I'm trying to figure out why my built LS1 is consuming oil at an alarming rate. I estimate 1qt of Mobil 1 every 150 miles or so. Granted, I've only put 500 miles on since buying ~6-months ago. I was originally told the problem was due to faulty valve-stem seals, but the new seals did not solve the problem. The previous owner said the Patriot heads were one of the 'bad sets' that had bad valve-stem seals and were causing the issue. Since it's such a simple fix (even with the heads on the car), I didn't exactly 'buy it.' Regardless, the parts are there for a stout motor (and the price was right ). I'm told the motor has 20k+ miles on it, but I don't know how long it's done this. Since the previous owner thought the cause was in the heads (seals or guides), I assume he never suspected the rings to be the fault.

The motor smokes significantly at WOT as well as when I shift at higher RPM. Same thing when I give it a quick rev. I believe it smokes at deceleration as well, but that's hard to detect. The exhaust will leave a phenominally dirty stain on my driveway after idling for 5 minutes (looks like black soot and water from condensation). Also, the rear bumper will be covered in small black spots (they're oily, I believe) after a quick 20 mile drive. I've pulled the intake and the entire intake is oily. Thus, I'm guessing I'm getting significant blow-by.

I have a box of receipts from the previous owner showing the machine work, balancing, most of the parts (missing the receipt for the rods). He told me he assembled the motor. From my investigation, the motor consists of the following:
JE pistons: PN: 194883. 3.905" (99.19mm)
spiral locks
Total Seal Rings: PN: MS7984 5. 3.903 1.5 1.5 3.0
scat h beam rods w/ ARP bolts
patriot 59cc cnc'd heads with double valve springs
hardened pushrods
LG g5x3 cam
ARP main studs and head studs


Let the discussion begin. If we determine it needs to come out, I'll start pulling the accessories off tonight. Spring is here and I want to start building my FI FRC...

 

Faulty piston ring/rings?

 

that's my guess, unfortunately.

 

very similar to what my car is doing. I have a 402 with a procharger, talked to Rippie and they think its my rings and pistons, the slp 402 was never ment to be boosted and it pretty much let go the other nite. I still have good oil pressure and it doesn't knock when i run it but it smokes quite a bit even at an idle.

 

To test the seal of the piston rings, I suggest you perform a compression test on all cylinders. Record the compression on each and then squirt some engine oil into the cylinder and crank the engine over several times and perform another compression test. If your cylinder compression is significantly greater after sqirting the oil into the cylinder, it's possible / likely you've got bad piston ring seal.

Perhaps a compression leak down test should be considered as well.

Do all of the spark plugs look the same, or are some much more oily and fouled with carbon?

 

From what I recall when I did my LT's just a couple months ago, the plugs all looked the same.

Let's say, for arguments sake, I notice no difference between any of the cylinders before/after adding oil to the cylinder. This would indicate the rings all seated/sealed properly, correct? Where would I look (other than the leak-down test) if the compression test yields the results above?

Note, I'm not saying this will happen. Rather, I'm trying to paint an if/then scenario to create more ideas.

 

From what I been told, forged engines will use oil but this does seem to be a bit much.

Hope that it works out for you.

 

I find that amazingly hard to believe. 1000's of guys building motors in this world and if any one of them sold a motor with a customer understanding they would have to add oil to their new mill due to consumption... they wouldn't be building motors. I'm sure others will agree.

 

Can we assume that the previous owner knows how to assy an engine ( big if) and the rings were installed correctly and that the tolerances of piston to wall are correct?

Has the engine shown these symptoms from day one of the rebuild?

Do you have an oil catch can?

The Total Seal gapless rings you have mentioned have the napier scraper face design for the second ring ( which is the revised design for 2001-2004 LS1-LS6 and the LS2) but has lower ring tension at 11lbs (compared to the above OEM revised ring's 13 lbs ).

Is the LS1 still utilize the OEM PVC system? Never a good design.

 

I cannot speak to the competency of the previous owner.

I cannot say whether or not it has done this since the rebuild. The oil consumption was blamed on the heads, but I am not certain if the heads were put on when the bottom end was rebuilt or if they were added after/before.

I do not have a catch can. It is running the factory LS1 PCV system, unfortunately.

Please elaborate further on the factory rings verses the Total Seal rings and how their differences are connected to oil consumption/etc. I'm no engine builder by any means, but certainly comprehend if it's spelled out in detail.



Also, I pulled the plugs in anticipation of my compression test later this evening. Every single one is black and oily. There is actually a considerable amount of oil/carbon. Note: pictures will blow-up to high-res... big suckers.

IMG_1708.JPG

IMG_1710.JPG

 

Compression test numbers. I let each cylinder build pressure for three strokes, for reference.

#1: 181-182
#2: 200
#3: 173-174
#4: 180
#5: 175-176
#6: 171-172
#7: 176
#8: 180-181

Per these numbers, nearly all the cylinders are roughly as much as 15% lower than the high of 200psi. However, if you remove the high and the low, they're pretty close. Regardless, I'm headed out to shoot some oil in the cylinders and see if the numbers improve.

 

Lots of variation...... The oil test should be interesting...

 

needless to say, I've only tested two of the cylinders with a dab of oil and the results were as many expected.

#4: 180 (dry) and 225 w/oil

#8: 180-181 (dry) and 219 w/oil

Thus, I have all the accessories off and would have the heads off if I had 12-pt sockets. Somehow, mine have walked off...

(yes, I'm pulling the heads first, then the shortblock as I figure this would be easier. I can be convinced otherwise, however.

 

Well you definitely have a mechanical issue. Not having a definitive history does not help the diagnosis.

The issue with the rings in general on all LS1/LS6 engines was a combination of items. (1) the cylinder bores are siamezed that leaves a small 20mm slot between the top of the bore for coolant flow. The result is hot spots that cause bore diameter and bore distortion and bore taper (cooling issue was reworked on the GEN 4 LS2). The machine tolerances for the cylinder bores from the factory were far from acceptable ( later tightened on the LS2).
(2) add to that the thin 1.5 mm rings and the OEM ring tension of 9 lbs made it difficult to seal , particulary when engine rpm was high (3500-up) with a no or low load ( high engine speed at low MAP) condition existed which caused ring flutter.

(3) the PVC system design on the LS1 allowed fouled crankcase vapors pass into the intake manifold. The LS6 reposition the oil seperator baffle under intake manifold which was away from the accumilated vapors. This was better but not at all perfect. The LS2 has two crankcase oil seperators / baffles , positioned at the fouled vapor exit and at the fresh air inlet. ( some LS2 owners still complain of blow-by and use oil catch cans).http://forums.corvetteforum.com/c6-c...l-problem.html

In 2002, GM issued ID #894549http://www.rjsmith.com/gm-894549.html .

This was to address the oil comsumption issue for 1999-2002 LSx engines. Look at the oil consumption rate. The revision was to replace only the second compression ring with a napier scraper faced ring with increased ring tension (13 lbs). Some were happy , others not. Also to revise the owners driving habbits.

Also in mid April of 2001 , new revision pistons were added to the production line 2001 model year LSX engines. This was to eliminate the cold start piston slap complaint by decreasing the dimension between the pistion and cylinder wall and adding a polymer anti friction surface to the piston skirt. This was revision was used thru the 2002 model year (M/Y).

For M/Ys 2002-2004 the revised napier /13 lb ring packs ( all three rings) were installed. Oil consumption was better but some still complain.

I just wanted you to get a little history of the oil consumption issues with the LSX engines.

Oil get by either the rings ( for various reasons from poor installation, napier face installed upside down, clyinder bore distortion or tolerances). Valve seals, either the seals or valve guide tolerance/ wear. Or PVC

What I've done in the past is to attach a constant air source inturn to each cylinder ( spark plug hole) and listen ( with a stethoscope if neccessary) for air leakage on the compression stroke of each cylinder. Air that is heard thru the tail pipes is exhaust valves. Thru the oil dip stick is rings. Thru the valve covers or valve stem is obviuosly valve seals. ect.

 

What was the solution OP???

 

Do you see any thread sealer on the rocker studs for the intakes? Looks a bit like plumbers putty.

 

I think you are going to find a ring/piston issue.

 

Over 4 months I hope he found something....

Hate to bump an older thread but these threads are resources, so having the last chapter missing is no bueno...

 

LOL My bad,I never looked at the dates!

 

Several were correct... it was apparently a ring issue. What caused it, I'm not sure. The rebuild had just 22k miles and according to the previous owner, it burned out from the very near the beginning (if not the beginning).

Regardless, a quick hone, check the balance of the assembly, and reassemble the shortblock and all seems well. I only have 430 miles on the longblock and I haven't switched to Mobil1, but everything seems fine.

I'll probably have the tune updated for the new G5x4 soon enough... right now, I'm taking it 'sort of' easy...