I have a 1996 F350 with a 7.3 diesel engine. When it first starts it makes a loud rattling noise and it is slow to accelerate. When you push on the gas instead of ahooting up to 3500 rpms it crawls. After it warms up the rattling noise stops and it accelerates fine. Does anybody have any ideas what could cause this?

Bad glow plug(s) possibly? Not a powerstroke guy I dont know much about them, but I would look there first. Does it make a difference if its plugged in? Also a small fuel leak could cause some rough running at first until the air gets worked out of the system.

I know the 13-letter-poop-spreader engines (International) have a high-pressure pump to drive the fuel pressure.. no oil pressure, no fuel.. Wonder if there's an oil-pressure issue, maybe low or something, that is causing the poor fuel delivery? I know that viscosity is opposite (high oil pressure cold, lower when warm) so I'm just taking a stab at it.. Thinking aloud, if you will..

Not a PS guy either... had a Ford Ranger Diesel years ago... as the weather got colder became harder to start until I was starting on only 1 cylinder... all but 1 glow plug out. I understand there are glow plug relays, controls, sensors... Only guessing. Are there any codes? Gotta start with that.

No codes.... Check engine light not even on.... Wonder what tis is going to cost.... lol

Welcome to the HEUI fuel injection system. High pressure oil fires the injectors, and when it's cold the oil is thick and they are pretty lazy until the oil warms up.

I'm not exactly a Ford guy but I do understand the fuel system in a basic sense. Cetanefreak is right. The oil thickens up and harder to pump to the injectors. So there is a certain amount of lag till the oil temp comes up. Another part of that is the computer trying to control timing and fighting the cold oil as well. Block heater or a oil pan heater helps a bunch in this problem.

i ran the 7.3 for years at work. We had nine of them when it came to cooling off even in the 50 we had to plug them in. We had a rule who ever got there first would go out and try to start them all. Most the time the higher mileage truck sounded like they were running on one cylinder and where trying to blow up till the started to warm up. We had three or four truck in the 300k plus. For the first 15 mins they ran they sounded horrible.

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i ran the 7.3 for years at work. We had nine of them when it came to cooling off even in the 50 we had to plug them in. We had a rule who ever got there first would go out and try to start them all. Most the time the higher mileage truck sounded like they were running on one cylinder and where trying to blow up till the started to warm up. We had three or four truck in the 300k plus. For the first 15 mins they ran they sounded horrible.

Yes the 7.3LPS diesels use a HEUI system. If all the glowplugs and the controller are working good, I would have half the notion you either have the wrong viscosity of oil for winter, or you are using cheap oil in a engine that needs quality oil. All diesels have the same problem of hard starting with the wrong oil viscosity, but not always as pronounced if they do not have a HEUI injection system (some no HEUI Bosch injection pump users, not in trucks AFAIK, but still a diesel, share the injection pump lubrication sump with the engine, and will have the same problem as definite as a HEUI system). Always use CD grade or better oil, Rotella T works awesome in most diesel engines, and it isn't terribly expensive either.Most PS users I have talked to consent without hesitation that Rotella T 15W40 is the best for performance and good starting. In my experience with diesels it has proved to be true (not having a PS I cannot speak directly from my experience, only others).Edit: If you live in mostly cold weather, use 5W40 Rotella T instead of 15W40.