New prop doesn't fit - trim tab is in the way

**zmoz** · 08-28-2003, 04:31 PM

I bought a new prop this morning for my '74 150hp inline 6 mercury outboard. Went from 19 pitch to 21. Now the damn thing doesn't fit...the trim tab is in the way! What do I do? Do they make different size trim tabs or something?

**mxz** · 08-28-2003, 04:56 PM

You can get a flat one without the tab or just saw your tab off. I don't think they really do much anyways except for corrosion control.

**zmoz** · 08-28-2003, 05:04 PM

I'm glad you said that...I just spent the last half hour cutting it off.

Now I've got a different problem...the inner round part of the prop...the cylinder that the blades attach to...is to long. When I tighten down the prop nut it won't spin, because it is too tight. Is this the wrong prop?!?

**VELOCITOY** · 08-28-2003, 05:28 PM

HEY ZMOZ...You need a different thrust washer by the sound of it...If you know what type of prop it is, post it & I'll bet one of the gurus here will probably be able to give you the part number you need to make it work...These guyz know their ****e...

...

**baddjonny** · 08-28-2003, 05:35 PM

try the thrust hub from the old prop bet you have the same problem I just had on a old outdrive the new thrust hub is thin and fit's on a tapered shaft the old style has a much longer thrust hub with a square sholder and using the new one let's the prop go back too far and hit the carrier cover cap the old hub should work your problay using a new flow torq 2 hub.

jon b

**zmoz** · 08-28-2003, 05:58 PM

I tried the washer from a different prop - I don't know what it was from but it came with the boat. It was much thicker, and I thought it would work, but when I tightened the nut down it was still too tight. I think the problem is that the old prop would go inside of the lower unit a little bit, the newer prop has a bigger diameter and does not go in. Did I get the wrong prop?

**MarkHP** · 08-28-2003, 06:25 PM

What is the diameter of the gear case?

**zmoz** · 08-28-2003, 06:28 PM

Originally posted by MarkHP
What is the diameter of the gear case?

I haven't got the slightest idea...how do I tell?

**MarkHP** · 08-28-2003, 06:35 PM

Is the prop binding on the inside edge of the gearcase or the back face of the prop/gearcase. If it is the inside of the gearcase where the pop fits check for nicks and dents. If it is the back face then the thrust washer is too rhin for the prop.

**MarkHP** · 08-28-2003, 06:38 PM

I had a similar thing happen when I got a new prop. The thrustwasher was just a little too thin , about 1/16th inch. I added shim washer and all was fine. I was fortunate that the shim washer was splined otherwise it may rotate and cause wear on the thrust washer.

**MarkHP** · 08-28-2003, 06:43 PM

I guess I should read your post a little closer. you say the new prop is not going into the gearcase and the old one did a little. What is the diameter of the two props where they go into the gearcase?

**zmoz** · 08-28-2003, 07:00 PM

Originally posted by MarkHP
I guess I should read your post a little closer. you say the new prop is not going into the gearcase and the old one did a little. What is the diameter of the two props where they go into the gearcase?

Yes, the old prop is slightly less than 4", the new one is slightly more than 4 1/4".

**MarkHP** · 08-28-2003, 07:22 PM

Yup. That's it you have the wron prop. The new one is for a 4 1/4" gearcase. Measure your gearcase where the prop fits in, this is the size you need, usually a 3 1/2". Where did you get the prop?