idle air control replacement

R

roger275

Member
Jun 24, 2009
94
TX Gulf Coast
Boat Info
380 Sundancer 2003 (Sold)
280 Sundancer
Engines
4.3 Liter MPI Mercruisers with Alpha 1
I think I have a bad IAC on one of my 4.3 mpi's. Was idling along today when it died and then became hard to start. Runs good above about 1200 rpm. Can anyone direct me to instructions how to find it and replace on this engine; and where's a good place to order these kind of parts?
Thanks!
 
i just did mine a 5.0mpi, same symptoms you got.
IAC valve is located on top of inlet manifold just behind throttlebody with one hose and wire plug attached.
Took me about 5 minutes to replace and all is good now.
Make sure you get the gasket as well.
 
I have read a lot about bad IAC valves - but have had no problem...yet. Guess I should pick up a spare and be ready. I have had both ignition sensors fail on me within about 30 running hours of each other.
 
I too just had to replace the IAC valve on a 5.0 Merc this week. Wasn't holding idle, but fine >1K rpms. Got the 2 beep/minute warning, but all else was good. Quick replacement as indicated here and running like a clock. part was $98 with gasket.
 
On all of these IAC valves failing (both of mine have) are any of you finding ones you have changed fail or is it always just the originally installed ones? Just wondering. Also, has Mercury ever come out and explained why so many of these are failing? :huh:
 
Mine also failed within 2 weeks of each other. I've checked the failed units and have noticed a significant amount of deterioration in the resistance against the vavle piston itself. The older ones to not close properly and allow too much air to go through at idle. Other research I have seen (not from Mercruiser) indicates they fail most commonly due to external contaminants (they get dirty).

As far as I know, the factory originals are the only ones that have been failing - I can't recall anyone on CSR saying the replacement IAC failed??? That could be more a matter of timing than improved engineering, IMO.
 
One of mine failed also. Got a new one and put it on and everything was good. Got my replacement at Marine Max and paid 125.00. Can you get them at the auto parts store?
 
gerryb said:
As far as I know, the factory originals are the only ones that have been failing - I can't recall anyone on CSR saying the replacement IAC failed??? That could be more a matter of timing than improved engineering, IMO.
Click to expand...


I have replaced mine three times now on the starboard side. I suspect its a power surge thats happening at some point.
 
beachcombersc said:
I have replaced mine three times now on the starboard side. I suspect its a power surge thats happening at some point.
Click to expand...

Ours on our recent 215 WE was with a sudden decel of power. Could've been coincidence, but all was well before and it was a sudden change to NO ability to drop past neutral.
 
My Merch Tech told me that the Original ones from the factory seem to not last long I just had mine done in June. He said he's yet to replace one that was already replaced. He can always tell cause the original is painted black and the new one isn't
 
Morpheus said:
My Merch Tech told me that the Original ones from the factory seem to not last long I just had mine done in June. He said he's yet to replace one that was already replaced. He can always tell cause the original is painted black and the new one isn't
Click to expand...

My thoughts exactly!.....I guess time will tell if I loose another. Gotta be the black paint! Funny thing is that before I knew about all the issues with them I went anywhere with no concern of having a spare. Now I wouldn't go anywhere without a spare and am a little nervous with just one. :wow:
 
roger275 said:
I think I have a bad IAC on one of my 4.3 mpi's. Was idling along today when it died and then became hard to start.
Click to expand...

Did you get the soft alarm? Two short beeps? If not, it's not the IAC as the alarm goes off when it fails, at least it did on my boat. Check the IAC muffler, even after replacing my failed IAC it was still hard to start, the muffler was full of dirt. Replaced it (a $1.44 part) now all is good.
 
I had an IAC valve go bad without any sort of alarm notification :huh:


BTW that silly foam muffler really does work well in the way of air noise deadening. I replaced missing mufflers on both engines. Very quiet - what a difference!!
 
I replaced mine on my 2006 4.3 mpi's in my 280DA and I got them at the auto part store. They are the same as the one on a 1998 Ford Turus. Imagine that! Take one to Oriley's and they will match it up. Cheaper than Marine Max
 
"I replaced mine on my 2006 4.3 mpi's in my 280DA and I got them at the auto part store. They are the same as the one on a 1998 Ford Turus. Imagine that! Take one to Oriley's and they will match it up. Cheaper than Marine Max"

Can anyone else confirm this? It looks to be a good find.
 
A friend just had the same problem on a 2004 280DA with 4.3s. They replaced both IACs @ $130 each, and the mufflers were $1.30 each. Same alarm. Boat runs well now.
 
Just replaced mine. "Check Engine" thing on Smartcraft came on w/ a double beep every 60 seconds. Very slow idle and would die trying to back into the slip. No loss of power at speed. Took 5 minutes to change. Plus $98.00 for the part and gasket.

Dennis
 
You must log in or register to reply here.

Forum statistics

Threads
113,218
Messages
1,428,820
Members
61,115
Latest member
Gardnersf
Back
Top