New Case of Broken Carburator Joint (Intake Manifold) Bolts

First off, I want to say that the "boots" between the carburetors and the engine are not "manifolds" or "boots." Boots cover things and protect them as their chief function. Manifolds being may into one, or do the reverse. These are called "Carburetor Joints" in the technical literature applicable to these bikes. They are made of metal (aluminum) encased in rubber.

(As a side note, the "boots" between the airbox and carburetors are called "Airbox Joints.")

They are quasi-unique to each bike (year and model). Swapping can be done, but you better know your part numbers and how to cross reference. And on all the ones I've seen, #1 and #2 will differ from #3 and #4.

They are prone to dry-rotting, cracking, crumbling, deformation and other ways of opening up the intake to atmospheric pressure and causing all sorts of fuel and air problems.

Most will say do not touch these until you are forced to. Seal them with liquid electrical tape, RTV, bicycle inner tubes, or some combination, before you EVER THINK about replacing them.

Personally, I think this is short-sighted. If you do not replace them at your earliest convenience you are BEGGING the galvanic corrosion to get worse and make an impossible mission truly impossible. I'd go fix them today, if you still have stock bolts. JUST USE CARE!!!!!!! (And don't say THIS post wasn't ALSO a warning AGAINST doing this... I'll get there, too!)

The bolts on the Carb Joints have a tendency to shear off at the head, leaving a protruding, flush, or below flush piece of soft steel bolt. The problem is these bolts are STEEL. Inside ALUMINUM. Check out the Galvanic Reactivity Chart to see why this is a dumb idea. Not only that, but they are SOFT steel. So they even look like they are turning when you remove them, but they are really twisting in preparation for snapping.

From my VAST amount of research I've gathered this is the many-years consensus on removal of these bolts.

--Easy-Outs will likely be a frustrating, losing battle.

--Drilling and tapping CAN work, IF IF IF you are darn-certain you got the center line of the bolt hole and you have some REALLY good carbide bits, preferably left-hand in case they manage to remove the bolt for you!

--Kroil is FAR superior to PB as a penetrating oil. Use it liberally. More liberally than gun control in Chicago!!! (That is, if you're still at a step that may allow you to turn the bolt for removal, such as a vise grip or faith those reverse drill bits will snag it out, but please, forget the EZ-outs!!!)

--Heat can help, but be careful how you apply heat. Don't do it unless you have good advice (I do not) or you have experience (I do not). I have seen posts where guys say the heat from MIG welding a nut on the stud, or using a #3 probe on an oxy-cetyl torch will do the trick. Others say a hair dryer. Don't take my word for it!!!

--Impact can help. That is, hitting the tool you are applying a LOW amount of torque to with a force that will transfer the force AXIALLY down the fastener. This helps relieve the stress on the threads, break loose corrosion, and relieve your own stress, too!!!

So, here's how NOT to end up here. If you have stock bolts, do this, today.

1) Get some Kroil Oil.
2) Use it liberally, ad nauseum, in excess, in abundance, to death. Shoot for getting as underneath the bolt heads as you think you can. Do it daily, twice daily, 4x daily if you can, for a while. For as long as you want to wait to tackle this job. (Side note: I had two 82's, one where they all came out just fine with on eblast of PB 30s after spraying, and another where two bolts snapped after days of repeated soaking and spraying, your results WILL VARY).
3) When you're ready, remove your carbs (I won't provide those instructions).
4) Get an impact DRIVER (not an air wrench!)
5) Get the adapters you need to use on this bolt for the driver
6) If you want to use heat, do so how you see fit, I can not give advice here.
7) Start using your hammer and impact driver, slowly, carefully, methodically (you could potentially try simple hex keys to see if they come loose, but make sure your bolts are TURNING NOT TWISTING). If the hex keys fail, then move on to the impact method.
8) Buy zinc-plated, galvanized steel, or aluminum bolts ONLY!!! There have been recommendations to go SS Steel... but you'll be back here in no time. Check the Galvanic Reactivity Chart if you don't believe me.
9) Use a tap, some tapping oil, brakleen, whatever to clean out those bolt holes nice and good. Remember, with taps, even an already tapped hole, go in about 2/3 of a turn, back out 1/3. Repeat, occasionally backing most of the way out to clear debris.
10) Apply anti-seize to the bolt threads and insert them into the head, no tightening at all, then back them out.
11) Check for debris on the threads embedded in what's left of the anti-seize.
12)Re-clean everything if necessary, keep repeating 9-12 until clean.
13) Apply more anti-seize (whether you had the extra cleaning or not) and get ready to reattach your Carburetor Joints.
14) Reattach your Carburetor Joints.
15) Feel good that you are probably set for way longer than any other service interval and this won't be your shortest link in your service interval chain!

Now, if you've broken a bolt:
1) If you know what you are doing, proceed, if not, skip to step: GO TO MACHINE SHOP WITH YOUR REMOVED HEAD (only after carefully following instructions on this site to remove your heads cleanly, "easily" and safely).
2) Get some Snap-On or other style bolt extractor kits that include reverse drill bits and a centering guide that will guarantee you get the bolt on center.
3) Have some Mystery Oil or other machinist's lube ready and go SLOW with the drilling. These metals don't work well with speed. Make sure you are corded. This ain't no job for the cordless!!!
4) Move up in drill sizes from smallest to largest necessary for re-tapping.
5) Tap your hole.

Now, if you really screwed the pooch and already started a hole off-center:
1) Go to a machine shop that can EDM that thing out of there.

(That last one is what THIS GUY RIGHT HERE, the OP is on his way to do right now).

ie - I'm not a hypocrite, I'm teaching from my hard-earned lessons!!!

Anyone know of a cheap machine shop or tech school in Columbus Ohio or up to Marion Ohio area?!?!?!?

 

this is totally the wrong time of year to try to get those bolts out, unless you have another bike. those bolts have been in there 30 years, another six months won't matter at all.
you don't need a carbide bit to drill a steel bolt.
Kroil doesn't seem to work because the manifold is rubber and seals the bolt, try it anyhow.
the only way to heat the head is run the bike, there's just too much mass there to heat any other way, short of a oven.
you just need to spin the drill bit, not kill it. a lot of battery drills will break your wrist.
if you find a shop with a plunge EDM, good for you but machinists were removing broken bolts long before EDM's were invented. just take it to a pro and don't tell him what machine to use

 

omalley576's post is most worthy of consideration.

However, his "Doing them Now" ... is advice that should have been issued 15 or 20 years ago.

The Galvanic Corrosion that virtually WELDS the problematic SOFT STEEL Fasteners to the Aluminum Head, ... IS NOT --> Going <-- too happen.

It already happened back when the Gobal Community was fretting over what would happen when the Calendar switched from 1999 to 2000.

In the interest of protecting your sanity.
When you decide to remove the Thingies the Carbs stick into ...
Be prepared for fasteners to be seized.

This is NOT a Maintenance chore for you do at the BEGINNING of the Season.
You MUST accept the distinct possibility that those Fasteners have already seized.

Don't walk across a Mine Field to spend a buck at the Ice Cream Truck!

Don't do anything that will make a Bad Situation, ... worse!

 

When I pulled the intake manifolds, I managed to snap the very first one before getting wise to the torch trick. Every other bolt came out simple with about 10 seconds of heat from a tightly focused torch flame on the aluminum surrounding the bolt (taking care not to singe the intake manifold!). But every engine head has been subjected to different conditions and elements, so I wouldn't say anyone else for sure will have just as easy time with it.

 

When faced with a snapped-off intake bolt, years ago RickCoMatic suggested drilling a TINY Pilot hole along side of the snapped stud, intersecting the aluminum threads, so that Kroil (or any penetrant) absolutely would get to the bottom of things. (no waiting for days and multiple applications)

Tapping on the bolt/stud will help release it.

I once snapped a head bolt on an outboard. I welded a stud on nice and square and called it "fixed" !! I topped it with a nut and washer.

 

That was years ago.

We forgot to mention "Environmental Factors" and Geography.

My most recent adventure with a Seized Fastener was on a 900 Head.
Broke the Bolt.
Drilled the Bolt.
Applied Muscle to the EZ-Out.
Broke the Aluminum "Ear" off the Top of the Manifold Port.

Needed the Head repaired.
Top Section removed.
Built back up with Aluminum Material
Machined to match Gasket.
Drilled and Tapped.

In a conversation I had with a Machinist, this afternoon ... he said EDM to Burn a TAP or EZ-Out might prove to be too risky for CAST Aluminum.

 

The reason this is such a major issue on the 650/750/900 series and not so much on the 550s is that some of the bolt holes GO THROUGH.

On the 550 heads, the manifold bolt holes are "blind" and they don't have this problem nearly as often, if ever.

Kroil will help immensely but you have to get it where it will do some good, in the backsides of the holes.

Finding them is the trick. Some barely go through, and may even have bits of casting "web" over them (but not completely.) If I recall correctly (and I'm nowhere as intimately familiar with my 650 as I am with the 550s) they don't all go through. I couldn't tell you which do and which don't without closely studying a head.

 

Here are two more things to do before you pull the Head and drive to the Machine Shop.

1. WELDING
Take a flat washer with a hole that is just a little smaller than the diameter of the bolt and weld it on to the remnant piece. Welding a washer to the remnant is said to be a lot easier than trying to weld inside a nut.
Dress the weld flat with the washer.
Then, weld on another washer. Dress. And so on.
After 3 or 4 washers you will have what amounts to a new head on the bolt.
Now, … you weld on a Hex nut to those washers.
This process takes just long enough to thoroughly heat the whole bolt, which in most cases will loosen up the seizure enough to get it out.
Maybe!

Pandora’s Box.
Presented here, for discussion purposes ONLY.


2. BETTER LIVING THRU CHEMESTRY
In an Old Datsun 240Z Forum; this was presented as a last-ditch shot at getting the thing out.
Take some Modeling Clay.
Build a Reservoir that will allow you to drip-in fluid that will contact the remnant piece within the housing.
Use dilute Nitric Acid.

::: Editors Note. Dilute? Shouldn't this be a whole less ambiguous? A percentage?? :::

Put-in drops of Nitric Acid.
The Nitric Acid ::-->> supposedly <<--:: dissolves the Steel leaving the NON-Ferrous Material untouched.
Discuss.

 

I'll give you that. Considering the season JUST started and most have had their bikes a while. And what is just one more riding season after 30 years?

However, the point of a forum is to hold onto information, long term, for others to benefit from whenever they happen across the information. I wrote this from that standpoint. Anyone searching the forum and reading this post some random day in the future might benefit from it and heed the warning.

I should, however, clarify that "NOW" IS relative. Why do it NOW when it's already had 30 years to corrode? Well, there ARE some cases.

1) Not everyone is in peak or just-started riding season. In Alabama, it's pretty hot and toasty to be riding in-town. In Canada, I'm sure riding season is barely getting started, if at all, yet.

2) My carb joints were shot, NOW, my joints were WAY gone. They'd already been RTV'd twice, from what I could tell. I could squeeze them and see broad daylight all over the place. And one was split around the mounting bolt. No. Good. HAD to be done NOW. And I just purchased my bike.

3) Putting off the inevitable until later for a little bit of pleasure now doesn't help the situation. And a LOT of the posts I've seen on here have people saying they will wait until their joints NEED to be replaced. Even saying they'll RTV them to get by. That's short-sighted. It'll just make the situation far worse. Especially if they plan on waiting 5-10 more seasons before they decide that is the time they "need" to be replaced.

4) Every bike is different. Or, really, every owner and his environment is different. A 100k bike always garaged and treated well in Arizona probably doesn't have the problem as bad as a 10k bike left outside for 30 years in salty locations, or muggy, humid locations. All of thise could impact one's definition of "now".

I beg to slightly differ. I've been drilling on this sucker for 15 minutes at a time here and there for over a week now. I'm barely into it. I broke one of my cheapo B&D black-ox bits and a LH drill bit I got from Harbor Freight. I dulled my brand new titanium bit. Last night, I bought a set of cobalts (Sear's didn't have carbide) and I drilled more last night using that one bit than I did 10 times over with all the rest, combined. the bit is still sharp as the day I bought it (okay, same day... but you get my point).

Absolutely. That's a good seal!!! But then again... so is a bolt head directly against anything else we use penetrating oil on. This stuff works by bubbling up, boiling out, outgassing, weeping, capillary action and other manners. It gets in places. It gets in places other things don't get into. It gets in places things aren't supposed to be able to get into. That's its thing.

I've seen a few posts where it helped. It certainly can't hurt. Okay, it CAN hurt. It can provide one with false hope.

One could also destructively remove the joint and make room for the oil to get it in there!

I didn't say anyone should heat the head... I said they can apply heat. It's been done as long as man has had both flame and screws!!! It's intended to be a local heating, anyway. If engine heat helped, I'm sure the instructions would always be to run your bike around town, come home, start removing stuff. (Although, now that I think about it, I might actually try that if I have any future problems... exhaust headers, perhaps, when that day comes.)

I am the confuse. I couldn't agree with you more; however, it seems like you are trying to negate something I said by restating it. I didn't say anyone should kill anything. I said go slow and go corded. A battery will die before you're done. Or you'll overheat it from the constant, steady use. Cordless drills are not meant, and should never be used for continuous duty like that. And, as you have pointed out, they'll break your wrist!!! Get that drill bit all the way through where it grabs and shabam!

Touché. I don't know a whole lot about taking anything to a shop. I worked with a bunch of Mechanical Engineers that spent a lot of time in a shop. I've heard whispers of what goes on from them and here in the forum. I have spent some time myself machining small parts. I've also seen countless threads and posts on here that recommend the "only solution" is to stop, and go to a machine shop and have it specifically EDM'd outta there. Apparently this is bad advice? As Rick has now stated here, his machinist says it's not wise to do in cast aluminum. [Although, Rick, you are the one who preached EDM'ing more than anyone in all the posts I've been reading ]

 

Too. True.

I agree, however, I meant this in the context of "now" being when the reader reads it. Could be ten years from today. It's something that needs doing, one way or the other. Current information in the forum supplies the details about A) the problem of snapped bolts, B) the problem of bad carb joints, C) why the bolts are bad, D)how to get unphuqued, E) what to do and what bolts to use to prevent this in the future. However, no single thread or post contains all this information. I'm trying to add to our knowledgebase. And I wouldn't compare this to mine fields and ice cream. I'd say not doing it is more like ignoring the fact that you walked outta the house nekkid to go to the ice cream truck. You might wanna fix your problems sooner rather than later!!! But, yes, don't fool with this at the beginning of riding season IF IF IF you don't have to. However, some will have to. That's life.

 

--THIS-- is important information that I haven't seen anywhere else, yet! I didn't think about the possibility of damaging the head in this specific manner!!!

Also, everything I have read so far recommended EDM'ing, so I suppose it's pretty important to point out that it may not be the best idea.

And, as Pollock has stated, don't tell your machinist what to do, anyway, take the problem to him, tell him the truth about how you got there, and let him decide the best course of action. Just get one with experience!!!

 

I forgot to mention Fitz's recommendation in my post, and I've seen him tell this tale on here before. Heed this advice!

 

{{SIDE NOTE: I used to have a Z32! Not your Datsun body, but the Z32's were great. Hope to get one back someday. I had the '84 Anniversary Edition. The REAL one!!!}}

I did stumble upon something called Tap-X. I'll quote the site in case it ever goes down.

from: http://www.chemical-supermarket.com/pro ... ductid=574
It's called "Tap-X Broken Tap Removal Kit #680-117"
It's from a company called DGR Industrial Products
I did not find an MSDS or other chemical information on the site.

 

When you arrive at the point where you snapped-off the bolt, messed with it, had the thought that you shouldn't fool with it any more.
Decided to give it another shot and drilled it slightly off-center, inserted the EZ-Out and applied supernatural force without anything happening.
So, you heat it up and give it another shot only to have the Chinese-made extractor shatter, leaving you on a raft with no paddles, so far up sheet-creek you're off the map, ... and the only person who understands how bad you just messed-up is the one-and-only Rod Serling, whose voice you hear trying to comfort you, ...

Bring it to a Machine Shop.