1 Topic by aventari (edited by aventari 2017-08-29 03:27 PM)

  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Topic: Melted plug electrode

The car is a 93 Honda Accord with the stock 4 cylinder F22A6 motor.

The spark plugs have 3 races on them, car was running great, and 3 of them look absolutely perfect and brand new.. They are 2 heat ranges colder than stock.

I just checked them this weekend getting ready for the Buttonwillow race, and #3 cylinder:

http://i.imgur.com/h7ekrWg.jpg

Electrode completely melted.

I'm guessing it's from the injector being clogged or something and running lean, overheating the cylinder and melting the plug.

2 races ago we did dump a jug of gas in the car that had been previously been used for holding a bunch of old dirty rusty contaminated gas in it, and that almost immediately clogged the fuel filter. We just kept running the car and replacing fuel filters. We went through about 3 or 4 filters that weekend and after. So I guess a tiny contaminate could've clogged the injector during that debacle.


A friend has a shop with an injector cleaner/test bench which can view spray patterns and measure output, so I'm going to test the injectors ASAP

After checking the plugs I adjusted valves and everything was good except one of the exhaust valves on the lean cylinder #3 was tight, .007" compared to all the others at .012"-.014" (spec is .012")
So I think that valve/seat had started to burn along with the plug.


Then I did a leakdown test and got
cylinder
#1 87%
#2 81%
#3 74%
#4 58%

For all cylinders I heard the air in the crankcase which just tells us worn rings BUT for #4 cylinder I heard air in the sparkplug hole of #3 which tells me that there's a head gasket leak between the two. Maybe that's why the plug burned up? I don't know, I've never heard of anything like that.

I then did compression test and got (from memory)

cylinder
#1 175
#2 170
#3 155
#4 140

I'm going to wait on results of the injector test and see if we have a bad one, but I'm thinking it would be a good idea to pull the head and replace the gasket/have the valves cleaned up.

What do you think?

Takata R&D :: 1993 Accord - team captain - rear drum brakes lol
GoPro 360 Heros :: BMW E28  - co-captain
  • From: Tustin, CA
  • Registered: 2010-12-30
  • Posts: 3,275

Re: Melted plug electrode

Regardless of plug condition, the head needs to come off after hearing air out of 3 while testing 4.  I suppose the Lemony way to go would be to break out the valve lapping suction cup tool and lapping compound to reseat the valves.  Or just have a valve job done.

1990 RX7 "Mazdarita"  1964 Sunbeam Imp (IOE 2013 Sears Pointless) 2002 Jaguar x-type (Winner C-Class 2021 Sears Pointless)
Gone bye-bye
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)  1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites)

3 Reply by aventari (edited by aventari 2017-08-30 11:44 PM)

  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Re: Melted plug electrode

well shit, I hooked up the injectors and checked the flow

http://i.imgur.com/qsuaAo7.jpg

cyl 4 - 3 - 2 - 1
Ugh.

Takata R&D :: 1993 Accord - team captain - rear drum brakes lol
GoPro 360 Heros :: BMW E28  - co-captain
  • From: SF Bay Area
  • Registered: 2012-01-06
  • Posts: 721

Re: Melted plug electrode

The plug looks seriously overheated.  Most likely it's from pre-ignition.  Did you look at the spray pattern of the injectors? A stream of fuel will cause a lean condition. Check the piston surfaces.  Does #3 look different than the others?  That cylinder is way too hot. That's what killed the head gasket.

Capt. Delinquent Racing
RUST-TITE XR4Ti - '21 ARSE-FREEZE-APALOOZA  I Got Screwed
The One & Only Taurus V8 SHO #31(now moved on to another OG Delinquent)
'17 Vodden the Hell - (No) Hope for the Future Award, '08 AMP Survivor, '08 ARSE-FREEZE-APALOOZA Mega-Cheater
  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Re: Melted plug electrode

Yeah spray pattern looks good too. And as you can see the flow is even enough between them

Takata R&D :: 1993 Accord - team captain - rear drum brakes lol
GoPro 360 Heros :: BMW E28  - co-captain
  • jrbe
  • Effluent
  • Offline
  • From: Central CT
  • Registered: 2009-06-23
  • Posts: 921

Re: Melted plug electrode

Is the pvc system still in place?  Does it happen to dump into the intake manifold around your melted plug cylinder?
How about oil control rings on that cylinder?  Could they be stuck to the piston and not scraping the cylinder down?
Any oil smoke on decel / tip in?
If you're hearing air from one cylinder into another that could mean head gasket leaking issues, could also leak oil into the problem cylinder.

Lots of chunky stuff on the porcelain, looks like burnt oil to me. 

Also check the injectors at smaller pulsewidths if you didn't already.  Sometimes you'll get one that just doesnt want to fire or doesnt have good spray pattern around 2ms.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?
  • Registered: 2015-05-13
  • Posts: 122

Re: Melted plug electrode

I have been through similar with a 95 B18 motor. The low compression and the air leaking between cylinders is probably a burnt or junked up valve. I wouldn't assume it is a head gasket. Looks like you have two things going on, a lean burn and a bunch of contamination that passed through the cylinder from your contaminated gas. Assuming you have cleaned up the gas contamination you are now left with junk burned on the spark plug and at least one valve. The lean burn on just one cylinder could be a leak at the intake manifold and in a rare case the exhaust manifold. I have seen the intake manifold vibrate loose on both a D series and a B series block. First indication is one cylinder is burning leaner than the rest.

8 Reply by aventari (edited by aventari 2017-09-08 03:03 PM)

  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Re: Melted plug electrode

Thanks for all the replies everyone

You were 100% right mopar fan.

I pulled the cylinder head and noticed the intake manifold nuts were a little loose. I didn't think much of it.


http://i.imgur.com/hu9QiKxl.jpg


Then I noticed the intake manifold flange had broken! It looks like it broke from vibration because the manifold was loose.
And of course that caused the lean cylinder too. Problem solved.


I'm getting the machine shop to weld the manfiold back together and they said it needs all new exhaust valves and guides so it's getting that too.

http://i.imgur.com/MSZgVNEl.jpg



While it's apart I did a quick 3 hour port job in my garage

(click for big)

Clean, bare head:
http://i.imgur.com/oYkBoQGl.jpg

Stock ports:
http://i.imgur.com/i1DUAQvl.jpg?1
http://i.imgur.com/CdsZAvol.jpg?1
http://i.imgur.com/2wMZfXXl.jpg
http://i.imgur.com/m1ln0fTl.jpg

Polished chambers
http://i.imgur.com/vZtIUTHl.jpg

Finished ports
http://i.imgur.com/5ox73Vil.jpg
http://i.imgur.com/zP00uQ2l.jpg


Tomorrow I'll pull the pan and take the pistons out and dingleball hone and re-ring the shortblock

A new set of el-cheapo rings is $22 shipped from ebay, I love Hondas

Takata R&D :: 1993 Accord - team captain - rear drum brakes lol
GoPro 360 Heros :: BMW E28  - co-captain
  • Registered: 2015-05-13
  • Posts: 122

Re: Melted plug electrode

Spend a couple minutes polishing those exhaust valve stems before you put it back together. Then run them through the guides and feel for any dragging. Replacing the exhaust valve guides means they are going to be a little tight. You can check the valve stems to make sure they aren't worn too much but my experience is that on these Honda engines guides wear, not the valve stems. I am afraid of a valve stick after a valve guide replacement and you know how catastrophic that can be.

Count on checking valve lash on at least those exhaust valves at the end of Saturday at your first race. I try to do a Friday test and tune on a new build but that is more of a sanity check. The real break-in is that first day of racing on a Saturday.

10 Reply by aventari (edited by aventari 2017-09-10 04:45 PM)

  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Re: Melted plug electrode

Great idea, I will put 'valve lash check" on the Saturday night list!

I'm getting new valves with the news guides so I'm hoping the machine shop will ensure they run right in the guides. It's a good shop I've used for 20 years. I'm getting the cheap $9 valves though.

Yesterday I honed the bores and cleaned up the pistons.


http://i.imgur.com/4IdRxTml.jpg
http://i.imgur.com/LP4CIDRl.jpg


http://i.imgur.com/3Yizw76l.jpg
http://i.imgur.com/25MhD1al.jpg

Weird damage on the rod bearings. On every upper bearing, there is a little missing piece of the coating in the exact same location next to the tang. That's a hole about 0.5 mm deep

These are $11 cheapo "Enginetech" replacement bearings from Rockauto that I installed 4 races ago. This time I splurged and ordered $30 Sealed Power rod bearings.
See the missing piece

Takata R&D :: 1993 Accord - team captain - rear drum brakes lol
GoPro 360 Heros :: BMW E28  - co-captain