I hate aluminum!

[BodybyFisher]

So I decided to do spring maintenance for my Be Honda Powered Pressure Washer with CAT pump original cost about $750 two years ago.

Changed the Oil

Changed the pump oil

Changed the Fuel Filter, cleaned the fuel bowl

Went to pull the spark plug (it was not changed before and this is the third season) and it was hard to remove the spark plug, every turn felt tight. I knew this was not good. When I got the plug out, the top third of the ALUMINUM threads were ripped out!

The bottom 2/3s was fine, why I have NO idea.

I was unable to thread a new plug in. I went to the dealer and everyone was telling me HELI-COIL, na not for me. This was an M14 1.25 pitch thread

I removed everything and pulled the head, got an M14 1.25 pitch spark plug chase/tap, and ran it in from the bottom, thereby cleaning up the top third that was wiped out.

Then I put the plug in from the top and it went in and I torqued it to 15 ft lbs, I didnt press my luck and go any further. If I have to I can always heli-coil it but I ran it 8 hours yesterday and it was fine.

Why does this happen, anyone venture a guess?

[Cadillac Jim]

My guess is that the plug didn't have anti-seize in it and moisture worked down into the threads and corroded the top 2/3 of them. It's possible that the plug was pulled and cleaned/gapped without a spray of anti-seize before it was put back in. It's also possible that it was over-tightened and the top 2/3 of the threads was warped (i.e., a strip-out waiting for plug removal).

I wouldn't use helicoil. A helicoil can leave an end showing in the combustion chamber that may cause detonation. I would use an insert, e.g. a Timesert. Trust me, Timesert will have the insert for your pressure washer; just give them the plug part number and they will give you the insert part number. This all is good for making sure that the insert (1) fits the plug and head and (2) is the right length to end where the plug ends. This awaits the next plug change so you have time.

You did put anti-seize on the plug threads?

[BodybyFisher]

Hi Jim, this is the first time the plug has been out, it must have come this way from the factory, as I bought it new

Its not the top 2/3, its the top 1/3 that is messed up, so I am biting 2/3's of the threads, I don't plan on removing the plug again.

I did not use anti-seize. Do you think I should? I never plan to remove the plug again. It looked perfect, with over 1000 hours on it.

If you think I should add anti-seize, I can try backing it out tomorrow and applying it. Thanks

[Ranger]

If you don't plan on ever removing it again Mike, I'd forget the anti-seize.

Helicoils have been used for years to repair spark plug threads (as I'm sure you are aware). I would not have hesitated to use them in this application, but then that is always still an option should the plug need to be removed in the future.

[JimD]

Mike:

I am not a fan of paste-type aftermarket anti-seize products for several reasons. One, anything that behaves as a lubricant will scew the torque values. Two, there is no guarantee they are effective.

Put those two together and you have the potential for a threaded junction that is over-torqued due to a product that might not be effective.

Automobile engine makers have been threading ferrous spark plugs into aluminum heads for decades. They know to specify parts that mitigate the predictable galvanic corrosion where the "steel meets the aluminum". And you will not see any paste anti-seize compound on the assembly line for those engines.

Honda knows this. Maybe whoever supplied the spark plugs failed to meet Honda's specifications.

[Cadillac Jim]

JimD has a big point - this does not sound like Honda factory work, but it does happen, apparently.

Yes, I believe in anti-seize, but JimD does have a point - about aftermarket products.

When I had my Quad 4 HO, I always replaced the plugs myself when a dealer tech had been in there. Doing it right takes two torque wrenches and three chemicals - anti-seize for the plug threads, silicone grease for the plug boots, and threadlock for the coil cover.

The assembly process was to spray the plug threads and torque them in, then to apply silicone to the boots and "blue" threadlock to the boltholes for the cover. The two coils were bolted onto the cover and included the plug boots, and the whole assembly needed to be worked on so that all four plug wires engaged, then torqued. Only once did I find that a dealer tech had done it right, and that was when one of the coils was replaced. Most of the time at least one plug was just finger-tight and had never been tightened down and with that one exception they were never torqued at all, much less equally. Most of the time at least one spark plug connector was not engaged but pushed up into the boot instead of down over the plug.

The chemicals that I used were GM parts expressly recommended for my Quad 4 HO. No aftermarket for me.

The warning about helicoils causing detonation is anecdotal; I have heard never to use helicoils on spark plugs in a racing engine for that reason.

[BodybyFisher]

Thanks guys, a new head I found out today is $100, so its not a total disaster. I can buy a new head if the need be.

The plug that did the damage was an NKG, and to be honest, the threads on the plug looked damaged, maybe that was the problem

I was aware as you noted that I could eventually heli-coil this, so I had decided not to use the anti-seize because of what I learned from the GURU, that the torque reading would be messed up and I could foul the plug.

Everyone I spoke to said to use anti-seize but my gut said no.

A little history, when I was about 6 or 7, my parents owned a 54 Packard Carabbean convertible with a flat head 6 that had an aluminum head. At some point, it cracked and I recall my Dad trying to repair it, he was unable to, and he had a real hate of aluminum as a result of that and his experience during the war, he kept speaking of its cracking due to overheating and he feared putting coolant in when the engine was hot. I recall him saying that when the engine was hot, that cast iron and aluminum heated and cooled differently and that was a problem. He sold that car for a crazy $300, and the guy who bought it said he was a collector and he would fix it and it would be worth a lot because only 500 were made!

I actually saw it on the highway once in Wildwood, NJ.

Here is a photo of it, same wire wheels that I cleaned myself at 6 years old, but the car was all red. The windows, brakes, top and windows worked via hydraulic fluid, when the hydraulic pump went bad, NOTHING worked! It was a beautiful car, but our next car was even MORE beautiful, it was a 55 Cadillac Fleetwood.........The Packard had a Cadillac look to it, but it was no Cadillac which was obvious during my first ride in the Fleetwood....

[KHE]

Mike,

I would take the head to an automotive machine shop and have them install an insert and then replace the spark plug. That would be cheaper than buying a helicoil tool or Timesert kit just for a one-time use.

[BodybyFisher]

Mike,

I would take the head to an automotive machine shop and have them install an insert and then replace the spark plug. That would be cheaper than buying a helicoil tool or Timesert kit just for a one-time use.

Thanks Kevin, that is a good idea. Dumb question there are inserts available for this application do you think?, are them Timesert brand or some other, thx

[Cadillac Jim]

Packard upper management had a hard-headed resistance to going to a V8. I recall a quote from a Packard history book, "The V8 engine has a primary imbalance." That is true of dual-plane crankshaft V8s, but Cadillac compensated for that when they went to a dual-plane V8 for the 1924 model year by adding the now-familiar counterweights and decreasing the mass of the flywheel. The result is that Packard's first V8 was in 1955, not 1949 or earlier as it should have been, and the fate of the company was all but sealed by 1955.

In attempting to compete with their straight-eight flathead, Packard went to an aluminum head for 1954 and got 200 hp out of a 327 cid straight eight. This was the highest development of the flathead engine in a mass-produced car, anywhere. I didn't know that they had a six-cylinder flathead with an aluminum head. I also didn't know that they used a brittle alloy that resulted in cracked heads. The usual Edelbrock practice for aluminum heads for flathead Fords was to use a soft alloy that was best known for stripping out threads with very low torque, and those didn't crack, in spite of the inherent Ford flathead V8 flaw of running the exhaust between the cylinders just below the heads, something that existed in every Ford V8 from 1932 to 1953.

[BodybyFisher]

Then it is possible that I am wrong all of these years Jim in thinking that it was a 6 cylinder, thank you for correcting that, it was a straight 8, wow. Thanks

[KHE]

Mike,

I would take the head to an automotive machine shop and have them install an insert and then replace the spark plug. That would be cheaper than buying a helicoil tool or Timesert kit just for a one-time use.

Thanks Kevin, that is a good idea. Dumb question there are inserts available for this application do you think?, are them Timesert brand or some other, thx

I'm not sure - There are Timeserts for spark plug threads but they are for cars & trucks. I'm not sure if they would be the correct length for a small engine. I'm sure a Helicoil exists but by the time you bought a kit, it would be less money to take it to a machine shop and have them install an insert. My guess is you'd be looking at $20.00 - $25.00

[Cadillac Jim]

The size, threads, gasket type, and length will be determined by the spark plug part number, such as NGK BC7ES, then the insert for that plug should be the same regardless of the engine, other than an aluminum head would be assumed. For NGK specs, see (right-click on link and select New Tab/New Window)

http://www.ngk.com/s...anufacturerID=1