Do check and replace spark plugs frequently...

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Sandroad said:
IMHO, based on the condition of the plug, the manufacturer doesn't have any reason to be at fault. I think @hoser and others have it right and the plug was loose for a long time, leading to the failure. Since this is the first report of a plug failure like that on MUD (just the top of the plug blowing off), I agree with @Trunk Monkey that this is huge anomaly and no reason to replace plugs frequently (or blame the manufacturer for a loose/burned plug).
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I think I tried so say 'check and replace' meaning 'do not leave alone just because they are longlifed' and 'replace if any sign of malfunction whatever the reason' in a shorter format. Sorry if leading to other interpretations - was kind of surprised of the event, been motorized and somewhat looking after them for 40yrs. Never been at such a thing before nor heard of anything like it.
 
Do you have the old plugs? It would be interesting to see how they spec out?
 
Just throwing this out there, do you think there is a possibility that the last individual that changed the plugs either damaged some threads on the head or cross threaded the plug until it was tight?
 
I was thinking the same thing Sean. But the threads don't show that, at least from what I can see in picture.
 
Any chance wrong plugs (wrong gap) were used, so it runs too hot, causing damages?
 
sean2202 said:
Just throwing this out there, do you think there is a possibility that the last individual that changed the plugs either damaged some threads on the head or cross threaded the plug until it was tight?
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There is such a chance - or at least I cannot say there is not.
 
Thinking about this yesterday as I serviced a v twin vanguard 16 HP. This engine is also fully exposed to the elements. The plugs were both loose and could be removed by hand. Both crush washers on plugs were brand new. Probably a couple hundred hours on plugs...and I even used the machine quite a few times and never noticed.

Different engine but my point being some people are more careful or skilled than others. There is also a time that one gets distracted and forgets to complete a job 100%.
 
Just to Update on later events....

A helicoil fix did the trick on the plug and thread, an auto-electrician fixed the wireing, and it could run again. At first a little rough, then ok. For a short while... It started sending out huge white clouds and smelling like burned coolant, which was also very visible at the expansion container. Worst when cold, lesser when hot. Deemed the cylinder head was cracked. Swap engine needed.

After lengthy seeks and trial to get agreed stuff delivered, i recieved my money back and drove 2000 km's to pickup another one without futher wait or hassle. All 3 available in the EU appeared to be located in Sweden well north of its capital. Over here most run diesel - mine is a gasoline setup;)

When back it took some weeks to replace it, mending the frame for surface rust while at it. It started on its first rotation and sounded great! Might partly be due to replacing the middle silencer with some piping only ;)

But under load it ran rough. Computer fault suspected, but after a while having had the battery off and resat warnings it began to run as it should - calm and even, powerful when throttled.

So after months of effort, wait and money my hundy is back to former glory. Just passed its yearly MOT and freshly coated in Pava, its JP for another 530.000 km's I hope :)

Thank you so much for all your input on the way - great to consult with you when having trouble, it does save a lot of time and money to get problems put in perspective fast.

Oh, cost wise it was 10K DKK for the initial helicoil and wire thing, then 19K for replacement engine, 5K to fetch it and 25K to replace it including new timing belt, water pump, plugs and so forth. Roughly 60K DKK or 10K USD for the whole stunt, adding the cost of achieving an additional car for the meantime (1987 MB S124, around 30K DKK or 5K USD total)

The pain to this mostly is, that it was not really needed, had there been better work and observations around the plugs being properly seated. A costly lesson learned.

Kind regards to everyone having followed this on the way ;)

Henrik
 
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"Houston we've a problem"...

I'm sound this alert here as well.

I'm even more convinced now, this was due to a loose spark plug. I've now some very good anecdotal evidence our sparks are loosening on their own. I've been finding way to many loose spark plugs. In most cases it's been the inner plugs #3, #5, #4 & #6 that I find loose more so than the corners #1, #7, # 2 & #8. I also see more signs of heat on these inner plugs & coils.
I've now found plugs loose on what I believe are factory installed spark plugs with less than 60K miles on them.:worms: All crush washers look crushed and evenly so, yet some looser than others.


This leads me to believe they are loosening based on heating and cooling cycles. So effect may be more with how many warm ups & cool downs cycles rather than miles on odometer. For this reason I'm lower my inspection PM of spark plugs to 30K miles or 3 years. Years is something I never consider on spark plugs, until now.

With daily short trips, in 3 yrs we'd have 1,095 cool down cycles. Even that may be too many cycles!
 
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I'm wondering if he had gotten imitation spark plugs. Which I never knew was a thing until recently.
 
For me, the spark plug that blew does not look like the denso he has posted. The top is different as well as the Iridium tip. IF the OP cut open the coil pack sleeve, then we can compare it to the Denso.
 
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