Broken cam cover bolt

[northern_aqs]

I have an 87 S and am in the process of changing the cam chain tensioner pads, valve/cam cover gaskets etc.

When I removed the cam cover bolts I discovered that the middle bolt at the front of the cover (directly behind the cam gear cover) was broken. It appears the PO had repaired it previously by welding the bolt and it broke when I attempted to remove it.

Short of removing the cam gear cover to get better access with vice grips, I feel the best option is to mig weld something onto what's left of the bolt to extract it for replacement. I don't want to pull the timing belt to pull the cam gear and cover to get at the bolt as my timing belt it just 4000 miles in.

My question is; if I disconnect the battery and ground my welder to the block , will I be safe from cooking the dme and electrics?

[944 Ecology]

You probably want to spend the time to remove the rear cam gear cover if you're going to do any welding near it. It is made of magnesium and magnesium does burn with a white heat once ignited. In addition, check out the prices for those gear covers... They are quite expensive when they can be found.

Additionally, before you consider welding, try this for removing the remainder of the cover bolt:

http://www.craftsman.com/craftsman-10-pc-impact-grade-bolt-out-trade-damaged/p-00952165000P?prdNo=1&blockNo=1&blockType=G1


My vote is to do it right the first time.

[northern_aqs]

I agree with doing it right the first time. The bolt has broken midway down the shoulder, leaving approximately 1/2" sticking up out of the head with a diameter less than a 1/4", making finding an extractor small enough a challenge. I think I can control the spark (wrapping the gear cover with leather and turning the mig down) and prevent a fire, my biggest concern is the potential for ecu damage.

I'm having quite a difficult time finding replacement bolts; I may need to call you and make up a minimum order if you have any.

[gtroth]

The cover bolts should have a flange above the threads that is against the head when tight, maybe 13mm in DIA, and ~3mm high. That's about perfect for a bolt-out to grab. Are you seeing something different?

[northern_aqs]

It sounds like you're describing the valve cover bolts on a NA or Turbo. On the dohc variants, the cover is held in place by a tapered bolt, a rubber grommet and a thrust washer. My bolt has broken off half way down, just above where the threads are visible. With the size of the bolt shaft, no wonder the torque spec is only 6 ft/lbs.

I picked up a fairly beefy tap handle with the hopes it will slip over and tightened down, grip what's left to remove the remaining bolt.

I bought a new bolt from my local porsche dealer for a semi-reasonable $11.

[jeffrsmith]

Good luck, let us know how you make out.

[gtroth]

Originally Posted by northern_aqs

It sounds like you're describing the valve cover bolts on a NA or Turbo. On the dohc variants, the cover is held in place by a tapered bolt, a rubber grommet and a thrust washer. My bolt has broken off half way down, just above where the threads are visible. With the size of the bolt shaft, no wonder the torque spec is only 6 ft/lbs.

I picked up a fairly beefy tap handle with the hopes it will slip over and tightened down, grip what's left to remove the remaining bolt.

I bought a new bolt from my local porsche dealer for a semi-reasonable $11.

No, I'm talking about the 16V. See the flange just above the threads on (14) and (15)? That's what I grab with a bolt-out when these break.

[Arizona_928]

Those are very easy to break off from being over torqued, and usually are a PITA to remove. Easy outs in my experience work 1 out of 10 times I have used them. Usually the easy out breaks. You're gonna wanna try to weld a nut to the top stud. That's the easiest method...

[northern_aqs]

I see what you're referring to, but the shoulder of the bolts don't actually touch the valve cover to fasten it down on the 16v, the rubber grommet fills the hole in the cover to center the bolt and the thrust washer holds the cover down. Ergo my confusion with your description.
If the bolt had only just broken now, then I'd use an extractor because presumably there would be material for it to grab. In this case it had broken and been "repaired" by a previous owner by welding the bolt back together and grinding it small enough to fit through the grommet.

[gtroth]

Originally Posted by AZ_porschekid

Those are very easy to break off from being over torqued, and usually are a PITA to remove. Easy outs in my experience work 1 out of 10 times I have used them. Usually the easy out breaks. You're gonna wanna try to weld a nut to the top stud. That's the easiest method...

Yeah, do not even try an easy out. Try the bolt-out liked above if there's something to grab.

You might also try this stud puller

[Arizona_928]

Yeah it's same design as the 4v 928's. I haven't attempted to remove them with the head still in the car. lols I think it may be doable...
Most break flush or just under. I had luck with one using a pick to try to rotate the stud. not fun. haha

[MB968]

The tool that I use to get out broken bolts (when a part of the bolt is left proud), or bolts with the head stripped is a very small pipe wrench. Pipe wrenches are designed to grip tighter onto the part you are trying to remove with the more torque you apply. So, they rarely slip on the part. I have one that is only about 6 inches long so I can also get into small places.

[northern_aqs]

Happy to report that the extraction of the broken bolt and installation of the cam tensioner pads went smoothly, however the condition of the old pads was surprising.

I ended up welding a 10mm but to the remains of the bolt shaft with a mig welder after disconnecting the battery. The repaired bolt backed out without any fuss.

When I removed the cam tensioner, the old pads looked discoloured but intact with slight "grooving" top and bottom.

The reality upon disassembly was that the front lip that wraps around the leading edge on the bottom pad was missing, having broken at some unknown point in the past.

I feel like I dodged a bullet with lucky timing, had the pad disintegrated enough for the chain to bind, I'd be looking at sourcing a replacement head.

When time allows I'll post pictures. I had opened the valve cover to inspect the pads because there was no record of replacement when I purchased the car 2 months ago; had I not been neurotic about sorting the car out correctly and just relied upon visual appearance without disassembly I wouldn't have use of the car for some time and expense.