I just got my rebuilt sleeved 93 7.3 turbo engine put in and running in my truck. It has massive blow by, and has a shake at idle. The exhaust runs clean with no blue or white smoke. I have a road draft tube on it and the vapor is bad enough to see out the window at idle. Is it normal to have a lot of blow by on an engine with 80 km's on it? Would a bad injector cause the shake but produce no smoke? I also have a 6.9 solid flywheel on it, are these flywheels balanced to the engine or are they neutral balanced? The flywheel ran smooth on my n/a 7.3, but I'm wondering if the added mass of the turbo pins/rods with the 6.9 flywheel is putting it out of balance. Thanks.
Rebuilt engine ques
- Thread starter BigDiesel
- Start date
mattplumber
Full Access Member
I would guess pump timing is the root cause of your problems here. How did you use a 6.9 flywheel? Are you running an old 4speed or a zf-5 speed? The 6.9 flywheel will only work with a t-19 4speed. If its somehow being used behind a zf then I would guess that would cause a hell of a shake. As far as blowby is concerned: Did you re-ring the pistons? If so they will need to seat properly. If they havent yet, then it would cause the engine to puff clouds...........
Have you broke it in yet?
I'd change out the first oil and filter to get the machine residue out , then put a load behind that sucker and find some mountains and stand on it. Until you seat the rings it's going to be a bit sloppy
I'd change out the first oil and filter to get the machine residue out , then put a load behind that sucker and find some mountains and stand on it. Until you seat the rings it's going to be a bit sloppy
You cant load it too much, just watch temps and stuff. Luk does list a different flywheel for the factory turbo but not too sure differences.
Ive been running her pretty hard to try and seat the rings. After warming it up for the first time I ran her up to 3000 rpm in every gear exc 5th gear, and found a nasty 15 degree hill to pull a few times. The engine is being run without a turbo for now until I get the exhaust worked out so hopefully it wont hurt it. BTW it is completely rebuilt new pistons, rings, bearings, sleeved all 8, rebuilt heads, new pump, newish g codes. The timing has been set by my ear to close to my old engine that ran great. My biggest worry is the shake at idle. The flywheel is a 6.9 solid with zf5 disk and t19 pressure plate. Thanks guys.
Diesile
Full Access Member
The shake is definitely the 6.9 flywheel. Been there, done it. You need the 7.3 turbo
specific flywheel for that engine as is listed by Luk and others.
specific flywheel for that engine as is listed by Luk and others.
BigRigTech
Diesel junky
Does the disc have springs? I have a 1987 6.9 T19 flywheel on my 7.3 with a ZF, works mint and for over a year now...Smooth as a baby's ass.... 11" clutch disc with springs and T19 pressure plate....I don't know why people think there should be a shake from the 6.9 flywheel on a 7.3...The shake is probably caused by the fuel system such as a bad injector or air intrusion...A factory 7.3T would have had a DMF, nothing special about it - I have the DMF that came out of the donor truck that Goofy robbed the his 7.3T from.
....If you sit down and look at a IDI flywheel, there is no real balance weight like you would see on a SBF flywheel.Diesile
Full Access Member
Guys, one more time on this issue. On the FACTORY TURBO 7.3 IDI engine the larger wrist
pins cause the need for a differently balanced flywheel which is why there is a separate
one listed in Luk. Key words are FACTORY TURBO. The n/a 7.3 can use a 6.9/n/a 7.3 flywheel. I had that problem and fixed it with the turbo 7.3 flywheel.
pins cause the need for a differently balanced flywheel which is why there is a separate
one listed in Luk. Key words are FACTORY TURBO. The n/a 7.3 can use a 6.9/n/a 7.3 flywheel. I had that problem and fixed it with the turbo 7.3 flywheel.
BigRigTech
Diesel junky
I don't know, doesn't make sense to me...All 8 rods have the same pin weight so I can't get it through my head how that could affect the balance of the crank...This is probably why I failed physics....
...All I can see online is that the factory turbo motors were sold with a 12" clutch instead of the 11" unit that came in the N/A idi's....As far as I know a 7.3 crank is a 7.3 crank regardless if it was N/A or Turbo from the factory.
...All I can see online is that the factory turbo motors were sold with a 12" clutch instead of the 11" unit that came in the N/A idi's....As far as I know a 7.3 crank is a 7.3 crank regardless if it was N/A or Turbo from the factory.
It makes a difference because the RECIPROCATING weight is a lot more.
The vibration dampner has more counterweight in it vs the n/a. If there is no visible counterweight in the 7.3 t flywheel does it mean its neutral balanced? The engine only shakes at idle if I rev it up a bit its not as bad. If it were fuel system would it smoke?
racer30
Full Access Member
I agree with diesile, the bigger rist pins and heavier rods will need differant balance. replace the flywheel and you will be ok. did you have your assembly balanced?
After looking at alot of pictures of the dmfs from the turbo and the n/a it looks to me (visibly) that the only difference visibly is the 12 inch vs 11 inch clutch. Even the flex plates look the same ie the balancing slots cut in the same spots relative to crank bolt holes, torque converter bolt holes drilled in same spots. The flywheel bolt holes point to the same spots on the back side, and the crank indexing spot (absence of a crank bolt hole) points to the same dampening spring as the n/a flywheel. The slots cut for balance on the engine side of the flywheel are even the same. So it appears to me that the difference in mass has been taken up by the vibration damper. The engine manual states also the changes from n/a to turbo flywheel are not discernible other than by part number. I am going to try swapping my g codes for my good known bb codes out of my n/a engine to see if that fixes it. If it does not then there is indeed a difference. Thanks guys for your help.
icanfixall
Official GMM hand model
Your issue is the resip. element was not balanced. This means the crank, rods & bearings, pistons with rings & pins plus the front dampner and the flywheel. This is how I had my turbo upgraded 7.3 non turbo block balanced. If it spun around in the engine it got balanced. Lots of weight was added in the mid plain (the center of the crank) to make it correct before the shop could match up the rest of the mas of parts. You can hear my engine running but you can't feel it... Now thats giving me a funny feeling at idle or driving down the road. Its kinda too late to balance things now but you micht try the 7.3 turbo flywheel and front dampner. These engines are low rpm so its not really that big of a balance issue. I even talked with Eric the head engineer at Mahle about their turbo pistons being so out of balance in a set of 8. He told me the differance in weights between pistons could be as much as 14 grams and it would not hurt anything nor reduce the longevity of the engine.... Well I didn't buy into that thought but he was the expert. I just could not run that far out of balance on each piston....BTW... Get rid of those G codes for a set of new BB codes. You may have a issue with the semi new G codes you said you installed.
