TOPIC: Flying Scott Powehead R&R Rookie Mistake

I completed my Scott 60 powerhead R&R and replaced the side gasket which was bad. At the same time I replaced the powerhead gasket between the powerhead and the motor plate. Amazingly enough I reassembled everything properly, set the timing and she fired right up. And then the poewrhead began to get real hot. After it cooled a bit I re-fired it and gave a quick inspection of the tell-tale. It was peeing out of the motor very nicely, but the water in my test bucket was not hot. That's when I noticed that there was no water in the exhaust.


This picture is from last summer, see the water shooting out the back? Thats water after its run through the motor and is expelled with the exhaust.

So last night I pulled the lower to inspect the impellers (Scotts have a cooling impeller and a baby impeller for the "bail-o-matic".) The large impeller was in good shape but the little one was torn up so I replaced it. Then with the lower still off, I took the exhaust cover off and shoved a hose with a high pressure nozzle in the water pump line. I was expecting the water to shoot out the hole in the bottom of the powerhead but it was barely a trickle up into the water cavity but the water was shooting out the tell-tale hole in a 12 foot long stream.


My guess is the powerhead gasket is misaligned (cant see how that could happen, but...) or that I must have filled the water hole with grease/gunk when I was cleaning the motor plate. Tomorrow I'm going to order a new set of gaskets and remove the powerhead again.


However when I had it apart the bottom crankshaft seal looked a little suspect so I'm going to justify my need to take it apart again so I can replace that seal.


Disclaimer: This picture is from a 40hp powerhead which is identical from the bottom to my 60hp powerhead.

(1) Does anyone know if that seal comes off by removing the four bolts (red arrow) on the bottom? (Please say Yes.) Or am I gong to have to crack the cases open? (Please say No.)

The blue arrow points to the spot where the water comes in to the motor. Something is blocking this. R&R Fail!

You mention that the little one was torn up. Before you rip apart the head again, is it possible part of the impellor got into the system and is blocking it? Did you try to reverse flush the system?

Might be worth a try before you do all that work again. Hard to believe that the grease would get that solidified in so short a time, or that there would be that much the pressure from the impellers wouldn't just push throgh it. Or, quite honestly, that the gaskets could be that far out of alignment!

Either way, hope you find an easier soultion than another rip apart!

Good news! No, you don’t have to split the cases to change the seal, but you have to pull the retainer. The seal retainer is machined to project into the block and is sealed with an O-ring. It also has a lip towards the outside to prevent the seal from blowing out, so push toward the seal towards the inside of the retainer when you remove it.
Be careful that you pull the retainer straight out and not cock it in the block. I use an old knife blade to get it started. Tap the blade into the parting surfaces on opposite sides of the seal retainer until you get it out far enough to use two screwdrivers.
You can get the seal and O-ring from Discount Marine, or you can usually find them locally.
Shims on the alternator end retainer set crankshaft endplay so you shouldn’t have to worry about that.
The Bail-A Matic impeller can’t get into the cooling system when it self-destructs. The water it scavenges from the bottom of the boat is pumped out into the exhaust chamber. I doubt that would be the problem. I do agree with whatsleft that it’s unlikely you could have plugged it with grease or anything like that, and the gasket couldn’t shift that far.
It’s possible is that the base gasket didn’t have one of the water ports punched out. That sandwich gasket has two holes and only the one is used for the water from the pump. If the gasket cutter didn’t get a clean cut, the punch out could still be there. It would mean that manufacturers Q.C. missed it. You then saw the one hole, but didn’t notice it didn’t line up with the outlet. Unlikely, but possible.
Another possibility is that some later 60 HP had thermostats. If yours has one, and it decided to fail closed, that would slow down the flow considerably.
Good luck tracking the problem down.
Don

Thanks guys!

>but didn’t notice it didn’t line up with the outlet.
I hate to admit it but I didn't even pay attention to it and I'm hoping that's it.

>Another possibility is that some later 60 HP had thermostats.
I dont see any in my parts diagrams... if there was one, where would it be located?

When I pull the four bolts on the retainer (#37) It will need to be pryed out (with equal lifting pressure under all sides so it comes out straight)... is this correct?

Just got off the phone with Laings and I ordered another set of gaskets and the lower seal. (I called Discount Marine but he was out of stock for the exhaust cover gasket.)

I told them about my water problem and Laings said the hole for the water inlet can be in slightly different locations (up to 1/2") away and that I might have to punch the gasket to open the water hole. (Like I said Rookie mistake.)

So I will give it another try and it will be good medicine to replace that lower seal, so why not? Every time I take the motor apart I learn something new. Thanks for all your help!

When I pull the four bolts on the retainer (#37) It will need to be pryed out (with equal lifting pressure under all sides so it comes out straight)... is this correct?

That's correct.

FF thanks for the tips! So here's what I did after work tonight. Remove all accessories and the powerhead 2 hours.

The water hole in the gasket...


The water hole in the motor plate...


Whoops missed it by 1/2" and I didn't pay attention. Got new gaskets and the lower seal coming in so I'll put it back together next week. At least I'll be able to sleep tonight.

Everyone makes mistakes when learning. Good thing you where smart enough to watch it close and diagnose it accurately before taking it apart! I managed to drill about 16 screws through the bottom of my boat a misaligned gasket is good work!

Shacomm
Well, I think I know what happened. You were blind-sided more than you made a rookie mistake.
In the pic below you see that the base gaskets I buy (I believe they came from Discount Marine and are original OEM gaskets) have two holes in them. I have at least six of them and they all have two holes.
The base plate in the pic is from a 75 HP motor. Notice the position of the hole in the base plate. Then take a look at your 60 HP base plate I re-posted just below. The holes are a lot more than a 1/2 inch apart.
Here is what I think (emphasis on I think) happened. When the 75 was developed more cooling was needed and Scott found a restricted area in the base plate. They designed a new base plate with the hole moved backwards to provide room for a bigger passage. You can easily see the larger passage in the pic.
Then they re-designed the 60 HP gasket to match the new hole position and started to build motors.
Eventually somebody, probably someone in the Scott parts department, realized that if they punched two holes in the gasket it would work in 60 and 75 HP motors and they only had to stock one part number.
They continued to build 75 HP motors with the single hole until they ran out and then switched to the two hole gasket.
Now, fast-forward fifty years. Someone decided there was a need for a Scott 60-75HP gasket sets and collected patterns from various sources.
Somehow they ended up with a single hole 75 HP base plate gasket and copied it. It can't work on a 60 HP without modification.
I suspect Liangs don't even know about the problem if they told you the water oulets vary a 1/2 inch and you have to be smart enough to punch it out. That takes it out of the rookie mistake column and moves it to parts supplier error! If this is the case then they owe you a big apology!
If you need to add a hole to the gasket you have and don't want to shred it, clamp two pieces of wood together (oak is best) and drill a couple of 1/4 in. holes through to bolt the pieces together. Then drill through with the drill for the size of the hole. Remove the bolts and clamp the gasket between the pieces. Then drill through gasket using the hole. If you don't have a drill big enough, drill as big as you can and do the rest with a rat tail file.
Both of us learned a lot on this one.
Don

Nice! Can you flip that base plate over and shoot a pic? I can see the water tube goes into the round area but I was kind of wondering how the water gets over to the hole. I know it'll get there... I'm just curious I guess.

The beauty of Fiberglassics is the next guy will see this and have a heads-up. I've learned more from the crew here than one could imagine. Its really cool to have the ability to ask and share. After-all there not that many Scott mechanics out there.

When I talked to Discount, he had the base gaskets but not the exhaust. I have no ill will towards Laings, in fact I'm glad they still have Scott parts.

Thanks again!

Got the new gasket (with both holes in it) and put everything back together and I've got cooling in my powerhead again! I've got some new smoke to deal with so I'm starting a new thread.