Hi,

I am currently considering purchasing an '85 Turbo Diesel 740 (5 speed). I already have a Volvo, so I know about a lot of their quirks, but diesel in general is something I don't know that much about.

What is involved in maintaining these, beyond normal Volvo stuff? Will I have a hard time finding parts? Are the oil filters harder to come by? Winter is cold here in Michigan, and I know you used to have to be very careful to warm a diesel up properly before it could be driven. What will I have to do for a diesel motor?

Also, what are common problems with Volvo diesel motors that I should look out for?

FWIW, my 85 D24T 740GLE wagon rated a AW-71 when no ZF22HPL or the better manual M46 conversion was available because I really liked the vehicle. It needs only a few extra tools to keep going, the injection timing dial indicator being the main one to purchase or make an adapter for the pump and use a cheap dial indicator. The other tools: a couple of you-bent wrenches, a steel dowel pump locking pin, and a metal cam locking plate, and most of all, a maintenance mindset. Much of the maintenance is the same as for VW, BMW, and Audi diesels. All my engine problems were not engine caused rather have been induced by others-fueling-gasoline-instead-of-diesel or by ignorant mechanics at both dealer and independents, that is , buy the Volvo D24 manuals and do it all yourself if you get this unique car. Good luck.

I've had diesels and turbo-diesels for many years and had to learn them the hard way after getting shafted by an "expert" over a water pump. They are wonderful cars to drive with a powerband that actually fits right if you have the manual transmission. As everyone else here has said they can be outright expensive to work on unless you can find a VW mechanic with long gray whiskers and can still see or you have the skills to work on a rather complex diesel engine with no room for errors. These things have rubber cogged drive belts for the overhead camshaft and injection pump, no index keys on the cam itself and must be timed with the proper tools, these alone can set you back half a grand alone should you buy them outright. Glowplugs come in 3 pairs and you need them all to start especially in michigan, even 2 cold cylinders will make it very hard starting at -10F.

Now for the good stuff
At 100k miles treated well it will go a LONG ways if you take care of it, that means a steady diet of Mobile-1 oil and change the timing belts. These engines like to rev and you get some serious kick after 2500 RPM when the boost comes on, the thing will go like a rocket to 5 grand and still get some good milage figures. Many here claim to get around 30-35 MPG, I get into the high 40's and have attained over 50 MPG a few times running skinny tires. I would expect nothing less than 30 MPG in mixed driving and if the car is a stick you're going to have a time keeping your foot off the accelerator as these things are fast for a diesel.

Things to do
Change that timing belt, I don't care what the previous owner says and I won't discredit him. They are cheap insurance any way you look at it. Also change the oil and go with Mobile-1 synthetic, if you can locate a Fram PH-977 filter use that one as its a monster filter with lots of surface area and doesn't bypass when cold as its internal bypass is set to around 35 PSI. It will hang down a bit further than stock so be sure to check if its going to become a road hazard. If the car starts without a plug-in heater right now without any blue or white smoke I would assume most of the glow plugs are working. Do a compression check and look for pressures over 500 pounds, anything less is suspect and under 475 I would consider a ring job in the near future. Last but not least change the coolant and flush that baby, give it a D24T enema with the garden hose heater core and all and when refilling DON'T use that Dex-Cool crap go with the old reliable antifreeze. A hose set if you're so inclined will set you back a few hundred bucks because of the special shapes and lack of demand. I had to make my own lower hose using copper pipe and rubber hose junctions to make it to the thermostat housing, it sits on the water return side. It was my fault for letting a clamp rub through in the first place but glad I did as I went to silicon hoses and made my own.

Starting out in the morning is going to take you longer if you really care about the cars engine. Don't just start it and take off, you should allow the temp to rise to the normal position on the gauge plus another 5 mins to make sure everything is oiled up and stable, these engines suffered badly from wall wear. Another thing that puts them in the grave fast is short commutes, if the oil never reaches operating temp it doesn't do its job and again you end up with accelerated wear so plan on at least a 15 minute drive on the highway, the longer the better and when you do get destinated allow another few mins to allow the turbo core to cool down so the bearings dont coke up. Other than that the D24T is an absolute blast to drive. The Brickboard FAQ regarding diesels means nothing if you have a passion for taking care of good machinery. I wouldn't put the D24T in the same leauge as a Mercedes diesel but then again you're going to win the race on a freeway entrance going against a MB 300TD if you're driving a stick. Automatics on the other hand I won't comment on, I had one and converted it to a stick!

There are several diesel owners on this forum myself included that can give you advice or help should you need it, first and foremost get the Volvo Green Book on the turbo diesel engine, they come up every now and then on flea-bay and they are about the most essential tool you will need for the car along with a GOOD breaker bar and torque wrench that goes to at least 350 foot/pounds. This one's for the crankshaft bolt and dont even think of using torque wrench wrists, its gotta be done right the first time!

Got any other questions Im sure someone here including myself will have an answer for ya!

Badge988

Unless you have a liberal minded VW diesel mechanic around, or plan on spending about $500 in special tools and factory manuals to work on it properly, steer clear. If that doesn't scare you off, they really are nice engines.
You would really need to gete a compression test done on it before buying to make sure it will start next winter ( cheap trick for getting rid of bad diesels is to wait till warm weather to sell and let the next guy find out next winter )
Do a search at the bottom of the page, you'll find volums on the subject.
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale

I'm the guy selling th 1985 740 turbodiesel. I parked it in my garage this winter and used the block heater - it started fine with temperatures down to 20F (and that was after sitting for 2 weeks) but I didn't try starting it when it was colder than that (used my gas 740 Turbo). The previous owner lived in Grand Rapids, MI and he ran it all through the previous winter using the block heater as well.

Zack
1980 245DL M46 274k
1985 744TD M46 251k For Sale
1988 745T+ M46 203k

If that engine only has 100k on it, I'd imagine it should be in pretty good shape. For that price it would be pretty hard to go wrong.
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale

Unless you have someone that will work on it for you I would pass on the whole diesel adventure. I currently have one in the line up and once they are dialed in they are pretty good little cars but finding someone to work on them who really knows what he is doing can be tough. Parts availability is still there for them. Starting cold, well I have lived in So. Cal my entire life so I am not the best guy to answer that one. I can tell you from the techs that I have worked with that have lived in cold country (Deleuth to be exact) that the diesel will not even consider starting in the winter unless all 6 of the glow plugs are in tip top shape. They do take awhile to warm up, even here in sunny California so I would think that it would take something like a small enternity in Michigan. They require valve adjust twice as often according to the factory, every 15K instead of 30K, they go through air filters faster for sure, they all seem to benefit from fuel additives (it kills the bacteria that grows in diesel fuel), the 75K is the big service on that car where both of the timing belts and the water pump get changed out as well as the valve adjust and the rest of the service. They will absolutely destroy the cylinder head when and if the belt goes. The turbo charged 700's are not too bad and once spun up to speed on the highway they are pretty darn nice but are a bit on the doggy side from stop light to stop light. An M46 5 speed car huh? That is kind of a rare one, I have driven and worked on a few back in the day and they seemed to work ok. I'd prefer an auto though. Strange as it was the ZF auto transmissions that were so bad in the gas cars seemed to work just fine in the diesels, go figure?

More or less that is it in a nutshell, unless you have either the tools and the know how or a compentent Volvo diesel mechanic at your disposal I would be more inclined to pass on it.

Good Luck,
Mark

I've had my turbodiesel a few years, and have spent as much time working on the regualar part of the electricals as the engine. that said, I have done timing belts and headgasket (because the PO didn't torque one of the bolts). I'd pay $500 extra for the stickshift, as the auto shifts just as the power starts to come on. Power? it is every bit as good as my NA '79 gasser. I have about $43 of special tools, but I am pretty inventive. I pretty much wouldn't trade for a gas model.

They will absolutely destroy the cylinder head when and if the belt goes...
Well, since the valves and piston both go straight up and down, sometimes you can just replace the cam folowers. The valves do stamp a bit of a mark in the piston though.

IMO these are better than the VW motor because with 6 cylinders, there is less of a tendency to vibrate the car apart.

Repais will likely be quite costly if you don't learn to do them yourself. The cooling system is a weak point due to its unusual complexity. Dealer charges $500 for the dozen or so coolant hoses.