Rear main vs tranny input seal leak

[Gaz64]

Your oil level is really determined by the pan manufacturer, ie: 7 quart pan, 8 quart pan etc.

In a wet sump engine, the further away the oil is the better, although it is a fine line if the oil pump can't self prime or stay primed.

If have now made your own oil level, the crank will have more oil on it than normal and being flung around a lot more.
Combined with more oil pressure and probably more oil flow from the rod bearings ends up as a harder job for the rings to control.

How much work was done to ensure adequate drainback from the heads?

Are you sure you didn't break any rings on assembly?

[Texasdoc]

I'm sure no broken rings. They all went in as expected. None were forced into place. I used a set .030 ring compressor (not adjustable).

No work on drain back from the heads. Stock block. As shipped AFR 195 Renegade heads.

I followed Canton's instructions on setting the oil level. It is a 7qt pan. Click here - Canton 15-660. I also used their adjustable dipstick. Clicky Canton 20-850 - "These dipsticks need to be calibrated for each application."

Any other recommended ways to appropriately set the dipstick level? How far down from the crank does the oil need to be? I guess I can measure the distance from the oil pan flange to the bottom stroke of the crank/rods and then measure from the top of the oil pan down - fill with oil while measuring and make sure I don't go above that level (give 1/4 inch extra space just for good measure?)

I did a cold compression test tonight. I ordered a leak down test kit and will do that when I get it. My compression numbers were:

1 - 185
2 - *
3 - 185
4 - 195
5 - 175
6 - 173
7 - *
8 - 178

I couldn't test cylinder 2 or 7. I couldn't get the compression adapter that screws into the head in place due to header interference. Although, these all look pretty good. The right side (1-4) looks a little higher than the left (5-8) but I may have held the starter a few seconds more on that side.

[Gaz64]

Agree with your thoughts on the oil pan.

I'd be concerned about the lower compression pressures on Bank 2.

If in doubt, I'd repeat the test, fully charged battery, carb wide open, no fuel etc.

Your lowest of 173 is less than 90% of your peak of 195, more than 10% difference.

I would be EXTREMELY interested in the pressures of 2 & 6.

I'd bet they follow the same pattern.

Having said that, it appears Bank 1 is healthy, Bank 2 has compression loss across the whole bank, which could be a headgasket issue, which could also be your crankcase pressure issue.

A leakdown test is now mandatory.

Ultimately and unfortunately, I'd say the engine has to come out.

[Jac Mac]

7 quarts is the 'System' capacity, I assume you have a normal size filter so that probably holds about 0.5 to 0.75 of a quart, more if your using a remote filter & lines. So if you simply poured 7 quarts in and calibrated the dipstick before starting the motor you might have an issue there.
Depends on any windage tray or baffle system in the pan, but ideally you want to keep the crank and rods about 1.5" or more away from the oil level in the pan. This becomes a bit of a balancing act with stroker cranks because if you get the oil level too low the pump can pull air rather than oil, eg the pickup needs the oil level to be at least 2" above it with engine running.

[Gaz64]

Yes Jac,

That is a very good point.

The op should have filled his engine with the stated 7 quarts, run the engine to fill the system (galleries,pump,filter), then marked his dipstick.

[Jac Mac]

Scaling up your drawing of the oil pan suggests that the 'square box' dimensions are 3.0'deep- 13.5" wide-8.5" long, that portion would only hold ~5.6 us quarts, so if as mentioned earlier the oil level with 7 quarts would be quite a bit above that 'box' level and very close to the crank/rods in your application.

[Texasdoc]

I'm waiting for UPS to deliver my leak down tester. I realized that I performed the compression test with the throttle closed. I repeated it today, holding the throttle open. Essentially same results with higher numbers.

1-200, 2-unable, 3-215, 4-210
5-190, 6-190, 7-unable, 8-210

I also measured the outside dimensions of the "box". It is 12.5x10x4 inches. This calculates to 500 in3, which is 8.66 US liquid quarts to completely fill the box. I'm not sure how thick the steel of the pan is, but I'd guess it doesn't subtract a ton. Add the pickup mass, lets say 8 quarts fits inside the box of the pan.

[Crazy useless math]
The bottom of the box is 8 inches below the centerline of the crank. That makes it 4 inches above the top of the box. Stroke on the 408 is 4 inches - half that to get 2 inches down travel of the crank. Since the box 4 inches tall and 8 inches below the centerline, that means the top of the box is 2 inches below the bottom of the crank stroke (center of rod journal). Rod journal is 2.311. Half that is 1.65ish. Add another half inch for the rod cap and bolts. Make that 2.2 inches. So the crank and rods extend 0.2 inches into the box. Add one inch space, that means I can only have 4 - 1.2 = 2.8 inches of oil in the box. That is 6 quarts of oil. That seems pretty close to the "7 quart SYSTEM" - 1 quart for filter and the internal oil passages = 6 quarts added at oil change.
[/Crazy Useless Math]

So, I guess I should add 6 quarts to an empty pan, then mark the dipstick from there. (One quart down on this pan equals about 1/2 inch.)

I will post the leakdown test when I get it done. Should I do the leak down test on a cold or warm engine? I think a warm engine would be more accurate, but don't want to burn my fingers on the headers.

[DanEC]

Compression and leakdown test are best done on a warm engine. As a suggestion I would loosen the spark plugs up before starting the engine to warm it up. Aluminum heads don't like spark plug removal when hot . They are more prone to sieze and strip.

[Texasdoc]

Edit: Mods, do you want to move this to the small block forum? It is no longer about transmissions.


Is there a conversion for the percentage between hot and cold?


If not, I guess I'm going to have to warm it up, then (somehow) remove the headers to do the tests. I can't get the adapter port screwed into the spark plug hole with the headers in place.

I could do them all but two and seven, reheat, wait until the headers are cool, the remove and do 2 and 7 before it cools.

[RICK LAKE]

Texasdoc Couple of quick questions, who piston rings are you running and where they gapped correctly? Is it possible you have the pcv valve up side down? This is easy to do. Is it possible you have a set of piston rings with the end gaps lined up? A leak down test is not going to show you alot some times. Need to add a little oil to help seal the rings to the piston walls for a better reading. Rick L. Ps before pulling this motor apart is there any way you can get a good low pressure gauge and mount it to the PVC location and lets see what the pressure reading are. We may be over thinking this and going down the wrong path.

[Gaz64]

Texasdoc,

You say you have one breather filter on one rocker cover.

Is the filter oil soaked from the engine? Who makes the filter, and it's dimensions?

The reason I ask is sometimes a fresh engine may have a higher than average blow-by until the rings have seated.

How did you "seat the rings"?

Personally I'd still have a large breather hose to the carb airfilter, then the crankcase pressure is vented with no restriction like a small valve cover filter might have.

Gary

[DanEC]

Originally Posted by Texasdoc

Edit: Mods, do you want to move this to the small block forum? It is no longer about transmissions.


Is there a conversion for the percentage between hot and cold?


If not, I guess I'm going to have to warm it up, then (somehow) remove the headers to do the tests. I can't get the adapter port screwed into the spark plug hole with the headers in place.

I could do them all but two and seven, reheat, wait until the headers are cool, the remove and do 2 and 7 before it cools.

Considering all you describe above, I think I would probably do the leak down test on a cold engine. A cold engine piston clearances and ring fit are a bit looser than when the engine is warmed up so the cylinder to cylinder variance may be a little greater. There isn't a conversion factor that I'm aware of and a lot of it has to do with how well your engine bores were machined and the clearances and type of ring pack. Forged pistons often were set up pretty loose. Technology has probably overcome that by now. But - on a leak down you will still be able to listen to see if there is a weak cylinder (or more) are and where it's leaking - out the exhaust, out the intake or in the crankcase.

[Texasdoc]

Rick, I bought a stroker kit from Blykins. It had the crank, rods, pistons, and "plasmamoly" rings. It was a whole set. I don't remember the brand of the rings but could look it up if needed. I tested each set of rings in their specific cylinder bore and checked the ring gap. All were within spec.

Rings were installed offset per the diagram in Monroe's book. Unless they spun inside their bores, they are still set that way.

The breather on the driver's VC was from O'Reilly. Click Here. It doesn't list the specs but does list the size. I could easily blow thru the filter without restriction. This provided filtered air,but it was never under vacuum as it would be if I connected it to the main throttle body filter. The filter is not oil soaked. Dimmensions are listed on O'Reilly's website.

I'm going to delete this filter on the VC. I'm going to run a breather from the passenger side VC that connects a tube to the main carb filter base. It has a 1/2 inch ID tube. The driver's side VC gets a PCV valve and plumbed into the base of the throttle body.

I didn't perform any specific ring seating procedure. Just started it and drove it around town. No WOT blasts, but I wasn't babying it either. Definately medium pull runs upto 5000rpm.

I did replace the rear main seal today. Took 4 hours from first oil pan screw out to last oil pan screw in. The last seal that I just put in there was a PTFE "Special, upgraded, never fail, even prevent pregnancy in your neighbor's cat" seal. The internal seal lip of it was shredded! I'm not sure what caused it to shred like that. I did have it installed with the lip facing forward. Both the upper half and lower half were destroyed. I just put in a regular rubber RMS this time.

I should get my leak down tester tomorrow and will test. Likely have to do a cold test first. Not too keen on pulling the motor out yet. I will put a tsp or two of oil in the cylinders to help seal. Then see what I get. If I have still have problems and have to pull the motor, I'll remove the crank to inspect the block side of the RMS groove. While replacing this one, the crank looked fine. A little heat discoloration where the RMS rides, but the crank was smooth. I did soak the RMS in oil for 30 minutes prior to installing. (I did that with the PTFE seal too.)

[Gaz64]

Ok, good info.

That little filter is too small.

I'd have 5/8 id at least, the larger the better.

The 3/8 id may have been a restriction and allowing the crankcase to pressurise, hence pushing the dipstick out.

As to the rear seal burning up, either the seal is running too tight on the crank, or lip facing forward is the wrong way.

Some seals have an arrow showing shaft rotation direction.

Do not put oil in the cylinders prior to leakdown test.

As long as you have no loss past the valve seats, and only a loss of 2-10% into the crankcase would be ok.

More than likely you'll have 10-20% loss with a fresh bore/ring set.

Your compression test looks ok.

[RICK LAKE]

Texasdoc Can you get us a couple of pictures of the motor? It sound like you have done your home work with installing the stroker kit. I got a kit from Brent and did he same sizing and everything to install the kit. I got 484 cubes of rotating mass and run tall valve covers to clear the Erson setup. There are shields inside both covers. The R/S valve has my pcv going to the main port at the base of the throttle body and have a Cheap Cal custom breather on the other side. I had it the other way and was sucking oil through the motor when racing. Went to the other way and no problems. I don't see how there is any way with both a vacuum source and open breather can cause a pressure buildup inside the motor. We need to get a gauge on this and check the internal pressure when driving.
If a head gasket breaks, you get coolant high temps and smoking 90% of the times out exhaust. Oil leaks speak for them selves, rtv, gasket failure, seal cut, simple to find and repair.
Is it possible the the block is warpped? When cold it seals and hot it leaks? The last thing would be a cracked head. Have to be on the exhaust side and blowing a small amount of pressure back into the motor through a bad valve stem or port crack.
Piston rings do flutter when the motor is running, the chance of a couple of cylinders getting end gap to line up is like winning the lottery but if the leak test show air getting into the bottom of the motor, we have an issue. The other idea is that the cylinders are not round and would need to measure both taper and out of round. The head studs or bolts may have distorted the cylinder walls and the rings are not staying flush. As the motor expands from heating up the clearance grows up to .001" This is not alot but for gas to escape, it doesn't need much.
Here the thing, and this would get you through the summer without chasing this leak, add a vacuum pump with a low output of 3-5 psi and seal the system. Car the car for the summer and in the winter or down time pull the motor and have it done over by a pro machinist. That pump will not hurt anything at low pressure and keep the motor sealed without leaks.
Other choice is a tank and lines hooked to both valve cover and run 2 small filters on top. Have the pcv valve working. I see no way for this block to build up pressure. You do need a drain to return the oil back to the motor.
And the fight goes on. We will get it. Rick L.

[Texasdoc]

Cold engine. No oil placed in cylinders. This is with a new leak gauge. Summit Link

Cylinder 1 - 3% leak
Cylinder 2 - 3.5% leak - minimal hiss in exhaust
Cylinder 3 - 2% leak
Cylinder 4 - 4% leak - minimal hiss in valve cover
Cylinder 5 - 3% leak
Cylinder 6 - 3.5% leak - minimal hiss in exhaust and valve cover
Cylinder 7 - 4% leak - minimal hiss in valve cover
Cylinder 8 - 2% leak - minimal hiss in valve cover

I would think that with these numbers, there is not significant blow by. Especially when the engine warms up, the rings should get tighter and less blow by in the valve covers. I'm not sure about the exhaust hiss. I have hydraulic lifters. They may be too tight - they are set at 1/2 turn past zero lash.

No smoke in the exhaust. No water in the oil.

Going to add a 5/8 inch line from the PCV to the throttle body. Going to add a 5/8 inch line from the breather to the intake filter. See what I come up with. No current photos of the motor, but will add photos soon - likely tomorrow, though.

[Gaz64]

Nothing wrong with those figures.

The hose for pcv valve only needs to be suitable for the valve and the nipple on the carb, generally 3/8.

It's the hose from the valve cover to the air filter that needs to be large, generally 5/8 or larger.

Under light throttle the air flows from the air filter into the crankcase back via the pcv valve to manifold vacuum. There is also little blowby.

Under moderate to heavy load, blowby is higher and there is no flow via the pcv valve, so air flows from the valve cover to the air filter, now in reverse.

If the blowby air is restricted like the small filter nipple you had on there (3/8), then crankcase pressure could build, dipstick comes out, oil leaks etc.

[Texasdoc]

Here is a picture of the rear main seal I removed.

[Jac Mac]

Can you take another photo as per drawing on this pic.

[Texasdoc]

Not sure exactly what picture you want:



Breather Side to Air Filter



PCV side to throttle body.