Oil injection pump?

[henryb]

I have read in these pages that this part is one area of concern. After they get to this age, they have a tendency to fail.

So I hunted down a replacement part, matched numbers. It came with a copper bushing and a replacement gear. I was sure that I read somewhere that it was in fact the gear that fails because they were plastic? But mine came as a metal gear???

Does this mean I don't have the correct part or was there an upgrade?

Any ideas? I will try to include a picture.

 

[Bkopsick]

I have the newer engine but from what I've read on this forum, the new replacement for the older gear was upgraded from a plastic gear to a more reliable metal gear.

 

[Ankeneyou]

You won't use that gear, just the pump itself. There is a plastic drive which you'll use off of your ski to run the pump.

They very seldomly fail, it's typically the 3/32 oil injection lines that fail if never replaced. Proper maintenance and it should last forever.

Where did u buy the pump though and how much? I'm considering a new pump just for my build just because the entire ski is now new again.

 

[henryb]

I picked this up on eBay for $40.... After calling my local Merc dealer and they quoted me over $400(CDN) for a new one.

There were some that were cheaper, but I picked this one because they say the part is tested, cleaned, lubed and had the gear and bushing. They also said it came off a 2000 Challenger with a 210HP... Which is exactly what I have.

 

[Ankeneyou]

Ah, my bad you have a merc. Calling [MENTION=16022]Dr Honda[/MENTION]

 

[jamepc]

The plastic gear you are referring to is on the crank shaft and cannot be replaced unless the motor is torn down. That plastic gear is driven by the metal gear in your picture. The existing one is also metal.
It's unlikely you would have to replace the metal gear since it drives a much softer plastic gear. You might as well pull out the existing gear and inspect it since you'll have the pump off, it just pulls straight out of the hole.
The part that tends to wear down with age is the plastic gear on the crankshaft, and that's usually due to an overheat condition.

 

[henryb]

Thanks for the update, it all makes sense. Is there a good way to inspect the plastic gear with just the pump and metal gear shaft out? Things to looks for?

 

[jamepc]

I looked at my existing plastic gear with a bore scope but you can only see a small portion of it and really can't tell much at all.

 

[henryb]

Hmmm, that really doesn't help too much then... So I'm really not that much ahead, unless my pump unit is about to fail.

What kind of job is it to get to that plastic gear? And is there a metal version of that gear as an upgrade that someone mentioned in this thread?

 

[jamepc]

It's a complete engine removal and teardown to get to the crank shaft. Well I guess you wouldn't have to take the heads off. Don't think it's worth it unless you plan on rebuilding the motor anyways. Many people would say that if you knew the motor never overheated then the original gear should be good. With that said, Mercury new gear has been redesigned and improved. If you're not sure, some folks would say to just pre-mix.

 

[Dr Honda]

The plastic gear you are referring to is on the crank shaft and cannot be replaced unless the motor is torn down. That plastic gear is driven by the metal gear in your picture. The existing one is also metal.
It's unlikely you would have to replace the metal gear since it drives a much softer plastic gear. You might as well pull out the existing gear and inspect it since you'll have the pump off, it just pulls straight out of the hole.
The part that tends to wear down with age is the plastic gear on the crankshaft, and that's usually due to an overheat condition.

He wins the prize for today.


So, yes... the plastic gear is on the crank. (deep in the engine) When you over heat the engine, that bushing swells, and puts more drag on the metal gear, and it has a tendency of taking out the plastic gear.

The other issue is that the gear is 2 parts, and on a rare occasion... the bolts break.

The "New" gear is a fiber filled composite. The original gear was simply a thermolpolymer.


FYI... when I did my rebuild... my plastic gear looked great !! SO it's not always the culprit when there are issues. (But I put in a new gear to be safe)


Here's my crank. You can see the plastic gear toward the left side.