Mercruiser 5.0 Mpi issue

[QBhoy]

Hi all !
Has anyone previously known or came across a situation where the shaft on the distributor appears to be bent or off centre ? It was dark and not thoroughly looked at properly at the time. The boat is not currently anywhere near me and haven’t been back to it since. But a Quick Look at the time, I’m almost sure the rotor brush assembly looked to be off centre, meaning the cap wouldn’t sit home and mated face to face where it should be.
What are we thinking might be going on if that’s the case ? Bushes failing perhaps ? It looked a fair bit deflected to me (but was very late on and dark at the time). It should be known that not long before that. The boat completely cut out whilst running. The cause of the issue after inspection, was that the rotor plastic brush gear unit has came loose and its two retaining screws. I did think it strange at the time and put that down to the screws coming loose. But thinking otherwise now.
Thanks all.

 

[Stinnett21]

I've owned this motor since new in 2002 and I've not experienced that. It has 1,620 hours. I've replaced cap/rotor every few years, that's all. I'll follow along.

 

[dubs283]

I remember my first beer

 

[Stinnett21]

I do too it was nasty, then I came to my senses. But what does that have to do with QBhoy's issue?

 

[QBhoy]

I've owned this motor since new in 2002 and I've not experienced that. It has 1,620 hours. I've replaced cap/rotor every few years, that's all. I'll follow along.

Thanks Stinnet.
I’ve had her for about 10 years now. Went through about 5/6 diz caps over the years. She hasn’t been in use for a few years recently. Really need to get back to have a look at her. But fearing the worst for her. I’ll report back when I get a proper look. In the meantime, I’d still love to hear if any thoughts or previous experience relating to this. Thanks for replying.

 

[Scott Danforth]

The dizzy body is plastic. I would swap to a biller dizzy body

 

[Fun Times]

Over the years of reading threads on boating forums regarding this design cap and rotor, it had been reported to where there had been roughly about sixish incidents as to where the rotor (and/or cap) didn’t sit down properly leaving it (one of them ) cockeyed and causing odd running issues.

Sometimes it would seem when you set them down, there was a need for a little bit of finagling involved to get the right fitted balance… all this even when the screw holes are in perfect condition in which they do tend to break or strip out easily even if trying to be careful.

PS: if you happen to spill your beer inside the distributor cap and rotor area, the engine might run as if it is drunk off its aft end.

 

[QBhoy]

Over the years of reading threads on boating forums regarding this design cap and rotor, it had been reported to where there had been roughly about sixish incidents as to where the rotor (and/or cap) didn’t sit down properly leaving it (one of them ) cockeyed and causing odd running issues.

Sometimes it would seem when you set them down, there was a need for a little bit of finagling involved to get the right fitted balance… all this even when the screw holes are in perfect condition in which they do tend to break or strip out easily even if trying to be careful.

PS: if you happen to spill your beer inside the distributor cap and rotor area, the engine might run as if it is drunk off its aft end.

Haha. Great advice at the end there. Brilliant.
Yeah. To be fair. That’s a really good point it wouldn’t be the first time it hasn’t seated too well in the past. I’ve been one of the biggest critics of this design on here for years now.
You might just be right about that causing a little deflection in there after all.
I’ll report back on what I find. Still haven’t been back to the boat yet. Hope to soon.
Thanks again.

 

[Fun Times]

I’ve been one of the biggest critics of this design on here for years now.

Yes, I have taken notice of that both here and on a couple other boating forums as well if I recall back correctly and actually thought of you when I recently re-saw some diagnostic type information regarding this cap/rotor design.

You may have seen it already but if not, see page 14 in the following bulletin,

https://www.offshoreonly.com/forums/attachments/general-q/577324d1652222576-350-mpi-horizon-base-timing-bul-2011-11r2-hvs-clocking.pdf

Instead of reading how to build the testing tool, this guy made a video of it for setting the distributor up to run better.

 

[QBhoy]

Yes, I have taken notice of that both here and on a couple other boating forums as well if I recall back correctly and actually thought of you when I recently re-saw some diagnostic type information regarding this cap/rotor design.

You may have seen it already but if not, see page 14 in the following bulletin,

https://www.offshoreonly.com/forums/attachments/general-q/577324d1652222576-350-mpi-horizon-base-timing-bul-2011-11r2-hvs-clocking.pdf

Instead of reading how to build the testing tool, this guy made a video of it for setting the distributor up to run better.

Very interesting stuff there. Lots to consider there

 

[QBhoy]

Yes, I have taken notice of that both here and on a couple other boating forums as well if I recall back correctly and actually thought of you when I recently re-saw some diagnostic type information regarding this cap/rotor design.

You may have seen it already but if not, see page 14 in the following bulletin,

https://www.offshoreonly.com/forums/attachments/general-q/577324d1652222576-350-mpi-horizon-base-timing-bul-2011-11r2-hvs-clocking.pdf

Instead of reading how to build the testing tool, this guy made a video of it for setting the distributor up to run better.

Thanks very much for this fun times. Really appreciate it. After a proper read today, seems I have a few things to consider when I get to the boat

 

[QBhoy]

Hi all. Just closing the issue and post…

Thanks so much to you all ! It was indeed the distributor at fault. The shaft had vertical play of silly proportions!! Was allowed to move that much, it was cross firing, hitting the cap with the rotor and all sorts. This all caused two of the plugs to crack the porcelain too.
A whole new distributor assembly fixed her as good as new !
Thanks again.

 

[Scott06]

Hi all. Just closing the issue and post…

Thanks so much to you all ! It was indeed the distributor at fault. The shaft had vertical play of silly proportions!! Was allowed to move that much, it was cross firing, hitting the cap with the rotor and all sorts. This all caused two of the plugs to crack the porcelain too.
A whole new distributor assembly fixed her as good as new !
Thanks again.

How many hours were on it?

 

[QBhoy]

How many hours were on it?

850 as of yesterday. 21 years old. She likely did well to last that long

 

[Lou C]

How much money did the bean counters save by making a plastic distributor? I still have the original 1988 Prestolite points/mechanicsl advance distributor. Works fine as always; a set of points/condenser & few drops of oil on the advance mechanism wick is all it needs…

 

[Lpgc]

If the average speed of a car / truck is (say) 40mph, then 850 hours use would only be 34000 miles. I can understand engine components such as blocks / pistons / etc not lasting as long in a marine environment but why would a distributor only last the equivalent of 34000 miles?

 

[Scott06]

850 as of yesterday. 21 years old. She likely did well to last that long

Yeah but all of those hours were tapping the rev limiter, trimmed out testing your garage full of props....

I just hit 400 hrs, boat is 20 years but engine that was installed after PO owner cracked the block is 9 yrs /360 of those hrs.

 

[Stinnett21]

My 2002 5.0 MPI has 1,618 hours. Still turns 5000 rpms runs like new. All fresh water trailered though.

 

[QBhoy]

Yeah but all of those hours were tapping the rev limiter, trimmed out testing your garage full of props....

I just hit 400 hrs, boat is 20 years but engine that was installed after PO owner cracked the block is 9 yrs /360 of those hrs.

Haha. There has been a fair bit of prop testing…but the overwhelming majority of the hours have been spent at either 1200 rpm or about 2500/2600 rpm cruising at around mid to late 20’s.

 

[QBhoy]

If the average speed of a car / truck is (say) 40mph, then 850 hours use would only be 34000 miles. I can understand engine components such as blocks / pistons / etc not lasting as long in a marine environment but why would a distributor only last the equivalent of 34000 miles?

Not sure. There was a service bulletin about these things on a few occasions