Workhorse 8.1 Spark Plug

[Mudfrog]

Hi,

I've searched for, found, and read several threads concerning spark plugs and gap for the 8.1 liter engine. Unfortunately, i'm as confused as ever.

I had the burnt spark plug issue show its ugly head a while back in 2009. Replaced plugs (denso to 41-983) and wires (oem to Taylor 409s) and hummed along until just recently. Once again, encountered the miss and some backfiring under light load.

Went straight back to check the plugs and wires to find everything looking good from a visual standpoint. Pulled the plugs to check gap and unfortunately, had one of the Taylors leave its metal crimp on the plug. Nothing burnt, seemed to be a factory defect in the wire. (this may have been my problem).

Going with new UP Magnum wires and am awaiting their arrival. My question, which plugs? I can get the 41-983s and i feel these are a cooler heat range than the iridiums that have been discussed in the forums. The iridiums, on the other hand, sound like the way to go for reliability and longevity but i don't want to make any potential problems worse.

And i suppose while we're here, with stock set up,, .045 or .060? How bout down the middle at .053?

2003 Itasca Sunova, approximately 15,000 miles total,,, about 7,000 since failure in 2009. Yes, our rig sits a lot more than it goes.

Any advice is appreciated as this has gotten my head to hurting..

[Stuff-Happens]

, , ,Me, I went with the AC Delco 41-101 Iridium spark plugs & Taylor Cable 99615 both from Amazon ( good pricing & delivery ). . . Ran Iridium spark plugs in my plane - not cheap - but NEVER an issue.. RV runs great with this combo. . .Good luck as very frustrating running into issues when you want have fun!!!!!

[EasyPace]

I went with the 41-101s with .045 gap and UP Magnum wires last year. Very happy with them thus far. I recommended them to a friend, and he's happy with them as well.

[vettenuts]

Originally Posted by EasyPace

I went with the 41-101s with .045 gap and UP Magnum wires last year. Very happy with them thus far. I recommended them to a friend, and he's happy with them as well.

I also went with the Magnum wires and smaller gap plugs. I would definitely go with the smaller gap as this will help with high speed misfires that you won't even feel.

[stearn]

Do you have the vents that Workhorse added to stop the heat build up? I am going on 30,000 miles with GM wires and original plugs.(after the vents were installed) I am planning to replace my spark plugs with the Iridium so also interested in your post.

[Mudfrog]

Originally Posted by stearn

Do you have the vents that Workhorse added to stop the heat build up? I am going on 30,000 miles with GM wires and original plugs.(after the vents were installed) I am planning to replace my spark plugs with the Iridium so also interested in your post.

I don't have vents installed. At this time, i'm leaning towards something else causing the issue. I'm really thinking, and hoping, that the defective plug wire mentioned above was the problem. There's no telling what the connection was like before the crimp came out completely. By the way, there are no engine codes showing.

I stopped with my check of the spark plugs when the crimp came off so have two that i haven't gotten to yet, cylinders 1 and 3. Doubt i'd see any problems with those so figured i'd wait and change them out when the new wires come in. The other six looked good with no signs of burn, arc, or foul. Wires looked new, no discoloration, and were nice and supple at the plug.

[Lit]

I replaced fuel filter and the spark plugs with AC Iridium .060 gap, UltraPower 8.1L Magnum Spark Plug Wires. When I replace the wires they all looked very good. I cleaned MAF sensor and replaced the air filter. My Workhorse 8.1 runs like it did when it was new.

[Mudfrog]

Hmmm, was doing some more searching and ran across this from an older thread.

Originally Posted by Duner View Post
I highly suspect one or two burnt spark plug wires. The back 2 plugs on either side run the hottest and burn open right at the connection to the plug. You will know they're burnt when you remove the boot and the connector stays attached to the plug. The best ones on the market are stainless steel and designed to prevent this burnt wire problem on rv's with the 8.1 engine.

The connector that came off on me was on #5 cylinder. That wire looked brand new on the outside but reading this, it sounds like it could have been burnt inside.

[stearn]

Before I added the vents , #5 #7 wires would fail. The vents are simiular to the system they use on race cars to help keep the brakes cooler. My plug wire problem showed up at 12,000 miles , then again at 13,600 , and again around 16,000, and those were Taylors ! Now at 48k still good. Omney's web site is a good place to find some 8.1 tweeks. FYI my wires would break at the connector that goes on the plug.
There are many posts on this forum on this subject. I hope I'm not over stepping, I just remember how annoying burnt wires were !

[Switchflicke]

Could someone direct me to more info about these 'vents' . I am getting to the place where I think the plugs and wires are due for at least a look at. Plus at idle I can hear one or two spark plugs in the CB radio when the squelch is disabled. Thanks

[stearn]

You can see and purchase the vents and hose at www.pitstopusa.com . They are called bumper mount brake ducts. I believe the hose is 3" . My ducts are wire tied to the grill with the attached hose is routed and wire tied to allow air to flow to the back two plugs. I am sure if you see someone with the Workhorse you will see how the duck work is installed. I had my doubts , but what do I know over 30K with no engine miss due to plug wires. I might add a fellow workhorse owner had the ducts installed and still had the same problem but not as often. When we compared installation we found his hose on the pass side wasn't aimed right. Hoping we fixed it!

[Mudfrog]

I'm looking into adding ducts to direct air over the manifolds but i can't help but wonder if i need to go ahead and add a powered duct fan as well. No doubt it's going to help while moving but what about when stopped and idling? I realize engine heat will be lower overall but with no air flow over the manifold,,,

By the way, to dissipate the heat after highway driving, i do let the engine idle a minute or so before turning it off. I'm assuming this is a good idea but any thoughts on this would be appreciated as well.

[stearn]

Originally Posted by Mudfrog

I'm looking into adding ducts to direct air over the manifolds but i can't help but wonder if i need to go ahead and add a powered duct fan as well. No doubt it's going to help while moving but what about when stopped and idling? I realize engine heat will be lower overall but with no air flow over the manifold,,,

By the way, to dissipate the heat after highway driving, i do let the engine idle a minute or so before turning it off. I'm assuming this is a good idea but any thoughts on this would be appreciated as well.

I was thinking about adding boat bildge blowers to the system, but decided to wait and see the results of the vents in the grill. So far I have found the blowers would have been a waste of time and money. I believe the heat problem shows up while engine is under power, at idle you are letting things cool down .

[Mudfrog]

Originally Posted by stearn

I was thinking about adding boat bildge blowers to the system, but decided to wait and see the results of the vents in the grill. So far I have found the blowers would have been a waste of time and money. I believe the heat problem shows up while engine is under power, at idle you are letting things cool down .

Thanks for the quick reply. I'll try the same, just ducting for now.