Hi, I'm helping out a friend with a couple of mysterious problems on her '82 240D, 24X,XXX miles. She has been on a continuous road trip for 3 years and I'm trying to help her continue along.

This will be difficult as I have very limited knowledge of the vehicle so I'm looking for suggestions that I can look further into the next time I have the chance to see the car.

First off, she's only had the car a couple of months but has been getting between 10 and 12 miles per gallon, on the highway!

The strangest part is that it doesn't smoke, leak, or smell like unburned fuel. So where is it all going?

Injectors? Timing? I don't know when the valves were last adjusted or what the chain stretch is but it seemed to run smoothly, nothing drastically wrong. I would think that whatever would cause such poor mileage would be very obvious but of course, I have not a clue.

Let me know if you guys have some ideas of what I could take a look at the next time I see the car.

The next mystery is that the car is going through a quart of oil every 2 - 3 hours on the highway.

Again, no smoke out the tailpipe, no wet underbody, no obvious sign of where in the world an entire quart of oil would go every 2 hours.

This thing is the Bermuda Triangle of fluids.

I barely know this person but was so confounded by these two issues that I just have to look into it, I'm extremely curious what in the world is going on.

So again, if anyone has some clues for what else I should be checking it would be most appreciated.

Thanks!

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

Are the tire properly inflated? At 10 mpg I would feel something must be terribly dragging the vehicle to a standstill. Next i'd look for fuel leaks.

How are you also determining fuel economy? If the tripometer is wonky well than you will get wonky numbers.

How does your coolant look?

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-Typos courtesy of my mobile phone.

Are you certain about the fuel usage. Has a proper test been done ~ Fill tank to top, run for the tank, refill to top & calculate.
If it is not known when the valves were last adjusted then they are overdue.
If it has a paper air filter element, it should be changed, or at least cleaned with compressed air.
If she has only had it a couple of months, has the oil & filter been changed?
Does the motor have much blow by?
Has it been run on WVO or some other alternate fuel?
Is there signs of oil in the fuel line away from the primary pump?
I hope these points give you an idea of what to be looking for.

Good Luck !!

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

shes been on a continuous road trip for 3 years, and she only has had this car a couple months. What happened to the last one?

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is the odometer accurate? these are known to slip and fail. verify this first. if it's slipping, it's an easy fix.

If a GPS is available start using that to record distance. The odometer could be spot checked for accuracy by resetting the trip and noting the vehicle odometer and over a 10-20 miles stretch.

Are you sure the car isn't a 6.9 because 12mpg would be perfect.

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

Tires were only at 32psi per doorjam, I had her increase that to 44psi as specified on the tires.

I looked for fuel leaks but didn't find anything, I figured a fuel leak of that quantity would be very obvious.

She has been tracking her mileage in a book but I did not check distances against mapquest to see if they were reasonable. They were at least consistent and the speedometer seemed accurate.

I didn't get a look at the coolant, I'll make sure to check that next time.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

She had a Vanagon, not sure what happened to it but she still owns it.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

No 'proper' testing has been done but she has calculated this MPG nearly a dozen times based on different trips and conditions. I'll double check with her the amount of fuel and distances.

The oil and filter were changed but I haven't heard back from her about the valves.

Not sure about the blow by but it doesn't smoke and seems to run good, well, really it runs great for an '82.

It has been run on WVO but the mileage is the same with diesel.

I'm not sure about the oil in the fuel line, how would you go about checking that?

Thanks for the tips and ideas.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

Good point.

As good as this car is running I think it's a good bet that something with the calcuation of the MPG is off.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

I agree that something is a-miss with the calc's. Either that or the odo is way off. She should be getting around 30 highway. Only way to be sure is do the complete fuel tank use test. I'd do it twice in fact. That should prove the mileage conclusively. If it really is as bad as it seems my first task would be to verify the odometer accuracy and if that's good then delve into other weired and wonderful problems. But frankly I don't have a clue what could cause a 240D to drop to one third of it's mileage.

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Please put the tire pressure back down to the 32PSI that is indicated on the door jam, the pressure marked on the tire has nothing to do with the proper inflation for the vehicle on which it is installed.

The 44PSI you see on the tire is the MAXIMUM pressure the manufacturer will allow and have the tire still be under warranty.

You can see a small MPG increase by overinflating but that also causes tire overheating and excessive and premature tire wear/failure.

The handling and traction capabilities of the vehicle were developed around a tire that is inflated to 32PSI.

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1982 240
460,000 miles total
140,000 on Rebuild

[QUOTE=holtonmusicman;

You can see a small MPG increase by overinflating but that also causes tire overheating and excessive and premature tire wear/failure.

The handling and traction capabilities of the vehicle were developed around a tire that is inflated to 32PSI.[/QUOTE]

I thought that Under inflated tires cause overheating? At least that's what was blamed on the Ford Firestone fiasco.

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'70 F100 shortbed
'82 Diesel Westy
'83 Euro 300TD
Curtlo Viper
Yeti ARC
Surly long haul trucker

The Brake Rotors/Drums Should be RED To WHITE HOT.

Seriously,check for hung up brakes.

BUT,BBBBB,BUT, I'm afraid the Oil Consumption and Horrendous Milage may be
related to lack of Compression related to the Rings.

(8-16 Oz. of oil, every 25 miles,approximately... Ain't Good)

The reason Layback40 asked about WVO usage IS that it's known to cause
Ring "Stickage".

Lepään tapaukseni

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'84 300SD sold
124.128

How does inflating the tire the manufacturers maximum cause overheating and premature wear/failure? Personally I usually run near the max and I have not had these problems.

Why would a manufacturer warranty a tire that they know is going to prematurely fail at the pressure they have allowed to be printed on their tire?

Seems a bit odd to me.

All I've ever noticed by running the max psi is a stiffer ride.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?