Volvo Penta md2020 exhaust 100% blocked with white gunk

[Bregts]

Hi all,

Maybe someone has seen this before?




After arriving in New Zealand I had to leave the boat on it's own for almost two years. Before lay up I changed the oil and flushed the engine cooling system with fresh water and salt away. So for two years the engine wasn't touched. Engine has 2300 hours on it and maintenance was done every three months when cruising.

About a month ago I tried to start the engine but without luck.
I have been troubleshooting for a month now and still can't get the engine started but today ..... I took the exhaust manifold/mixing elbow off and it was 100% blocked with some white gunk on the engine and the exhaust side. See attached pictures.

The white stuff was relatively easy to remove so that left me with just carbon built up and a 10mm diameter hole. Just for testing purposes (I know I have to replace the mixing elbow) I mounted it again and tried to start the engine but still with no luck.

I have tried all possible ways of venting the petrol system for a month now and I do get a steady stream at the injectors so I don't think it's that. replaced diesel filter twice and I do feed the engine now from a funnel high up on the wall just to make sure. New diesel also.

I have two new batteries. 1100CCA together so that should be fine for a 600cc diesel.

Air intake is fine.

I do get white smoke coming out of the air intake after crank tho.
I took the valve cover off today and white stuff what limited to the exhaust side and didnt built op in the engine and everything looks ok there.


Does anyone has any clue what the white stuff might be?
Anyone an opinion on how the engine cranks in the attached video? I'm out of options besides taking the engine head off now which I rather not do.

Any input is greatly appreciated.

IMG_0149 (1).MOV

[Bregts]

Cranking video: CrankingVideo.MOV
Does this link work for anyone else? It doesn't for me?

[olaf hart]

Looks like calcium deposits from salt water.

A bit of a worry it’s going back inside the manifold.

[Bregts]

Originally Posted by olaf hart

Looks like calcium deposits from salt water.

A bit of a worry it’s going back inside the manifold.

Indeed. The day before lay up I motored for about three hours to the shipyard, no problem at all. I don't see that happening with a blocked exhaust or water going back into the block so the white deposit must have happened while unused on the hard
I used this engine nearly daily while cruising for 3.5 years and it never skipped a beat, no smoke or anything strange right up to putting her up.

[davido]

Video plays audio only for me.

I am confused by your statement "The white stuff was relatively easy to remove so that left me with just carbon built up and a 10mm diameter hole." Are you saying there is a remaining carbon buildup that closes the passage to 10mm, or there is a 10mm water injection port?

Does the cranking of the motor sound different (more labored) than when you parked the boat 2 years ago? Significantly different? What did the cranking sound like when you tried it a month ago?

[sainted]

The white smoke coming from the intake indicates that the valves aren't seating. You probably have white gunk on the valves or valve seats. There's also a good chance that the piston rings are no longer seating, giving you poor compression.

It seems likely that you had a cooling water leak somewhere that was slow enough that it didn't prevent the engine from running as long as you ran it every day. Thus when you stopped running it, the coolant (either fresh or raw) leaked into the exhaust manifold and evaporated, leaving the white powder. Yes, coolant leaves a white powered when it evaporates.

You can try pulling the head and checking the valves, but it would be a shame to go to all that work and find that the rings are bad. Bite the bullet and pull the motor.

Good luck.

[captstu]

I am guessing that one or more of your pistons has rings that are not seating. Conventional wisdom is you have to pull the engine. That is not always true.

While you were likely to end up pulling the engine, I would remove one or more of the injectors and put 10 mL of oil in each injector you remove. Seal it back up try to start the engine. If the engine starts immediately you know the problem is you’re a piston rings are not sealing.

Since your engine was running well, you may be able to break loose the stuck rings by repeating the oil process in each of the cylinders one at a time. If the engine run slightly longer each time you do it you’re on your way to the repair. Just keep putting in a while a few cc in each cylinder until the engine starts and runs on its own.

Cheaper and easier than a total engine rebuild and it might be just as good.

[senormechanico]

I have the identical engine and it cranks way faster than yours in the video.
A few years ago, my exhaust elbow got stuffed with carbon and was easily cleaned out.


The crankshaft momentarily stops dead several times in your video.
Is your battery voltage up to snuff? Just something to check.


With blowback from the intake it looks like airflow restriction causing back pressure and slow cranking because the compressed charge has nowhere to go.
Check exhaust passages to the valves.


I would think if rings weren't seating, it would crank more smoothly without much compression.

[SV Bacchus]

Maybe I am missing it but said you pulled the manifold and the elbow, was the white stuff in the manifold as well and if so, all the way back to where it mounted to the block?

If so, did you look into the ports in the block and was the white stuff inside the ports in the block as well? If so, I'm afraid I agree with the others to pull the engine.

[mark maulden]

Pull the valve cover and see if you have any bent pushrods. If so, pull the tappets to be sure none are broken. Can do that with a magnet at the end of a flexible coil rod. This would indicate stuck valves and the head comes off

[thunderhoof]

The blocked exhaust looks exactly like the one from mt MD2030. The problem is that the exhaust / raw water mixer elbow corrodes through and then injects water directly into the exhaust manifold, where the buildup occurs. I tried to have the manifold cleaned out, but this revealed that the manifold had a leak into the fresh water cooling jacket. One new manifold plus stainless raw water mixing elbow later all is well.

[piloto]

Marvel mystery oil

[PaulMarion]

Unfortunately you have one cylinder without compression the other two have some. Most folk are not aware that if they leave a motor sitting for long periods of time oil will dry from around piston rings, leaving the rings to loose their seal and thus compression. Also as suggested by others valves are possibly stuck as well. If you can remove injectors and add a few squirts of engine oil via an oil can into each cylinder, re-fit the injectors and try again you may have a chance. Also as mentioned by previous posts it would be smart to remove the rocker cover and inspect for any valves/ push rods not moving up and down = stuck valve/s as well. To leave a motor long term, you must add oil to each cylinder, after removing injectors, and turn the motor over so that oil coats bores and rings. Doing this overcomes the acids left in the cylinder from combustion. Valves are harder to treat as they have no oil around the seats and therefore any that are open will rust over a period of time resulting in leakage and therefore also loss of compression.

[Perna]

Just my thoughts:

How far in did the white stuff go? Are the exhaust ports now clear right down to the valves?

If the white stuff got to the valves there is a good chance they are not seating properly. If you can get some oil onto the valves this may get them sealing enough to get some combustion going. Not too much oil, you don't want to fill the cylinders and cause any hydraulic locking as oil is not compressible.

White smoke is partly combusted diesel so you may not be far off.

What is the white stuff anyway? Crystalline salt from evaporated sea water? Some sort of biological gunk growth?

If it is salt well it wouldn't bode well for any surfaces it came into contact with. Pretty corrosive I would guess.

I would agree the next major step would be to pull the head if you can get to it.

Let us know how you get on and good luck.

[jimbunyard]

Originally Posted by Bregts

Hi all,

Maybe someone has seen this before?

Attachment 176125
Attachment 176126

After arriving in New Zealand I had to leave the boat on it's own for almost two years. Before lay up I changed the oil and flushed the engine cooling system with fresh water and salt away. So for two years the engine wasn't touched. Engine has 2300 hours on it and maintenance was done every three months when cruising.

About a month ago I tried to start the engine but without luck.
I have been troubleshooting for a month now and still can't get the engine started but today ..... I took the exhaust manifold/mixing elbow off and it was 100% blocked with some white gunk on the engine and the exhaust side. See attached pictures.

The white stuff was relatively easy to remove so that left me with just carbon built up and a 10mm diameter hole. Just for testing purposes (I know I have to replace the mixing elbow) I mounted it again and tried to start the engine but still with no luck.

I have tried all possible ways of venting the petrol system for a month now and I do get a steady stream at the injectors so I don't think it's that. replaced diesel filter twice and I do feed the engine now from a funnel high up on the wall just to make sure. New diesel also.

I have two new batteries. 1100CCA together so that should be fine for a 600cc diesel.

Air intake is fine.

I do get white smoke coming out of the air intake after crank tho.
I took the valve cover off today and white stuff what limited to the exhaust side and didnt built op in the engine and everything looks ok there.


Does anyone has any clue what the white stuff might be?
Anyone an opinion on how the engine cranks in the attached video? I'm out of options besides taking the engine head off now which I rather not do.

Any input is greatly appreciated.

Attachment 176123

I have 2 MD2020s; they're both probably about 10 years older than yours.
The heat exchanger/manifold on mine is cast iron. In your picture, the mounting surface for the mixing elbow appears to be aluminum. If this is the case, the white material could be oxides of aluminum or some such combination of electrolytic product, especially if the gasket between them has a graphite component in it.

If the corrosion' is easily cleaned off, and the sealing surfaces are still good, and there is no evident damage further into the manifold, I would not suspect that the damage has extended to the valves.

That little engine is trying hard to start; the video played both audio and visual fine for me.

As SM says, the first problem is getting the engine up to proper cranking speed. The most common problem for an engine that has sat for a while is a bad ground, though there can be a bad connection on the positive side that causes the same symptom. The rapid slowdown exhibited when cranking shows either a connection, cable or battery charge problem, all which must be fixed first.

Not so common is corrosion between the starter and the block, or between the starter solenoid (the one on the starter itself) and the starter, which is best addressed by removing the offending part, cleaning the mounting surfaces and remounting with some sort of anticorrosion agent. A quick fix can often be had though by loosening and tightening the mounting bolts..

Once you get the engine spinning fast, you may find it starts with little further action; it's going to be rough for a bit but will likely smooth out as everything reseats itself.

If it still won't start, try a tiny squirt of starting fluid, with no glow plugs, whilst spinning the engine over. It should attempt to start, and may start and run, smoothing out as it goes.

If not, more drastic measures are called for, beginning with the simplest and proceeding to the most complex.

That the engine ran fine when laid up would lead me to simple things, provided no water was ingested into the top end.

If the engine starts and continues to run rough, or has problems like weird or no throttle response, the fuel pump likely has sticking internal parts and needs to be cleaned. The pump on this engine is fairly simple; if you are experienced and patient, it is possible to do this yourself. If you're not, you should be able to find someone who is...