Tuesday, June 21, 2011

1985 Volvo 740 Turbodiesel (Volkswagen D24T diesel engine)

Check out that stylish and modern pinstriping!

Most European car enthusiasts who watch TV will remember the BMW "Advanced Diesel" commercial that's been aired recently - the one that depicts a Benz diesel shaking like a bobblehead, followed by a Volvo wagon, presumably diesel, chugging up a hill and spewing black soot all over the road behind it.



They've got a point. In the 1980s, when gas prices hit the equivalent of close to $5 per gallon, automakers realized that there was a huge market for "alternative fuels." This should sound familiar, but in the 80s, the craze wasn't hybrid technology: it was diesel. Some of the most memorable creations of the time period include the GM diesels developed by Oldsmobile (epic fail), the Mercedes-Benz OM603 diesels (most of which seem to still be driving down the road today!), and, of course, Volkswagen diesels, which have always been fairly popular in the US.

Volvo, however, took a somewhat easier route and built their cars with Volkswagen diesel powerplants for those who insisted on buying an "oilburner." From 1983 to 1986, they offered the 740 and 760 with a turbodiesel straight six, and the 240 with a non-turbo diesel straight six. 


The engine is  larger than most other passenger car diesels- the Mercedes engines of the era had five cylinders, VW's typically had four. Research reveals that the engine is in fact a truck engine, normally dropped into the VW LT commercial vans alongside a list of military vehicles. But the only passenger cars that the D24 or D24t engines ever made it into were the Volvos.


Source: Wikipedia.org, "Volkswagen LT" article
Source: Wikipedia. Very cool military vehicle.

Needless to say, using a truck engine like this didn't make for the smooth, clean, refined diesel that Americans wanted to drive. Driving a 740 diesel feels kind of like, well, driving a Volvo 740 that someone dropped a school bus engine into... Because that's basically what they did. 




Of course, my thoughts/comments on this unrefined, smelly powerplant aren't exactly commensurate with what the average American would think. My dad had a 1986 Jetta diesel when I was quite a small child. I don't really remember the car's driving characteristics, but I do remember sitting in it and pretending to drive it. Maybe I love diesels so much because I inhaled too many of the fumes as a toddler- all I know now is that I happen to think they're pretty fascinating machines, for one reason or another. Maybe it's the simplicity of the design. You can run most diesel engines with no electrical supply. They're all mechanical. In theory, a diesel engine would continue to run even if it were completely submerged in water (provided it didn't have any gasket leaks!)


Here's a video of my latest "project," a 1985 Volvo 740 Turbodiesel, with just 215,000 miles - unfortunately UpShift isn't yet equipped with Smellovision, so you'll just have to imagine the wonderful fumes of Ultra Low Sulfur Diesel burning out the tailpipe for now. 



The previous owner bought the car in 2003. He was the third owner of the car, based on what I can piece together from the large stack of paperwork I found in the glovebox. The first owner of the car seems to have been a Volvo employee. Amusing receipts/records include an event in 1993 when the driver filled the car with gasoline and then experienced "poor running," and in 1995, the engine was completely rebuilt with new pistons, bearings, etc. I suspect this was prompted by a snapped timing belt - read on to learn more about this.

Right now, even with 215,000 miles, the car runs like a top! At 200,000 miles, the previous owner (PO) replaced the turbo along with a host of gaskets, and the vacuum pump. This cost over $2,000 at the Volvo dealer. And at 185,000, the transmission was rebuilt. Needless to say, I just had to snap this car up when the PO mentioned that he "wanted it to go to a good home" on a Volvo forum.  This is one reason why it pays to frequent niche forums- you can find really cool stuff.



It's got cosmetic rust (this is Ohio, after all) and the interior is positively filthy. The turn signals are kinda schizophrenic. The previous owner kindly mentioned to me that the power antenna doesn't work (I laughed), and that you have to encourage the fuel gauge to work by "tapping" it- something I learned on my gas-powered 740. But for some reason I still love the car. 

Despite the owner's frequent oil changes and other maintenance, for some reason he neglected to change the timing belt. This is serious business when dealing with a D24 / D24T engine- it's an interference engine, meaning if the belt snaps, the engine is trash because the pistons will hit the valves and shatter into pieces.  To reference the rental car lady from Planes, Trains, and Automobiles, "you're F***ED." 

Unfortunately, this belt seems to have caused the demise of many of the D24 engines. The timing belt service requires a specialized tool to hold the crankshaft that most garages don't have. It holds the pulley steady when you loosen the bolt, which is applied at 450 pound-feet of torque. I can't even find one; I'm planning to borrow one from a fellow forum member. The local Volvo dealers, normally quite helpful, drew blanks. Even if the mechanic could obtain the right tool, many times they either failed to line up the timing marks exactly, or they failed to tighten the pulley bolt to the 450 lb-ft spec. This causes the pulley to slip, which causes the engine to skip timing- basically the same effect as having the belt snap.

So while the D24t isn't a bad engine in itself, it has gained quite a reputation as an unreliable heap- undoubtedly because of the issues with service tools and mechanics who didn't know how to maintain a diesel. I happen to love it. Look for a "how-to" pictorial soon for the timing belt, along with other articles pertaining to this car. 

Feb. 2012 Update: Look here for a collection of links, part numbers, and a few tips for the timing belt service.

5 comments:

  1. You're lucky! I wish I could find a Volvo with a turbodiesel but they're definitely getting scarce.

    ReplyDelete
  2. I laughed at the little things you have to do with your 740D24T. They're the same I have trouble with on mine also but I have to say it is one of the smoothest running hiway cars I have ever had. It sounds like a tractor at idle but acceleration-wise, it's like a hot knife through butter, not quick by any means but smooth and shifts at 2500rpm and still pulls with no lag. Uphill is still a 3500 to 4000 shift. I love my smelly tractor especially the fuel economy. I got the timing belt changed as soon as I bought it at 240000km so I averted a meltdown. Should last quite a while, been seven years so far and running better than ever.

    ReplyDelete
  3. @Keith- I agree. The highway driving reminds me of my Saab 900 turbo, just really smooth, like the powerband was designed with highway cruising in mind. I'm currently in the process of doing the timing belt because mine hasn't been changed since 1996, and then I should be driving it around quite a bit. Plans are to eventually put the drivetrain in a wagon.

    It sounds like you're good about keeping yours up, I hope you can enjoy it for many more years!

    ReplyDelete
  4. Thank you for this informative post. I featured a low-mileage 740TD for sale on my blog.

    ReplyDelete
  5. Its very interesting and informative and I enjoyed reading it. Thank you for sharing such informative post.

    ReplyDelete

Your comments are welcomed and encouraged! Unless they're spam, of course.