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View Full Version : Broken bolt on thermostat housing @#%&^



Mart
04-19-04, 09:09 PM
I am in the process removing my intake because of a leak, when I was taking the thermostat housing off the bolts were really stuck so I used some liquid wrench on them and let them sit for a day, lubing know and then.

Today I tried to remove them and they both snapped off.:mad

These bolts were a 9/16 head I don't think that they are the correct ones and were probably cross threaded, boy was I P***ed.

Has anybody got any sugestions for repaing these two broken bolts.meaning the half that is stuck in the intake.

Help.... Mart:( :cry

bossvette
04-19-04, 09:16 PM
you will need to find someone with a mill to drill the bolts out without messing the aluminum of the manifold. It may be cheaper to buy a used baseplate though.

Mart
04-19-04, 09:47 PM
Here's a pic of the broken bolts.

http://members.rogers.com/c4vette/images/myresto/brokethermo.jpg

Mart
04-20-04, 07:10 AM
Any other suggestions..... Anybody.

Is it time to move to a different intake....suggestions welcome.

taegdh
04-20-04, 08:10 AM
I would recommend moving slowly.

1. Fill the coolant hole with rags.
2. Use a prick punch to make a center point mark.
3. Drill out the center of the broken bolt, starting with a 1/8 inch bit. Use liberal amounts of PB Blaster or Liquid Wrench for lube while drilling and to displace the corrosion. Then take a small drift and tap it a few times. You know like a dentist on your molar, not a steel worker on a rivet.
4. Try to use an E-Z Out. If it doesn't go, go to a 3/16 inch bit and drill that out and try another E-Z Out. repeat 3.
5. If it still doesn't go, go to a 1/4 inch bit. and be prepared to keep using liberal amounts of PB Blaster. Tapping before you try each.
6. Be prepared to re-tap the threads after you get them out. Clean them up properly.
7. Don't go like a wild man to a whore house, or you'll end up buying a whole new manifold, when all it takes is patience.
8. Flush out the cooling passages of your engine to remove ALL shavings or they'll end up where yo don't want them. A magnet might be of help here.

Lots of luck

1Bad86
04-20-04, 10:47 AM
I feel your pain man. I did the same thing to my intake. Then really F'd it up try to repair it. I ended up buying a new higher flow intake from TPIS.

Bill75
04-20-04, 11:19 AM
Mart,

Even though this looks like the end of the world, it's repairable. The key is to drill out the broken bolt in the exact center. If you don't have the right equipment such as a Bridgeport, I wouldn't attempt it. Take the manifold off the car and bring it to a competant machine shop or auto machine facility. They have the right equipment to deal with it.

The easy out suggestion mentioned might work but in my experience dealing with similar situations, they're rusted so badly that you do more damage fooling with it.

Good luck

Bill

bossvette
04-20-04, 12:25 PM
without a mill to properly center and hold the drill bit in the steel bolt the drill will "walk" and screw up the aluminum. a machine shop can do the job and you could also have them install Heli-coils to be sure the threads are full depth and hold properly.

steve464
04-20-04, 12:35 PM
If the easy out won't work on its own use liberal amounts of heat like a propane or mapp gas torch and try the easy out again while the manifold is hot. If that doesnt work drill out the old bolt completely and get a helicoil kit and drill bit, about $30.00, this will install a stainless steel coil that will accept a new bolt. Get stainless bolts to fit the helicoil.

Good Luck

Steve

KOPBET
04-20-04, 12:56 PM
I have to ask this question to you easy-out fans: If the bolt broke, why wouldn't the easy-out break since it is very hard and somewhat brittle? If the easy-out broke inside the bolt, would'nt that make a bad situation worse?

:confused

livinez
04-20-04, 01:26 PM
Ya, its bad to break a easy out, but if done right its a rarity.
If I have decent access I like to grind the offending bolt flat or if its recessed or hard to get a grinder on I take a punch and beat a flat spot. Even if I can grind it smooth I still give it a few hard shots with a flat punch 1st to help break up the corrosion in the threads. Then I use the previously mentioned "prick" or centerpunch for my drill start.
Always start with a 1/8" drill then go to the size you need. It makes it much easier to get close to center and make adjustments if you are off with the larger bit later. And it is much easier on the larger bit. Oh yea, I always use lots of break free or whatever and heat, every time.
Had the samething happen on my rebuilt. I just drilled the old bolts out and went straight to the helicoil.There is so much electrolisis there that the aluminum threads appeared beyond saving. After the loktite for the helicoil was set (overnight) I used stainless replacement bolts with lockwashers and neverseize.
The helicoils wrer also used on 4 of 6 exhaust manifold bolts as the studs for the header pipes snapped and I just drilled those obsinate buggers out.
Also went with a 180 thermostat and changed the fans sensor to the lowest on temp available (214 degees on I believe it was)

No I dont use spell checker :(

plumcrazy
04-20-04, 02:24 PM
just went throught the dreaded filler kneck removal. fortunatly mine came out.
had an idea of what to do if they didnt.being a maint tech i have access to all
kinds of industrial equipment and fasteners you may not have the same acces
and may need a professional to remove

here is what you need if you can get it.
1- 3/8 coupling nut
1- 3/8x3/4 bolt
assorted brill bits

stuff the fill opening in the manifold a rag
remove the plenum and throttle body

1)drill the center out of the 3/8x3/4 bolt w/ a 1/8 drill bit(drilled out in lathe)
2)thread the coupling nut on whats left of the stud if all possible,if not center punch it
3)thread the bolt into the coupling nut
4)use the same bit you drilled out the bolt with and carefully drill a pilot
hole through the broken bolt
5)increase the bit size by 2 after each pass through the bit untill you get
to 5/16
6)tap out hole with a 3/8x16-unc tap
7)blow all traces of metal away from the entire area
8)replace the stat,filler neck, plenum and throttle body

AND DONT FORGET TO USE PLENTY OF ANTI-SIEZE!!!!!!!!!!!!!!!!!!!

good luck

chris

plumcrazy
04-20-04, 02:32 PM
oooops geuss i should have read all the posts first.
livinez already got ya started

kopbet
the easy out is harder than the bolt is so the bolt will go before the
easy out but we have been known to break one or two at work every
now and then. i personally dont like em, if you think about it you are expanding the bolt outwards toward the treads so if its a really stuck bolt how is it gonna help ya
i myself like to drill and retap the hole

ghr4news
06-15-14, 10:18 PM
Hi plumcrazy: Had a couple of questions on the reply to the post. As you can imagine, I've just joined the list. Mine is an 86...What were they thinking back then at GM? Didn't their engineers realize sooner or later the thermostat was going to need replacing & why couldn't they've come up with a better design for the housing.. Well, by the stories that have come out recently; with all the recalls, I guess I've answered my own question. They weren't thinking period.
Ok, now that I've vented!
I tried the old twist it method with a vice grip after I allowed liquid wrench to sit for a while. That didn't help, but now I have no thread left on what's left of the bolt, just a nice piece of flush metal sticking out.
Here are my questions:
1. Do I need to re-thread the bolt so the coupling nut will thread on? What's the reason behind using a coupling nut?
2. When I drill down the center of the bolt with the 1/8 drill bit, do I drill all the way down? How will I know when to stop?

I wont use an easy out because I had a similar problem to another reply on the post; the easy out broke inside the old bolt and it took me for ever to drill through that tungsten steel easy outs are made of.

Outside of taking the manifold to a machine shop, any other suggestions would be appreciated.
thank you,

George



just went throught the dreaded filler kneck removal. fortunatly mine came out.
had an idea of what to do if they didnt.being a maint tech i have access to all
kinds of industrial equipment and fasteners you may not have the same acces
and may need a professional to remove

here is what you need if you can get it.
1- 3/8 coupling nut
1- 3/8x3/4 bolt
assorted brill bits

stuff the fill opening in the manifold a rag
remove the plenum and throttle body

1)drill the center out of the 3/8x3/4 bolt w/ a 1/8 drill bit(drilled out in lathe)
2)thread the coupling nut on whats left of the stud if all possible,if not center punch it
3)thread the bolt into the coupling nut
4)use the same bit you drilled out the bolt with and carefully drill a pilot
hole through the broken bolt
5)increase the bit size by 2 after each pass through the bit untill you get
to 5/16
6)tap out hole with a 3/8x16-unc tap
7)blow all traces of metal away from the entire area
8)replace the stat,filler neck, plenum and throttle body

AND DONT FORGET TO USE PLENTY OF ANTI-SIEZE!!!!!!!!!!!!!!!!!!!

good luck

chris

Antz81
06-16-14, 12:18 AM
I tried the old twist it method with a vice grip after I allowed liquid wrench to sit for a while. That didn't help, but now I have no thread left on what's left of the bolt, just a nice piece of flush metal sticking out.
Here are my questions:
1. Do I need to re-thread the bolt so the coupling nut will thread on? What's the reason behind using a coupling nut?
Ideally you would have thread left on the bolt for the coupling nut, if the coupling nut won't go on because of the damaged thread then you will need to use a die to cut a new thread onto what remains of the stud.
A coupling nut should be used as it is around 4x longer than a normal nut so can attach the bolt to the remaining stud securely.


2. When I drill down the center of the bolt with the 1/8 drill bit, do I drill all the way down? How will I know when to stop?
yes, drill all the way through the bolt. This must be done in a lathe as this hole must be straight.

I know i'm not plumcrazy, but i understand what he's trying to achieve.

hcbph
06-16-14, 04:45 AM
A couple of things that might help. First is what you use to help break the threads loose. I've seen the results of a 50-50 mix of ATF and acetone. Seems to work much better than regular PB Blaster, Kroil, etc. Use a centering punch to get the exact center where to drill. Use a left twist drill bit to drill the hole. They're available from H.F. and if you luck out it may grab enough to turn the stub out without the need for an ezout.

WhalePirot
06-16-14, 12:43 PM
If the bolt broke, why wouldn't the easy-out break?Sadly, I have more of those 'tee-shirts' than the smiling ones and I am not new to this hobby. To clarify, I have broken more EZ-outs than not and they are a bit*h to drill out, especially with HF caliber bits.

The ATF+acetone mix is reportedly the best, but is the corrosion going to allow it to seep to where it's needed. TW, this may not be Chevy's fault if improper maintenance from a PO existed.

Sometimes, the seemingly more elaborate and expensive option is actually the opposite. Given the banter here, I'd suggest that taking the intake to a professional is best. Odds are, the manifold, otherwise, will be ruined and will need replacement. :w

mailmaninvette
06-16-14, 08:11 PM
A machinist that I know removed 2 mount bolts that I broke off in a Tracker aluminum front differential . He used a tig welder starting in the center
of the bolt and building a ball of weld to turn with vice grips . One bolt did not want to turn so he added more heat by making the ball bigger. It took
him about 10 min to remove both bolts , he made it look easy . A good welder with steady hands and a tig welder should be able to do this.

kpic
06-17-14, 07:07 PM
I have to ask this question to you easy-out fans: If the bolt broke, why wouldn't the easy-out break since it is very hard and somewhat brittle? If the easy-out broke inside the bolt, would'nt that make a bad situation worse?

:confused

The drilled hole "relaxes" the bolt. The key is start with a small drill and continue drilling with larger drills until you have the largest possible hole. Buy a quality set of easy outs; junk ones will break and they are a bear to remove.

How to use an Easyout (http://jaw.iinet.net.au/motorbike/easyout.html)

Getting a steel bolt out of aluminum is probably the easiest.