25K Miles Post-Rebuild Woes

[Spaghettiohead]

Heyy all,

I've got 25K miles on my rebuild now. Still running strong, and just got home after a 6K mile trip in ten days. I'm already planning on another rebuild since I'll be pulling the engine to replace the front cover and oil pump.

She's running strong, and one highway tank at 70mph netted me 47mpg on non-ethanol gas last week...but my oil burn has steadily increased over the last few months from 1 quart every 4K miles to 1 quart every 1K miles, exactly where I was prior to the rebuild. Compression is still good and she pulls strong. I know I have a leaky rear main seal, but it can't possibly account for ALL the extra burn.

I used Keith Black pistons and Hastings rings in honed (non-bored cylinders). I need to nip this oil burning on the next rebuild. I've already decided on a shop in Houston that I've heard good things about, as opposed to the shady guys I used last time. I'll have them check over the head and bore the cylinders.

Any other thoughts?

[Macgyver]

You have to have them drill oil drainback oils or the problem will just come back over time.

http://www.youtube.com/watch?v=UrnblJ8VZtY

[Chub]

I was writing this first as if you had done the rebuild yourself but I now realize you had a shady shop do the work that may have not checked for my suggestion:

How many times did you check your Hastings rings before you installed them? I got a set and the end gap of the lowest ring was way too big. I can't remember the exact size but it was more than fifteen thousandths beyond the service limit and I had to send them back and get another set to fix the end gap issue. Having too much end gap on the lower ring would definitely not help keep the oil out of the combustion chamber and it is something that may have been overlooked.

[Spaghettiohead]

Thanks guys. The new pistons had ginormous oil drainback holes already. Thought I was in the clear.

The Hastings rings though...not only are the cylinders probably somewhat out of round, but the ring gap I know for certain was out of spec - I checked myself but followed some bad advice (was told they would definitely close up with expansion from the combustion temps). I'm sure they do, but that's why you have the tight end of spec grrrrr...

Could that explain the increased oil burn over the last few months though?

[anmasher]

Perfect Circle molly rings are supposed to be about the fastest and most guaranteed to seat, honing is different though (320 grit, IIRC).
What's the story with the head - was it from J&C?

Follow the break-in procedure to the letter and it should be fixed this time.

EDIT: Lack of oil drains wouldn't cause any problems after only 25k. As for the rings closing up during operation.... Why do we measure them (and have the specifications for) when cold? Within spec when cold = within spec when hot. The opposite is also true. The oil burning is likely because the cylinders weren't perfectly round and/or the honing wasn't done right. What was the mileage/maintenance before the rebuild?

[ehunter]

Originally Posted by Spaghettiohead

Heyy all,

I've got 25K miles on my rebuild now. Still running strong, and just got home after a 6K mile trip in ten days. I'm already planning on another rebuild since I'll be pulling the engine to replace the front cover and oil pump.

She's running strong, and one highway tank at 70mph netted me 47mpg on non-ethanol gas last week...but my oil burn has steadily increased over the last few months from 1 quart every 4K miles to 1 quart every 1K miles, exactly where I was prior to the rebuild. Compression is still good and she pulls strong. I know I have a leaky rear main seal, but it can't possibly account for ALL the extra burn.

Your story sounds very similar to mine.

I could have sworn all my consumption was due to the rear main seal and it was murder trying to validate whether it was or was not. I even bought a cat-eye scope to inspect the narrow space between the flywheel and the seal so I could watch/see where the oil was seeping. You can only see one side/half of the seal with the scope because there is not enough room to maneuver up the other side. That one half was bone dry. In the end I figured it was a lot less work to redo the oil pan as opposed to pulling the engine to redo the seal. Bottom line is the leak was the pan lip, not the rear seal, and it was impossible to 100% validate the source.

It was a good call re-doing the oil pan first as it is a lot less work and that DID stop the leak. Beat the hell out of pulling the engine. Bad news is this still did not stop my oil consumption. Yes, I had holes drilled in the pistons.

Another problem that started after the rebuild, and got worse and worse, was a P301 condition. I could never get it to go away. When I could not take it any longer it was at the 30k mark. Turns out I was loosing cyl compression in #1, and #3 was not far behind. My new mechanic told me my J&C head was on its way out due to the seals and the metalurgy looked out of place on the overhead cams. They replaced the head, the P301 went away, the great compression came back, and I am rechecking the oil consumption again. Jury is still out.

The car runs smooth, but the downside is only 36mpg where before I did the overhaul I was at 40mpg.

[OldNuc]

The fit of the piston to the cylinder is critical and has no real allowance for wear and honing. Recycling the OEM pistons requires careful piston measurement and comparison to careful cylinder measurements. This is not really a DIY job unless you want to buy some rather expensive tooling. You are at the mercy of the machine shop for this. The best approach is to bore oversize and fit new pistons.

[laser3kw]

Thanks guys. The new pistons had ginormous oil drainback holes already. Thought I was in the clear.

imagine that..... "drain back holes" and still as oil control probelm.

[Spaghettiohead]

Well my head is original. They did the standard valve job and that's about it. I heard some horror stories (more than one) about J&C lately so I stayed away from them.

The honing and cylinder roundness is no doubt to blame, along with the out-of-spec ring end-gap. What a shame to tear apart an engine that's running otherwise great :-/

While I have some attention here too, are there any good shops in the Houston/San Antonio/Austin area that can be recommended?

[OldNuc]

End gap is not the cause of excessive blowby or oil consumption. Up to 0.040 end gap has no impact on either blowby or oil consumption. Out of round, taper or worn excessively does however.

As of right now there is no mail order mass rebuilder that has impressed. Several did in the past though.

[ehunter]

Originally Posted by Spaghettiohead

The Hastings rings though...not only are the cylinders probably somewhat out of round, but the ring gap I know for certain was out of spec

When you bought the rings, weren't they specific to your piston bore measurements?

Once the pistons insert into the bores the resting gap of the rings compresses significantly. From that point heat would close up the gap even more. I would also think different rings from varying materials would expand differently.

Where did you get the spec numbers for the gaps and are they to be measured after the piston is mounted in the bore?

[laser3kw]

From that point heat would close up the gap even more

actually it doesn't. The cylinder bore enlarges as the engine warms up to running temperature. Although the piston and rings also expand, the bore expands more (function of circumferance ). I experimented on smaller race engines. It is not uncommon to set ring gap as close as .001. when warmed up to 200º, that gap becam .005 or more. Came to the conculusion after many experiments that that type of ring gap was not needed, ended up around .005 cold. I have purposely heating the block and piston to the same temperature and measuring them to see just how far I could set the skirt clearance. I have even gone the route of honing a "hot block" to try to eek out a little power under the assumetion that the bore would be rounder during operation.

[ehunter]

Interesting

When I did my engine I wish I knew this. I would have measured. It will always remain an unknown now in my case but maybe I can go back and figure it out with a pencil and paper. I did record my bore radius sizes, I know what rings I used. What would I need to do from there?

From an angle of racing... you were probably going for a tight fit for max compression. Might my compression numbers be a positive/negative indicator of ring gap tolerance?

[OldNuc]

Originally Posted by laser3kw

actually it doesn't. The cylinder bore enlarges as the engine warms up to running temperature. Although the piston and rings also expand, the bore expands more (function of circumferance ). I experimented on smaller race engines. It is not uncommon to set ring gap as close as .001. when warmed up to 200º, that gap becam .005 or more. Came to the conculusion after many experiments that that type of ring gap was not needed, ended up around .005 cold. I have purposely heating the block and piston to the same temperature and measuring them to see just how far I could set the skirt clearance. I have even gone the route of honing a "hot block" to try to eek out a little power under the assumetion that the bore would be rounder during operation.

Don't forget using a torque plate when honing performance engines. There is a ton of experimental data from the ring manufactures regarding these low contact pressure rings and oversize cylinders. Using a wear limit of 4-6 thousands as OK to just re-ring is asking for trouble in most cases. Silv-O-Lite has specific gaping instructions for ring gap in high performance engines using their hyper-eutectic pistons. Those pistons get considerably hotter in the crown area under heavy sustained loads than you would expect. Take a look at the piston crown cooling systems in large stationary or locomotive diesel engines. Those are not hyper-eutectic pistons either. Many high load gas engines have a small hole drilled on the rod big end that lines up with the crank oil port when the piston is at BDC to squirt on the underside of the piston crown.

[OldNuc]

Originally Posted by ehunter

Interesting

When I did my engine I wish I knew this. I would have measured. It will always remain an unknown now in my case but maybe I can go back and figure it out with a pencil and paper. I did record my bore radius sizes, I know what rings I used. What would I need to do from there?

From an angle of racing... you were probably going for a tight fit for max compression. Might my compression numbers be a positive/negative indicator of ring gap tolerance?

Ring manufacturer data indicates that at any RPM above cranking ring gaps of 0.040 or less have no measurable impact on leakage. Air has inertia. Standard rings are sized for standard cylinders. Calculate the circumference of the standard cylinder and then calculate the circumference of the oversize cylinder and subtract, then add the result to the cold ring gap expected to approximate the actual. The real problem is the ring contact pressure is markedly reduced in an oversize cylinder regardless of end gap.

The beast approach is to always re-bore and fit new pistons to the new cylinders. This generally means adding ~250.00 to the rebuild cost.

As an interesting aside Chrysler has adjusted its acceptable motor oil consumption rates for 2012-2013 Chrysler, Dodge, and Jeep gasoline vehicles (Chrysler Bulletin #09-001-12 Engine Oil Consumption Guideline):

• First 50,000 miles of engine life: one quart per 2000 miles
• Engines with over 50,000 miles: one quart per 750 miles
• Aggressive driving conditions: one quart per 500 miles

***** So you traded your paid for Saturn for a nice new Chrysler product and a payment book because the Saturn oil burning was irritating you.

[laser3kw]

Don't forget using a torque plate when honing performance engines

interesting note on torque plates; people will try a torque plate and claim they don't work. They buy or make a suitable plate, bolt it on the block (or head if you are doing valve seats - also done at elevated temp ), torque it up, drop thier $800 dial bore gauge in the cylinder and take some measurements and claim "see less than 2 tenths (.0002) difference! I knew it was BS".
Truth is, it takes hours for the block to stress enough to show the true distortion. I would set mine up the last thing of the day and come back the next day and do my work. I have seen some really lobed cylinder patterns with a torque plate.
Another subject that affets our engines, cylinder sleeve to aluminum lining thermo transfer. Good boundry contact and the cylinder and rings seat up and leak less. If you look at a well worn cylinder, even with the cross hatch still visible, you can see "light" and "dark" streaks or burnish marks, usually at consistant spacing. This is cause by the sleeve press and the thermo conductivity. The poor spots pucker up more and the rings wear them down tenths more than the good thermo contact areas. Thus, "poor ring seal" and coked up rings from blow by.
On the subject of poor thermo conductivity, I have heard of Saturn blocks slipping the liners out if they are "hot tanked" or wash with steam. A good press fit liner shouldn't do that. The suggestion is to warn the shop about this posiblity.

[OldNuc]

The knowledgeable shops attach a dummy deck to hold the sleeves in. All steel sleeves fall out of aluminum blocks. Back in the English single cylinder period sleeve removal was done in the kitchen oven by heating the cleaned bare barrel to about 325F and then stuffing a very damp sponge through the bore and the sleeve falls out on the floor.

[laser3kw]

heating the cleaned bare barrel to about 325F and then stuffing a very damp sponge through the bore and the sleeve falls out on the floor.
07-18-2013 12:02 PM

very true- been there - done that - got in trouble from the old lady!
But hot tank or steam is 212º and our running temps up to 245º?
that temp should not let the sleeve loose (hench lose thermo conductivity and heat transfer)...........

[OldNuc]

They creep more than fallout due to differential expansion with the head off. cooling is always a hassle in small engines and the Saturn is not an unmitigated disaster for an engine designed to be a grocery getter. The fun starts when you attempt to make a race motor out of it as the Hp/cu in is ready pushed up near as high as you want to go before things start going wrong.