Milky gear oil and pressure testing the gearbox

I was changing the gear oil for my Selva Madeira outboard and noticed that the color of old oil was somewhat milky which indicates some presence of water. The color of the oil was not white but gray.

Milky gear oil.

I have noticed that the outer oil seal on the propeller shaft does not look particularly healthy, the lip of seal is pushed outwards, maybe the water is going in there ? I have changed the oil already once during the summer, I did not use new O-rings in the plugs, I know that is not a good practice.

The outer oil seal does not look healthy.

I wanted to do a pressure test for the gearbox, Dangar Marine has posted a nice video how to do it. I used very inexpensive parts to assemble a simple pressure test rig.

Parts list:

- gear oil pump (Biltema)

- fuel system pressure gauge (Biltema)

- one T-connector 

- bike hand pump

- hose clamps

I did a check for the test rig by raising the pressure to 10 PSI and put the connectors under water to see if there were any leaks, everything looked good and the rig was able hold constant pressure for several minutes.

A simple gearbox pressure test rig.

Selva Madeira has three oil drain holes, the yellow connector fits only to one of them.

I don't have Selva service manual so I decided to do similar test that was done in Dangar Marine video for Yamaha 50 gearbox. I increased the pressure to 10 PSI and there was not drop in the pressure after 30 seconds, not even after 60 seconds so I think that the seals are working quite well (at least when the motor is not running).

The only oil drain hole which accepts the yellow connector.

The gearbox was able to hold 10 PSI over 60 seconds.

I'm not sure why there was water mixed in the gear oil if the pressure test gives good results.

I plan to replace at least the oil plug O-rings and consider replacing the lower unit oil seals which is a harder task.

Solas Amita 3 losing paint

The winter is coming so it was time to take my boat from the water.
After inspecting the motor I noticed that the Solas Amita 3 (11"x17") aluminium propeller has lost some paint from two blades. The areas were in the same section of the blade and of similar size.
The low pressure side of the propeller looked good as new.
I'm wondering what has caused this, last season I used Solas Amita 3 11"x16" and it survived the whole season without any paint issues.

I have raised the engine three holes so the propeller operates closer to the water surface, sometimes the motor sucks air and hits higher RPMs and then suddenly the grip returns.
So I guess the ventilation can be the root cause, I suppose cavitation should cause problems on the other side of the propeller or at least closer to the tip of the blade.

Paint (or coating) is missing from two
blades on the high pressure side.

Everything looks good on the low pressure side.

Selva Madeira power trim problem

I was at sea and suddenly noticed that Selva Madeira 40 power trim was going up but not down.
I tried also the tilt switch on the motor but it didn't work either. I was able to get to the harbor slowly but surely.

When I pressed the down switch there was a clicking noise coming from the relay but the trim motor was not spinning at all. I did some study on Youtube, once again thanks to Dangar Marine, there is a nice video about outboard trim-tilt relays.

You can see Selva Madeira trim-tilt relays in this diagram (number 55). The Selva part number is 8515070 and the relay is manufactured by Hella and the product code is  4RD 931 680-01.

I opened the engine cover and checked the relays visually, nothing special spotted my attention.
The plan was to take relays off and switch them in order to see if one of them was faulty.
I used a small flat screwdriver to detach the relays and put them back in different positions.
For my surprise the trim started to work fully, I was able to trim it up and down.
I removed the relays again and tried to clean the connectors but they were in quite good condition. I sprayed some WD-40 to the relay base also.

Hard to say what was the root problem, maybe some conductivity problem.
This was a cheap fix! 😁

Selva trim-tilt relay part #8515070 (5-way relay 40A)

Trim-tilt relays connectors

Relay base

Testing over the hub cleaver on Selva Madeira 40

Today I made a test drive with Signature 10.5"x 18" over the hub cleaver propeller.
This was the first cleaver I have tested and compared to Signature semi-cleaver the difference was quite dramatic. On the first try I was not able to get the boat to plane, the outboard was screaming 6300 rpms which is 800 rpm over the maximum and still the boat was doing only 8 knots or so.

I was able to get the boat to plane when I moved myself to the center of the boat and the outboard was at WOT. With all other previously tested propellers the boat typically starts to plane extremely fast.

I guess the over the hub design, smaller diameter and Selva's quite large gear case is not the ideal combination but still I'm having hard time to understand why the hole shot is so bad.

Once the boat was planing the overall feel was quite good but still I noticed that the outboard was revving much higher than compared to Solas 11 x 17 round ear propeller.
I know that cleavers should be run very high, I don't have a jack plate and the outboard is mounted to uppermost position. However I was able to hit 6000 rpm without much effort so I think the problem not fixed by raising the engine even more. I think the propeller could have more pitch, maybe 20".

The top speed was a couple of knots slower compared to Solas 11" x 17" but I didn't want to push Selva over 6000 rpms.

Installing Hill Marine Signature over-hub cleaver propeller

I'm continuing the never ending quest for finding the optimal propeller for my Selva Madeira 40 outboard. I'm mainly interested to get the maximum top speed.

I have been reading lots of propeller theory and finally wanted to install a real cleaver propeller and see how it behaves.

I ordered 10 1/2" x 18" Signature cleaver for Yamaha 40-60 hp from eBay, this propeller has over-hub exhaust which means that exhaust gases go to propellers blades instead of going through the hub. In theory this kind of design should provide less drag and help with the top speed. On the other hand the hole-shot can suffer, I was willing to take that risk.

Signature 10 1/2" x 18" cleaver

Installation was very easy as I have previously installed Signature semi-cleaver propeller, I used the same XHS hub kit with slightly modified Yamaha thrust washer.

The weather was very windy so I didn't want to go for a real test drive, I only made a small test in the harbor. If I compare this propeller to Signature semi-cleaver 11 1/4 x 18 the difference is huge based on my limited tests at trolling speed. The semi-cleaver behaves more like normal round ear propeller whereas the cleaver seems to have very poor hole-shot, I raised the motor RPMs over 2500 and the boat was going only 5 knots. I think this mainly due to over hub exhaust, I'm a little afraid will the boat even plane 😅

Tiny-Tach tachometer blackout and reset

I was at sea enjoying great weather with my Selva Madeira when I noticed that Tiny-Tach tachometer stopped operating, there was nothing on the screen and pressing the button did not help.

I have been using Tiny-Tach to monitor Selva Madeira RPMs, I have been very satisfied with it,
I bought some cheap tachometers from China but was not able to even install those due to too short wires. The only thing I was a little skeptical with Tiny-Tach is that it has an internal battery which cannot be charged or replaced. I have read that the battery should last several years and my Tiny-Tach was less than a year old. Outside the season I have kept Tiny-Tach indoors to avoid freezing temperatures.

I contacted Tiny-Tach UK because that's where I got the Tiny-Tach with an extended sensor cable. The customer service from Tiny-Tach UK has always been great and now I got instructions how to reset the Tiny-Tach:

First lift a corner of the front sticker and peel it back.

To the right of the select button there is soft 'potting'.

Using a straightened metal paperclip or something similar probe the soft potting.

The object is to short the battery and reset the display. It may take a few attempts to reset.

It should go through a set up display and revert to zeros.

I followed these instructions and after a couple of reset attempts the device started to show zero hours. They even mailed me a new sticker to put on the display! 👌

The root cause of the problem remains still a mystery, it was extremely warm day so maybe the device overheated, this is just my speculation. The Tiny-Tach representative said this can be caused by too much red sensor wire or if the white wire has a poor or non-existent ground to engine block.

Resetting TinyTac using pincers.

Ready to install new cover sticker.

Good as new!

Selva 50HP Madeira 684cc MAGNUM Boat Performance Spark Plugs revisited

I wanted to test again Brisk racing spark plugs (NOR14LGS) now that I have upgraded to larger carburetors and lifted the Selva Madeira outboard to the highest mounting position.

I'm comparing against Champion L78 which is one of the recommended spark plug types by Selva owner's manual.

I'm only interested in the top speed gain and after careful testing there was a 0.4 knots difference favoring Brisk spark plugs. This difference is so small that it might be caused by weather, how high the outboard was trimmed and the differences in GPS accuracy.
I also found that my Selva Madeira was not trolling well, the engine stalled many times maybe due to too low RPMs. I raised the idle RPMs to 1200 but when the gear was on the RPMs dropped sometimes below 800 and Brisk spark plugs were not able to keep the engine running. With Champion spark plugs this did not happen.

To sum it up I'm not planning to use these Brisk racing spark plugs because I want the outboard idle and troll properly. Champion spark plugs are also very inexpensive.