How/Why to Change Spark Plugs in 8.1's

[Hampton]

Runs rough or misses or gas mileage is down or top end is not high enough.

Why do it yourself? 45 minutes per engine, $6 per plug on line. 1.5 hours and $150 total for 2 engines versus about $475 at the dealer ($17 per plug).

Only trick is to remove the rubber hose off of the fitting on the bottom of each exhaust manifold to make accessing the two aft plugs on each side MUCH easier.

Go for it!

 

[Hampton]

Old plugs from port engine. All are the same as one-another. I couldn't believe that the wires were AC Delco!

 

[Liquid Pleasure II]

Just make sure you use the platinum MerCruiser recommended spark plugs. I just bought my DA over Labor Day and after a few cruises the SB engine would not turn over.

After pulling the plugs I saw the previous owner put Wal-Mart plugs in...no wonder it didn't start. After the SB fix, 2 days later the port engine had the same problem.

I know, I know I should of changed both at the same time but the marina only had enough plugs for one engine at that time.

Spend the $$ for the right plugs and forget about any issues going forward.

 

[trit21]

Did you change the wires back to original Mercruiser as well or leave them as they were?

 

[Two Peas]

What torque setting do I use to tighten the plugs?

 

[skibum]

Huh? Torque setting for spark plugs? Turn them in until they seat by hand, then maybe 1/2 -1/3 more turns with a wrench until it stops, then a little "ummph" to tighten. Hmmm... somewhere around 40 ft/lbs.

 

[Two Peas]

Thanks. I thought I had read a specific setting for these ones, but couldn't find the reference.

 

[Kreole Kid]

Runs rough or misses or gas mileage is down or top end is not high enough.

Why do it yourself? 45 minutes per engine, $6 per plug on line. 1.5 hours and $150 total for 2 engines versus about $475 at the dealer ($17 per plug).

Only trick is to remove the rubber hose off of the fitting on the bottom of each exhaust manifold to make accessing the two aft plugs on each side MUCH easier.

Go for it!

John, what's the correct part # for the plugs and the wires, if you know?:huh:

 

[1stSeaRay]

The plugs for your motors are AC DELCO (AC 41-983)

I assure you they can be had for way less than $6 each and the ones that come from autozone are the same as the ones from the marine store. Don't believe me? Go pick one up at the dealer and compare (33-863622001)

gap is 1.5 mm (0.060 in.)

Info above is from Mercruiser Service Bulletin 2006-03
http://ww2.justanswer.com/uploads/ROCKETBOAT/2008-12-09_042519_SPARK.pdf

 

[Jimmy Buoy]

I just got 16 for 2.85 each from http://cgi.ebay.com/ebaymotors/AC-D...r_Truck_Parts_Accessories&hash=item45f0728b82

Just mention SeaRay.

 

[Jimmy Buoy]

Oh, and if you put some dialectric grease in each spark plug boot with a cu-tip it helps get the boot completely onto the wire so you hear/feel that "snap" of the ring going on the top of the plug.:thumbsup:

 

[Two Peas]

I paid 2.45 each. I changed all 16 in about an hour today with not a single drop of blood shed. Mechanix wear gloves help a lot. Hampton's suggestion to remove the one hose helped. Changed oil and filters too. Now on to the impellers...

 

[Kreole Kid]

Jimmy, I feel ya on the pricing, but look at the small print at the bottom of the listing,

These plugs were removed from new, never run engines, and I will guarantee that they are 100% functional. These will ship in bulk packaging.

I think I would have a problem with that. How many engines does one have laying around that haven't been run, at all.

Just me, but I think I'll take a chance at a local Chevy dealer, but I DO APPRECIATE the link.:thumbsup:

 

[Two Peas]

Kreole, the ebay dude is taking the plugs out of new crate engines that he is making in to racing engines ( I think)... my plugs from him were absolutely brand spanking new.

 

[Jimmy Buoy]

I'm the third CSR guy that I know of that bought these. Upon close inspection, they do not appear to have been fired at all. They don't even have socket marks. Solved my issue and I have no complaints, nor do the others.

That being said...The rule is - if you don't feel comfortable, don't do it!

 

[Kreole Kid]

Ok thanks Andrew, I might have to take Jimmy up on this offer.

I wonder if those "racing engines" would be a good fit for our boats, ya know, have a "sleeper go fast":grin:

 

[Kreole Kid]

I'm the third CSR guy that I know of that bought these. Upon close inspection, they do not appear to have been fired at all. They don't even have socket marks. Solved my issue and I have no complaints, nor do the others.

That being said...The rule is - if you don't feel comfortable, don't do it!

Sold:thumbsup:

 

[Two Peas]

My Amex can't handle 250 gph at wot! :grin:

 

[Kreole Kid]

2nd glass of wine now, I posted earlier that I splashed today and I had a popping / misfire sound coming out of the starboard engine. I'm gonna change the plugs, wires, and filters. I assume this will solve my little problem.
Although I have been out of commission for over two months and today was the first day I took her out.

Any thoghts:smt100

 

[chumbley]

Huh? Torque setting for spark plugs?

Sure! Granted, I never torqued plugs when I was wrenching for a living, but I probably would today (it's been like 25 years). You can develop a "feel" for it, but not if you've never done it!

Turn them in until they seat by hand, then maybe 1/2 -1/3 more turns with a wrench until it stops, then a little "ummph" to tighten. Hmmm... somewhere around 40 ft/lbs.

Is that guide for tapered plugs or regular gaskets? 14mm or 18mm size? Cast heads or aluminum? :huh:

I believe the 8.1 uses 14mm tapered plugs. The guide line for 14mm tapered seat plus (in cast or aluminum) is 1/16 of a turn past hand tight, or about 10-12 ft/lbs of torque. Please don't try to turn them 1/2 a turn or put 40 ft/lbs of torque on them!