Bolt broken in block
Well once I finish up the head gasket I hope it’s sealed! Isn’t the crush washer on the underside of the bolt head supposed to act as the seal for the threaded hole though? I guess it doesn’t matter too much since it’s so seized that it didnt come loose.
‘83 Platinum N/A 944
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spacecad3t
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If ya dont got a welder... You could try to glue a slightly smaller/shorter nut to it using this crazy sh*t from Locktite.
I wouldnt want to have to use this approach myself... but I would if I absolutely had to... I use to mill parts on 10,000RPM CNC with just this glue holding them together...
I wouldnt want to have to use this approach myself... but I would if I absolutely had to... I use to mill parts on 10,000RPM CNC with just this glue holding them together...
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michaelmount123
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Suggest you don't stress over this. Do put a drop of green (wicking) Loctite on what's left of the bolt. It's quick, effective, and long lasting. Then worry about something else.
Would it be suggested to apply the drop of green loctite from the inside of the block rather than the outside? I think I might have better access from there. I’m also slightly worried if I ever do plan on removing that stuck bolt that the loctite would make it even more difficult to extract
‘83 Platinum N/A 944
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dr bob
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FWIW ---
The 928 crowd has been sweating those frozen bolt problems for a while. In some cases, the aluminum boss on the water jacket gives way when a long-enough "irresistible force" is applied. Were I in your shoes, I'd be drilling the old bolt out gradually. That means getting a good centering punch mark in the broken stub, and slowly drilling with firm pressure on the bit. small bit first, like 1/8" stubby for a pilot hole, then gradually larger. I don't know what access you have with the engine still in the car, but there are some angle drills that may be enough. Then gradually larger on the bits until you end up picking the bolt thread metal out of the aluminum. Grease The Drill Bit, so chips stick to it and can be rescued before they fall into the water jacket,
On the V8 block, these bolts are 10mm thread with a 13mm head. In spite of what the workshop manual states, the tightening torque needs to be in the 15 lbs/ft range, typical to a common 8mm bolt with a 13mm hex head. The bolts use aluminum sealing washers, and some seem to think that you need enough pressure to pinch and gall the washer. Instead, I propose using some Teflon pipe sealing paste on the threads and on the sealing faces and the washer. Then the 15 lbs/ft is more than sufficient to get the seal you want. the paste also lubricates the threads, and with the reduced torque you'll stand a much better chance of getting the bolt out again some day.
Maintaining coolant seems to be a big factor in extending the life of lots of things. Watch the pH and make sure it doesn't drop below maybe 8.5 lowest. Helps some with galvanic corrosion where the coolant is passing across a steel bolt shaft in an aluminum water jacket. I plan on replacement at two to maybe three year intervals even if I don't drive the car much. Coolant is cheap.
The 928 crowd has been sweating those frozen bolt problems for a while. In some cases, the aluminum boss on the water jacket gives way when a long-enough "irresistible force" is applied. Were I in your shoes, I'd be drilling the old bolt out gradually. That means getting a good centering punch mark in the broken stub, and slowly drilling with firm pressure on the bit. small bit first, like 1/8" stubby for a pilot hole, then gradually larger. I don't know what access you have with the engine still in the car, but there are some angle drills that may be enough. Then gradually larger on the bits until you end up picking the bolt thread metal out of the aluminum. Grease The Drill Bit, so chips stick to it and can be rescued before they fall into the water jacket,
On the V8 block, these bolts are 10mm thread with a 13mm head. In spite of what the workshop manual states, the tightening torque needs to be in the 15 lbs/ft range, typical to a common 8mm bolt with a 13mm hex head. The bolts use aluminum sealing washers, and some seem to think that you need enough pressure to pinch and gall the washer. Instead, I propose using some Teflon pipe sealing paste on the threads and on the sealing faces and the washer. Then the 15 lbs/ft is more than sufficient to get the seal you want. the paste also lubricates the threads, and with the reduced torque you'll stand a much better chance of getting the bolt out again some day.
Maintaining coolant seems to be a big factor in extending the life of lots of things. Watch the pH and make sure it doesn't drop below maybe 8.5 lowest. Helps some with galvanic corrosion where the coolant is passing across a steel bolt shaft in an aluminum water jacket. I plan on replacement at two to maybe three year intervals even if I don't drive the car much. Coolant is cheap.
dr bob
1989 928 S4, black with cashmere/black inside
SoCal 928 Group Cofounder
928 Owner's Club Charter Member
Former Ex Bend Yacht Club Commodore Emeritus
Free Advice and Commentary. Use At Your Own Risk!
1989 928 S4, black with cashmere/black inside
SoCal 928 Group Cofounder
928 Owner's Club Charter Member
Former Ex Bend Yacht Club Commodore Emeritus
Free Advice and Commentary. Use At Your Own Risk!
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Tom
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I originally thought this was a tiny M6 bolt, which all-too-often snap on the 944. It's awfully hard to center punch and drill those without veering in to the block (without a drill boss/jig). On a bigger bolt like this, I agree you'd likely be able to start small and work your way up with minimal risk to the block. Bonus points for reverse drill bits that stand a chance of breaking it free and spinning it out. I think space is the biggest constraint though -- but where there's a will there's a way. Now if you could drill from the inside, you'd have reverse bits on the cheap...dr bob wrote: Mon Mar 02, 2026 1:47 pm FWIW ---
The 928 crowd has been sweating those frozen bolt problems for a while. In some cases, the aluminum boss on the water jacket gives way when a long-enough "irresistible force" is applied. Were I in your shoes, I'd be drilling the old bolt out gradually. That means getting a good centering punch mark in the broken stub, and slowly drilling with firm pressure on the bit. small bit first, like 1/8" stubby for a pilot hole, then gradually larger. I don't know what access you have with the engine still in the car, but there are some angle drills that may be enough. Then gradually larger on the bits until you end up picking the bolt thread metal out of the aluminum. Grease The Drill Bit, so chips stick to it and can be rescued before they fall into the water jacket,
On the V8 block, these bolts are 10mm thread with a 13mm head. In spite of what the workshop manual states, the tightening torque needs to be in the 15 lbs/ft range, typical to a common 8mm bolt with a 13mm hex head. The bolts use aluminum sealing washers, and some seem to think that you need enough pressure to pinch and gall the washer. Instead, I propose using some Teflon pipe sealing paste on the threads and on the sealing faces and the washer. Then the 15 lbs/ft is more than sufficient to get the seal you want. the paste also lubricates the threads, and with the reduced torque you'll stand a much better chance of getting the bolt out again some day.
Maintaining coolant seems to be a big factor in extending the life of lots of things. Watch the pH and make sure it doesn't drop below maybe 8.5 lowest. Helps some with galvanic corrosion where the coolant is passing across a steel bolt shaft in an aluminum water jacket. I plan on replacement at two to maybe three year intervals even if I don't drive the car much. Coolant is cheap.
I'd worry green loctite might actually break up the corrosion that is keeping it stuck (and hopefully sealed) as is? If I were going the 'deferred maintenance' route, I'd JB-Weld it from the outside. Some well-respected engine builders to that on freeze plugs and drilled oil gallies -- and this isn't much different than that. Although... I wouldn't be able to sleep if I did that on my car, so would most likely find a way to get a drill bit or welder in there to get it out. But that's more of an affliction than recommendation.
Well I’m going to pressure test the coolant system when the head is back on and see if it leaks. If not, I’ll just proceed as normal. If it does though I will try the wicking green loctite. I’ll leave the extraction for another day when I’ve got nothing better to do
‘83 Platinum N/A 944
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Tom
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I little RTV might help too, with less to 'deal with' than JB-weld...Poorsche44 wrote: Mon Mar 02, 2026 6:38 pm Well I’m going to pressure test the coolant system when the head is back on and see if it leaks. If not, I’ll just proceed as normal. If it does though I will try the wicking green loctite. I’ll leave the extraction for another day when I’ve got nothing better to do