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I apologize if this is a silly question, I've been searching diagrams for the last half an hour and can't seem to identify the part I'm after. I have a '92 F250 7.3 IDI Non Turbo
I have a coolant leak coming from the engine component directly below the vacuum pump. This side is caked up with oil and so it's tough to identify exactly what this engine component is. It was dark when I took this pic so it's terrible, I'm just hoping someone can identify what this is for me so I can order the correct part to replace it!
Below the vacuum pump would be the engine mounted mechanical fuel pump if you have one. Many have upgraded to an electric fuel pump. I don't think it would be leaking coolant. Oil maybe. If it's coolant any chance its coming from your water pump and running over and down to the fuel pump? I really can't see much in your pic. Kinda guessing here where the leak is coming from. Check radiator, hoses too. Maybe get a pump up coolant check tool that connects to the radiator cap and pump up the system, look for leaks. Some autoparts stores will lend them.
Last edited by BigBlue2; Dec 12, 2025 at 11:22 PM.
I agree with BigBlue. The only way that the fuel pump is leaking coolant is if there was a massive crack in the block under the thermostat. But that is incredibly unlikely because it is very tick metal between the coolant passages and the fuel pump cut out. You should pressure test the system and check for leaks. It could even be leaking from the thermostat gasket and dripping down onto the fuel pump.
Let me first say, the combination of leaks this thing has had I've been slowly fixing (truck sat for nearly 20 years in a field) made it seem as though it was coolant leaking. However, I am relatively new to diesels and the colour may have thrown me off... BigBlue, you were bang on, it was the mechanical fuel pump that was leaking diesel. I replaced that last night ( what a struglle) and she appears to be happy now.
Thank you for your support gents, very appreciated!
Make sure you keep an eye on the oil level in your crankcase. The mechanical fuel pumps have been known to pump diesel into the crankcase when they fail. It's happened to me more than once. Finally, I went to an electric fuel pump.
