Community Forums

Isaac-1 · 07-28-2017, 03:33 PM

I just finished changing the spark plugs and spark plug wires out on my 2002 Safari Trek with 8.1L Vortec engine, and I was wondering how often do you change the spark plugs on your engines?

My Trek has about 76,000 miles on it, bought it at 74,000 last year and have maintenance history from previous owner back to about 50,000 miles. The plugs I removed were Autolite Irridiums so not originals, and were showing slight oil fouling and other degradation (I have seen way worse). I also replaced the spark plug wires with Taylor Extreme wires (found a set on sale at a good price), I am glad I did as one of the previous (unknown brand) marked as silicone 7mm wires was burned through at the end and I had to pull the connector off the spark plug with a pair of pliers to get the socket wrench on.

From all this I can tell I should not expect a 100,000 miles out of these new Irridium plugs, but without knowing if the ones I just removed had 25,000 miles or 70,000 miles on them I am at a bit of a loss knowing when to plan to change them again.

lrsses · 07-28-2017, 05:15 PM

You may find the plugs will outlast the Taylor Extreme wires as many have found them to fail early as that may burn through due to heat from the exhaust manifolds. t

Isaac-1 · 07-28-2017, 06:24 PM

Perhaps, but I suspect they will hold up better than the no-name 7mm silicone jacket plug wires that I removed today, of which only 1 was at /near the point of failure.

LETMGROW · 07-28-2017, 07:02 PM

I recently changed out my plugs and wires on my 8.1. I used AC Iridium plugs and Belden wires. The Belden wires have a lifetime warranty. I used the original insulated covers over the plugs when I installed the plugs.
My MH has just over 30,000 miles on it. Everything was original when I removed it. I had no problem with the runability but just felt it was time due to age more than miles.
When I installed the plugs I put a dab of anti seize on the threads and a liberal amount of Di-Electric silicone compound on the plug wire terminals. This will make removal easier the next time this has to be done.
Depending on climate and road conditions the unit is driven in you MIGHT get 100,000 miles out of a set of plugs. If you drive in the winter time with salt on the roads which is common up here in the north you can forget getting the plugs out without damaging the threads in the aluminum cylinder heads.
I wouldn't risk the problems trying to stretch plug replacement to the limit. You can buy a whole lot of spark plugs with the money it would cost to remove and repair a cylinder head or worse yet replace it.
Lynn

bamaguy911 · 07-28-2017, 07:25 PM

Quote:

Originally Posted by lrsses

You may find the plugs will outlast the Taylor Extreme wires as many have found them to fail early as that may burn through due to heat from the exhaust manifolds. t

Agree! Those cast iron manifolds do a great job of retaining heat. If, (it's only a matter of time) when the manifold develops a crack, you might consider replacing them with a set of Banks Stainless Steel headers. They do a great job of quickly passing the heat through the exhaust system and keeping the plugs and wires less hot...not to mention increasing the power of the 8.1

Just replacing one OEM manifold is almost the same $$$ as the set of headers.

Isaac-1 · 07-28-2017, 08:19 PM

Thanks for the replies, Banks headers are certainly on the to do list if / when the iron manifolds fail. I did also use a small dab anti-seize and dielectric grease on the installation, the anti seize only due to reports of difficult to remove spark plugs on these engines, as the factory 8.1L vortec engines have iron heads, not Aluminum. As to the choice in plug wires, I found the Taylor extremes on sale and nearby, normally I would probably have bought the Ultra RV Magnum plug wires, however out of the handful of orders I have placed orders with them, the soonest anything has arrived with standard shipping is 9-10 days from the order date. I had free time to change out the spark plugs this week, next weekend I will be departing on a 3,500+ mile trip. I will keep the still functional 7mm no-name wires as emergency spares in case of failure on the road.

p.s. the wire that was burned through on the tip was the 3rd cylinder back on the drivers side

bamaguy911 · 07-28-2017, 10:42 PM

Yes, that tends to be the infamous hot spot! Have a safe trip!!

davebw31 · 07-29-2017, 07:09 AM

I installed two (2) 3" flex ducts from the front grill, down the top of the frame rails, terminating at the center of the exhaust manifold, and the end pointed to the center of the manifold, about 3-4" from the manifold. Each tube is of different length left or right do not remember which. Make sure you add 4-5" at end of tube to your measurement since it will have a bend at the end.

I too installed 10mm Taylor Extremes, however I also installed their Thermo Silicone Spark Plug Boots in plce of the GM heat shields.

You will get better life out of spark plugs by keeping the Mass Air Sensor clean! The MAS manages the fuel enrichment and timing.

Mudfrog · 07-29-2017, 07:34 AM

Bought Taylor Extremes for ours a few years back and only got about 5000 miles out of them before the dreaded miss/backfiring under load issue came back up. Just out of warranty but i thought i'd check with Taylor to see if they might be gracious enough to send a single wire. Nope,,, no good. Went to the Magnums and haven't had any problems.

Each 8.1 situation is different so hopefully the OP has better luck than i did.

AKIQPilot · 07-29-2017, 12:04 PM

I just changed my original plugs and wires 2 days ago with 42,000 miles on the motorhome. The plugs and wires looked good. Gap had increased to about .066-.067" on all the plugs. No noticeable heat damage on any wire.

I went with the Ultra RV Magnum plug wires and AC Delco iridium plugs gapped to .045.

My motor run significantly smoother with the new plugs and wires. It sure seems like it has more power.

I will change the plugs again in about 20,000-25,000 miles. Its easy and cheap and gives me a little look at what might be going on inside the motor.

Scorpion65 · 07-30-2017, 07:08 AM

I just bought a MH with a workhorse 8.1L engine. It seems to run fine. Has 30K miles on it. Should I change spark plugs and wires now or wait a while?

lrsses · 07-30-2017, 07:26 AM

If it ain't broke don't fix it.

vettenuts · 07-30-2017, 11:21 AM

Quote:

Originally Posted by Scorpion65

I just bought a MH with a workhorse 8.1L engine. It seems to run fine. Has 30K miles on it. Should I change spark plugs and wires now or wait a while?

I like to as preventive maintenance and so I know what I have

AKIQPilot · 07-30-2017, 12:42 PM

Quote:

Originally Posted by Scorpion65

I just bought a MH with a workhorse 8.1L engine. It seems to run fine. Has 30K miles on it. Should I change spark plugs and wires now or wait a while?

There are probably a few other things you should spend your money on first but new spark plugs and wires would be near the top of the list after that.

If your motorhome has all the handling fixes or already handles great then you can skip that issue.

An electronic Tire Pressure Monitoring System should be at the top of the list.

Monitoring the engine parameters that will cause damage to the 8.1 would be right up there too. A fuel pressure gauge and a good obd scan gauge would do the trick.

Send a small sample of transmission oil out for analysis would be near the top of the list too.

Spark plugs and wires would probably land next on my list of things to do to a motorhome to make it run better and be set for the long haul.