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1991 Gmc Topkick 5 Tonne


 
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Megan
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PostPosted: Mon Apr 26, 2010 12:33 pm    Post subject: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

I am working on 91 Gmc topkick with a 366 gas engine. This truck is burning through spark plug wires every 150-200kms. I have replace cap, rotor, plugs, manifold heatshields are in place. I have even tried thermal tape and nothing works. After speaking with the Gm dealer apparently this is a known problem on this model and they had a recall (5N06) out for this same concern but their solution is to replace all the parts I have already replaced..... Has anyone run into this before??? Thanks Smile
 
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ericlb
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PostPosted: Mon Apr 26, 2010 5:43 pm    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

where exactly are they burning, ? if there touching the exhaust or anywhere that is hotter than the normal parts of the engine, you need to get a longer set of wires and route them away from the heat, you can get a longer set at places like napa or carquest, go in there ignore the pimple face kid at the counter, he wont know how to do this, find the owner or a older gent in there and explain the problem to him, in the ignition wire book, under the counter or in the back, the wire sets have the lengths listed, look for a kit for gm big block that is longer then the set speced on the computer for that truck route them away from the engine using wire stands, tie wraps or whatever it takes
 
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Megan
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PostPosted: Tue Apr 27, 2010 6:54 am    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

Thanks for your reply but I have already done that as well. The recent set I put on was from Napa 8.5mm truck wires with porcelin boots. The manifold heatshields are in tact and no leaks at the manifolds or even the donut gaskets. I have the wires well alway from any unnecessary heat. It always starts with the #8 wire burning through first then by the time the truck gets back to the shop 20kms or so the only 2 wires that arent burnt are usually #1,#2.... Also the service engine light comes on intermittently when I scan it says code retrieval sucessful but no codes come up nor can I delete them... ECM maybe??? It is OBD 1.... Thanks again I just want to blow this truck up!!!
 
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Kruse
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PostPosted: Tue Apr 27, 2010 8:28 am    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

Google "Summit Racing" and look at their web page. On their search site, type on spark plug wires. You should be able to find a high temp set of wires like MSD 5554 or similar that will last longer than what you have been getting.
Still, you must have some extreme temps to be getting such a short wire life. Have you had a good mechanic thoroughly check this out? I"m wondering about retarted timing or something similar.
 
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Megan
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PostPosted: Tue Apr 27, 2010 10:43 am    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

Kruse excellent question about the timing but yes that has been checked as well... Since this concern has been ongoing and Thousands of dollars have been spend at 'a good mechanic' I have been doing all the work myself since last Aug. Even the 'experts' at GM are scratching their pumpkins Lol. That is why I am here in hopes someone has experienced this concern and can help me out... BTW I have been working on cars for 22 years however medium duty is new to me.
The speed shop I went to recommended the thermal tape for the wires to me....
 
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Dennis/Ohio
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PostPosted: Sun May 02, 2010 6:20 pm    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

Just a guess, could harmonic balancer be slipped on the rubber and you can"t use a timing light. Time it by ear, advance to highest rpm at idle then retard it about 1/16th turn. Or just retard until is doesn"t ping under a load. My "86 366 requires 89 octane or more.
Just a guess, your truck is newer than mine. Dennis...
 
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deere23
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PostPosted: Sun Nov 05, 2017 8:29 am    Post subject: Re: 1991 Gmc Topkick 5 Tonne Reply to specific post Reply with quote

Megan wrote:
(quoted from post at 13:33:12 04/26/10) I am working on 91 Gmc topkick with a 366 gas engine. This truck is burning through spark plug wires every 150-200kms. I have replace cap, rotor, plugs, manifold heatshields are in place. I have even tried thermal tape and nothing works. After speaking with the Gm dealer apparently this is a known problem on this model and they had a recall (5N06) out for this same concern but their solution is to replace all the parts I have already replaced..... Has anyone run into this before??? Thanks Smile



Hi, I have been having the same problem. Did you ever get it fixed?
Stan
 
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