Burned Spark Plug Wires - Manifold Heat

[chromatic]

I have a 2008 Itasca Suncruiser 35L Motorhome with 11000 miles.
Last week I became aware of a "miss" in the engine particularly at lower speeds. I took it in to a Workhorse Service Center and was told the spark plug wires near the manifold were burnt and needed replacing.
In addition the manifold had a crack in it. The tech asked me if I ran
the RV in overdrive and I answered yes. He said I should not run the
motorhome in Overdrive, particularly when towing.
I am interested in comments from others who have had this experience.
Thank you for your comments.

[DriVer]

Quote:

Originally Posted by chromatic I am interested in comments from others who have had this experience..

and this is this the Workhorse Service Center that told you not to tow in overdrive? I've never heard of such a thing.

The reason you have a cracked manifold and burned wires is because the manifold was defective from GM and it burned out the wires.

You tow in 6th Gear OD and don't worry about it. The engine and transmission will pick whatever gear it needs without and help from you OR the service center for that matter.

If I had the option, I might be looking for another service center.

Quote:

He said I should not run the motorhome in Overdrive, particularly when towing.

It would appear by this comment that there would be conditions where under normal operation Overdrive is not recommended. This is not a valid statement.

The only time that we all have agreed here to not run in Overdrive would be in the "Whoopdees" or "Severe and frequent switchbacks." ... otherwise you run that OD 6th gear all you want. The drive-train like I said will take care of itself.

[chili's trip]

Quote:

Originally Posted by chromatic I have a 2008 Itasca Suncruiser 35L Motorhome with 11000 miles. Last week I became aware of a "miss" in the engine particularly at lower speeds. I took it in to a Workhorse Service Center and was told the spark plug wires near the manifold were burnt and needed replacing. In addition the manifold had a crack in it. The tech asked me if I ran the RV in overdrive and I answered yes. He said I should not run the motorhome in Overdrive, particularly when towing. I am interested in comments from others who have had this experience. Thank you for your comments.

I heard the same thing today - Workhorse SC in Holland MI.

[DriVer]

Quote:

Originally Posted by chili's trip I heard the same thing today - Workhorse SC in Holland MI.

About the failure or the no use of OD while towing?

[stearn]

It's curious to me how these wires start going bad after several miles? Then don't take long after repairs to go bad again. My problems started at 13K then again at 19k, then less than a thousand? Got vent kit installed this summer, and so far so good ! (Knock wood) !!

[TXiceman]

Back with the old GM 454, they were having problems with burnt plug wires. The solutions were to put on headers or get some high dollar wires with ceramic extensions to get the wires away from the heat. Seems like some engineers never bother to look at any Lessons Learned.

Ken

[KJINTF]

Stearn

What is the "vent Kit" you referenced above?
My '09 with less than 10K miles is showing signs of defective wires

Regards
Ken

[stearn]

If you go to the Workhorse web site
http://workhorse.com/Default.aspx?tabid=71&List=0&CategoryID=21&Level=a &SortField=7 it shows the kit. Do a search in this forum some have posted pictures of their installation. . Their posts are very informative!

[DriVer]

Quote:

Originally Posted by KJINTF What is the "vent Kit" you referenced above? My '09 with less than 10K miles is showing signs of defective wires.

KJINTF,

Please review the material located here: Engine Ventilation Cooling Kit.

The kit in the majority of the cases where it is used, resolves many issues with burnt out plug wires. The kit is quite often fitted while the vehicle is under warranty. Very few vehicles exhibit this problem and many times it is seen as a engine enclosure issue since the majority of owners do not burn out plug wires.

This engine has what is called a rear dump manifold and it does get hot back there but not so much that it burns out everybody's wires.

[max49]

I'd say the 8.1 ,in motor homes, is notorious for burning SP wires since I've never heard of it on any other engine. The fact that that WH had built and installs the the specially made vent kit for some customers, attests to that, but they stopped well short of a recall , to do them all. It's hard to understand why this gets blamed on the house builder since mine seems wide open and you can see and reach the plug wires from the wheel wells. I'd bet it's the exhaust manifold style that puts it too close to the plugs.
The 8.1, in a boat, gets pretty close to zero ventilation and burnt plug wires have'nt been an issue with them.

[DriVer]

Quote:

Originally Posted by max49 The 8.1, in a boat, gets pretty close to zero ventilation and burnt plug wires have'nt been an issue with them.

Max, Marine engine have special water cooled manifolds. Perhaps you over looked that.

[Full-Timers]

Oh No! Not another recall!

No seriously, I had the brunt plug wire issue at 600 miles and then again at about 1200 miles. I worked closely with the Workhorse engineers (via phone calls) and was their Ginny Pig. We tried different plug wires, insulators, and finally the vent kit. The vent kit did the trick for me.

[max49]

Quote:

Originally Posted by DriVer Max, Marine engine have special water cooled manifolds. Perhaps you over looked that.

True, I remember having to drain them before winter. However, why do other MH , car or truck engines not have the SP wire issue?
I burnt one during the 3 yr warranty and then 3 more in the next 2 years.

[DriVer]

Quote:

Originally Posted by max49 True, I remember having to drain them before winter. However, why do other MH , car or truck engines not have the SP wire issue?

I believe we were talking about the engine enclosure ...