IAC - How long 'til it fails again?

[old-thirty-three]

Greetings to all,

After just replacing the Idle Air Controller this week on my Port Engine, I am wondering what the average life of this part is? My Starboard engine had what I will call a "soft" IAC fail about six months ago (~130Hrs). By "Soft" I mean the Smartcraft alarm picked it up, but the engine never exhibited Idle issues. My Port engine experience this week (now at ~170 Hrs) was a hard and fast failure. The Smartcraft alarmed first, but within 10min, I had idle issues and within 20min the engine would not idle at all. Of course, as a well informed CSR member, I already had a spare part on the boat and had the part replaced in no time.

So, now I don't have a spare - and have two new IAC's. Anyone's guess on when the next round of failures is expected? Anyone gone through multiple replacements on the same engine? Curious if there is a trend and wondering how soon I should stock up on replacements?

Hope everyone has a Very Merry Christmas!

 

[Kreole Kid]

Good Question about the life expectancy!!! I hope someone chimes in soon, cause my port side went out this season so I replaced it right away but didn't think to pick up a spare. Guess I'll call the dealer and order one next week...

 

[jason78]

Always carry at least one spare IAC. There are alot of factors that go in to how soon they fail. I would say 130 hours and especially 170 hours was a pretty good run based on failure rates I have heard on here before. I had one go out at right around 100 hours. Sometimes they start giving you a little bit of trouble and sometimes they just completely die which can leave to stranded if on a single engine and limping home if you have twins.

The best thing one can do to help extend the life of this part is keep the IAC muffler (a 99 cent part) changed. When they get dirty it restricts airflow to the IAC, potentially causing it to fail earlier. Presentation has a good write up on here about the location of the IAC muffler. I do mine about every 6 months. Some people just clean it but considering the price, I just replace mine.

See post # 8 here- http://clubsearay.com/showthread.php/36072-Impeller-IAC

 

[Kreole Kid]

Thanks Jason!!! Now, Where is that damn muffler located:huh:

 

[jason78]

Thanks Jason!!! Now, Where is that damn muffler located:huh:

Dont know about on the 8.1 since the intake is different. Probably right under the flame arrestor, like the small blocks. You can go to www.mercurypartsexpress.com , enter the serial number and pull a diagram.

 

[Kreole Kid]

Have Nooooooo Clue what I'm looking for, :smt100

 

[jason78]

Have Nooooooo Clue what I'm looking for, :smt100

Go to this link and view Item #5 on the diagram. Keep in mind, I did not have your engine's Serial number to plug in so I picked a random PCM-555 8.1L Horizon Inboard for reference. Yours should be the same but enter your serial number in the search field to be sure before you order anything.


http://www.mercurypartsexpress.com/us/parts-search.html#epc::md855146mr1119ar4259

 

[susanandlance]

Are the EFI's the same as MPI's?? For the IAC valves???

 

[Kreole Kid]

Thanks sooooo much Jason


Sent from my iPhone using Tapatalk

 

[jason78]

Are the EFI's the same as MPI's?? For the IAC valves???

I am pretty sure it does but not sure if it is the same part. Reference the before mentioned Mercury Parts Express Website, enter you engine serial # and pull up the Throttle Body Diagram. That will give you all the latest information and most up to date part numbers.

 

[susanandlance]

Thanks Jason, How's things up on Lake Wylie??

 

[jason78]

Thanks Jason, How's things up on Lake Wylie??

Doing just fine here. Have not done much winter boating this season but plan to try and change that starting tomorrow. I think I will take her out for a mid afternoon cruise. Probably need to hit the gas pump soon too. :smt089

 

[daddyox]

For me, both engines within 5 or so hours of 180....what are the odds?.....I carry spares.

 

[jason78]

Well, I'm guaranteed to have troubles this year for opening my yapper, but.....I've never had any issues with the IAC in my MPI engines (three boats and counting) some of which had hundreds of hours put on them by myself. I wonder if there is an enviromental issue at play here. I don't take any special care, but my engine room is always clean, and we boat in freshwater.

The 340 has a little over 200 hours on it, and so far so good.

You have done it now Scott. You may as well buy a spare now. I am suprised you have not had a problem with one, especially after that great historical account of Sir IAC Newton a couple years back.

Really though it must just be luck. I was previously moored at a Sea Ray dealer and saw where these have gone out on new boats with very few hours. Even though my bilge is extremely clean, I have had them go out and I have seen these go out on bilges you could eat off of as well.

 

[carterchapman]

I wonder if it is a "big block" vs. "small block" IAC issue...I think they are different P/Ns.

None of the 8.1s on my dock have had an IAC problem...we range from 126 to 256 to 375 hours...

 

[Woody]

Well, I'm guaranteed to have troubles this year for opening my yapper, but.....I've never had any issues with the IAC in my MPI engines (three boats and counting) some of which had hundreds of hours put on them by myself. I wonder if there is an enviromental issue at play here. I don't take any special care, but my engine room is always clean, and we boat in freshwater.

The 340 has a little over 200 hours on it, and so far so good.

I haven't had any issues either. I've often heard it said the IAC's have a mind of their own, so as soon as I got my boat I also bought 2 IAC. The ones that are on there won't fail for fear they'll be replaced. :grin:

 

[Nehalennia]

I had to replace my IAC 1.5 years ago because it would not come back to idle after excelerating. It was the original(that I know of). I've put on over 200 hrs since and haven't had an issue (fingers are crossed)