Known 4.3 distributor cap problem?

andrewterri

Chief Petty Officer
Joined
Jun 25, 2014
Messages
437
I am almost positive you guys have told me mercruiser had a problem with distributor caps but i can not find the post. i am referring to a 2014 4.3 mpi. I am wanting to replace now before i have any problems but was it only the cap that had issues? I am thinking the old post also said not to use OEM because they still have the same design problems. What brand should I get?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,307
All the crab caps will fail. Its a poor design
 

QBhoy

Fleet Admiral
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Mar 10, 2016
Messages
8,286
Hi
I have a similar V8 version MPI. On these mpi, the diz cap is a known issue. If you have the same it will also be. It’s the flat crab shaped diz cap that has the issue. As far as my experience goes, it caused by condensation gathered during winter storage and sometimes just that the caps are poorly made or designed at least.
With the usual condensation problem, during storage the cap tends to gather moisture in it and cause a surface coating or even corrosion on the terminals. If it doesn’t cause issues at spring start up time, it likely will soon after. Occasionally even if it visually seems ok. I’ve been through a few caps now. Mostly caused by this reason, but one time a brand new replacement cap fitted mid season just failed for no apparent reason all together.
Best thing to do is crack open the cap before storage and spray wd 40 in there and leave it open...even then keep a spare one if you use the boat at sea or far from help.
At the very least, do this and change it every 2 years. My advice anyway.
I also have a sneaking suspicion that some failures are also caused by not fitting the cap perfectly down before tightening the two screws. If you aren’t careful it’s easy to think the cap is in position and tighten screws...but it’s not quite and you end up cracking the cap when tightening. I’ll own up to this once !!
 

andrewterri

Chief Petty Officer
Joined
Jun 25, 2014
Messages
437
I can not believe that cap is selling for 65 dollars!!! For a plastic distributor cap :mad-new:
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,803
Have not heard of this on the 4.3s, yes on the V8s it has been a problem.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
ACDelco D328A GM $27.89
Same equipment that is shipped to Mercruiser by GM
 

JoLin

Vice Admiral
Joined
Aug 18, 2007
Messages
5,146
The problem I had with Merc OEM caps is contact corrosion. Merc did away with the brass coating they used to put on the contacts- Sierra caps are still coated. Sierra is what I use.

My .02
 
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