1985 Accord Spark Plug Melts
 

Hey all, I have a 1985 Accord LX which I love. Everything works perfect and it's been in my family since new, Just turned over 100k miles. When I was driving the other day on the freeway with the A/C on the car just lost power and ran like crap. I got it to a local shop and they found the #4 spark plug melted. I had them do a tune up and valve adjustment, car seemed fine but melted the same plug again going up a big hill under power a few weeks later. The mechanic thought it may be a vacuum leak but could not find one, he even used his smoke machine on it. So It's bugging the crap out of me now, the car runs fine unless I put power to it, say over 4k rpm going up a hill, then it will melt that same plug. I have also noticed there is a clicking sound from the head when cold that goes away after a few minutes of driving. This was not there before the initial issue happened on the freeway. Sorry for the long post but I love this car and want it running right, any ideas? tia

Try adjusting the valves & then measuring compression. Let us know what you find.
- valve lash needed to be changed?
- compression numbers?

It also might be an injector getting fouled, causing that cylinder to run lean?

Ah Jim, all of the 2nd gen's were carb'd.....reading too many posts again.

"Anpmech"-Yes check the valve lash and comp. I'd suggest the comp first. I'm going with a stuck valve or carbon build up on one (intake) or more valves, hope that it hasn't burned it. Ever used a product like SeaFoam? If the comp checks out and the valve lash is then checked and pans out, look at the EGR next....going out on a limb on this one. Been "way" too long since I played with one of these......

What brand and part number plugs are in it now?

Oh yeah, carburators. I used to own some of them in a former life...
Sorry about that.

It's got NGK BUR6EB-11's in it I believe. I have a Haynes manual so I'll get the compression specs there. I think pep boys has a compression tester for $30 or so. I'll start there. No to the Seafoam, I'll look into it.

I have heard from reading around that the timing belt could have slipped? I would think the car would run like crap though if that were the case.

Might check to see if places "rent" a comp tester, usually you put down money and upon return of the tool they refund your money.

Ok, again it has been over ~15 years since I had one of these, You should be able to pull the cover on the t-belt (upper) and line up the marks to see if the belt has slipped. I agree it would have performance issues (when the plug isn't melted) if it was off a tooth but I've seen some where the dist timing was adjust to come close to overcoming that.

Good luck and let us know what you find or how it turns out.

I'm puzzled. What melts? The spark plug wire plug connector? I have a hard time believing the spark plug body is melting. How is it removed if it melts?

Melting the spark plug end connector might be caused by a cracked head allowing hot exhaust gases to blow on the spark plug lead. It wouldn't take long either. Sounds like pulling and rebuilding the head may be necessary.

Head cracking can be caused by overheating incidents, or simply age.

good luck

It's the electrode melting at the tip of the plug. I don't think anythings cracked, the car has just 100k on it and it has been well taken care of. It has never overheated, actually it runs cool. I drove the car yesterday and it still runs fine during normal driving it's just this damned plug melting if I put power to it for any length of time. I do believe that #4 cylinder is running lean for whatever reason all the time. When I put power to the car it just gets hotter and melts the plug.

Does this car have points or ignitor system? Perhaps something in the spark generation/distribution could cause too large current flow? Seems unlikely.

Check engine timing to be sure it's correct at different engine speeds. Perhaps too advanced timing might cause spark plugs to see higher temps. This could also be a fault of the timing advance system.

good luck

I would check intake valve lash on that cylinder.