Diesel Frequently Asked Questions

While diesel Volvo’s were never very popular in the USA (along with diesel passenger cars in general), with rising gasoline prices and the availability of alternative fuels such as biodiesel and waste vegetable oil (WVO), they are enjoying a resurgence in popularity. Therefore, I have put together this FAQ to help people who are interested in these cars.

1 Which Volvo cars came with diesel engines (USA)?
2 The engine is made by Volkswagen? What?
3 How can I make my Volvo diesel last?
4 I’ve heard you can modify the engine’s cooling system?
5 Where can I find more information on Volvo diesels?
6 Where can I find parts and tools for my Volvo diesel?
7 What about Biodiesel?
8 What are the specialty tools? Are they required?

Which Volvo cars came with diesel engines (USA)?

Volvo 240 Diesel: 1981 – 1985. Had 2.4L straight-6 Volkswagen engine (D24), non-turbo, about 85hp. Very few still on the road. Came as a 4 door sedan or 5 door wagon. Had M46 5-speed manual transmission or BW55 automatic transmission.

Volvo 260 Diesel: 1980 – 1982. Generally the same as the 240, but more luxury options.

Volvo 740 TurboDiesel:
1985 – 1986. Had 2.4L straight-6 Volkswagen engine (D24T), turbocharged, about 110hp. Can be found, although like the 240 series, good condition cars are rare. Came as a 4-door sedan or 5-door wagon. Basically the same engine as the 240, but with a turbocharger and associated equipment, including stronger crank and connecting rods, piston oil-squirters, and upgraded injection pump. M46 5-speed manual transmission (rare) or ZF22L automatic transmission with lockup torque converter at approx. 57mph.

Volvo 760 TurboDiesel: 1983-1985. Generally the same as the 740, except with more luxury options.

Volvo 940 TurboDiesel: 1991?-1995? Not shipped to USA. Basically the same as 740/760 but with more options and an updated body style. Same motor, although some came intercooled (commonly called the D24TI or D24TIC). All 740/760 turbo diesels were not intercooled. To get an intercooler on your 740/760 turbo diesel, you will need to get one from europe.

Note: All 240/260 Diesels were not turbocharged, all 740/760 Diesels were turbocharged. It is possible to put a D24T in a 240/260 engine compartment, and it has been done, although it’s a bit of a squeeze.

The engine is made by Volkswagen? What?

There’s a lot of hullabaloo about outsourcing these days, but it’s been going on for decades in the automotive industry. Volvo’s are a Swedish car, but many of their components were built in other countries, such as Germany, France, Belgium, and Canada.

For their diesel engine, Volvo outsourced production to Volkswagon, who, at the time, built three indirect-injection diesel engines that were used in passenger cars. The 1.6 liter 4-cylinder, the 2.0 liter 5-cylinder, and the 2.4 liter 6-cylinder. Volvo mainly used the 2.4 liter, and in a few rare cars, the 2.0 liter. The 2.0 was also used by Audi in their diesel passenger cars, and the 1.6 liter was used extensively by VW in many of their diesel cars and trucks, in both NA and turbocharged versions.

Since the Volvo’s are rear-wheel drive, the engine is mounted front to back, rather than side to side (transversely) in the front wheel drive VW’s.

The 2.0 and 2.4L engines share the same transmission bellhousing pattern, but it is different from the 1.6L pattern. Really, the 2.0 and 2.4L engines are more closely related to eachother than they are to the 1.6L engine. However, the nice thing is that any competent VW Diesel mechanic should be able to do at least the basic maintenance on a Volvo diesel, and many of the parts are interchangable.

‘D24′ and ‘D24T’ are Volvo nomenclature. Volkswagen calls the engine ‘LT35′ since it was originally a light truck motor. The ’35’ is supposed to be from the physical weight of the engine.

How can I make my Volvo diesel last?

From Tom Bryant:

1. Use Mobil 1 (synthetic) 5W-30 year ’round.

2. Change it as often as you feel you must. I change my oil and filter every
25,000 miles, and recommend the same to anyone who will listen. (No that’s not a typo, 25K miles).

3. Don’t overheat it.

4. Never, never, use any ether; it can and will break the rings.

5. Keep the timing correct and the valves adjusted.

6. Keep the cold start thermostat working.

7. If you’re producing any black smoke, adjust your injection pump to get rid
of it. It will only take a few seconds. Engines run better, start better,
have more power, and last longer if they’re not getting gummed up with soot.

8. Use only genuine Bosch glow plugs, and replace any that don’t work before
they cause a problem. There may be other brands out there that work well, but
I’ve seen too many off-brands that have problems to want to take any chances.

9. Rebuild your injectors when their cracking pressure drops below spec.

10. Change that front timing belt on schedule (75,000 miles). You can ignore
the rear one as much as you care to. I change the rear one every 150,000
miles.

11. (Added by me) In a warm climate, modify your engine’s airbox so that the pre-heater intake is closed off and the engine only sucks cold air all the time. In a cold climate where the intake pre-heater system is essential for warming up the engine, make sure your airbox thermostat (which controls the intake air flow) is working properly. Otherwise, the thermostat can get stuck in the “hot” position, and the engine will be sucking in hot air from the engine compartment all the time.

12. (Added by me) If you can afford it, intercool your turbodiesel (D24T). Intercooling it will allow you to run the same boost level with lower exhaust gas temperatures (as the intake air will be cooler), which reduces engine wear and emissions. Another option is to use the intercooler to run a higher boost level with the same exhaust gas temperatures for those interested in increasing performance.

I’ve heard you can modify the engine’s cooling system?

Yes, and you should. The D24’s main weakness is that if it starts to overheat much at all, it’s pretty much done for. Therefore, the cooling system should always be in top notch shape. Unfortunately, the OEM hoses had a lot of problems. First, they were not the highest quality, and often would leak. Second, they are very expensive to replace from the Volvo dealer due to their somewhat abnormal shapes. Thus, they were often not replaced on schedule. Third, the cooling system pressure was set at a level that was probably higher than it should have been. However, there are solutions to these problems and other ways to shore up your cooling system.

1. Evans Waterless Coolant (evanscooling.com). The nice thing about this is that it won’t boil until 375F at 0 psi. This way, you can run your cooling system at zero psi to decrease the liklihood of leaks.

2. Low-pressure or No-Pressure Radiator Cap Still working on a source for this part, but the idea is simple: Less pressure = less chance of popping a coolant hose. May require a custom expansion tank in order to use an aftermarket radiator cap. If so, check out Evans Cooling (link above) as they sell these items.

From the D24 Mailing List: “A lower pressure radiator cap can be obtained easily, just by purchasing a new one intended for a gasoline non-turbo volvo. The newer caps can also be modified to be zero pressure caps by removing the rubber one way valve diaphragm that allows air to enter the system if it’s under a vacuum while cooling.”

3. Brass adaptors and new coolant hoses By replacing your coolant hoses with straight pieces with brass elbows, you eliminate two problems – the low quality of the OEM hoses, and the expense of replacing the hoses later. Plus, you can find the parts for these at any plumbing store, hydraulic supply store, or automotive supply store.

4. Digital Engine Temperature Sensor (Engine Watchdog) This device provides a digital readout and an audible alarm which signals you if your engine goes over its normal operating temperature. Available in Degrees F or C.

5. Coolant Level Float This device would measure the level of coolant in the expansion tank and signal the driver if the coolant level drops too low. Not too sure about the specifics of this, but it may require and aftermarket expansion tank as well.

From the D24 Mailing List: ” A possible source of a coolant level sensor, is swapping out the expansion tank from an 850, which has a sensor and takes the same radiator caps, and connectors (I think). I haven’t actually found one of these to test if it will work, but it might be virtually a bolt on solution. ”

6. Fan Upgrades To improve cooling, many people install an additional electric pusher fan in front of the radiator/AC condenser assembly. This is particularly useful on hot days when running AC. Another option is to replace the fan clutch in the mechanical fan with the so-called Tropical Fan Clutch, which is available from Dave Barton. However, it would be wise to contact him to confirm that the fan clutch will fit a diesel fan; otherwise modification may be required.

Where can I find more information on Volvo diesels?

The D24 Mailing List
This is a great resource for discussing the cars and the motors, and there are some very knowledgable people who use this list. You can read the D24 Archives to learn a lot from past discussions.

The SoDak Blog
Lots of good information here about the journey of a 760 TD, including timing belt replacements, injection pump tuning, and more.

VWDiesel.net
This website has a very active community, and there is a lot of relevant information here. Check out the Discussion Forums and the Links as well.

Brickboard 700/900 FAQ
There is a ton of info here if you have a 700/900 series Volvo, and more specifically a good bit on Diesel Engines.

Swedishbricks Diesel FAQ
This is not really a FAQ, as there are not specific questions and answers, but more of a compilation of people’s experiences and emails. Still a good read.

Where can I find parts and tools for my Volvo diesel?

VWDieselParts.com
Parts, custom tools, and a community forum.

Import Parts Specialists
Have some of the essential parts, like glow plugs and injectors.

GermanAutoParts.com
Carries parts and most of the essential specialty tools.

Rapid Parts
Sells parts for diesel VW’s and Audi’s.

Swedish Parts Wholesale.com
Stocks a wide variety of D24 and D24T parts.

Greaseworks.org
Specializes in VW diesels, but can supply you with the materials needed to convert to biodiesel or WVO.

Your Volvo Dealer
Essential for parts like headgaskets and seals, and other stuff if you can’t find it elsewhere. If you are a member of the VCOA, you can get a discount at many dealerships.

What about biodiesel?

The original fuel system for the D24 and D24T was not designed to accomodate biodiesel. Therefore, eventually you will have to replace your fuel lines and re-seal your injection pump with biodiesel-compatable materials to run biodiesel effectively. You will also have to replace your fuel filter much more often, especially during the first few tanks of biodiesel, as it tends to clean out crud in the lines, which gets caught by the fuel filter. Thankfully, many of the fuel lines are metal on Volvo’s, so replacing them is a fairly inexpensive job.

If you want to learn more about biodiesel, here are some useful links. Refer to their links pages for even more information.

Biodiesel.org
A great resource, especially for locating biofuel pumps and planning a trip.

Greaseworks.org
A great source for information and biodiesel conversions on VW cars and motors.

GoBiodiesel.org

Portland, Oregon’s biodiesel and WVO Co-op.

What are the specialty tools? Are they required?

For the most part, absolutely YES, they are required. Here is Tom Bryant’s list of specialty tools from the D24 Greenbook and his comments on each. All part numbers begin with 999.

Number: 1801-3
Description: Standard Handle (used with drift 5207 and 5208)
Do I have?: No
Comments: Easily substituted.
Number: 2520-8
Description: Engine stand (used with fixture 5206)
Do I have?:
Comments:
Number: 2810-3
Description: Lift Beam (removing and installing engine)
Do I have?: No
Comments: Easily substituted, but sure wish I had one.
Number: 2901-0
Description: Clamping Pliers (clamping water hoses when removing injection pump)
Do I have?: No
Comments: Vise Grips work well.
Number: 2903-6
Description: Oil Filter Wrench
Do I have?: No
Comments: Easily substituted.
Number: 4090-0
Description: Puller (removing pilot bearing)
Do I have?: No
Comments: Easily substituted.
Number: 5006-5
Description: Lift Bracket (replacing front engine mounts)
Do I have?: No
Comments: Easily substituted.
Number: 5017-2
Description: Drift (removing and installing crankshaft bushing)
Do I have?:
Comments:
Number: 5033-9
Description: Support (used with lift bracket 5006-5)
Do I have?: No
Comments:
Number: 5112-1
Description: Locking Sector (for locking flywheel)
Do I have?: Yes
Comments:No serious engine rebuilder should be without.
Number: 5115-4
Description: Lift Hook (used with lift bracket 5006-5)
Do I have?: No
Comments:
Number: 5185-7
Description: Lift Hook (front, removing or installing engine – used with 2810-3)
Do I have?: No
Comments:
Number: 5186-5
Description: Lift Hook (rear, removing or installing engine – used with 2810-3)
Do I have?: No
Comments:
Number: 5187-3
Description: Wrench (Vibration Damper)
Do I have?: Yes
Comments: Absolutely essential for changing timing belts.
Number: 5188-1
Description: Wrench with extension arm (Vibration Damper Bolt)
Do I have?: Yes
Comments: Must have or make a substitute.
Number:
Description: Breaker Bar (extension arm) for use with 5188-1
Do I have?: Yes
Comments: 3/4″ drive by 2-1/2 ft long, with 1/2″ x 3/4″ adapter. Use to tighten center bolt to about 600 ft pounds
Number: 5190-7
Description: Gauge (installing camshaft)
Do I have?: Yes
Comments: Must have or make a substitute.
Number: 5191-5
Description: Adapter for Compression Test (for connecting pressure guage)
Do I have?: No
Comments: Substitutes are readily available. My Compression tester was made by KD Tools.
Number: 5192-3
Description: Support for dial indicator (for measuring piston height)
Do I have?:
Comments:
Number: 5193-1
Description: Stop (for locking injection pump gear)
Do I have?: Yes
Comments: Must have for serious work.
Number: 5194-9
Description: Holder (for Dial Indicator when adjusting injection pump)
Do I have?: Yes
Comments: Must have this or one for VW Rabbit, etc. This one is preferable.
Number: 5195-6
Description: Pliers (for removing Valve Disks)
Do I have?: Yes
Comments: Must have this or one for VW Rabbit, etc.
Number: 5196-4
Description: Press tool for Valve Disks
Do I have?: Yes
Comments: Must have. VW Rabbit tool won’t work.
Number: 5197-2
Description: Belt tension gauge (for timing gear belt and pump drive belt)
Do I have?: No
Comments: Very expensive and probably next to useless anyway. The rule is don’t overtighten belts. A loose timing belt is a happy timing belt. Timing belts should be snug but not stressed.
Number: 5198-0
Description: Straight edge (for setting TDC for cyl. 1 (flywheel casing removed))
Do I have?:
Comments:
Number: 5199-8
Description: Wrench for camshaft gears (front and rear)
Do I have?: Yes
Comments: Must have.
Number: 5200-4
Description: Adapter (installing crankshaft front seal and camshaft seals)
Do I have?: No
Comments: Easily substituted.
Number: 5201-2
Description: Wrench for center nut on rear camshaft gear and pump gear
Do I have?: Yes
Comments: Must have.
Number: 5202-0
Description: Puller (for idler pully)
Do I have?: Yes
Comments: Must have for serious work.
Number: 5203-8
Description: Clutch Centering shaft (for clutch disc)
Do I have?: No
Comments: Substitutes are readily available. Mine was made by KD Tools.
Number: 5204-6
Description: Puller (for injection pump gear)
Do I have?: Yes
Comments: Must have for serious work.
Number: 5205-3
Description: Puller (for crankshaft front seal)
Do I have?: No
Comments: I’ve never needed one.
Number: 5206-1
Description: Fixture (for Engine Stand)
Do I have?:
Comments:
Number: 5207-9
Description: Drift (for installing pilot bearing)
Do I have?: No
Comments: A hammer works fine.
Number: 5208-7
Description: Drift (for installing rear main seal)
Do I have?: No
Comments: A hammer works fine.
Number: 5218-6
Description: Drift (removing and installing valve guides)
Do I have?:
Comments:
Number: 5219-4
Description: Drift (removing and installing valve seals)
Do I have?:
Comments:
Number: 5220-2
Description: Drift (installing intake valve seat)
Do I have?:
Comments:
Number: 5221-0
Description: Drift (installing exhaust valve seat)
Do I have?:
Comments:
Number: 5222-8
Description: Gauge (checking valve height in relation to camshaft)
Do I have?:
Comments:
Number: 5224-4
Description: Reamer (valve guide)
Do I have?:
Comments:
Number: 5233-7
Description: Guide pins, M11 bolts (installing head)
Do I have?: No
Comments: I’ve installed only one 11 mm gasket, and I got by.
Number: 5234-3
Description: Guide pins, M12 bolts (installing head)
Do I have?: Yes
Comments: Book says 4, I have 2. Two are enough. No cylinder head should be installed without using these, although I will admit to installing many without using them.
Number: 5235-0
Description: Removal tool for 5234-3 (for removing guide pins)
Do I have?: Yes
Comments:
Number: 9950-0
Description: Adapter, engine rpm (used with Volvo Monotester)
Do I have?: No
Comments: Never remotely felt the need.