Engine/Transmission (1994 - 1998) overhauling 5.9

[LMcCary]

How do you get new oil rings to seal in the Cummins block? I am a 40+ year mechanic(Master ASE Auto and Truck Certified) and have never had ring sealing problems, until now. My '97 5. 9 was purchased from a burned truck, and the engine was stuck. So I overhauled it with after market parts. After 30,000 miles of oil burning (400-450miles to a Quart), I replace the engine with a used '96 model. The failure analysis class and my 40 year Cat and John Deere instructor disassembled the engine and found nothing wrong or that would cause the excessive oil useage. It was obvious that oil was coming by the oil rings and was being burned. Chrysler dealer says that this is common and the only way to stop oil useage on used blocks was to "machine hone" the cylinders. I have always used glaze breakers on other gas and diesel engines sucessfully.

Open to Your experience with this problem. Please NO B. S.

 

[MRose]

When I worked at a Masey Fergoson / Kubota dealer years ago, customers would come in complaining of high oil consumtion and we'd hook there tractor up to a pto water dyno. Work the living snot out of the motor, full throttle pulling it down to idle under a load for 20min. You could see the hp come up as you did it. Customers never came back with oil issues after that. Diesels don't break in till they work.

 

[LMcCary]

I had several good pulls on it. One was at 3000ft. above sea level on a 6% grade and 12,000lbs of trailer behind it while passing all traffic. (The truck weighs 6800lbs dry) Probally lost a quart on that mountain.

 

[41jay]

Have you ever though of gettin your head ported and pollished I heard my dad talkin about how it helps a motor so much when over haulen it. sorry could not have been more help.

 

[moparguy]

Quick story. I bought a 91 250 with 160k on it. It always used a quart of oil in 700 or so miles. My brother and I drove it to elk camp after a year of ownership pulling a 6,000 lb. trailer. We made a hard fast trip from Arkansas to Montrose, CO. (crossed the Rockies) showing the Cummins no mercy, just made sure it had oil. On the way back it stopped using oil.



Today, 5 years later at 220,000 miles it'll use a quart of oil in 4000 miles. Hard to believe but at 160k the rings were not seated. Took 20 hours of hard work to get them to seal.



RJR

 

[RTillery]

I sell engine rebuilding equipment to machine shops and Detroit Diesel Reman West is one of my main customers. Todays engine technology is advancing at a rapid pace. Cylinder wall finish is quite an involved science and if requirements are not met precisely, problems can occur. Trying to meet the combination of emissions, economy, and longevity are taxing the situation. Companys are spending $35K to $60K on power honing machines to put the required finish on a rebuilt engine. The harder blocks, and harder rings, with low tension need the perfect mating surface to get past that break in period and seal properly.

Doing it by hand can work, but chances of the rings seating properly are reduced. I suspect your finish was too fine to allow the oil rings(probably chrome) to seat in and seal up. You may have had a little taper or out of round in the cylinder. Most ring manufactures are requiring from a 15ra to 30ra with differences varying depending on the block, ring pack, application. The only way to determine this is with a profilometer. These can range from about $2000 to $50,000. If a hole is not near perfectly round and straight top to bottom, and has the correct surface finish, chances of sealing are lessened. The major rebuilders won't buy this stuff if it is not required, but to rebuild engines at a top level, it is. Sorry for your trouble. If working by hand on cylinder, it is best to use a rigid hone and err on the rougher side (usually).

 

[JCulp]

i have rebuilt about 15 or 20 5. 9ctd and the first ones we tried to use aftermarket parts and they leaked and blew oil past rings untill we started buying cummins parts there is truly a diff and i dont use after market any more they just dont hold up for us . hope this helps josh

 

[mechanic]

I sell engine rebuilding equipment to machine shops and Detroit Diesel Reman West is one of my main customers. Todays engine technology is advancing at a rapid pace. Cylinder wall finish is quite an involved science and if requirements are not met precisely, problems can occur. Trying to meet the combination of emissions, economy, and longevity are taxing the situation. Companys are spending $35K to $60K on power honing machines to put the required finish on a rebuilt engine. The harder blocks, and harder rings, with low tension need the perfect mating surface to get past that break in period and seal properly.

Doing it by hand can work, but chances of the rings seating properly are reduced. I suspect your finish was too fine to allow the oil rings(probably chrome) to seat in and seal up. You may have had a little taper or out of round in the cylinder. Most ring manufactures are requiring from a 15ra to 30ra with differences varying depending on the block, ring pack, application. The only way to determine this is with a profilometer. These can range from about $2000 to $50,000. If a hole is not near perfectly round and straight top to bottom, and has the correct surface finish, chances of sealing are lessened. The major rebuilders won't buy this stuff if it is not required, but to rebuild engines at a top level, it is. Sorry for your trouble. If working by hand on cylinder, it is best to use a rigid hone and err on the rougher side (usually).

I agree with RTillery. Todays rings need a very precise finish. The glaze breaker is not able to produce a proper finish for modern rings. It will be to course or to fine and will usually have chatter marks in the walls. Also it is now recommended that you wash the cylinder walls with soap and water and a stiff brissel brush.

Also, the block from a burned truck could be warped. It would take a bore gauge to find, and it may miss some problems. Also the ring manufactures have a procedure to "Seat" the rings on start-up after the rebuild. This is critical. Check with the one you used to see what they recommend for your application.

The brand of ring is also important. Some just are not very well enginered and not of good quality. Generally, Sealed Power or Hastings will be equal to OEM and in most cases are the OEM.

Hope this helps a little, just my 2 cents worth for free.

 

[Andy Redmond]

Let me throw out something, valve stem seals. Fed. Mogul valve stem seals can cause some grief sometimes. My brother had this problem, new Cummins stem seals (yes they are likely manf. by Fel-Pro Diesel) no more oil consumption.



Has anyone put the . 221 orifice and manometer in the crankcase breather tube to verify ring blow-by? Its its ok, think stem seals.



Just a thought, good luck



Andy

 

[mechanic]

I would have to have more information on the truck that had oil consumption through the valve seals. I have not found the valve seals to be a problem on a diesel. I have seen diesel V/W s with worn out guides and bad seals and still not use oil. (Gas V/Ws will drink oil with the valve seals in same condition).

If you think about it, most normally aspirated diesels do not have a throttle valve, therefore are wide open to the atmospheric pressure. So they have very little vacuum at the valve stem/seal area, so there is nothing to draw the oil into the intake ports. In a forced induction diesel (or gas) engine there is positive pressure at the valve stem/seal area, so the oil rather then being drawn into the port is rather pushed back up the valve stem into the rocker box. So it dosen't follow through to explain oil consumption through the guides. The only way that could happen would be if the "venturi effect" of the air flowing through the intake port were to develope enough vacuum to draw the oil in against the pressure, which is a possibility. The same basic senerio would apply to the exhaust side of the engine. I would like to see something from Cummins or someone with an enginering background. If it is doing that then we need to add that to our list of oil consumers.

 

[Vaughn MacKenzie]

Ol Blue on NW Bombers had a problem with trashed valve guides on his '01 HO but I don't think it used a lot of oil. Just had an erratic miss. Guides were trashed by antifreeze in oil caused by head gasket issues.



Vaughn

 

[Andy Redmond]

I assure you that valve stem seals can cause oil consumption as I discussed. The gent noted huge clouds of smoke on decel (manual trans) and during idle and at launch after extended idle. The engine rebuilder warrantied the stem seals and no more oil consumption (say 12 oz. over a 6K drain interval vs. the qt each 400 miles).



I've clipped a portion/quote from a Cummins Trouble-Shooting manual



Valve Guide seal, Cylinder head (002-016)

"Worn valve seals are typically detected by excessive smoke at ide or when the enine is unloaded when the vehicle is going downhill. Verify the condition by removing the valve spring and inspecting the valve seals. "



An engineer, gosh no? Just sharing what I learned from experience and hopefully it could be something simple like seals, rather than engine disassy for the ring seat condition. Again a manometer test should reveal ring blow-by if any.



Good luck

Andy

 

[LMcCary]

Valve seals will cause a lot of oil consumption, even on a Diesel. They will not use oil on acceleration, unless crank case pressure is very high. The seals will however cause oil smoke and consumption on decceleration and at idle. This is sometimes confused with bad rings, which will also cause smoke on decceleration.

I agree to the post earlier that stated the cylinders may not be perfectly round. Upon close examination of at least three cylinders had light rust piting in the oil ring run area. Low tension rings hydro-plane on heavily oil ladden cylinder walls. I am not used to the problems caused by overhauling engines that use low tension rings. Once burned and now learned. From now on I will have the block Power-honed to make the cylinders round.

Thanks for all of the replies.

LMcCary



White '78 Dodge crew cab, '96 5. 9 cummins, NV 4500, Dana 60 3. 54 diff.

 

[mechanic]

After reading the posts in response to mine, I would agree that under the conditions set out in the posts, that valve seals could cause the problem. I would suspect the exhaust side would be the bigger problem because of the flow dynamics of the exhaust flow when decelerating or idling. The presure/vacuum pulses would be sharper under those conditions. I had not considered that in my

 

[mechanic]

Valve seals will cause a lot of oil consumption, even on a Diesel. They will not use oil on acceleration, unless crank case pressure is very high. The seals will however cause oil smoke and consumption on decceleration and at idle. This is sometimes confused with bad rings, which will also cause smoke on decceleration.

I agree to the post earlier that stated the cylinders may not be perfectly round. Upon close examination of at least three cylinders had light rust piting in the oil ring run area. Low tension rings hydro-plane on heavily oil ladden cylinder walls. I am not used to the problems caused by overhauling engines that use low tension rings. Once burned and now learned. From now on I will have the block Power-honed to make the cylinders round.

Thanks for all of the replies.

LMcCary



White '78 Dodge crew cab, '96 5. 9 cummins, NV 4500, Dana 60 3. 54 diff.

After reading the posts in response to mine, I would agree that under the conditions set out in the posts, that valve seals could cause the problem. I would suspect the exhaust side would be the bigger problem because of the flow dynamics of the exhaust stream when decelerating or idling. The presure/vacuum pulses would be sharper under those conditions on both intake and exhaust, but I think the greater would be on the exhaust. I had not considered that in my thoughts of the previous post, and as stated, I have not encountered such with any of the engines I have worked on.



Low tension rings do indeed have a problem with heavy oils, but should not have a problem with the recommended weight for a given engine.

Also be cautious about using blow-by or rather the lack there of, as the sole vindication of the rings. I have seen hundreds of engines that had good compression and little blow-by, but had bad or never seated oil rings and they used oil like a fiend. One of the main offenders in this senerio was the 71> Pontiac 455 engines. They had oil consumption to the tune of a quart in 200 miles and good compression rings.

We had good success in reringing them and giving them a 100 to 105 mph run-in after reassembly. (Done in short bursts form 70 to 105 to 70 to 105 to 70 - ect. 3 to 5 times. ) Not reccomended for the Cummins.

This is what makes the TDR so valuable to us the owner / mechanics, the fact that we all learn from each other and refine our knowledge and add to our experience without having to make all the mistakes ourselves.

I have been working on mechanical things for 52 years, rebuilt my first Briggs & Stratton at 13 or so, and rebuilt a 235 Chevrolet at 15, after that there are many. Have been a professional mechanic for 33 years. 7 years in engine, transmissions, differentials and front ends.

26 years as a shop owner operator. I say the above not to sound better then, but to say I know that I can always learn something new. Thanks for the correction / addition.

 

[RTillery]

While valve seals are always something to consider on an oil burner, I haven't seen them as a culprit as often as gassers. Our diesels do not have throttle plates and do not generate the vacuum like gas engines. When the throttle is closed on a gas motor on deceleration, a high vacuum is generated on the intake side of the engine, especially at higher RPM's. The piston is trying to pull air in and the throttle stops it. Think of putting your hand over a vacuum cleaner hose. Same thing. This negative pressure can pull oil down the valve guide if excessive clearance and a bad seal allow it. That is why you sometimes see them smoking going down a long hill. Our diesels do not have this restriction on the intake so much less vacuum is generated. The exhaust side of the engine is not effected nearly as much. It tends to stay closer to atmosphere or positive pressures so oil is not pulled in. You can look at gasser engines and often they use a much more aggressive seal on the intake compared to the exhaust. Guide to stem clearance and seals should always be checked on diesels, but they tend to be less critical than gassers. Throttle plate vs. no throttle, makes a difference. Another reason for the superiority of diesels!



Positive crankcase pressure can have an effect too. A bad ventilation situation caused by excessive blowby and no place to go can cause positive pressure within the engine including the top of the cylinder head. If the pressure in the crankcase goes very positive, it can push oil down the stems if it is allowed to gather or puddle/pile up there, if the pressure on the port side is less. Then you get a combo effect. Blowby causing pressure, seals and clearance allowing oil to be pushed down the stems. Seals are important on a rebuild, but the clearance between the valve guide and stem is critical to a good valve job. The stem/guide is not only the bearing for the valve head, it is also the locating device that allows the valve head to accurately close on the valve seat and seal off the combustion chamber. An accurately closing valve will run cooler, increase combustion pressures, and control oil. Chain of events. Cool stuff. The internal combustion engine is a marvel.

 

[LMcCary]

You mechanical experience id similar to mine. I started out on Lawson 2-cycle engines at 10years old,graduated to motorcycles,outboard motors and had a outboard repair business while in High School. Then cars, tractors, and light trucks to the machine shop where I became the Maintenance Sup. for 8years. From there to Oil rig building where I became Materials control and Mechanic Sup. Later, due to the oil field crash, I worked for UPS on their package cars. Left there in '86 as HD truck Sup. Owned a business for 11years, where I worked on most wheeled vehicles, including farm equip. Now, I am the Dept. Chair of he Diesel Equip. program at a local College. Thanks again for all of the replies. Sometimes I need others to vent on, in order to see my mistakes.