Stupid engine question

[sneuman]

I have a one-cylinder Volvo Penta MD1B in the boat a boat recently. I can''t think of a more basic question to ask, but as I know nothing about engines, here goes:

I put the compression lever down to start, should it stay down while in operation. I''ve been doing it that way simply because lifting it again stalls the engine, so I assume that''s bad. I just want to make sure I''m not wrecking the engine.

Also, no matter how hard I try (and I have tried!), I cannot get the dipstick out. Can the oil level be checked by looking into the oil hole?

Many thanks,

Scott

[Jeff_H]

First of all you need to pick up a good diesel engine primer because these are extremely basic questions and if you own a diesel long enough you will need to know a lot more about it to use the engine safely. A good book on the topic is Nigel Calder''s ''Marine Diesel Engines''.

When the compression relief valve is open it allows air into the cylinder. This effectively reduces the compression of the engine to near zero making the engine easy to turn for the purposes of getting the engine up to starting speed when hand starting the engine or starting the engine on a low battery. Since a diesel needs high compression to ignite the fuel, it cannot actually run with all of the compression relief valves open. In normal operation the valves should be kept closed and you should have no reason to open them.

You can only read the oil level at the dipstick. The oil filler opens to the valve gallery and a probe through the filler hole cannot reach the sump (bottom of the engine where the oil is collected). You need to get your dipstick out. On many marine engines the dipstick is screwed into place although that is unusual on small diesels where they usually just have a rubber stopper that is integral to the dipstick. If you are having that much trouble extracting the dipstick, there is a chance that you are actually trying to extract something other than a dipstick. At some point soon, you will also need to extract the dipstick in order to change the oil in the engine.

Jeff

[fourknots]

I had an MD-2 which is the same engine with 2 cylinders.

The engine should start without using the compression lever - it just makes it easier to spin. There is usually no reason to use it in regards to starting, so leave it down. You haven''t hurt anything doing that, you''ve just taken away the compression and the engine won''t run.

And yes, the dipstick is screwed in. I usually had to use pair of pliers to remove it if it had been awhile. There is a seal on the dipstick by the threads - make sure it is not hard. If the seal leaks air into the oiling system, it can''t build pressure and your low pressure alarm will not shut off. Damage will follow. If it''s not sealing, replace it with an o-ring until you can get the right part (I used an o-ring for 2 years and just made sure the dipstick was very tight.

The dipstick screws into an oil strainer, make sure your aren''t removing this when you unscrew the dipstick. You''ll see.

You can still buy the tech manual from Volvo, though it''s expensive, like everything from them.

Calder''s book is good.

[VIEXILE]

The cylinder in the Volvo MD1 and MD2 engines is fairly big, and, in colder climates, raising the compression lever for a few strokes to get things going often helps. Otherwise your belts tend to scream or you just can''t roll it over. Push the starter button and move the lever down and she''ll fire. There''s an adjustment on the underside of the valve cover to make to assure the lever is doing something and not forcing the valve open while in the down position. The Volvo manual that''ll work is probably around $30.00. If setting the valves, make SURE the measurements in the manual are correct magnitude. I wasted several hours one day due to a Swedish engineer''s mis-placement of a decimal point (which is shown as commas in the manuals). Easy engine to rebuild - at least as far down as the transmission. I use the rubber rings that come with the Racor replacement filters for the dipstick ring. KW

[sneuman]

thanks all. this reassures me a bit. i''ve been starting with the lever down and leaving it down, so i guess that''s ok. with the dipstick, i guessed that it might be screwed into the block too, but the ring at the top (which looks like a simple pull ring, but apparently isn''t) hits the injector as I try to back the stick out. WD-40 and much pressure has not managed to free the pull ring, so i''m a bit stuck on that front.

[pirateofcapeann]

Scott:

You need help! Perhaps, more help then you can get on Sailnet!

The compression lever stays down unless you’re trying to manually crank start your engine, a thankless task if there ever was one! One sticks the business end of the crank handle over the nub of the camshaft, lifts the compression lever and starts cranking! Once you think you''ve got the flywheel spinning fast enough, you reach with one hand (still cranking for all you’re worth with the other) and slap down the lever. This is when you find out that you were wrong and the engine doesn’t quite make it through the next compression stroke! It forcibly starts to turn backwards against your effort and just to show you who''s the boss, it tosses your sorry mortal body across the cabin.

Trying it single-handed, I was only successful at it once. I had a sense of pride as I sat crumpled in my bilge, sweating profusely with blood soaked knuckles and sore wrists and forearms as I watched my MD7A ticking over in submission. Never again!

As for the dipstick, it is quite possible that it is a screw on type, but my Volvo didn’t have one. No, you’re not going to be able to tell anything from looking down that tube, except that the inside of that motor is a mighty dark place!

Haul that lump of cast iron out of your bilge and get an outboard!

Pi

[windancer1]

sneuman,
I have two, yes two md2bs and the dipstick screws out. As has been stated, make sure it seals good. Also when you change the oil, screw the screen out also and clean it.

Dave R.

[sneuman]

Thanks Pirate,

But I found a bloke yesterday who owns the same engine and got the lowdown from him. What I thought was the oil dipstick was in fact something else entirely. So, at least I know where to look.

Cheers,

Scott

[captrad]

You''re fine. A diesel engine ignites the fuel by compression, not spark like a gas engine. That''s why the engine will not run in the decompression mode. I use the decompression mode if I am working on the diesel and have to turn it over by hand. As far as the dipstick goes, you need to get it removed. you can''t measure the oil by looking into the filler. Keep in mind that the oil is in the oilpan under the engine while the filler is at the top.