Smoking Volvo Penta MD 11C

[Pedersen]

Hi all.
I'm going through serious problems with my Volvo Penta MD 11C (1985) and need some advice.

First the motor was over-heating big time. The cylinders were reaching some 85 degrees (Celsius) on the outside. After trying all kind of things I eventually got the cylinder liners pressed out and emptied the galleries of huge amounts of salt and other sediment (it's raw water cooled).The rest of the cooling system has been cleaned and checked out with bits and pieces replaced and should really be as new. Also, I have been been quite thorough following the correct procedures in assembly. But... now the motor is belching copious amounts of grey-white smoke even when cold. Worse than before and even at low revs. It doesn't really smell of diesel just a bit of exhaust smell and not really any diesel on the surface of the water. The motor starts well even now in winter. So, it must be steam, I think.

The two cylinders on the motor are separate and have a facility to decompress one at a time. Doing this, I thought perhaps I could detect whether one cylinder had a faulty gasket (they're both new of course) or tiny crack somewhere around the compression chamber but no such luck. The amount of smoke or steam was just the same and at all revs.

I don't think there's enough heat anywhere else to produce this amount of steam when the whole system is still cold. So, what am I missing....? The procedure of decompressing one cylinder at a time should point in the direction of one cylinder having a problem I would think? But both is a bit unlikely - or...?

Any advice or ideas out there?

[Viking Sailor]

If drop in RPM for each cylinder is nearly the same when decompressed - check your exhaust.

[Charlie]

Did you try a leak down test? If I remember correctly the MDII has glow plugs and you may be able to find an adapter to perform the test that screws in. In the US you can pick up a decent tester from Harbor Frieght that might work. Here is a good video in case you have never performed a leakdown test https://www.ericthecarguy.com/videos...leak-down-test

I am going thru the same problem but cannot find an adapter to perform the test on a yanmar engine.

[Pedersen]

Reply to Viking Sailor: Could you be more specific? What part part of the exhaust system do you mean? Manifold and elbow are fine and water (and smoke/steam) is passing through the rest just fine. I think the RPM drop is about the same.

Reply to Charlie: The MD 11C do not have glow plugs.

[Viking Sailor]

It takes a lot of heat to get steam out the exhaust. The only source of enough heat is the combustion gas in the cylinders. Raw water leaking into a cylinder will generate steam. The chance that water leaking into both cylinders on a Volvo is small, and the engine continuing to run is even smaller. Thus, there will be a larger drop in RPM when lifting the decompression lever on the good cylinder.

Steam can also be generated when mixing the hot combustion gases in a restricted exhaust elbow or hose.

Also, make sure you are really seeing steam and not white smoke.

If I was in your place - I would pull the exhaust elbow and hose making sure that they are clear and intact. Then recheck the valve lashing's per the MD11 manual. Also, if you pulled the fuel pump - make sure that the injection time is correct.

At this point, your best bet might be to get a experienced Volvo mechanic to have a look at your engine.

BTW, I have a '78 MD17C.

Best of luck....

[Charlie]

If it does not have glow plugs then you need to perform the test thru the injector holes. A leak down test identifies the source of leaks in the engine. I had an MD II that I had to nurse thru two seasons while I accumulated the money to repower. Very solid simple to work on engine. Sounds like the compression is strong since it starts in cold weather.

[Pedersen]

Thanks guys!
The only indicater I have for steam is the lack of a pungent smell of diesel. It would be a lot simpler if it was white smoke. I'll check again when the weather clears (if ever!).
I'll also check the drop in revs again to rule out any one cylinder or injector to be at fault (the injectors have new nozzles and have just been checked and adjusted).
Finally, and depending on the result of the various tests I'll look at the govenor to check if everything moves freely. If that's ok I'll pull out the high pressure fuel pump and have it serviced or possibly find a secondhand one and replace it.
Maybe all will be well - I'll send a prayer to the great green volvo god...!

[Viking Sailor]

Another thing you can do is the carefully feel the along the exhaust hose to see if it seems excessively hot. If the hose feels hot then there is not enough raw water flow. (Duh) Oh, and don't forget to check your water lift.

The difference between white smoke and steam is that white smoke spreads out horizontality and settles out of the air, and steam rises quickly dissipating vertically. Also, there will be more steam when the air is cold then when it is warm.

[Pedersen]

Managed to check the motor running this morning despite the challenges of a bleak Danish winter!

I let it run at 1800 revs (max is 2500) for a little while and then decompressed each cylinder at a time. They dropped to excactly the same - 1300 revs on both cylinders. So, that should leave cylinders and injectors out of the equation.

The smoke is indeed horizontal but doesn't smell of diesel at all. When decompressed the smoke is belching out from each cylinder at a time. Still not really sure if it's steam or smoke but betting on smoke.

I have checked the exhaust hose a while ago and the cooling water spouting out aft - just luke warm. The elbow is as unblocked as new.
What you call the water lift, I assume is the hose from the manifold to the elbow reaching up above the waterline. It should be fine.

Next step will be to have a look at the govenor but I would really like to be sure about the smoke/steam. I'm trying to persuade a marine mecanic to have a look without charging a fortune. Labour costs are extremely high in this little country!

[a64pilot]

You check timing?

[Viking Sailor]

White smoke is normally a fuel problem. Either, a rich mixture, or dirty fuel.

A definitive way to check for dirty fuel is to run a couple of liters of freshly purchased and visually clean diesel through the engine. No smoke - dirty fuel.

A rich mixture is normally the result of incorrect fuel injection timing or bad injectors. Here are a couple of questions to help narrow down the source of the problem:

1) Did you remove the fuel injection pump from the engine?

2) You stated that the injectors were serviced - could they possibly be adjusted to the wrong specification?

3) Are the inlet valve clearances set to 0.30 mm and the exhaust set to 0.35 mm?

4) Is this the procedure you used to adjust the valve clearances?

Turn the engine over in the correct direction of rotation until the valves for one cylinder "rock". Then turn through a further revolution and adjust the valves for this cylinder. Do the same for the other cylinder. After a trial run, the valves should be readjusted while the engine is still hot.

[DougR]

When you dissembled the cylinders and liners, and reassembled everything, did you keep the liners, cylinders and under cylinder shims all in the same location? That is, #1 liner, #1 cylinder and #1 shims were returned to the #1 cylinder location on the block. Mixing up the liners and cylinders and shims can cause changes in the compression ratio on the individual cylinders.

On the MD11 engine, compression needs to be checked and readjusted by measuring the piston to cylinder head clearance whenever the liner, cylinder and or pistons are changed. This is fairly easy to do with the heads on the engine, and it's detailed in the workshop manual.

Erratic compression could be causing the smoke.

DougR

[Pedersen]

Thanks all for your responses!
Just a couple of replies to your postings.

The liners, shims etc. are (to the best of my abilities) reassembled correctly.

The fuel looks clean in the glass bowl of the water separator and the two filters are new.

I haven't touched the fuel injector pump or govenor at all (including the timing).
The injectors was adjusted by an authorised Volvo workshop.

I did have problems with the valves and the procedure: I was told the large valve is the inlet and the smaller one exhaust, ok fine. However, I couldn't get the workshop manual procedure working, so I adjusted the valves one at a time at max. clearance and re-adjusted with the engine warm.
I have a lurking suspicion regarding this because this is the only part of the fuel system that have been touched since the problem appered.

[Viking Sailor]

The exhaust valve is the one nearest the transmission. It is valve that is located under the oil fill opening in the rocker arm cover, and what the decompression lever holds open when it is raised. I have adjusted the valves on the MD17 many times using this procedure without a problem. What part of the adjustment procedure are you having a problem with?

Also, you might want to check the air intake filters after running the engine to warmed up a little bit. Shut it down and remove the air filters and see if there are any signs or smell of smoke around the air intakes, or in the air filters. While the air filters are off restart the engine to see if the smoke is reduced. Don't run the engine very long with the air filters off. (Alternately: Give the air filters a really good cleaning and reinstall.)

The only spec's I could find on the injectors are that the opening pressure = 17.0 Mpa, and the setting pressure, new spring = 17.8 Mpa. There is a note in the service manual that cautions to: "Never fit a copper washer under the injector, this will cause engine to smoke."

[Sputnik]

I guess you have the manual:

Cylinder Leak Tester Petrol Engine Compression Leakage Leakdown Detector Kit UK | eBay

Have you checked the cold start button is returning to off? It is a button that pushes down on the top of the injector pump. It should pop up once the engine starts, but if sticky may not be doing so.

Neil