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Halbert

Flat Distributer Caps

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I m posting this to try and help everyone and anyone that has had this happen. I took my 240 Chaparral Sig. in for yearly service. I have a 350 mag with fuel injection. Everything checked out at the shop and I went on my way. Took it out, and the boat wouldn't start! Wow, just had it in the shop, and now it wouldn't start? Ladies and Gentlemen, to say the least, I was.......not going there, but you get my point. I decided to check everything, I mean everything myself. Yes, I took the boat back to that shop, and yes it started right up. Go figure.

After going through everything, IAC, plugs, wire, spark, fuel pressure, etc. etc. etc. Found that the Flat Distributer Caps are notorious for failure, and yes it was a brand new cap i purchased at the end of the season last year! After doing some research, and speaking with a number of reputable mechanics, they see this all the time. They really do work sometimes, and completely fail other times.

I replaced the cap, and have been running and starting the boat for a few days with absolutely no problems.

I hope this helps anyone having similar problems.

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Yup. Its definately a problem and I had you exact issue. Worked in the shop but not at home before going to the ramp. Took it back to the shop and it started right up. Mechanic went straight for the distributor cap and said that it was shot. They also told me that it needed to changed yearly. Go figure. Does anyone have a "better" or more reliable cap they use??

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Use a NAPA top shelf cap and rotor with copper contacts and you will have no more problems. They actually sell three different grades, and I have had problems with the other two. If the distributor has been removed, have the cam to crank retard offset checked with a bi-directional scan tool. An offset here of more than +/- 2 degrees will cause crossfire in an Vortec distributor cap resulting in early failure.

W

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Wingnut is correct, absolutely.

The flat cap is notorious for cracks.

Often, they crack when molded, or during the assembly process.

These cracks are less than the width of a human hair, so cannot be easily seen.

There are a few tricks to use to detect the cracks in the part, but the best one is that the engine won't start.

Get the very best cap you can (napa gold is way good), and the problem goes away.

Mike

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So it doesn not have to be from the mercury dealer?

A few months ago is when the dealer changed mine and when I went out last weekend, I had a hard time getting her to start and I was trying to remember if it had already been a year. Not so but if Im having the same issue then I want a better cap.

I have a Mercruiser 5.7 MPI. What cap am I going to ask for, heck, what motor am I asking to get a cap for?

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So it doesn not have to be from the mercury dealer?

A few months ago is when the dealer changed mine and when I went out last weekend, I had a hard time getting her to start and I was trying to remember if it had already been a year. Not so but if Im having the same issue then I want a better cap.

I have a Mercruiser 5.7 MPI. What cap am I going to ask for, heck, what motor am I asking to get a cap for?

a 1997 Vortec Chevy 5.7 for a pick-up C-1500 will work just fine. NAPA Gold please.

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Halbert @ you must have been reading my mind. Just came by UPS today ordered 2 new caps & rotors. One to be installed, one to be stored on board. Wingnut@ like the idea of NAPA gold will go with that next time. Great timing, good post any chance of a NAPA part number?

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I have a 2000 Mercruiser 5.0 EFI. Does that engine have the problem cap? If so, does anyone have the NAPA part number for the replacement? I'd rather change it now, if necessary, then get stuck on the water. Thanks. Hy

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HVS Distributor (aka GM's crap cap) came out on MerCruiser small block V8 MPI and V6 MPI around 2002, and is used to present day on these MPI engines. Seeing an engine in a boat is often older than the boat itself, you almost certainly have the MerCruiser Thunderbolt type distributor. MerCruiser 'EFI' models (throttle body injected) and earlier 'MPI' models (multi-port injection) used GM ignition (non-HVS) on earlier '95-'98 models, than switched to MerCruiser's Thunderbolt ignition around '99 for a few years. Wish they'd go like the 496 and new 8.2L engines and eliminate the distributor altogether.

If you're looking to install a new cap and rotor for your MY 2000 5.0L EFI, MerCruiser part # 805759T3 or Quicksilver part # 805759Q3 is the cap & rotor kit. Biggest problem with that ignition was the ignition sensor* under the rotor. Cause the engine either not to start, or to run rough. (engine won't start being the more common in our experience) New MerCruiser sensor design part # 87-892150K02 or Quicksilver part # 87-892150Q02 came out around 2005, and is much more reliable and robust. Thunderbolt ignition came out around '87, and is still used today on MerCruiser V6 and small block V8 carb'd engines.

* the rotor assy usually gets wrecked when changing out the ignition sensor. Sensor is item # 6 in the link below. Best to change out on your terms and timing rather than wait for it to give you problems down the road.

1999-2001 5.0L MerCruiser EFI

http://www.marinepar...9500+99/4856-80

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Gippy@ you I think I will be looking into that Napa cap. Sounds much more reliable than GM cap.

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