[rteichman]

If you have been following my saga on "strange thunk sound" you will know that I have an engine mounting issue. Specifically that the bolt has sheared off INSIDE the block. Does anyone know of a way to get the bold out without removing the engine? I'm just not in a position to pay for the removal of the engine and all that.

Any creative ideas would be appreciated.

 

[Vulcan Grey]

It is possible. depends on which side of engine, as far as how difficult it will be.

The left of the block has the tighter space, and you'd probably need to remove the exhaust manifold and heat shields to do it. I know of a beginner who removed his exhaust manifold in about 3 hours... fiftyone.page

If it is the other side, then the job is much easier!


An easy out is really not an option! They only work when you tighten a bolt that is performing a clamp load and you pop the head off. Once the clamp goes away the bolt will spin out. Every easy out I have seen is broken off inside the bolt that was stuck by corrossion or stuck tight in a bottoming hole. They don't work, and then you just have a hardened easy-out stuck in the hole.

The best technique is to use a bullet nosed carbide grinder (hopefully slightly smaller diameter than your 8mm stud. You use the grinder to create a dished shape in the top of the broken off bolt, CENTERED on the diameter, so you can then drill the bolt out with a drill in the CENTER. Use a drill bit that is smaller than the diameter of the bolt. Then the thread of the old bolt should be easy to pick out with a pick, leaving the aluminum thread intact. If not, then you have to re-tap the thread to clean it up, or drill and tap to a larger size! Or you can Helicoil it back to the original 8mm size.

 

[carbuff]

So, the motor mount bolt is broken (one of the three) where it screws into the block?





Is it on the driver's side (under the exhaust manifold)?

Is it broken flush to the block or is a little nub sticking out (possibly within the motor mount hole)?


First, check the other two bolts on the motor mount. If they are loose you need to remove them one at a time, 'chase' the threads with a tap & die, and make sure they can be re-inserted easily. Do this one at a time.

Then, prepare to remove the other (broken) bolt.


Best way is to support the motor (jack under the oil pan with a thick board to spread the weight). You may then loosen the other two bolts, and the bottom vertical mount bolt (which cannot be removed with the exhaust manifold in place). THEN you may be able to move the motor mount pedestal away far enough to grab a "nub". Attack the nub with a vise grip, mine is a thin-jaw type that can get into a 1/2" wide space.

If that fails to move the broken stud, you will need to try an extractor. Drill a hole in the broken bolt (the motor mount can act as a guide so it won't slip if the other two bolts are holding it tight). If you use a reverse ("Left Hand" drill bit and are lucky, it might come out.

13 Piece Left-Hand Drill Bit Set

If not you will use the hole you drilled on a regular extractor.

http://www.gearwrench.com/gearwrench-720dd-screw-extractor-kit.html


I'm not sure about drill access, you might need a right angle drill.

 

[aschen]

can you post a pic or can somebody post a pic of the general area?

Then we can put our collective Mcguyver hats on

 

[rteichman]

I'll ask for pictures, but there is no nub, the bold is sheared off below the surface

 

[carbuff]

I'm waiting for the info about which side is broken....in this or the THUNK topic.

I'd take Colin up on his offer. Even a six-pack...

Don't give up hope Rob

 

[rteichman]

Sorry, its the side the AC compressor is on. Looking from the back to the front its on the right side. I'm waiting to get a picture from the mechanic, probably not till tomorrow

 

[esprit888]

I wouldn't want to volunteer him but Guy Therien is very close to you in Beaverton, great Esprit guy, if he has any room amongst his six V8's then he may be willing to help out. I know he checks in here once in a while or you could email him ( Guy's Lotus Page ) just don't tell him I had anything to do with it rotfl . One thing though, if two out of the three are still tight I doubt this is the cause of the 'Thunk'!

Sorry, its the side the AC compressor is on. Looking from the back to the front its on the right side. I'm waiting to get a picture from the mechanic, probably not till tomorrow

 

[jtrealty]

Sometimes you get lucky and the nub is in there threaded but not tight. By working it slowly and patiently with a small ball peen hammer and a center punch you can rotate it right out. If it is difficult to turn the only option is to try to drill it out. In such a case center-punching it accurately in the center is imperative. Next is to use an angle drill and a left hand bit if you can get it and the angle drill will run in reverse and try drilling it out staying centered inside the bolt. Once through you go up through the sizes till you can remove it. Sometimes during the process it will spin out. More often you have to drill it out and in doing so you damage the threads. Not the end of the world, you overdrill it and use a thread insert. This takes patience and not a little bit of a machinist's skill. Most mechanics hate this kind of freehand work, especially in tight quarters. This is not meant to be done by a novice. Messing this up can do a LOT of damage if you hit cooling passages, oil passages, go off center, etc.
David Teitelbaum

 

[Vulcan Grey]

Sorry, its the side the AC compressor is on. Looking from the back to the front its on the right side. I'm waiting to get a picture from the mechanic, probably not till tomorrow

There is tons of room on that side!

All you would have to remove is the air filter box (maybe), oil filter, oil cooler sandwich plate, and maybe coil packs...

Not a problem to remove a bolt and tap new threads there...

 

[amanda11270]

My motor mounts were left loose by whoever worked on my gearbox prior to my ownership, I had to tighten them, the drivers side was tough, the passenger side had all kinds of room, like everyone else said, that is the side to have one broken of either. I found this problem due to a minor thunking sound upon buying the car, it was one of my first fixes to my car.

 

[mieczkow]

I have been through a similar experience not with a motor mount bolt but with the button-head bolts which hold on the rear main seal and not too long ago with a transmission drain plug which had to be drilled out. I had the button-head bolt snap off while using a paddle-type extraction tool leaving a 6M stub in the block with no nub and a bolt remnant which was corroded and seized. Your situation will take a lot of patience.

You are fortunate that this is on the passenger side of the engine as there is a lot more room to work there than on the exhaust side, as Travis pointed out. Here are a couple of things I would suggest if you are going to try and remove it yourself. I would definitely pull the air box and if you are working from the top I would take off the plenum. The more room the better. If the surface of the remnant bolt is fairly flat/level then striking it with a punch to center the drill is not too difficult but if the surface is very torn up, craggy, irregular it will be hard to create a nice centered dimple to begin to drill. If that is the case I think you should use a micro carbide grinder (dentist drill size) to create a center "pocket". Definitely invest in a reverse or left-hand drill set. It greatly enhances the chance of "walking" the broken piece out if you are drilling in the same direction as the bolt would unscrew. I have found a right angle pneumatic drill to be the most comfortable option for this kind of drilling since it is so much lighter than an electric drill. If you are going to do this over a few days keep soaking the stub with Kroil or some other lubricant. When I have drilled out stubs like this I like to start with a relatively small pilot hole and then gradually increase the drill size so there is not an attempt to take out to much material at once - it's easier to control the process that way. The ideal progression is a well-centered small pilot hole which is gradually enlarged in a series of small steps.

Good luck! I know these sorts of challenges can be really frustrating but hang in there and you will get the problem solved. And even if you end up doing some damage to the existing threads you can time-sert or helicoil the blind hole so that the mount can be successfully re-attached,

 

[carbuff]

if two out of the three are still tight I doubt this is the cause of the 'Thunk'!

Disagree, Colin,

As I've said, I've found these bolts loose on three Esprits. It's not uncommon for them all to be loose, then one falls out (that was my scenario on Yellow Hornet's S4s). If the mount moves around enough, I can imagine one bolt might shear off.


Checking the motor mount bolts is now an item on my B service list (along with the bulkhead and front trunk bolts that David mentioned). TADTS I guess I just love to contort my body into difficult spaces. rotfl

 

[esprit888]

Respectfully disagree with your disagreement Here's my thinking, whoever did the A/C or fuel tank over tightened one of the mount bolts shearing it off, looked at it and said 'bugger it, no one will ever notice'. As long as the other two were tight I don't think it will move around, but.....if the other two were loose then I can see where you are coming from and it is feasible that it could twist and shear one but the others would have to be very loose. Either way its not the end of the world and being on the compressor side is a big bonus. I do agree with the bulkhead bolts though, I have had several cause a 'thunk' from being loose, noticeable when you get on and off the gas.

Disagree, Colin,

As I've said, I've found these bolts loose on three Esprits. It's not uncommon for them all to be loose, then one falls out (that was my scenario on Yellow Hornet's S4s). If the mount moves around enough, I can imagine one bolt might shear off.


Checking the motor mount bolts is now an item on my B service list (along with the bulkhead and front trunk bolts that David mentioned). TADTS I guess I just love to contort my body into difficult spaces. rotfl

 

[carbuff]

Here's my thinking, whoever did the A/C or fuel tank over tightened one of the mount bolts shearing it off, looked at it and said 'bugger it, no one will ever notice'.

Maybe...

Hopefully it's not that one motor mount bolt that connects the engine-to-chassis ground braid.... -eek-

 

[rteichman]

The shop is going to work on it next week. He has tapped out bolts before, but not in such tight spaces. He has the right angle drill and reverse bits. He is however familiar with working in tight spaces as he does a lot of work on Elise cars. Wish me luck.

 

[rteichman]

Just to let everyone know, the shop got the three bolts drilled out, and welded back the transmission brace. So all is good.... well until I see the bill LOL Thanks to everyone for your help, I suspect the posts that I copied from here to the shop via email might have persuaded him to go the extra mile

 

[rteichman]

Respectfully disagree with your disagreement Here's my thinking, whoever did the A/C or fuel tank over tightened one of the mount bolts shearing it off, looked at it and said 'bugger it, no one will ever notice'. As long as the other two were tight I don't think it will move around, but....

I think you are right. I posted on the other thread that the shop here found evidence that someone had already tried to drill out a bolt. So someone already knew about one of the bolts being sheared off. But then with the other bolts loose the engine started shearing one after another off until the engine was totally disconnected from the frame