Vortec 8.1 Spark Plug Wires

Pubtym · 12-06-2006, 03:12 PM

Recently, I have been browsing through topics posted on the Workhorse Owner's forum website.

There, I read several threads about 8.1 Vortec engine cylinder miss fire at high power... and the further "common" engine diagnosis of spark plug wire failure...especially at the #5 and # 7 plugs....mostly attributed to excessive pocketed heat at those plug locations.

Most plug wire sets were completely replaced under warranty by WH...which solved the engine cylinder miss symptom.

Has anyone on this forum been through this engine cylinder miss and sparkplug wire replacement routine with Workhorse?

Pubtym

Pubtym · 12-06-2006, 03:12 PM

Recently, I have been browsing through topics posted on the Workhorse Owner's forum website.

There, I read several threads about 8.1 Vortec engine cylinder miss fire at high power... and the further "common" engine diagnosis of spark plug wire failure...especially at the #5 and # 7 plugs....mostly attributed to excessive pocketed heat at those plug locations.

Most plug wire sets were completely replaced under warranty by WH...which solved the engine cylinder miss symptom.

Has anyone on this forum been through this engine cylinder miss and sparkplug wire replacement routine with Workhorse?

Pubtym

Charles99 · 12-07-2006, 02:33 AM

Sure we have. Wokrhorse will install a vent kit to direct some air on the back side of the engine. If you read some of the previous post, you will see the conservations we have had. I was eating plug wires every 2000 miles, after installing the vent kit, I have not had any more problems. I even burned up one of the Taylor wires that are supposed to hold up to anything. If you are burning up wires, get the vent kit.

KE0M · 12-07-2006, 05:01 AM

My previous coach, 1998 Itasca 34 foot sunrise with the 8.1 vortec, had that problem once in 40k miles. The problem of spark plug wire compromise caused 2 plugs to foul so it took not only a set of new plug wires but new set of platinum plugs. After the repair (at my expense since the coach was out of warranty) it ran like race car...even over Colorado mountain passes.

Larry

Pubtym · 12-07-2006, 05:29 AM

With the coach facing forward, am I correct to assume the odd numbered cylinders are on the right side of the engine...with #1 cylinder on the front of the block?

Will I be able to see heat damage on the individual wire(s)? Will I have to remove interior doghouse to inspect wires?

Taylor Spark Plug Wires?

Best bet...now that I'm awake this morning...is to take coach to local WH service center for diagnosis. I have 8500 miles on my rig now.

Clay L · 12-07-2006, 07:16 AM

If yours is like mine you can see all of the plus and wires from a sitting position underneath the MH.

I don't think the wire burning has been a problem with later model Winnebagos though. There seems to be plenty of airlow around the plugs. Some manufacturers didn't allow for enough and I think that caused the problem.

Charles99 · 12-07-2006, 10:15 AM

Pubtym, Go to the workhorse page and look over some of the previous post. Yes take it to a workhorse shop and request new wires and the vent kit. If you are looking down through the dog house and facing forward, the odd cylinders are on the left (Drivers Side). I spent time trying to fix it myself, before taking it to the dealer. I also had some damage to some wiring also. Remember, if you are burning up a wire made for high voltage and high temps already, what about the other stuff around # 5 cylinder. Get the vent kit and cool that area off.

DriVer · 12-07-2006, 05:58 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pubtym:
With the coach facing forward, am I correct to assume the odd numbered cylinders are on the right side of the engine.. </div></BLOCKQUOTE>If you are sitting in the driver's seat the odd-numbered cylinders are on the left side.

NASAGuy · 12-08-2006, 06:15 AM

I had this problem just a few months ago and submitted a post on this topic. I saved my old spark plugs and wires. Two spark plugs were somewhat fouled. All 8 spark plug wires had no visible flaws and each had the nominal resistance. My guess is that spark plug wires can cause the engine to miss because of breakdown of their high voltage insulating characteristics even though they are not visibly burned. I have no way to determine which wire(s) caused the engine to miss.

NASAGuy

Pubtym · 12-09-2006, 05:07 AM

I looked under both front side wheel wells and can clearly can see all the plugs and wires. Number 5 wire looks a little closer to engine block but there is plenty of air circulation/cooling room around all wires.

Noticed no burn proof heat socks on the wires.

Went to the Taylor Vertex web page to review the "Extreme Series" ignition wires set for motorhomes. I don't know technical details of OEM wires on my engine now...but for $60,,this Taylor set could be a worthwhile upgrade. Anyone ever install these Taylor wire sets?

DriVer · 12-09-2006, 06:00 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by NASAGuy:
I have no way to determine which wire(s) caused the engine to miss. </div></BLOCKQUOTE>The spark plug wires present a burnt or failed condition in the following area. Directly above the spark plug where the clip ties in to the head of the plug, it has been seen to fail internally in the connector and completely burn through inside the boot where it would not be immediately visible on inspection. A slight to moderate pull on the wire on the other hand will separate the wire from the boot and it will come directly off in most cases.

The inside of the metal plug shield can be observed as having changed color from orange to black. This is the most immediate sign that the plug has overheated. I have had one person tell me that he saw his plug wire dangling in mid air as it disconnected from the boot on its own.

A cold air vent kit is only designed to passively move a quantity of air, enough to reduce the temperature in the immediate area so the plug does not burn out.

After ~2~ plug wire failures, WCC will normally authorize the installation of the CAVK under warranty.

Some of our members here have had under warranty powered CAVKs installed using bilge blowers.

Depending on the coach builder and the engine enclosure, failures in plug wires can occur quite predictably or as in my case, I have 53,000+ miles with no wire failures.

Pubtym · 12-09-2006, 06:21 AM

Is an overheated plug a damaged plug? and should the plug be replaced too?