MD2030 problem

[marioxp]

Hello everyone,

I have a Volvo Penta MD2030 in my bavaria 36 2003. The engine was fully overhauled about three years ago and has run around 500 hours since then. It has been regularly serviced.

Recently I've noticed the following issues:

The engine is harder and slower to start, especially when cold, Starter works well and quickly.

When it finally starts, it produces some black smoke, not much, only noticeable at higher revs.

I have already replaced 2 out of 3 glow plugs, (the third one is hard to reach behind the bosch pump) but that didn't help much with starting.

Once running, the engine runs smoothly without vibration, but I can hear a sort of metallic knocking / rattling sound.

Has anyone experienced similar symptoms with the MD2030?

Any advice on troubleshooting steps or what to check first would be greatly appreciated.

Thanks in advance!

[Happysailor]

Hi,

Most of the times, black smoke is a sign of overloading which can be due to a too big propellor, much hull fouling in combination with too high fuel rack setting.

Assume you already checked the evident things like fuel filters, water in fuel, sludge in fuel lines etc etc..

With regard to your starting problem and rattling noise I am thinking first about valve clearances to be off, causing compression problems. This could also be another cause of black smoke as there is insuffient air to the fuel. To eliminate possible piston ring issues, you could take out your oil dip stick when running the engine and check if there is no pressure building up in the sump.

Depending on the running hours of your engine, your liners may have become a bit oval, which is stimulating blow by. Even when pistons have been out and ring replaced during general overhaul, this still can cause compression issues. (But then you would also have pressure building up in the sump)

Hope this helps with your deduction and quest for reasons!

[Keweetoo]

I had a similar problem with my MD2030C. Suggest you check the exhaust elbow is clear and pay particular regard to the heat exchanger mating surface which is vulnerable to pitting if there is any back pressure with exhaust water. It only needs a pinhole and the rear pre-combustion chamber can fail. This would be accommpanied by a drop-off in performance as well as smoky exhaust though you have not reported this so hopefully may be OK. We went through reconditioning injectors, compression tests, fuel pump tests until the only option was to strip the engine, possibly needing a new head and full reconditioning at which point we decided a better long term option was replacement with a Beta 30. This article from PBO June 2020 details the same problem we had.   https://www.pbo.co.uk/expert-advice/how-to-remove-a-marine-diesel-cylinder-head-step-by-step-64809/2

[marioxp]

I already wrote about the problem with the Volvo penta MD2030 engine, now I've checked a few more things and come to the following conclusions.

I've changed and checked all three heaters, changed both fuel filters, checked and cleaned the exhaust manifold, removed the air filter but the problem still persists. The battery is good and the starter is good because it turns over nicely and easily.

Engine has a hard starting but only the first time, if I turn it off quickly and start it right away, it starts without a problem, but if I leave it standing for 15 minutes, despite the fact that it's still warm, it has a hard starting. When it has a hard time starting, it throws out some black smoke, but it doesn't smoke when running, and it runs nicely, I haven't noticed that it has less power. I've driven it for a few hours and it runs nicely while driving.

What could be the cause?

[SYJetzt]

I would suspect a compression related issue. Maybe wear in cylinders/ pistons or valve clearances. A compression test will clarify this.

[elias]

What about the starter motor ? Do you have a spare to check it?

[marioxp]

I would suspect a compression related issue. Maybe wear in cylinders/ pistons or valve clearances. A compression test will clarify this.

Dear SYJetzt

This doesn't make sense to me because when the engine is running it works fine. And another thing is if I turn it off immediately after starting (5 seconds, the engine hasn't warmed up yet), the second start goes perfectly.

[marioxp]

What about the starter motor ? Do you have a spare to check it?

Dear Elias,

I have a spare one (old one) but I don't think the starter is the problem. The starter is 2 years old, and it runs fast and immediately.

I think the problem is in the fuel supply, that the fuel is starting to back up or air is getting in somewhere.

Because when I start the engine and immediately turn it off, it takes less than a second to start again, compared to the first start where it takes 10-15 seconds. Even when I drive for a long time, turn the engine off for 15-20 minutes, the engine is still hot, the engine has a hard time starting. So it doesn't matter if the engine is hot or cold, but the problem/difference is in the ignition whether it was turned off for a long time or a short time.

[Samoerai]

So I think you've answered your own question ;-) Follow the fuel line from start to end. You may choose your own start point, but it probably will be the last point on your list....

[Laysula]

A friend of mine had a similar problem on a Yanmar engine. Try as he might he couldn't find a leak, very difficult as it wasn't leaking out diesel only letting air in. he solved the problem temporarily by fitting a priming bulb just after the fuel tank and giving it a couple of squeezes before starting. Eventually he replaced the whole fuel system including uprating the filter to a Racor type and blanking off the fuel pump and fitting an electric one.