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Diesel 240: Odd noise

Well, I've had no luck figuring this problem out. Maybe someone here can help.

'82 240 Diesel. Ever since I got the car, there has been this noise that sounds like pre-ignition would in a gas car and it happens at the same times it would in a gas car-accelerating, on hills, etc. I checked the exhaust and valves and all that. Here's where it gets weird: The problem is bad with #2 diesel. The problem is nonexistent on bio-diesel. The problem is worse on vegetable oil. At first I thought it was the extra lubricity of the bio-fuels, but it gets bad on the vegetable oil (yep, have the kit). Any ideas what this might be? Someone suggested the vacuum pump, but I have trouble believing a pump noise would be effected by the fuel. Thanks!

Reply to
PT in OR
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The way you describe it the sound it apparently increases with speed so it sounds engine related. Do you have an exhaust leak somewhere? If not then it sounds more serious. If the car was converted to run on fuels other than diesel is it possible that the installer screwed something up? Maybe the timing?

Reply to
Roadie

Since it changes with the type of fuel and the degree of load on the engine, I'd almost have to guess that it is related to combustion chamber deposits and heat. My guess is that the Bio-diesel runs a bunch cooler, hence the noise disappearing, while the SVO runs the hottest. Have you pulled your injectors to see if there are any built-up deposits on them?

I agree with you regarding the vacuum pump.

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Reply to
Rob Smith

The vacuum pump can make a lot of noise! Mine does sometimes. Sounds like knocking on metal. I don't know what to do about it, and it disappears just like that after a few moments.

Reply to
Jakob Griffel

Where can I read more about this bio-fuel-kit? Do you have a link for me?

Reply to
Jakob Griffel

Yeah, but does the sound change depending on the type of fuel that you're running?

Reply to
Rob Smith

Here's a couple...

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Reply to
Rob Smith

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