First thanks to everyone here who gave advice and knowledge on my first diesel purchase. After an 8 hour round trip in a snow storm with bald tires I got my 89 F250 7.3/ZF5 4x4 home without incident.

I do have some concerns though. Before I picked it up I had a mechanic look it over and change the coolant and oil. He changed the oil before I could tell him what to use. He is a Ford certified mechanic and used Rotella standard diesel grade oil, not synthetic. He said in all his years(58 years old) he always used Rotella conventional diesel oil. He didn't recommend the synthetic. Either way the oil level gauge seemed to be reading low the whole trip up, half way between the first line and the "N" in normal. After driving about 3.5 hours I stopped to top of the fuel tank. After starting it again it was now reading around the n-o of normal. The needle was steady all the way up but I did notice today that the dipstick was about 3/4" to 1" from being complete down in the tube. The oil is also black but with no signs of coolant. Should I re-change the oil? Is this normal or do you think the mechanic lied about changing the oil?

I checked the coolant and it's full to the top with no signs of loss or oil so I'm hoping this means no cavitation issues. The seller said he never added the SCA's the 12 years he owned it. He said he put about 30K miles on it in that time because it was used just for plowing. His cousin bought it new so he said he would check with him to see if he added SCA's while he owned it. It says 31000 miles on the odometer and he told me it had 130K. The truck itself seems to be in good condition so I don't think it's 230K.

The other issue I had was even though it was blowing good heat the temp gauge never went past the "N" in normal and most of the time was way down by the "C" or the first line of the sweep. I was driving on the highway at speeds or 55-65mph most of the time in fifth. Should I be concerned?

I also just noticed the air cleaner is just sitting loose with the hold down nut and stud missing. The truck ides really smooth at 500rpm's without any fluctuating or jumping around. The whole way back home it seemed to run great other than the gauge issues.

I paid $2800 for the truck and a 8.5' Western Unimount plow so I knew it would need some work, but being new to diesel's I'm not sure if any of these issues are red flags of bigger issues. It has a new battery, new rear brakes and lines, supposedly a rebuilt IP, new controller, and something else I can't remember right now.

 

By the way the dipstick showed it was only about 1/4" from the full line but the oil is black.

 

h

 

It's not an oil level gauge. It's oil pressure, and by 1989, Ford had more or less turned it into a dummy switch. Basically, if it comes up at all, it's doing all it's going to do for you. It should come to the center of the gauge. If it doesn't, you probably need a new sending unit but I'm willing to bet your oil pressure is just fine if you had no issues on your drive home.

Our temp gauges are another area where Ford didn't exactly spend the big bucks. Even when working, they tell you little to no info. Most of us run aftermarket temp gauges to really know what's going on. It's a good idea if you ask me.

Black oil is perfectly normal for diesels, even almost immediately after a change. You should be more concerned if it's milky looking, which would indicate coolant in your oil.

Definitely get a wing nut on that air cleaner. Remember, in a diesel, there is no throttle plate to block of the intake track from the outside world, so having a good filter that's sealed against the air cleaner is critical. For that matter, if yours is NA, do some reading on water leaking past the cowl seal and into the intake. Definitely not what you want, so checking that seal is a good idea. It's not as critical for turbos because the intake is typically routed in a way where water can't really leak in there.

Mike

 

The oil turns pitch black in a matter of minutes after an oil change, that's just what it does. As long as he put 10 quarts of oil in the engine, and he didn't use a FRAM filter, you're good to go.

My temperature gauge also never climbs above the N / O region, usually it barely gets to the N. The only time it has was when I was towing an Explorer on a trailer up a steep hill, full throttle, ~25mph, for maybe 2 minutes or so. That got it up just past the R. This gauge, along with the oil pressure gauge (mine is dead centered 100% of the time the truck is running), are almost entirely useless.

 

Thanks a lot guys! You've put my mind at ease. I just found a 92 parts truck I might buy for all the parts I need for 89. I posted a thread on it with some pics.

 

On any diesel, having a good air filter, and fully sealed intake between the filter and engine are vital. Dust getting sucked into the engine will eat the rings/pistons/cyl walls fast. Not good for overall engine life.......

Like others have said, the gauges are practically useless. Mechanical gauges are worth the investment.
If the engine is running as cool as the gauge seemed to indicate, then you likely have a thermostat in need of replacement. Diesels do not like to be run cooler than designed. Power loss and excess fuel consumption can occur when running too cool. Both can lead to carbon deposits inside the engine, which is another can of worms......

 

I was doing 55-65mph all the way back with a 8.5' plow in the box. But It didn't seem to be getting great mileage so that could explain it. It was throwing good heat but not as much as I remember my gas powered F150's having. So the thermostat probably is the issue. I hope driving for 190 miles with that air cleaner like that didn't hurt the motor. It was loosely resting on the base. Hopefully it just needs a new stud threaded in and that it's not broken or stripped. I have to check it tomorrow.

 

A thermostat is a fairly cheap part and not a super difficult job to replace, but I'd consider the gauge first before you do unnecessary work. If you do replace the thermostat, use the OEM unit from Ford or International.

Mike

 

I'm definitely going to put the gauges in. What do you guys recommend for gauges?

 

and don't worry about regular oil in it. synthetic oil likes to find any place it possibly can to leak out.
my 88 has just about 497,000 miles on it and all i have ever run in it was valvoline all fleet 15-40.
like the other guys said, the temp and oil gauges in these trucks are just glorified idiot lights. if it moves, it is in the good range.
any mechanical gauge will tell you what is going on., but basically as long as you have 10 lbs oil pressure at idle you are good to go.

 

Where are you located? looks like a MN plate on the truck. If it is from MN I am VERY surprised at the lack of rust, good find.

Diesel Rod

 

Please do not make the mistake of buying a "STANT" or generic thermostat. The International/Ford part is very different in design, and not using factory thermostat can kill your motor through overheating. Please consult Ford Service Manual before changing your thermostat!!!!!
Most shops will install whatever their parts supplier stocks, and I have seen several trucks with aftermarket thermostat related problems.
Yes it costs $58.00 but it will last 15 years.

 

my 88 still has the original t-stat in it working fine, 26 years and close to 497,000 miles later.

 

Choose whichever style you like, and put the sensor in one of the two locations shown here:



Personally, I left my factory gauge working and used the other location only because I hated the idea of staring at a dead gauge every time I drove the truck, pointless though the gauge may be. Downside to this location is that it supposedly runs 5-7 degrees warmer than the factory sensor location, though I'm not sure that's anything more than an IDI old wives' tale to be honest.

Mike