Bad 7.3?

[Rystoltenberg11]

I have a 2001 7.3 with a TON of blow by. It has 139,364 miles, it is a 550 with a flatbed, and it used to belong to the local feed mill that serviced it every 20,000 miles. It was ran hard, and can barely do 55 mph full throttle. But for some reason it only smokes when it idles and when you start it. Not when it’s at throttle. Could it be a gasket of some kind or a bad line? Any advice would be greatly appreciated

 

[ss55]

I have a 2001 7.3 with a TON of blow by. It has 139,364 miles, it is a 550 with a flatbed, and it used to belong to the local feed mill that serviced it every 20,000 miles. It was ran hard, and can barely do 55 mph full throttle. But for some reason it only smokes when it idles and when you start it. Not when it’s at throttle. Could it be a gasket of some kind or a bad line? Any advice would be greatly appreciated

Worn rings and valve guides?

 

[rustred]

I have a 2001 7.3 with a TON of blow by. It has 139,364 miles, it is a 550 with a flatbed, and it used to belong to the local feed mill that serviced it every 20,000 miles. It was ran hard, and can barely do 55 mph full throttle. But for some reason it only smokes when it idles and when you start it. Not when it’s at throttle. Could it be a gasket of some kind or a bad line? Any advice would be greatly appreciated

thats peanuts for miles for that engine. so that means it was not looked after very good. 20 k is too long for services. should be 10 k. see that tells the story right there. blowby is a worn out engine.

 

[E.B. Haymakin']

I have a 2001 7.3 with a TON of blow by. It has 139,364 miles, it is a 550 with a flatbed, and it used to belong to the local feed mill that serviced it every 20,000 miles. It was ran hard, and can barely do 55 mph full throttle. But for some reason it only smokes when it idles and when you start it. Not when it’s at throttle. Could it be a gasket of some kind or a bad line? Any advice would be greatly appreciated

My brother had a 7.3 that had a defect where the fuel injector system passed through the water jacket. I can't remember all the symptoms but I do recall lack of power was one. I believe it was an issue in block casting towards the end of the 7.3 manufacture, or a few years prior to end of manufacture. His was in F-250 & when the new gaskets sealed it up in the repair the motor was top notch.

 

[Fritz Maurer]

Do a compression test before you worry about anything. Not long ago on this forum , a guy had a Diesel that wouldn't start .... and smoke was "pooring" from the exhaust.... it was later determined that it was air-locked... so how much smoke was it really making?

Trouble shooting is so much easier to deal with when real numbers are involved, rather than arbitrary terms that mean different things to different people.

Didn't that engine have a flapper downstream of the turbo? Are you sure that isn't jammed shut?

 

[Gambles]

You said it’s got blow by. How did you verify?
Start the motor up and remove the oil fill cap and just let it rest in the threads. If the cap is doing a big dance, you’ve got lots of blow by and nothing short of a tear down will fix it.

 

[rustred]

Do a compression test before you worry about anything. Not long ago on this forum , a guy had a Diesel that wouldn't start .... and smoke was "pooring" from the exhaust.... it was later determined that it was air-locked... so how much smoke was it really making?

Trouble shooting is so much easier to deal with when real numbers are involved, rather than arbitrary terms that mean different things to different people.

Didn't that engine have a flapper downstream of the turbo? Are you sure that isn't jammed shut?

you mean that john deere tractor that would not start ? nothing was ever determined , he presumed that.

 

[Fritz Maurer]

you mean that john deere tractor that would not start ? nothing was ever determined , he presumed that.

Ok, then ,he PRESUMED... whatever it is, the tractor is still running, I PRESUME, so there must be some accuracy in his PRESUMTION.

The fact remains.... no numbers equals guessing. Like the guys who PRESUMED the no-start condition was due to the sunken valves. So, actually, it was DETERMINED that the valves were not the problem when the compression numbers came back.

 

[rustred]

Ok, then ,he PRESUMED... whatever it is, the tractor is still running, I PRESUME, so there must be some accuracy in his PRESUMTION.

The fact remains.... no numbers equals guessing. Like the guys who PRESUMED the no-start condition was due to the sunken valves. So, actually, it was DETERMINED that the valves were not the problem when the compression numbers came back.

For sure. I agree the valve recession was not the problem. Cause he was giving it starting fluid and it still would not run. I don’t think he had it bleed properly, but I don’t see how it can be smoking when not bleed. Just not right.

 

[Fritz Maurer]

For sure. I agree the valve recession was not the problem. Cause he was giving it starting fluid and it still would not run. I don’t think he had it bleed properly, but I don’t see how it can be smoking when not bleed. Just not right.

I don't blame the guy for not wanting to do it , though... just getting the valve covers off a 7.3 is an adventure... and the turbo, forget about it. At least on a '95... they cram that engine in there, I hate V8s in pickups.... they should have put the DT360 in there.

 

[Rystoltenberg11]

I don't blame the guy for not wanting to do it , though... just getting the valve covers off a 7.3 is an adventure... and the turbo, forget about it. At least on a '95... they cram that engine in there, I hate V8s in pickups.... they should have put the DT360 in there.

You could have gotten a 460,or a 351 and 352 winzer. If you think those are easier to work on. ( there not)

 

[Rystoltenberg11]

You said it’s got blow by. How did you verify?
Start the motor up and remove the oil fill cap and just let it rest in the threads. If the cap is doing a big dance, you’ve got lots of blow by and nothing short of a tear down will fix it.

Yes. The cap dances around on its threads. The size of the smoke cloud is about 8ft tall and, when the wind is blowing, like 10 ft wide. It’s a huge cloud when you start it. But when it idles it just blows little puffs at a time.

 

[Rystoltenberg11]

Do a compression test before you worry about anything. Not long ago on this forum , a guy had a Diesel that wouldn't start .... and smoke was "pooring" from the exhaust.... it was later determined that it was air-locked... so how much smoke was it really making?

Trouble shooting is so much easier to deal with when real numbers are involved, rather than arbitrary terms that mean different things to different people.

Didn't that engine have a flapper downstream of the turbo? Are you sure that isn't jammed shut?

I have checked the turbo, to see if any exhaust lines where somehow pinched, but nothing

 

[JMOR]

You could have gotten a 460,or a 351 and 352 winzer. If you think those are easier to work on. ( there not)

On those candidates, I say, how easy, depends on year of mfg.

 

[joeysmith]

Anyone serviced the crankcase breather in those miles?
Usually gets forgotten about

 

[wore out]

I have a 2001 7.3 with a TON of blow by. It has 139,364 miles, it is a 550 with a flatbed, and it used to belong to the local feed mill that serviced it every 20,000 miles. It was ran hard, and can barely do 55 mph full throttle. But for some reason it only smokes when it idles and when you start it. Not when it’s at throttle. Could it be a gasket of some kind or a bad line? Any advice would be greatly appreciated

Possibly a clogged "CAT" or other exhaust system restriction?

 

[Fritz Maurer]

You could have gotten a 460,or a 351 and 352 winzer. If you think those are easier to work on. ( there not)

I think you may have misunderstood what I was talking about based on your engine options. I meant DT360... NOT a Y-block that has been out of production for 60 years.

The DT360 would have been direct competition to the 5.9, albeit 200 lb. heavier. The Cummins was easy to work on because everything was in the center of the engine bay , not jammed under the master cylinder and air conditioner.

If there are two Navistar 4700's for sale side by side, one with a T-444 and the other with a DT466, the 444 will be the last to go.

They were a popular engine with a cult -like following, but some applications were not warmly received.

 

[Bill of TN]

My 7.3 in my 99 F350 started blowing white smoke at an idle ( roughly 280,00 miles). replaced the turbo and all 8 injectors with new glow plugs and all is well.

 

[Rystoltenberg11]

I think you may have misunderstood what I was talking about based on your engine options. I meant DT360... NOT a Y-block that has been out of production for 60 years.

The DT360 would have been direct competition to the 5.9, albeit 200 lb. heavier. The Cummins was easy to work on because everything was in the center of the engine bay , not jammed under the master cylinder and air conditioner.

If there are two Navistar 4700's for sale side by side, one with a T-444 and the other with a DT466, the 444 will be the last to go.

They were a popular engine with a cult -like following, but some applications were not warmly received.

My grandfather has an old auto car semi, twin stick and Cummins swapped. Took the whole power train from a wreaked Kenworth T800 that didn’t even have 50,000 miles on it. The worst part is that T800 was the last one to role off the factory line.

 

[Rystoltenberg11]

I think you may have misunderstood what I was talking about based on your engine options. I meant DT360... NOT a Y-block that has been out of production for 60 years.

The DT360 would have been direct competition to the 5.9, albeit 200 lb. heavier. The Cummins was easy to work on because everything was in the center of the engine bay , not jammed under the master cylinder and air conditioner.

If there are two Navistar 4700's for sale side by side, one with a T-444 and the other with a DT466, the 444 will be the last to go.

They were a popular engine with a cult -like following, but some applications were not warmly received.

Could have also gotten a T444E if you think about it. The 351 Windsor hasn’t been out of production for that long, it was discontinued in 96, 460 in 78. Sadly I can’t find and 391s for sale near me, I have a Polaris RzR that has a bad engine. That would be fun with ether a 300,302 or 391.