Replacing an impeller and cup on OMC outdrive... use a grease?

TimberwolfFXDL · Dec 18, 2010

First off, eye candy:

When reassembling, should I use grease of some sort inside the cup so the impeller has a little help on first start up? I imagine it will help reassembly as well...

Lou C · Dec 18, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

The OMC shop manual says to use gear lube like you use in the drive, you could use dish soap too but it might evaporate before you get it started....

HT32BSX115 · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Yeah, and If you want to be "green", use vegetable oil.....

havasuboatman · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

I use that spray silicone because it doesn't attach the rubber like petrolium products will. It also doesn't matter if it dries.
Looking at your impeller, there is something you need to do before you reinstall that pump housing on the drive.
Make sure you have all of the broken pieces. If there isn't enough, backflush the P/S cooler to get the missing pieces of that old impeller out of it. Those little pieces tend to block the water passages. The restricted water flow makes your engine run hot and/or overheat.
The P/S cooler is the first thing the water hose that comes thru the transom goes in to and has two large water hoses (one on each end) and two smaller hoses that attach to the same side.

TimberwolfFXDL · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

p/s cooler? as in power steering? I don't believe I have power steering.

havasuboatman · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

If you don't have power steering, you don't have that cooler. If you are unsure, look at the front of the motor on the port side below the Alternator (on v8 motors) If there is a pump with a removable cap on it, that is the P/S pump.
You can also look behind the motor at the place your steering cable attaches to the transom and tiller arm. If there are 2 hoses attached to that piece, right next to each other, you have power steering. Most of the Cobra drive packages included P/S.

Gary H NC · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Looks like whoever had it apart before used white calk for gasket sealer...

Bellows adhesive or Permatex Aviation gasket sealer works well to hold the rubber sealing ring in place on the housing.
I use a little gear lube or grease when i install one.

I would be sure to back flush that system...too much missing off of the old impeller.

TimberwolfFXDL · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

I think most of what was missing was all balled up in that right side cavity in the first picture, but I will certainly backflush it.

Fun part is, the impeller was bad when I bought the bought apparently. I took it out on its maiden voyage (under my posession) and got about 400 yds off shore when it overheated. I had to limp it back to the launch, and by then, the motor was toast.

The bad: I had to replace the motor.
The good: shouldn't be any pieces in the new motor.

Lou C · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

There are a couple of tips to keep in mind when doing a Cobra impeller. It's easier than some, but you have to make sure that metal cage is in there tight, it can shift and then block the water passages. The shop manual says to glue it in place with OMC gasket sealer. Also, the gasket that fits in the slot for the housing can get out of place when you install it, the gasket sealer helps keep it in place. The fitting for that little hose that goes from the housing to the upper unit has to be open for it to prime easily from what I heard. I usually change them once a season but I've saved the old ones and they look like new. OMC gasket sealer on the bolts will help with not having the bolts seize in place. The other place you might find impeller bits is in the thermo housing.

TimberwolfFXDL · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

I ended up ordering a new housing. The old one had melted from the heat. you can see in the first picture where the cage rotated clockwise (as viewed) a bit. I didn't trust it, and for $20, a new one is cheap insurance.

proshadetree · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

I ordered a kit from e bay to do my cobra. It had the impeller, housing and all the gaskets. This had to be the easiest impeller I have ever changed. It went so fast I knew I did something wrong. For cheap insurance a lot of people install a clear hoes to tell if they have water flow and check it on start-up. Would have saved you an engine if you had it before.

TimberwolfFXDL · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

proshadetree said:
I ordered a kit from e bay to do my cobra. It had the impeller, housing and all the gaskets. This had to be the easiest impeller I have ever changed. It went so fast I knew I did something wrong. For cheap insurance a lot of people install a clear hoes to tell if they have water flow and check it on start-up. Would have saved you an engine if you had it before.

But you can't see that hose under the cover?

Or are you talking about a different hose?

LAC_STS · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

proshadetree said:
I ordered a kit from e bay to do my cobra. It had the impeller, housing and all the gaskets. This had to be the easiest impeller I have ever changed. It went so fast I knew I did something wrong. For cheap insurance a lot of people install a clear hoes to tell if they have water flow and check it on start-up. Would have saved you an engine if you had it before.

Yea if you look around you can get the which kit with the housing, plate, and impeller for about the same price as the kits that just come with the plate and impeller.

I dint think you would need a clear hose to check the flow. Just unhook the hose that feeds the t-stat housing.

TimberwolfFXDL · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

My kit came with the cage, plate, impeller, gasket and o-ring. It was this one:

I think I paid $25. Had I known better, I would have opted for the kits that came with the housing too

LAC_STS · Dec 19, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

I think I paid $35 for the kit I got with everything you got plus the housing. It saves you from having to scrape the old sealant out of the housing too.

I bought the kit you bought the first time too. Then I saw the housing one.

proshadetree · Dec 20, 2010

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

Re: Replacing and impeller and cup on OMC outdrive... use a grease?

You replace a hose on your engine then while doing pre-inspection look to see if water is flowing. I check mine before start up for fuel or oil in the bilge then crank it up and check hose. button it up and boat away.

sethjon · Dec 20, 2010

Re: Replacing an impeller and cup on OMC outdrive... use a grease?

TimberwolfFXDL said:
First off, eye candy:

When reassembling, should I use grease of some sort inside the cup so the impeller has a little help on first start up? I imagine it will help reassembly as well...

This impeller has to be in there more than one season. Every other season replacement is reccommended, but every season is smarter and ultimately cheaper on your wallet.

Replacing an impeller and cup on OMC outdrive... use a grease?

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