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ZUKIWORLD Discussion Forum => Technical Discussion - Performance / Modify => Topic started by: timv on December 20, 2011, 05:14:49 AM

Title: spark plug issue
Post by: timv on December 20, 2011, 05:14:49 AM
Ok guys.........I have a weird one. I have an '88 samurai, stock everything. When I rescued this thing it had sat for years in a field. I did cut out all the rust and welded in new panels, did all the normal drained everything and replaced, including gas tank, oil, radiator, flushed the block. I also did new distributor, coil, plugs, and wires. After messing with the carb for days she runs great.

So here is where the problem comes in. The spark plug in the front cylinder has melted twice. when I say melt I mean that the point melted and incrusted the electrode. The first time it happened I drove it about 30 or 40 miles over a week period and it started missing real bad. Thats when I found the plug melted. I replaced that plug and drove about 100 miles over a few week period and it started missing again. I checked and the same plug had done the same thing. I checked the other plugs and they look brand new. WTF?

Why would one plug do this and the other be fine. Other than the plug deal, this thing runs great. Help!!
Title: Re: spark plug issue
Post by: talonxracer on December 20, 2011, 05:23:37 AM
There is something generating abnormal combustion pressures in that cylinder. Do a compression and leakdown test.
Title: Re: spark plug issue
Post by: Skyhiranger on December 20, 2011, 05:47:59 AM
Have you adjusted the valves?  If not, it would be a good idea to do, since you have no idea when the last time it was done.
That valve could be oil fouled.  So the valve stem seals may be leaking badly on that cylinder.  Or the rings could be leaking.  A compression test would help determine if it is the rings.  No way to really check the valve stem seals though.
Title: Re: spark plug issue
Post by: mrfuelish on December 20, 2011, 10:55:12 AM
I know you said that you have new wires, but lately I have seen a few brand new sets that were bad and that one plug wire if it was bad might increase the voltage on that one plug.
Title: Re: spark plug issue
Post by: timv on December 20, 2011, 11:24:44 AM
Thanks guys...........I will do the compression test next and also pull the valve cover to make sure they are adjusted right. I will let you know what i find. Thanks again!!
Title: Re: spark plug issue
Post by: timv on December 24, 2011, 01:17:29 PM
Ok, I pulled the valve cover off and for the most part the valve lash was not bad. The one the was out the most was the exhaust valve on the #1 cylinder. It was too tight. I couldn't even get the gauge in there. Do you think that could of caused my problem?

The other thing o was to try is a leakdown test but I am having a hard time finding the tester. Anyone have any ideas where I could rent one or something? I don't want to spend the money to buy one unless I have to.
Title: Re: spark plug issue
Post by: Skyhiranger on December 24, 2011, 01:32:00 PM
Ok, I pulled the valve cover off and for the most part the valve lash was not bad. The one the was out the most was the exhaust valve on the #1 cylinder. It was too tight. I couldn't even get the gauge in there. Do you think that could of caused my problem?

The other thing o was to try is a leakdown test but I am having a hard time finding the tester. Anyone have any ideas where I could rent one or something? I don't want to spend the money to buy one unless I have to.

A tight valve could cause the spark plug problem.  If the valve was tight, then that would make the compression really low (or maybe even 0) in that cylinder and it could cause an incomplete fuel burn or other various problems.

Have you checked with the auto parts stores?  Most have a loan-a-tool program where you can borrow various tools.
Title: Re: spark plug issue
Post by: Merlin93 on December 26, 2011, 02:49:53 PM
I noticed that you're using NGK plugs.  Those are reported by most folks to be the most satisfactory brand for the Zuk.  I'd stick with them and the manufacturer's recommended heat range.  My '93 EFI Sami calls for BPR5ES.  With a stock-ish 1.3L, I would not spend my money on anything else different.
Title: Re: spark plug issue
Post by: timv on December 27, 2011, 07:55:08 AM
I have called several auto parts places to see if they loan or rent the leakdown tester but have had no luck. I am going to call a.few more places, maybe I will get lucky.

The only other thing I noticed when I pulled the cover was some sludge buildup on the inside of the cover. I am thinking of running some more seafoam through there and changing the oil again. Maybe I have a valve or 2 that are not seating all the way.
Title: Re: spark plug issue
Post by: timv on January 12, 2012, 01:58:58 PM
OK guys, I think the valve adjustment must have done it. I have been driving it for weeks and it is acting fine. I appriciate the input.

One other thing I want to pick your brains on. When my Samurai is running the exhaust is very strong smelling. Not so much like gas, but like really strong exhaust. Kinda like your face is right in front of the pipe. I do not have a Cat. convertor on it and it has new exhaust from front manifold all the way back. Any ideas on what I could check?
Title: Re: spark plug issue
Post by: talonxracer on January 12, 2012, 02:03:11 PM
Is the exhaust smell while driving?
Title: Re: spark plug issue
Post by: timv on January 12, 2012, 04:27:55 PM
It smells both when I am driving it and when it is idling.
Title: Re: spark plug issue
Post by: timv on January 15, 2012, 03:50:03 PM
Well, bad news. The thing has been running fine for several weeks and then today I burnt the sparkplugs on cylinder 3 and 4. They did the same thing that the #1 spark plug did several times. I pulled the #1 plug and it looked great.

I am thinking now that this may have something to do with running too rich. That may be where my strong exhaust smell is coming from too. Anyone have any thoughts? I really want to get this straightened out but don't.know what to try next.

Title: Re: spark plug issue
Post by: mrfuelish on January 16, 2012, 12:26:51 AM
check your down pipe next, they were double wall pipes and the inside pipe would collapse and create back pressure, there was a recall years ago.
Title: Re: spark plug issue
Post by: timv on January 16, 2012, 03:51:26 AM
Are you talking about the exhaust manifold where the pipe hooks in?
Title: Re: spark plug issue
Post by: mrfuelish on January 16, 2012, 01:46:45 PM
Not the cast iron part but the pipe that hooks to it and has a curve to it and goes to your cat.
Title: Re: spark plug issue
Post by: timv on January 16, 2012, 06:20:23 PM
Ok cool. I will check that next. I appreciate the idea. I will let you know what I find.
Title: Re: spark plug issue
Post by: timv on January 20, 2012, 11:56:53 AM
Down pipe is clear.

I have a possible new theory though. I have noticed that I am using oil. I have burned about 3/4 of a quart in about 3 tanks of gas. It is not leaking because there is no oil where I park it in the garage. I wonder if I am getting enough oil past the rings that it is causing the sparkplug issue? I have antifoulers on all the plugs but maybe that is hurting me is this case. Maybe it's causing them to burn up because of all the oil instead of just fouling up like normal.

Title: Re: spark plug issue
Post by: mrfuelish on January 22, 2012, 09:59:54 PM
I would take the anti foulers out and run it down the freeway real hard at night, pull off the freeway and pop the hood and see if your exhaust manifold is glowing at all.
Title: Re: spark plug issue
Post by: Boxcar on January 31, 2012, 05:51:53 PM
I know this is going to seem abhorrent to most of you guys.
I'm going to post it any way.
If your Zuke is still running the stock carb. Its screed up...After sitting that long I GARONTEE IT...
 Here is the part that's liable to generate hate mail...Take it to a shop and pay the $80 or so $ to have it diagnosed...They will plug it in to their computer and VIOLA no more guessing....
 Sounds like your running real fat--- extra fuel is washing past the rings ( which are old ) mixing with the crank oil (drain some and smell it- bet there is gas in it) Thinned oil washes back by the rings . All of this will cause the fowling, smell, and oil loss...Boxcar...