Recently purchased a 7.3 nonturbo , didn't know much about it when i bought it. However has 170 k, no leaks, great body, 4x4, and came with a working plow and tool box. Anyways shakes at idle & around 2k rpm the most, and sounds like an exhaust leak or rod knock/tick with any kind of load except idle. good amount of white smoke out of the tail pipethen sometimes grey then grey/blue , smells like fuel no oil in the "green coolant" vise versa .So i changed the oil " thick dark black" was a little low before i drove it home " didnt know about the hot oil check and it was checked semi warm. Also changed the fuel filter"some water" with atf to run through the system, the ip looks referb has yellow dots all over the screws and what not, however the injectors or grey with return lines with black fabric, leads me to think that the injectors are original. also replacing the serp belt ..."fell off driving", so after changing the oil and fuel filter the oil is already black after 15 miles, smells odd, and i ordered reman injectors and return kit. the oil normal gauge never really leaves the n -o area, but when i put my hand over oil fill no pressure. also no over heating .took the air cleaner off to look at sender and there is black sludge in the intake. Main question is, should replacing injectors solve the issues, should i check the cdr , what else should i check, what other issues could cause these problems? thank you.

 

My truck had the same symptoms it turned out to be head gasket they go between the passenger rear most cyl and the one in front of it it's happened to me on 3 trucks

 

headgasket ? even though exhaust isn't smelling sweet and there isn't any coolant loss? or oil coolant mixture?

 

Yeah it blows where theirs no water or oil passage. I'm replacing head gaskets on my 7.3 now ill try and post a picture

 

It is time if the mileage is correct to do a fuel system refresh, most will say that it needs to be done around every 125,000 miles, some have made it up to 150,000 miles before needing a refresh.

Question have you experienced any hard cranking when cold and appears to be better when up to operating temp. If so it could be a return lines for leaks or a bad injector.

First narrow down the injector issue, by cracking each injector seperately to determine if the noise/smoke changes. Example if a injector doesn't change the systoms then you have found the cause.

Head gaskets will leak one or two ways on these trucks, internal and exterior. You said that you don't have any liquids mixing. The external leaks usually show theirselves at the rear of the heads near the firewall, so crawl underneath and look up towrds the ends of the heads and the block meet. The sign will be a small drip of coolant or a whitish colored trail.

Now to your comment about the oil turning black right after your oil change, that it normal, since #1 oil that can not be drained from the engine oil cooler on these trucks is held no matter, what you do unless tear the engine down, #2 these engines produce alot of carbon when running which in turn turns the oil black very soon after changing. So don't worry about the color, just remeber to change at every 3000 for a N/A truck and 2500 for Turbo models and you will be fine. Also a tip use the Ford Motorcraft oil filter FL 1995, which fits the 1998 powerstroke trucks. It adds an addition quart of oil to your change and has better filteriing quality than our listed filters.

Hope this helps.....