Logo
FULL SITE MENU

383 MAG MPI Distributor Troubles

R

rod_stewart

Outstanding Contributor
So for the second time in 115 hours my 383 SBC EFI has eaten a distributor cap, crab style.
Both times we were cruising along nicely, and suddenly poof! She quit and won't start. Both times had to be towed back to the dock.
The first time the dealer finally figured out what was wrong. The second time I guessed it was the same problem, and sure enough.
Anybody ever heard of this going on with a MAG MPI??
I am at a loss.
There is absolutely nothing that looks different from the new and the failed cap.
For sure from now on I am going to always carry a spare.

Rod
 
...has eaten a distributor cap, crab style.
Click to expand...
Hi there Rod. I am at a loss for what crab style means. A picture is worth a 1000 words. Is the rotor sliding upward and destroying the inside? Merc. always locktites them in place. I guess that is why.
 
What year is the engine and during what time frame did the new cap & rotor go in place of the original cap & rotor?

Reason I'm asking is because back around August 2011 Mercruiser was having an issue with failing caps & rotors. Even though if you do a google search of Mercruiser crab style or sometimes called flat cap distributor cap, You will find many stories of this style cap giving people grief at some point in time since their introduction sometime back. In 2011 there was a short lived material change on the caps conductors giving even greater grief.

The latest cap & rotor kit part number is 8M0061335 with an MSRP of $97.08.
 
boat_tech said:
What year is the engine and during what time frame did the new cap & rotor go in place of the original cap & rotor?

Reason I'm asking is because back around August 2011 Mercruiser was having an issue with failing caps & rotors. Even though if you do a google search of Mercruiser crab style or sometimes called flat cap distributor cap, You will find many stories of this style cap giving people grief at some point in time since their introduction sometime back. In 2011 there was a short lived material change on the caps conductors giving even greater grief.

The latest cap & rotor kit part number is 8M0061335 with an MSRP of $97.08.
Click to expand...

boat_tech;
The engine was brand new in 2007, and the first replacement was in 2010. So I am guessing that both were of the original design.
Both lasted about 3 years; the first 65 hours, the second 50 hours.
The latest replacement is a Sierra part, so who knows how long it will last.
So from what you are saying there is some carbon or such material cast into these caps along which the spark is carried, and this material breaks down in time I gather?
I am happy to know that mine is not the only one affected, but I don't get why Merc can't come up with a proper solution to the problem.
At $98 bucks a pop, this is going to get old fast.
Plus you are always left in the middle of nowhere needing a tow, and there is absolutely no warning.

I think I am going to head into AutoZone and see if I can match up a Delco part that may last longer.
Any other thoughts?

Guy; the term "crab style" was the local merc dealer's, not mine!

Cheers,
Rod

I think
 
Rod: It looks like a crab w/its legs cut short from overhead. Leave it to a Purchasing Agent to tell a GM Engineer he has to design a cheaper cap they can sell for more. Can you cut the old one open and let us know what you find?
 
Is there a way to change to a standard distributor cap desing and rotor to match?

There is no need for the flat cap if not needed............just make the spark plug wire firing order correct for the motor.....

Not sure of this but thought I would throw it out. If you make it work or if someone else has done this then get some spar parts for future need.
 
kghost said:
Is there a way to change to a standard distributor cap desing and rotor to match?

There is no need for the flat cap if not needed............just make the spark plug wire firing order correct for the motor.....

Not sure of this but thought I would throw it out. If you make it work or if someone else has done this then get some spar parts for future need.
Click to expand...

kghost;
My thinking exactly.
I don't need the flat design for clearance or anything, so if I can find a standard cap that will fit the distributor that's what i will use.
I plan to cut the old one apart to see if I can figure out what keeps failing.

Cheers,
Rod
 
There are several posts on a few 'hot rod' sites I check once in a while....long story short - nobody "likes" them for the reason you experienced...several claim GM quit using them after a few years because of the frequency of failure...some reported "no problems"....maybe worth some research to see what cap & wire options are available.
 
Yup, same CAP used on my '97 Chev Tahoe, you can get the Brass Upgrade option, NAPA, any AP Store.. Exact Match. As for using a more traditional style??? the Rotor is Screwed to the Dist shaft though.. I did see that some engines have a tube running from the Dist to the Flame Arrestor so that it draws the air out of the cap, with a screw in fitting on the dist. my mech told me the dist has to have unrestricted air due to moisture etc in the cap building up and causing corrosion. - Good luck.
 
UPDATE:
I now have aobut 15 hours on the Sierra replacement cap and all is well.
Now that we are back from the lake I plan to look for a brass replacement cap as kainon has suggested.
Will post back with whatever I can find out.

Rod
 
Back
Top