Anyone have knowledge or experience with Volvo MD21A or MD21B to share?

[Vino the Dog]

Anyone know what thermostat to use in the MD21A?
Parts lists show the official one out of production and I don't want to open up the heat exchanger until I have a new one in hand. Is it any different than a normal automotive type and size?

[ullar]

Hi,
We have MD21A installed on our Amel Euros 41. It's an original installation from 1978 and we don't know about engine hours as hour meter has been changed at lest twice, and as third owner of that boat we don't have good records. However, our MD21A is going strong - even revs, just a very little smoke and with stable oil level.

But now we got a low oil pressure warning lamp light up when going on ~2000 RPM. Symptoms are as follows:
- normal oil level
- normal engine temperature
- when starting from cold the lamp comes up only after few minutes when engine has heated up slightly
- there is no change in engine sound when lamp comes up

Does anybody have any ideas or suggestions?

I suspect worn oil pump gears and that would mean finding the replacement pump and removing the engine to get access to oil sump. However, there seems like some access to the pump from the side of the engine, and some adjustment possibility to the pump. Does anybody know how that functions?

Any help is greatly appreciated.

Cheers,
Üllar

[ullar]

OK, was able to borrow a pressure gauge from friendly mechanics at local mechanical workshop. Replaced the oil warning light sensor with gauge and found the oil pressure being normal. What a relief! Would check the connection at the warning light tomorrow. I probably just need a new sensor.

[DougR]

I have an exhaust elbow for sale for an MD21A or B which was used for the inboard/outboard engine or for a close coupled exhaust. That is, it aims down at a steeper angle than the standard inboard elbow. New.

Available Norfolk, VA. $75 & shipping.

Also sea water pump body w/cam & cover plate for MD21A. (no shaft or support housing) Decent condition. .....Jabsco pump. $25.00 & shipping

PM me if interested for picture, etc.

DougR

[Vino the Dog]

New MD 21A question:

Does anyone know where to get the Lumatic CRH 30 low ohm resister used in front of the glow plugs? OR, is there a different resistor that will work in it's place? Mine failed and can't start without it. Dead in the water!

[DougR]

Go to " danotherm.com" and search for low ohm ceramic resistors.

They make a CRH 40 which will probably work just fine for you, but might require a few more seconds of glow time than the 30 did.

DougR

[Vino the Dog]

Thanks, Doug, found that site and see it. Now I just have to find out who sells them.

Also still interested in how to make one, mainly to know how they work. Reading forums on old tractors, lots of people have made their own resistor out of a piece of Nichrome wire, and others have changed out their glow plugs for ones that run on 12 volt and don't need the resistor. Apparently glow plugs typically run around 0.9 volts and the resistor is to drop the system voltage to the plug requirement. If this is the case, there is no reason one could not make a resistor so long as you know the size and length of wire to get the needed voltage drop.

If anyone knows about this, please comment.

[Lulu ind]

Hey, anyone knows where are zinc anodes in Peugeot Indenors coolant system? Blind or stupid but i just cannot find them...

[DougR]

For the Volvo Penta versions of the Indenor, the zincs are:

MD 21A- one zinc on each of the square heat exchanger end covers (port & starboard)

MD 21B - one zinc in the exhaust manifold front cover plate, none in the heat exchanger.

No zincs in the engine oil coolers.

One zinc in the Volvo Penta MS3 or MS4 gearbox cooler if the VP gear was installed. All other gearbox coolers may or may not have zincs.....check them out

DougR

[Erichotdoc]

I have a Hallberg Rassy 35 Ramus with the exact same problem. Did you replace the sensor? If yes, did it solve the problem? Thank you.

[ullar]

Originally Posted by Erichotdoc

I have a Hallberg Rassy 35 Ramus with the exact same problem. Did you replace the sensor? If yes, did it solve the problem? Thank you.

That was actually a bit funny story. I checked the connection to the warning light and that was what I found out: it wasn't an oil pressure warning light but a warning light for one of my alternators that is connected to charge the starting battery at the present. Why that misunderstanding? Well, I've an old boat and texts on an engine control panel are almost unreadable. So, I mixed up those two. I took off the malfunctioning alternator and found one of the coal brushes not fitting the ring properly. Had to cut that brush a little narrower, and my alternator is back to normal for now.

What a stress for almost nothing!

[ullar]

New question: I've got water in engine oil. And a lot of it. I pumped out 1,5 l bottle from the bottom of the sump and about a liter of that is water. That was after an oil change, 2 hours run and 2 days sailing on rough sea.

Also, it seems to be raw water. Firstly, coolant level doesn't change and secondly, it tastes salty.

Where can raw water get into engine oil in this engine? Already checked raw water pump and engine oil cooler - no leakages there.

Advice please.
Üllar

[boatman61]

Originally Posted by ullar

New question: I've got water in engine oil. And a lot of it. I pumped out 1,5 l bottle from the bottom of the sump and about a liter of that is water. That was after an oil change, 2 hours run and 2 days sailing on rough sea.

Also, it seems to be raw water. Firstly, coolant level doesn't change and secondly, it tastes salty.

Where can raw water get into engine oil in this engine? Already checked raw water pump and engine oil cooler - no leakages there.

Advice please.
Üllar

Head Gasket.. remove top end and fit new gasket.
But.. I could be wrong..

[ullar]

Originally Posted by boatman61

Head Gasket.. remove top end and fit new gasket.
But.. I could be wrong..

Thanks, Boatman!

My engine was rebuilt recently and during that was installed a non original, locally produced (Perth, Australia) head gasket. So, trouble from that direction is not impossible.

However, MD21A is not direct (raw water) cooled. How would raw water get to head gasket in that case? Also, there is NO white smoke of water vapor from engine exhaust.

[DougR]

If you are confident that there is no problem with the sea water pump seals and the oil cooler, then the next thing is the exhaust system and the exhaust manifold.

Two days sailing on a rough sea may have allowed sea water to back up the exhaust and enter the engine, seeping past the piston rings and into the sump.

Same goes for the exhaust manifold. I recall that the MD21 had a sea water cooled exhaust manifold, and if it corroded thru, sea water may have gotten into a cylinder that way. Also, the gasket on the front and rear of the manifold could allow sea water into the exhaust portion of the manifold.

DougR