Volvo Penta 3.9HP

[m1taylor]

In buying a second hand Avon Redcrest, got one of these thrown in. I have not even heard of this outboard before. Does anyone know the basics like whether it is two stroke, what mix it takes, and whether it is air or water cooled? Are they any good?

 

[FullCircle]

Air cooled , lever throttle which is effectively on or off. No gears. Noisy, smoky, ancient and no spares to speak of.
Mine starts 2nd pull every time I have tried it. It is covered in rust, no idea how long it will last, but it is at least 30 years old now.

 

[nyx2k]

i borroed one of these engines in the summer to move my 12ft dinghy about. very noisy and it ran on 50-1. i ran it flat out nearly all day and it never complained. it must have been 30-40 yrs olde

 

[VicS]

Aso appeared as a Crescent and an Archimedies Penta. I had (well still got but dont use) its slightly larger brother the (5hp) Volvo Penta 51. That has a remote fuel tank as does the longshaft VP39. and a reverse gear. As said noisy, but quieter than a Seagull. Very basic like a Seagull but with a much smaller life span.

50:1 fuel mix but being air cooled it should be better using oil for 2 stroke garden machinery etc (Volvo P. said 2% ie 50:1 if using VP outboard oil but 3% ie 33:1 if using other brands).
Plugs were Bosch W 240 T1, NGK B7 HS or Champion L81. The gap should be 0.02" (0.5mm).
The points gap is 0.012" - 0.016" (0.3 - 0.4 mm) and the ignition advance setting is 0.70"- 0.87" (2.0 - 2.2 mm)

Gear box oil is (like most outboards) EP90. Capacity approx 60cc

I always had problems with the plug fouling at idle speeds so always carried a spare and a plug spanner. For that reason I stuck to 50:1 fuel mix rather than 33:1. I never got round to trying an air cooled engine oil though nor did I really give a hotter plug a serious try. (I bought an Evinrude instead!) Maybe I should have simply leaned out the idling mixture a bit. Once running though it would run all day without missing a beat.

Use it while it runs but you won't get any spares for it so chuck it and buy something different when it packs up.

Oh I had to strip and clean the carb after a friend borrowed it and got water in some how. The main jet is the brass hex headed bit under the float chamber that also retains the float chamber, the slotted head on the top in the boss marked BING is the idle mixture adjustment and the hex head near it (and vertically above the main jet) is the idling jet. Thats what got bunged up in mine. If you remove the idling jet make sure you locate and do not lose the tiny fibre washer that it seats on. It may stay in the body or it may come out with the jet. The idle speed adjustment should be obvious but is tucked down the side a bit out of sight.


PM me if you need any further info from the owners manual or if you want to use the electrical output ( bit odd that is) if yours has one.

 

[m1taylor]

Hi, Thanks for that really full reply. I await the engine when it comes with the dinghy and assess it. Sounds like just the sort of engine to leave on a boat - unlikely to be stolen, and if it was, not too much of problem! Probably worth not using TCW3, but putting in ordinary cheap two stroke oil for hotter burning air cooled engines which may avoid the plug fouling.

 

[neil_s]

I have one of these - it can get my inflatable on the plane. Corrosion in the leg is the big problem. The engine is air cooled, but water is circulated around the exhaust manifold and then into the leg from a little scoop just behind the prop. The pipe carrying the water up the leg corrodes and water supply diminishes. You can keep it going for a while by running full bore and only throttling back for short periods, but eventually you will start getting burning smells as the rubber bearing in the steering swivel gets hot. Then you have to take it apart - that's the dificult bit!

Neil