Servicing an MD7a

[TrevorR]

We've got 2 md7a's in our cat I have been told they need servicing every 50hrs. they have had 40hrs to date. This year they will be used alot more so we thought before summer arrives service now rather than latter. The filters, oil.derv are guninue Volvo parts. I have been told other filters are just as good and much cheaper, someone suggested Renault filters,has anyone any thoughts on this?

[Ahi Andy]

I have about a 30 year old MD7A and I don't use Volvo brand filters. Volvo probably just puts their name on some other manufacturer anyway.

Here are the brands and numbers I use, but any good quality filter will probably do fine. I just matched what was on it when I got it.

Oil Filter - Fram PH3614
Fuel Filter - Napa 3373 (at Napa parts stores)

These are in US but I'm sure wherever you are there are comparable filters and cross reference charts. I've also read on several posts that you should use the most "primitive" oil that you can find. Around here that is Rotella non synthetic. Don't waste the money on expensive synthetics that may not be good for the engine.

The book says to change the oil filter with every other change but it is pretty cheap so if it has been over a year do it anyway. If you figure out how to get the oil filter off the engine without getting oil everywhere let me know.

Wow, two of these things to mess with. You make me feel lucky I only have one!

[Play Actor]

I just replaced my faithfull old MD17c, a 3 cylinder version of the same engine, after 32 years and 5000 hours. The engine is in great shape, but the transmission needed a rebuild, and I couldn't find the parts I needed. I never used Volvo filters - always used a Fram PH16 oil filter, and used a Racor fuel filter. Left the old Volvo filter in place, but never changed it, as the Racor was much finer. Servicing every 50 hours was a nuisance, but it did keep the engine happy.

[GordMay]

Greetings and welcome aboard the CF, TrevorR, and Ahi Andy.

[barnakiel]

MD7a here:

oil filters - any aftermarket brand (Sierra, Wix, UFI, stc.),
diesel filters - the same story,
diesel prefilter - CAV type with separator,

(You can look up any aftermarket site for their cross-table references. Wix has one, e.g.. UFI has one too.)

Oil - specs. as per engine manual, we use mineral, cheap, and change it often unless the boat is cruised extensively with heavy use of engine.

We do not follow any schedule for oil changes - just check the oil and you can see if it calls for a change.

We change transmission oil once a year.

We replace oil filters every second oil change. We change diesel filters - prefilter - at least once a year, engine filter - every second time.

Air filter we clean once a year (flush with diesel and dry).

Check raw water impeller, belt tension, coolant level (if you have fresh water cooling), etc..

Cheers,
b.

[TrevorR]

Thanks you guys that was just the info. I needed. Here in the uk we are advised to add something to the fuel because modern fuel has a lower sulphur content to accomadate moderm engines which rev higher. as we all know MD7a's are "chug chug" engines i.e. low reving. I'm no mechanic but it seems if you look after them the will look after you.
Remember BOAT break out another thousand!

[barnakiel]

The only thing I ever add to diesel is some amt of bacteria killer and then only when we use the boat little.

b.

[Kit_L]

Just changed the oil on my MD7 today, and changed the filter. My boat (Compass Northerner) has the MD7 mounted as low as possible to keep the prop shaft angle low, so oil changes are via suction pump using the dip-stick hole, rather than via sump-plug drain (I have never had a yacht; this might be the case for all of them).

Re, not spilling oil when changing filter, I just packed the space all around with rags, and made sure I tilted the O-ring side of the filter upwards as soon as I could; the little that spilled was caught completely by the rags.