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I have a 1984 300d Turbo Diesel. I was under the impression that these cars would get 28-30 miles per gallon. I am getting at best 24. The car has 244,xxx miles on it. It drives great and has been very reliable. Would an old timing chain cause the fuel delivery to be off? Just throwing out ideas. Any ideas about this? What are you out there getting on similar vehicles?? Thanks for any help or things I should look at that may be causing the lower mileage. I am not complaining at 24, I just wanted to see if there is something may be causing this mileage that may need repairing. Thanks again.
 

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Yes, the timing chain could be causing a problem. To find out, check the stretch. The actual timing could also be off, and at that high mileage, injectors could be an issue. Check out http://skinnerbox.steaky.org/ for the chain stretch and timing procedures.

Of course, this is assuming proper tire inflation, clean air and fuel filters, etc...
 

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Discussion Starter #4
Gas Mileage

Thanks for the replies. In the past 500 miles, I have replaced myself the: oil and filter, both fuel filters, coolant, power steering fluid, brake fluid, rear end fluid, air cleaner, glow plugs, tires, brake pads front and back, oil pan(the small one), oil pan gasket, drain pan plug, door checks on 3 of 4 doors, a new radio, air conditioning hose from the compressor to the evaporator(I think that was what it was called), and a windshield. I have been busy.

I have not checked out the link for the timing yet but will real soon. Also, I am getting a metallic ticking noise that happens sporadically. I noticed when I had the oil pan off, that the oil pump chain was pretty loose. Could that maybe be causing that noise? I have been running an injection cleaner and cetane boost in almost every tank since I purchased the car in April. It has been reliable and I really like the car a lot. I plan on keeping it for a long while. The oil pressure is at 3 when driving and at idle it is at 1.7 to 1.9. Is that correct for the pressure to go down at idle. I am under the impression that that is correct. The previous owner put a lot of work into the car in the last 5 years. A/C completely gone through, front end work, gas tank out and cleaned, car painted, among other things. The only thing really wrong now is the vacuum system for the door locks. I can lock the doors and within 30 minutes or less, the vacuum is gone. I have not really done any investigation on this yet, but I plan to soon. Any advice on this would be greatly appreciated as well. Thanks for reading my "novel".
 

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Wow! Sounds as though you have a new car there. Have you adjusted your valves recently? Of course sounds are hard to diagnose on a board like this, and vacuum leaks in your car usually affect the door locks without the locking system being bad.

Anyway, a metallic pinging sound could be any number of things on a diesel, and a loose chain is one of them. When my mother's timing chain was loose on her '93 diesel, it was knocking the inside of the valve cover.

On the other hand, you could be running too much fuel additive. Try running a tank of fuel without any additives and see if the knock is pesistent.

As for the oil pressure, it sounds good. You should have at least 1 bar of pressure for every 1000 rpm, so idling with 1.7 to 1.9 is strong.

The vacuum system is a pain on your car because everything is tied together, so (for example) your door locks could actually be healthy but an a/c controller could be bad. The quick checks would be to look under the hood and look for any loose connections, and also make sure nothing was knocked loose from the door strap jobs.

To try to be more methodical (and very time consuming), you might want to try the following: First, I believe if you do a search on this forum, you can find a vacuum diagram for your car. Then, get a mityvac and try to (from the diagrams) test each system individually. Once you find which system (A/C, locks, cruise control, etc.) is leaking you can hunt down the component.

Hope this helps, and good luck!
 

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Thanks for the reply cracker928.

It's been fun working on the old car. From the paperwork that I received, the last valve job was about 5,000 miles ago. So that should be ok for a while. I have no record of the timing chain being replaced, so, I will have to do the procedure to check the play in it. Thanks for your help and advice. Have a great 4th of July weekend!
 
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