Mercruiser 5.0 - Maintenance - Help and luck needed....

[connolk]

When we dewinterized our boat at the start of the summer we encountered a number of issues.
The steering was very stiff, there was a terrible grinding noise, and basically things were not running smoothly!
I booked the boat in with the marina mechanic for a dianosis, who proceeded to pull together a $3400 estimate for the work required!
Since this was about 50% of the value of the boat, and about $2500 more than I had available to get the boat running!
Living in the PNW, where we have only about 40 baoting days a year, I decided to take things into my own hands!

So, I started with the steering!
The mechanic had diagnosed the cable or the actuator!
After some googling I found an actuator for $160 (a MASSIVE reduction) and a cable for $110.
Before buying them both I decided to disconnect the two to see if I could isolate the issue!
Lucky for me it was the cable!
I got the part number off the cable, ordered a new one off the net, and installed it myself!

The noise was diagnosed as a gimbal bearing issue (we had previously suffered high water).
I googled this, and decided it was beyond my new found mechanical skills!
I did order the parts online at a saving of $100 but allowed the mechanic to do the hard work!

Then finally we had a working boat.....for a few days at least!
Last weekend we were out, and when we pulled anchor to head back to the marina the boat would not start!
We got towed to shore by a friend, and I set to googling the issue again!
I diagnosed the starter motor bindex (you could hear the starter motor spin, but not engage).
I pulled the starter motor, which upon further googling I found was a cheap Chinese unit (Aqua Amp is the manufacturer).
I bought an OEM rebuilt starter locally and installed that this evening.
Boat started first time!

However, the boat feels underpowered (a V6 bayliner was easily able to keep up with us, in a 5.0L V8, under full throttle).
I want to change the distributor cap, plugs and wires and have a couple of questions:

1) Do I need to set the plug gap? I bought the plugs recommended by my mechanic (41-BPR6EFS) which I believe are pre-gapped. I have read these could be 0.35 or 0.45 hence my concern!
2) I've read I will need to file down the plug socket. Does anyone know if this is the case!
3) How tight should I tighten the plugs? What torque?
4) I've read a lot about firing patterns? How do I go about replacing the distributor cap?? I know I have to be very careful about the wires....any help or pointers would be greatly appreciated.

Thanks in advance!!

Ah....the joys of boat ownership!

Kevin

 

[NHGuy]

Re: Mercruiser 5.0 - Maintenance - Help and luck needed....

There is an image around here of the shape you'll want to grind down the socket to. I'll find it. Without the ground down socket the plugs often break. The rotor under the distributor cap is stuck onto the distributor shaft with locktite, a mechanic's adhesive. When you remove the rotor it's done with 2 screwdrivers used as levers under the edge of the rotor. Then put a drop of the same stuff on the shaft and slide on the new rotor. Don't use too much, it should not run down the shaft.
My plugs came in at the correct gap, yours probably will too. A gap gauge is cheap, I'd recommend getting one and checking the new plugs. You just finesse the gauge between the electrode gap, if it doesn't fit there is a little slot in the end of the gauge which will slide over the curved ground electrode. Bend it a bit and recheck. If the gap is too big you can tap the ground electrode on something solid to close down the gap.
It's really important to retain the correct plug wire locations. A simple way to change them is to take em off the old cap 1 at a time and put em right on the new one. If you are going to do new wires do the same thing. By the way the cap has marks for which wire goes to which cylinder. Buy only original equipment caps & rotors. The aftermarket stuff stinks & doesn't last. If you get ignition wires I can say I had great results with some aftermarket stainless core ones.