I’ve got a 94 gt and upon removing the lower intake manifold I discovered that 3 of the 4 corner bolts were broken off, I’ve tried heat, I’ve tried lots of penetrating oil, and have tried easy outs over and over. I don’t know what to do as one of the bolts is drilled quite off center and another has a broken extractor in it. Don’t really want to get new heads, so what I need is as much advice as possible for drilling the bolts out and tapping the holes or what else I should do. Thanks in advance
Broken lower intake bolts
- Thread starter Mike3
- Start date
Drop them off at a machine shop.
They can look them over for valves, seats, seals, and flatness, all at the same time.
They can look them over for valves, seats, seals, and flatness, all at the same time.
I’ve got a friend who thinks we can drill and tap them coming to help me, but if all else fails, that is definitely something I’ll have to do. thanks for the reply, hopefully I’m successful in drilling and tapping as I don’t really want to pull the heads.
Order yourself some replacement ARP bolts.
Hardware store bolts (Grade 5) will leave you right back where you are.
Hardware store bolts (Grade 5) will leave you right back where you are.
And may I suggest tapping all of the threads on the heads for the intake bolts. A little dab of anti-seize also helps with removing them at a later date. By a little dab I mean just that or you will look like this:
One further suggestion would be to use studs in lieu of bolts. Just hear me out on this as I see it through tension and torsional forces on the threads. When using a bolt you are imparting torsional forces via screwing the bolt into the threads in the heads while at the same time inducing tensional forces on the threads in the heads as the intake gets torqued down. If you use a stud you are only inducing tensional forces on the threads on the heads as the stud is already screwed into the threads in the heads with zero load on them. When you install the lower intake and then start the process of torquing it down the studs are not twisting like a bolt.
Other nice thing is the studs locate the intake gaskets so you do not get gasket shift. I also think they torque better as I do not have leaks in this area anymore. Get the motor up to operating temp and then retorque one more time and done.
One further suggestion would be to use studs in lieu of bolts. Just hear me out on this as I see it through tension and torsional forces on the threads. When using a bolt you are imparting torsional forces via screwing the bolt into the threads in the heads while at the same time inducing tensional forces on the threads in the heads as the intake gets torqued down. If you use a stud you are only inducing tensional forces on the threads on the heads as the stud is already screwed into the threads in the heads with zero load on them. When you install the lower intake and then start the process of torquing it down the studs are not twisting like a bolt.
Other nice thing is the studs locate the intake gaskets so you do not get gasket shift. I also think they torque better as I do not have leaks in this area anymore. Get the motor up to operating temp and then retorque one more time and done.
Are the bolts stuck in the head or corroded into the intake?
If stuck in the head, I have always welded a nut on the broken bolt and worked it loose. Sometimes I go through a bunch of nuts before the seized bolt starts to move. Then nice part is you don't ruin the threads in the head.
If stuck in the head, I have always welded a nut on the broken bolt and worked it loose. Sometimes I go through a bunch of nuts before the seized bolt starts to move. Then nice part is you don't ruin the threads in the head.
They are seized into the head, also I’m not sure I’d be able to weld a nut with the heads still on the car.
Welp tomorrow morning I’m gonna pull the heads and call around with the local machine shops, should just leave it to the pros
A couple lists to bounce off of just to make sure you didn't forget anything:
Tools:
Parts/Supplies
Recommended/Optional
Tools:
| Item | Notes |
|---|---|
| Torque wrench | Essential for proper head bolt torque & pattern |
| Angle gauge | Required if using TTY (Torque-To-Yield) head bolts |
| Breaker bar | Useful for removing stubborn old bolts |
| Razor scraper / gasket scraper | Clean old gasket material from block/head |
| Thread chaser kit | Clean bolt holes, especially head bolt threads |
| Shop vac or compressed air | Clean out bolt holes before installation |
| Magnetic pickup tool | Save your sanity if anything falls in a valley |
| Feeler gauge (optional) | Useful for checking lifter preload, if reused |
| Engine hoist | If heads are iron and you're working alone |
Parts/Supplies
| Item | Spec/Notes |
|---|---|
| Head gaskets (pair) | Fel-Pro 9333PT1 or equivalent |
| Intake manifold gaskets | Upper & lower sets |
| Exhaust manifold/header gaskets | Match your setup (headers vs stock manifolds) |
| Head bolts (or studs) | One-time-use torque-to-yield — ARP recommended for reuse |
| Thread sealer or ARP thread lubricant | If using ARP bolts/studs (not all holes are blind) |
| Anti-seize | For exhaust bolts, spark plugs, etc. |
| RTV silicone | For corners of the intake gasket and end rails |
| Engine oil | For priming & replacing any drained oil |
| Coolant | You’ll lose a lot removing heads |
| Thermostat gasket | Cheap, always replace if disturbed |
| Brake cleaner or acetone | Final cleaning of gasket surfaces |
| Shop towels / lint-free rags | For block/head prep and cleanup |
Recommended/Optional
| Item | Purpose |
|---|---|
| ARP head studs | If you're planning more power, these are reusable and more secure |
| Oil dye & UV light | Check for leaks after reassembly |
| Replacement pushrods / lifters | If existing ones are worn or noisy |
| Intake end rail spacers (for EFI) | Helps prevent leaks from cork gasket blowout |
| Coolant bypass hose | May crack when disturbed during disassembly |
Was this? "Intake end rail spacers (for EFI)"
I see a couple parts upon googling, but am unfamiliar. Is it just a replacement for cork china wall gaskets?
I see a couple parts upon googling, but am unfamiliar. Is it just a replacement for cork china wall gaskets?
Yes. Only difference is that they usually made of aluminum or some kind of phenolic material.
Wonder which holds up better when the crankcase gets some pressure from blowby. I vent to atmosphere in the cars that run boost, but I have blown out gaskets when I tried to run the EGR system. The right way to do that is apparently to run a vacuum pump.
I run a closed system with my KB. I ran an additional line and separator and used the inlet leading to the TB as the second vacuum source.
So far, so good.
So far, so good.
I can't say for sure. The only time it was ever measured was on the dyno and that time, I still had negative crank-case pressure during boost.
Since then, I've added more boost, and more crank-case scavenging and have not measured case pressure.
Recall though (and you have have forgotten this part), I run a Kenne Bell and not a centrifugal so, even at WOT with my (3.5-4 inch, I've forgotten) inlet, there is "suck" in that line that I've tapped for my second crank-case vent. And that section is [after] my MAF.
With a Centri blower, I would have used the inlet leading up to the blower as my scavenge source.
I will add as a footnote that air volume is the target and not velocity. Too much velocity at the PCV port was responsible for picking up a lot of oil mist. With my second vent, it slowed the air to the PCV enough that it stopped scooping up oil mist (rather, it was greatly reduced).
You put a nut on the top of them, and then fill the center with a mig or flux welder. Then a ton of PB Blaster and heat, and turn off with a wrench. There must be a million videos on youtube on how to do this.
Kurt
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