Oil Burning Problem after rebuild - Help

Well after doing a complete engine rebuild, replacing the rings, valve seals, all the gaskets and o-rings and getting the engine back together #4 is buring oil like crazy. So after all that I took the engine apart again and the rings appear to be fine, the gaskets didn't show any signs of leaking. The only evidence was that the number 4 combustion chamber was very oily and the exhaust valve (all were polished) has a caked on oil residue. Now is this oil coming from the exhaust valve or coming out of the intake and baking onto the exhaust valve. Both valve seals appear to be fine (doesn't mean once isn't leaking). Number 4 never gave me any problems before so this is something new. Its so frustating after all thoes hours putting it back together and having to tear it down again. So what do you guys think is the problem? bad valve seal? or something else?

 

lLook in the oil in the case and look for gas and any sign of blowby. If all is well then Id do a leak down test atlest a competion test and if that is all good then Id bet on a valve leak. Look 2 see that the stems are not bent and the gides and seals are good . It sounds like a head problem . Dha you took the motor apat again so disregard the leak down test but do look and smell the oil for gas.

 

Did you hone and cross hatch the cylinder bores? If not, the rings probably won't seat.

Cheers,

Phil

 

Oh yes, the bores were honed and the ridge broke. The rings appear to be seating in fine, the other cylinders have no problems and they all reveived the same treatment. Here is an image of the #3 and #4 cylinders. As you can see the #4 is much cleaner than #3 overall but the exhaust valve is caked with residue.

 

Phil knocked that one down. Honing and Cross-Hatching is a must or the Rings won't be able to seal the Cylinder off. The Cross-Hatching keeps a sheen of oil on the Cylinder Wall. That sheen prevents gases from blowing by.

I hope you replaced the Valve Seals.
I have cracked new rings doing a ring job ... it happens.

Did you slip a ring down the hole and see if the gap was specs?
If the ring is too widely gapped ... you might have needed the First Over Rings!

 

Closely inspect oil control rings on number 4.

 

Yeah, I checked the clearances, and the rings put in were the 1st oversize, the end gaps filed to spec. I have already removed the bores and the rings are not broken and all of them appear intact. All the valve seals were replaced. This is what is so puzzling.

 

If you end up concluding that it is a ring seating issue, and not a seal issue, there are old school "redneck" mechanic techniques that could work for seating the rings the last little bit. I've had mechanics with 40 years experience mention that many motor jobs that they do get a little shot of abrasive kitchen cleaner, such as Bon Ami or Ajax (the cheap powders), in each cylinder before startup. I'm not talking a large amount, just a pinch through the plug hole, followed by a puff through a drinking straw to spread it around a bit, fire it up, and let it polish the rings into seating. I'm not saying there aren't risks, but on many irrigation pumping engines, such as 549 Internationals, the block is so hard that rings often won't seat. This is a possible solution if ring seating is the case.

Best Regards
XJ750GUY

--edit--
I would like to reiterate, this is not the correct way to fix any other problems that exist, but rather a solution limited to ring seating. I don't believe that the hardness of the XJ block or rings should or would require such a measure, but rather wanted to mention it as a "different" approach to a problem some may have had in the past or in the future. As this site tries it's best to recommend the correct procedures, often to folks with little to no previous experience, I felt I should comment on this.

 

I wouldn't recommend such a drastic action such as introducing cleanser into the Bores. It could collect on Valve and Seat faces resulting in needing a Valve Job in the near future.

I would recommend having a real close look at the Head Gasket. I'd be looking for a fingerprint indicating that the Head Gasket was allowing the 4-Hole to vent ... to either the Crankcase or the adjoining Cylinder.

This could have been proven with a Compression Check before the tear-down. Now, we have to suspect that the Gasket might have failed ... allowing for the 4-Hole to vent to some other cavity or adjacent Cylinder.

Further, it must be examined to see if the Oil Passage might have been compromised allowing Motor Oil to enter the Cylinder from a Gallery Dowel or failed O-ring sealing-off the Combustion Chamber from the Oil Supply.
Since this supply would have been under pressure, the trail from where it leaked to the Combustion Chamber should be evident on the Cylinder Head Gasket.

Additionally, a warped Head must be suspected. The Head's mating surface must be straight edged ... side to side and corner to opposite corner.
A feeler gauge must not be able to measure any warp or bow.
If this is the case the Head must be planed flat.

I don't know how much material can be removed to bring-back the flat surface ... but, I would suspect the least amount of surface should be shaved off the Mating Surface to guard against the possibility of Valve Crash into a Piston Crown.

 

Did you make sure the rings are up the correct way?

 

One of my first thoughts was that the oil passages that run by #4 might be leaking, I did take a good look at the head gasket and its squeaky clean, its appears to have been a good seal. It keeps looking more and more like the rings, or a warped head, which would be bad.

 

If there's no tell-tale footprint on the Head Gasket ... the Head Gasket, Seal, Warp and Oil Gallery compromise is ruled-out.

What are we missing here?

Get a strong magnifying glass and look for a crack in the Head in and around the 4-Hole.
We might as well look for everything if we don't know what it is.

 

Ok, I don't have the bores here, they are in my buddy's garage still on the bike, but I just spent the last 3 hours going over the head. I removed the valves from #4 checked the seals, the valve seats, the guides, and the head for any cracks. I didn't find anything. I am going to head over and take all the rings off #4 and check them over again, and look at the bore. At this point the choices are getting pretty slim.

 

Similar Problem .. Sigh. . blows oil when by all reasonable assumption it should not.
Younger son siezed his engine a while back.. I "repaired" it, although I did Not find ANY evidence of damage or more worryingly WHY the F'n thing siezed in the first place. Replaced with : Fresh Block, Pistons Rings, Head Valves etc, From another engine in fact ALL new seals gaskets yet Again. .. But I refused to pay for a full crack test on a $200 engine.
Serious blue smoke within moments of startup.. Am so pissed that I have not yet finished the Autopsy a year later.
Seriously suspect that something is pumping oil up into the bores...Have no idea what and it's Unproven as yet though.
Candid opinion: Once these things are worn they are for the Scrap bin.. Period...Never.. again, will I waste my time on 'rebuilding' one of these.. And I've been building Performance engines for a wee while (goin on close to 40 years now) so unless my Oltimer's is acting up I think I've gotten past the usual Newbie mistakes.
The son refuses to even sit on the thing, I want it ..out.. of my Shop.
Rascal just went out and bought a Brand New Honda 600 RR.. can't say as I blame him.. it's 100% undamaged by any previous incompetent owner.. has a warranty too

 

I'm beginning to think the problem must be within the Piston and Bore.

There must be something going on ... like the beginning stage of Piston Slap ... where the Piston's Skirt has worn down allowing the Piston to tilt within the Bore during its up and down movement.

Such a condition would be cause for an incomplete wiping of the Cylinder Wall of the Oil Sheen, and, ... in most cases cause the Oil not completely wiped by the Oil Control Rings to burn with the following Power Stroke ... and contribute to a smoking exhaust ... then, ... as the Piston Slap worsens ... foul the Plug with Oil before the inevitable failure of the Piston by causing the Piston to break with a connecting rod damage or failure following the
Piston's demise.

You are going to have to "Inside Mic" the Bore and check the Number-4 Piston for any "Out-of-round".

You might find that the condition of the Number-4 Hole dictates that you move-up to the 1st Oversize Piston ... which very well may be hard to find; I don't know. I haven't had to look for an over-sized Piston in well over 10 Years.

If the Bore is egged-shaped contributing to all this matter ... then, rather than go through all the trouble having the Bores machined to an Oversize
(for which we do not know how readily available Over-sized Pistons are to acquire) ... then, the wise choice would be to acquire an Engine from Salvage and either use it complete ... or, as the foundation for your reworked Head ... using the two Engines to make yourself one good running motor.

 

If this all doesn't work out I started looking for another engine. I think I found one which the owner says is in good condition, its actually the engine and the frame and wheels. He sold the rest off for parts.
If worse comes to worse I may just swap out the bores into my engine. The valve trane and the head appear to be fine. There is however some widening of the bores on the top of the stroke.
The reason for this rebuild was because the #2 piston threw a ring, all the others were running great. Now after the rebuild #1,2,3 work great, and #4 is burning oil like mad. So something changed, eighter rings arn't seating for any one of the reasons mentioned in this thread or something else is going on. I am going to check the ring gaps and condition on #4 again tomorrow, maybe put a little more light cross-hatch into the bore, then butten her back up and see what happens.

 

Just want to say thanks to everyone who gave suggestions on this one. After another complete tear down, a light re-hatch of the cylinders, cleaning of all the components again and re-assembly it appears to be running great. No more blue smoke, rock solid idle, almost like a new engine. I still don't know exactly what was causing the oil burning, but my best guess is ring related.

 

I'm glad to hear you got it back together and running nice.

Did you install any Velcro or Zippers in case you have to get in there again?

(LOL)

 

Glad you got it solved!

Cheers,

Phil

 

Heh, yeah I wish it had zippers. I've got the tear down and rebuild procedure down to a T now. Hope I don't have to do it again for a loooong time.