tried soaking the bolts in the manifold in Penetrating Oil for a week before I got serious about trying to undo the two aftmost bolts. But the problem is, unlike studs with nuts on them, the threaded part of the bolts are in the guts of the manifold 95mm below the head. Plus I found the flat washers under the bolt heads make a very good seal on the plastic manifold. Even though I was using an aerosol to deliver the penetrating oil as a stream under pressure, I doubt whether I got any of it at all where it would have done any good.

But I agree the hole I was in was very deep and I am glad to be out of it again.

 

Very intense repair!
Thanks for the pictures it does not look like fun either!
.
.
.