Field Expedient Engineering: JB Weld Porsche Cylinder Head Repair

Murilee Martin
by Murilee Martin

When your 1980 Porsche 924 craps out minutes after the start of its first race and you’re in rural Texas, parts might be a little hard to find. You won’t get far with a blown head gasket and big ol’ notches burned in the head itself. But, damn, the clock keeps ticking! The Moose Knuckles team called every junkyard within 500 miles, but nobody had any 924 (or Audi 100) cylinder heads. In fact, nobody had ever heard of them furrin thangs.

The Moose Knuckles were able to find a head gasket a few hours’ drive away, but they came up with exactly bupkis on the head. But then one of the guys remembered the fine print on the JB Weld package: Repairs Engine Blocks. Block, head, what’s the difference?

Picking up some JB Weld and JB Kwik, the Moose Knucks got right to work. Sure, combustion-chamber temperatures get higher than the JB Weld-rated 500 degrees F, but we’ve seen such repairs work in the past… on cast-iron heads. What will happen with an aluminum head?

Fill in the holes with that magical gray stuff, sand it down, and slap the head back on the engine. Take the car on the track. Return behind the tow truck. Repeat. Endlessly.

Because the track exit at MSR comes before the transponder loop, and the Moose Knuckles’ Porsche never managed a full lap under its own power, all those laps that ended on the hook didn’t count. Official race results counted the car as a DNS. On the bright side, the Moose Knuckles took home the I Got Screwed award.

Just so you don’t think JB Weld repairs always fail at LeMons races, here’s a JB-patched E30 oil pan from the same race. The car wiped out, bottoming the pan and cracking the hell out of it. Thanks to a generous application of metal-filled epoxy, the car finished the race.





Murilee Martin
Murilee Martin

Murilee Martin is the pen name of Phil Greden, a writer who has lived in Minnesota, California, Georgia and (now) Colorado. He has toiled at copywriting, technical writing, junkmail writing, fiction writing and now automotive writing. He has owned many terrible vehicles and some good ones. He spends a great deal of time in self-service junkyards. These days, he writes for publications including Autoweek, Autoblog, Hagerty, The Truth About Cars and Capital One.

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  • Panzerfaust Panzerfaust on Apr 29, 2011

    I've seen J-B weld used to repair VW vanagon crank case. Heat really wasn't an issue-except when the owner would use his Coleman catalytic heater to warm the engine up in the winter so it would start.

  • John Horner John Horner on Apr 30, 2011

    JB Weld to patch up an oil pan? Sure. JB Weld to fix a head .... never had a chance. JB Weld can't take the mechanical stresses or temperature. Didn't anyone at the track have a TIG welding set up? That could have worked.

    • Panzerfaust Panzerfaust on May 01, 2011

      Probably because a good portable TIG welder costs 3 times as much as any of the cars do. As I posted above, welding an aluminum head in the field is an iffy proposition. First it has to be of an alloy that can be welded, second the contamination from years of fuel, oil, coolant and other grime creates such porosity that you can't get much of a bead at all, or you have a weld fails almost immediately. But it would certainly be worth a try if the head was scrap anyway.

  • Wolfwagen Is it me or have auto shows just turned to meh? To me, there isn't much excitement anymore. it's like we have hit a second malaise era. Every new vehicle is some cookie-cutter CUV. No cutting-edge designs. No talk of any great powertrains, or technological achievements. It's sort of expected with the push to EVs but there is no news on that front either. No new battery tech, no new charging tech. Nothing.
  • CanadaCraig You can just imagine how quickly the tires are going to wear out on a 5,800 lbs AWD 2024 Dodge Charger.
  • Luke42 I tried FSD for a month in December 2022 on my Model Y and wasn’t impressed.The building-blocks were amazing but sum of the all of those amazing parts was about as useful as Honda Sensing in terms of reducing the driver’s workload.I have a list of fixes I need to see in Autopilot before I blow another $200 renting FSD. But I will try it for free for a month.I would love it if FSD v12 lived up to the hype and my mind were changed. But I have no reason to believe I might be wrong at this point, based on the reviews I’ve read so far. [shrug]. I’m sure I’ll have more to say about it once I get to test it.
  • FormerFF We bought three new and one used car last year, so we won't be visiting any showrooms this year unless a meteor hits one of them. Sorry to hear that Mini has terminated the manual transmission, a Mini could be a fun car to drive with a stick.It appears that 2025 is going to see a significant decrease in the number of models that can be had with a stick. The used car we bought is a Mk 7 GTI with a six speed manual, and my younger daughter and I are enjoying it quite a lot. We'll be hanging on to it for many years.
  • Oberkanone Where is the value here? Magna is assembling the vehicles. The IP is not novel. Just buy the IP at bankruptcy stage for next to nothing.
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