9/22/2019 How To Install A Helicoil In Aluminum
My car was leaking oil out the valve cover gasket and I first assumed theleak came from where the head and the upper timing case cover meet.(The valve cover extends over both the head and the timing case coverthat surrounds the timing chain).But when I took a closer look, I found that almost all of the valvecover bolts were loose and spun in place. Over 13+ years I hadmanaged to strip them one by one and had reached the end of the line.Unlike my first car ('76 Rabbit), these valve cover bolts have a shoulderthat stops compressing the valve cover gasket once it makes contact withthe head. In simpler terms, once the bolts are finger-tight, the gasketis fully compressed. Tightening beyond that point only prevents thebolt from coming loose. And tightening too far only strips the threadsinside the aluminum head.
What do you do when you strip out threads in aluminum? You eitherdrill and tap a larger bolt side (and use a larger bolt), or installan insert.One of the most popular varieties is called a Helicoilâ„¢, which looksa lot like a spring made of square wire. Basically you drill a larger hole, tap new threads, screw a Helicoilinto the new hole, then screw the bolt into the Helicoil. The insertis sized and shaped such that it digs into the aluminum and will stayin place when screwing in a bolt (or latter removing it). Edit listview subitem in vb6 shell. The ProblemHelicoil Installation
Helicoil inserts allow you to replenish the threads, even if the threads are completely removed from the bolt hole, a common occurrence with aluminium threads. The procedure for installing a Helicoil is the same for all hole diameters, and everything you need to perform the thread repair is included in a Helicoil kit. A Heli-coil is really only advisable for a one-time fixed repair. This means the fastener is basically permanent, as opposed to being removed on a regular basis for maintenance or even future repair. I use time-serts exclusively for all thread repairs. This is Ford's recommendation for spark plug thread repair. There is a special kit for this repair. How To Install A HeliCoil Insert. At this point, the insert is installed, but the job is not over. For all tanged inserts, the tang must be removed. Using a punch that fits snugly into the insert, place the punch into the insert until it reaches the tang. Hit the punch with a hammer. This should pop the tang off.
The M42 valve cover uses M6 bolts so you need to pick up an insertkit for that size like the one shown below.
My kit included ten inserts, a tap, and a special tool that allowsyou to drive in the insert as well as compress it for easier installation.However, you need several more tools to complete the job. The tools Iused are shown below. Not included in the kit are a 1/4' drill bit, a sturdy low-speed drill,tap wrench for the included tap as well as a smaller one for theinstallation tool, and finally a pin or solid punch and small hammer.You also need a shop-vac to pick up metal shavings after each step.
Afterword
In the case of my valve cover, I screwed in each bolt (with the coverremoved) and tried to torque them to spec. This identified the stripped bolts,which totaled eight, and I installed inserts for each.After dabbing some RTV on the gasket (where the timing cover meets the head), andreplacing the valve cover, two more bolts spun. One of those was alongthe lower edge so I installed an insert with the cover on (and left theother loose, for now).In order to make the drill long enough, I could only chuck the last3/16' of the bit, hence my advice to perform installations with the cover off.My car made the 800 mile trip home for Christmas without leakingoil.
If you have never drilled and tapped threads before, I recommendpracticing on a piece of scrap before attacking your engine,but the process is pretty straightforward. Perhaps the most difficultpart is overcoming the fear of drilling your head.
Stripped and broken threads are a fact of life in auto repair. Even if the threads are damaged beyond a simple re-tap, the mounting hole can still be fixed and reused. Helicoil inserts allow you to replenish the threads, even if the threads are completely removed from the bolt hole, a common occurrence with aluminum threads. The procedure for installing a Helicoil is the same for all hole diameters, and everything you need to perform the thread repair is included in a Helicoil kit.
Step 1
Remove the bolt from the stripped threads. If there is a broken bolt remaining in the hole, use a bolt extractor to remove the bolt from the threaded mounting hole.
Step 2
Place the Helicoil recommended drill bit for the hole size being repaired into the drill. Bioquimica thomas m. devlin pdf. Drill the hole deep enough to accommodate the Helicoil insert and the bolt that is going to be threaded into the hole.
Step 3
Tap the drilled hole with the tap specified in the Helicoil kit. Keep the tap straight with the hole. Turn the tap in a clockwise motion to thread the hole. Turn the tap until it binds, back the tap up a 1/4 turn; continue to thread the hole in a clockwise direction. Run the tap to the bottom of the hole. Do not try to exert heavy pressure on the tap. Carbide taps are brittle and can easily be broken off in the hole.
Step 4How To Install A Helicoil
Thread the Helicoil on the mandrel of the supplied Helicoil installation tool. Liberally apply thread lock to the Helicoil insert. Place the Helicoil insert into the hole. Thread the Helicoil insert into the hole until it rests at least a 1/4 turn below the surface of the metal having the stripped threads repaired. Remove the insert tool by turning it counterclockwise.
Insert the tang break-off tool into the repaired hole. Hit the end of the tang tool with a hammer to snap off the tang. If you are repairing the threads in a large hole, reach into the hole with a pair of needle nose pliers and grasp the tang. Twist the tang back and forth until it breaks free of the Helicoil insert. Allow the thread lock to set-up before re-installing a bolt into the repaired hole.
Items you will need
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