Tune Up Mercrusier 350 MPI Horizon

onislandtime

Want to get advice from Captains on tuneups for their engines. What spark plugs, distributor cap and rotors you use. This will be the first time I do a tune up.

zaverin1

Easy answer Is always use marine product and buy merc product.
Sold at west or your local boat store slash dealer.

Black_Diamond

I suggest using Merc OEM cap/rotor. 

Be extremely careful when installing the cap. You can easily break the tabs where it screws into. Ask me how I know. BTW of you do: $900 to replace the distributor. 

onislandtime

@Black_DiamondI thanks for the tip!

The question is what "specific" spark plugs, distributor and rotor "do it yourself" Owners/Captains use for my particular engines. I am a big supported in using marine grade products as they are made to last longer in the marine environment.  

rasbury

Think of it like a car motor- how long since the wires replaced? Change all the filters, I do once a season. Are you going to drain the lower unit? It's a pretty long list and I need to develop my own annual list of things to do......say, bein this a forum, I'm thinking there is some one out there much more anal than I am and has such a list- ? It does not need to be the end to all end list, everyone has different levels and knowledge of various systems. For example, I'm real good at putting it in forward gear and driving down my local river. Would it not be cool to put together a "fairly" comprehensive list of stuff to look at both for the new buyer and seasoned? I have seen just like me several people have no experience with boating at all (brave!) to someone like me with a little experience- I was given so much info on this site but if we could put something together like this , would also give the site more street cred! 

Michael T

Good advice from Ras - Here's what I have told friends in similar situations - google local marinas or even ones that are known to do a good winterizing job. They usually have posted "menus" for winterizing. Compare four of them and you will have a very comprehensive list for winterizing. I compiled one for friends once. If I can find it I will post it here.

onislandtime

I didn't post "how to winterize your boat" I post what spark plugs, distributor and rotor owners use on a Mercury 350 MPI Horizon lol

diggin2day1

These are the parts used on my 2002 350 MPI Horizon:
-Spark Plugs: A/C Delco 41-933(original plugs A/C Delco 41-932 were discontinued and superseded by 41-933)

-Fuel/water separator - 18-7944

-Fuel filter - Quicksilver 35-864572T

-Ignition wires- Quicksilver 84-863-656A

-Serpentine belt- Gates K061066 multi V-groove// Merc# 57-865615-003

-Distributor cap- A/C Delco D329A / Quicksilver 884790

onislandtime

@diggin2day1 thanks.

Liberty44140

My 2006 350 MPI uses the same plugs that diggin posted. 

Michael T

@onislandtime, a winterization list is a good checklist for things guys do once a year. Some guys do it in the Fall and some in the Spring but it's FAR more that just antifreeze and draining. In a good marina the list is quite long. If you strike-off the pure lay-up procedures there is a good list of minimum once a year maintenance items. That's what I was getting at. 

onislandtime

@Michael T This is not a post about weatherization. That's a another topic.

Michael T

Understood - the list of parts is usually the same regardless of the time of year you do the work. I was just trying to be helpful. :-)

LaRea

Can anybody comment on using automotive spark plugs rather than Mercruiser plugs?  My mechanic claims that an AC Delco  41-983 is identical to a Mercruiser 863622001, except that it costs $7 instead of $17.  

randy56

I put them in my boat this spring, no problem.

MDboater

Aren't the AC Delco automotive plugs more prone to corrosion than the Mercruiser plugs?

Michael T

@MDboater, that, among other things, is what I have been told over the years as reasons for using "marine designated" plugs but maybe I was scammed!

onislandtime

Based on research I have discovered some important information based on Marine parts vs Automotive. Who doesn't want to save money by doing your own repairs!

Too start "yes" automotive parts are the same except for one important aspect, Marine Starters, Alternators, Distributor caps, Rotors, Spark plugs, Fuel lines, Fuel pumps etc are CG approved because they are sealed and tested to prevent sparks.

Another piece of information I ran across while researching. The number one cause of explosions on boats are from "non" CG approved parts and poor ventilation (non working blower or not turned on). Second was not inspecting for leaks in the engine bay prior to engine.

So if you don't find any fuel leaks and or develop one while underway and use your blower, you may get away from blowing up your passengers so you can save $50! lol

A do it yourself tune up for twin engines (Distributor Cap,Rotor,Spark Plugs) would cost you about $200 every 3 years vs $130 to $150 with Automotive parts. (If the Automitive parts last 3 years in your marine environment)

Liberty44140

I looked in to the plugs when I bought my boat this past spring. 2006 350 MPI's. Initially the mechanic put copper plugs even though I had asked for iridium by part number. At the end of the day Merc recommends iridium and right on the side of the motor it says to use the ACD 41-932 which are iridium so I dont see why you would use anything else. I made the mechanic change them to iridium 41-933. 

Liberty44140

@diggin2day1are you sure on the serpentine belt here? I have a 2006 Mercruiser 350 MAG MPI Horizon with closed cooled and Marineengine.com is saying I need the 57-865615Q06 belt. You posted above 57-865615-003 which would be for raw water cooled. Sorry to double check you, I am looking for the gates alternative to the Q06 belt without much success. Indeed the cross reference you provided above on the 003 would be correct. 
Anyone else have to use the Q06 FWC size belt and know the gates alternative?

diggin2day1

@Liberty44140 - That is what the previous owner has written in the log book and he was spot-on with everything else. I still have my boat wrapped and can access the belt right now. My Merc is FWC as well. 

Liberty44140

Hey @diggin2day1 I think I may have found the answer. For the 2000 - 2002 350 MPI Horizon (FWC) the 003 belt you listed is the one that was used. Those engines were pre serial numbers starting with OM. My serial number starts with OW. For the 2002 - 2008 FWC 350's, they went to the belt ending in 006 or Q06 which is around 1.4" shorter. The 2002 - 2008 RWC uses the 003 belt. So that is why our engines are the same but different belts. Here is the site on this for anyone as lost as I was
http://www.marineengine.com/parts/mercury-quicksilver/application-guides/mercruiser-v-belts-and-serpentine-belts.htm

diggin2day1

Thank you @Liberty44140... some good info right there! 

onislandtime

For anyone that breaks the tabs on the distributor heres a link to a repair kit.
www.dormanproducts.com/p-53495-90449.aspx

J3ff

Liberty44140 said:

Hey @diggin2day1 I think I may have found the answer. For the 2000 - 2002 350 MPI Horizon (FWC) the 003 belt you listed is the one that was used. Those engines were pre serial numbers starting with OM. My serial number starts with OW. For the 2002 - 2008 FWC 350's, they went to the belt ending in 006 or Q06 which is around 1.4" shorter. The 2002 - 2008 RWC uses the 003 belt. So that is why our engines are the same but different belts. Here is the site on this for anyone as lost as I was
http://www.marineengine.com/parts/mercury-quicksilver/application-guides/mercruiser-v-belts-and-serpentine-belts.htm

Just in case you're looking for a cheaper alternative - this belt is 1mm smaller and I think should work... will update when it gets here. https://www.amazon.com/gp/product/B001QU68DG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1