Need to identify part...

[WVagent]

Hi everyone! Long time reader, first time poster.

I have a 5.7 Lt Mercruiser V8. Long story short, had to have the motor completely rebuilt for not properly winterizing. I'm a few weeks from completion and the gentleman working on my boat said that I need a shift interrupter.

However, I was ready to pull the switch and order one on Ebay but confirmed with him before I did to make sure it was the correct part. He informed me it was not. He said that there are two different switches, one on the cable and one attached to the motor. I apparently need the one on the motor but I cannot find any such switch or part number to order.

Can anyone direct me to what he might possibly be referring to?

 

[Bt Doctur]

Re: Need to identify part...

the shift interupter switch is mounted on the stbd riser with the shift cables. points ign and TB IV have it wired to supply a ground to the ign. TB -V uses it to supply 12v to the computer to stumble/stall the motor. The newest type can be wired to provide the ground.

 

[thumpar]

Re: Need to identify part...

There is only one shift interrupt switch. There is a neutral safety switch in the control. Maybe that is the mixup. Is he sure it is the interrupt switch and not the lower shift cable?

 

[wrench 3]

Re: Need to identify part...

Do you have a serial number? What is the part number of the "wrong" switch?

 

[WVagent]

Re: Need to identify part...

Unfortunately I don't have any serial number/part number. I don't even know what it is he's referring to.

He keeps saying it knocks the engine out of gear when shifting, but he's positive I don't need the shift interrupter I showed him. He said it's a little square box that mounts to the manifold with wires leading in to it.

I have looked at wiring diagrams until I am blue in the face and I can only find one thing labeled shift interrupter.

I wonder if it may be the neutral safety switch you mentioned. I will check with him tomorrow. Thanks guys, this is driving me crazy!

 

[achris]

Re: Need to identify part...

I'm going to ask a few questions.

1. Since Merc have been using the GM350 since the 60s, can we at least get an idea of the year....
2. Are you sure this is a Mercruiser and not an OMC? (could be referring to the EAS module of an OMC)
3. Is the guy working on it actually familiar with how a MARINE engine shifts? Because from what you say, it sounds like you know more about it than he does... The shift interrupt switch is what helps bring the drive out of gear, not some other switch... (maybe it's the reverse lockout switch... :noidea There is no switch on the engine... Maybe an electric shift drive? Refer back to question# 1...
4. What is the problem? What is it doing that it shouldn't be or what is it not doing that it should be?

Chris....

 

[Bt Doctur]

Re: Need to identify part...

the ignition module mounts to the port riser and the shift interrupter mounts to the stbd riser.
guessing the motor has no spark and he suspects the ign module is bad.

 

[achris]

Re: Need to identify part...

the ignition module mounts to the port riser and the shift interrupter mounts to the stbd riser.
guessing the motor has no spark and he suspects the ign module is bad.

Maybe.... But how does the ignition module help the drive shift? :noidea:

If he does suspect the module as bad, then OP needs to make sure he's gone through the proper diagnostic flowchart PROPERLY! They are too expensive to be buying as an "I think"....

Chris......

 

[Bt Doctur]

Re: Need to identify part...

" He said it's a little square box that mounts to the manifold with wires leading in to it. "
I would hope he knows the difference between a igniton module with wires (plural) and a shift interrupter switch with 2 wires. Does he mean intake manifold or exaust manifold

 

[wrench 3]

Re: Need to identify part...

The serial number should be on a sticker on the rocker cover or on a metal tag near the bell housing.

 

[WVagent]

Re: Need to identify part...

His inability to describe or name this part has me concerned. He has rebuilt my motor!

I pulled up a wiring diagram and I have to believe he's referring to an ignition amplifier/module.

Still waiting to hear from him so I will update everyone once I do.

 

[WVagent]

Re: Need to identify part...

I'm going to ask a few questions.

1. Since Merc have been using the GM350 since the 60s, can we at least get an idea of the year....
2. Are you sure this is a Mercruiser and not an OMC? (could be referring to the EAS module of an OMC)
3. Is the guy working on it actually familiar with how a MARINE engine shifts? Because from what you say, it sounds like you know more about it than he does... The shift interrupt switch is what helps bring the drive out of gear, not some other switch... (maybe it's the reverse lockout switch... :noidea There is no switch on the engine... Maybe an electric shift drive? Refer back to question# 1...
4. What is the problem? What is it doing that it shouldn't be or what is it not doing that it should be?

Chris....

It's definitely a Mercruiser, I have all the paperwork on it. Alpha One V8. I do have a serial number for the engine if that would help?

I took it to him to have my engine completely rebuilt. Had a cracked block! Bad consequence for not properly winterizing.

He tells me he's done but needs this one last part.

 

[achris]

Re: Need to identify part...

Find out EXACTLY why he needs a new ignition module... As I said earlier, they are expensive, and replacing them on a suspect is not a good option. Ask him if he has run through the TB-IV troubleshooting flowchart. If he looks blanky at you, find another mechanic, fast!!! But my firm belief it that if he thinks the module helps shift, don't even ask, just pay him what you own him, and find a new mechanic....

Chris.....

 

[Speakrdude]

Re: Need to identify part...

Hmmm...

 

[WVagent]

Re: Need to identify part...

I now have the part in hand. I'm pretty sure it's an ignition amplifier. Here is a pic.

 

[Bt Doctur]

Re: Need to identify part...

that would be the ign amplifier. A nose hair from a snail would be easier to find. A cracked block would not normally damage that unit.
There is a specific test procedure to check them. Most tend to convert to the Delco EST system to save money

 

[tazrig]

Re: Need to identify part...

That is the ign amplifier but has absolutely nothing to do with shifting. I would take Chris's advice and get to a new mechanic as fast as you can. :fear:lane:

 

[WVagent]

Re: Need to identify part...

that would be the ign amplifier. A nose hair from a snail would be easier to find. A cracked block would not normally damage that unit.
There is a specific test procedure to check them. Most tend to convert to the Delco EST system to save money

Are you saying it would be cheaper to replace everything with the Delco EST system? Does that mean new distributor cap, wiring, ignition etc.?

 

[Bt Doctur]

Re: Need to identify part...

Would you spend $400.00 for one? PM me if your interested .

I`m saying if you can find them ,there expensive, Even ebay ones run well over $250.00 and you have no guarantee they work.
You must use the specific trouble tree to test these amplifiers, you can`t guess about a no spark condition. For all you know the tach is bad or the shift interrupter is wired backwards grounding out the ign system.

 

[Bt Doctur]

Re: Need to identify part...

If you like, mail that one and I`ll test it for you.