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Packard Don

Re: Manifold colour & gaskets

#41

Home away from home

You definitely need to be sure one isn’t broken as it can really mess up the cylinder wall. How are the other cylinders?

Are the pistons original? I never had an original break but I did have an Egge one come apart where its top came completely off at the top ring so no cylinder damage, fortunately, as it was all relatively freshly rebuilt with only a couple thousand miles on it. A couple others had cracks so all were replaced.

Posted on: Today 14:49

53 Cavalier

Re: Manifold colour & gaskets

#42

Home away from home

Quote:

Packard Don wrote:
You definitely need to be sure one isn’t broken as it can really mess up the cylinder wall. How are the other cylinders?

Are the pistons original? I never had an original break but I did have an Egge one come apart where its top came completely off at the top ring so no cylinder damage, fortunately, as it was all relatively freshly rebuilt with only a couple thousand miles on it. A couple others had cracks so all were replaced.

#4 is basically dead, #6 is very bad as well, and the rest are not good.
1-90
2-89
3-76
4-9
5-78
6-45
7-65
8-86

Car still has the original Thermostrut pistons. They were coated when I had the engine apart to bring them back to spec.

Click to see original Image in a new window

Posted on: Today 15:01

TxGoat

Re: Manifold colour & gaskets

#43

Home away from home

It doesn't seem likely to me that the rings could be that bad. The piston in the picture looks good and the rings appear to be a good fit in the ring grooves. Were the cylinders honed properly? Ring gaps checked and set? Is it possible the timing chain has slipped? Could some of the valves have possibly hit the spark plugs? Could something have fallen into the engine, like a screw from the carburetor or a broken spark plug insulator or a dirt dauber nest? Hydraulic lifer issues? Head gasket?

Posted on: Today 15:50

Pgh Ultramatic

Re: Manifold colour & gaskets

#44

Home away from home

Put 1 tbsp of engine oil a cylinder. Then after maybe 20 seconds or something compression test it again and let's see those numbers.

If they are essentially the same as before then you have valve issues.

If they are significantly improved then you have ring issues.

Posted on: Today 15:53

53 Cavalier

Re: Manifold colour & gaskets

#45

Home away from home

Quote:

Pgh Ultramatic wrote:
Put 1 tbsp of engine oil a cylinder. Then after maybe 20 seconds or something compression test it again and let's see those numbers.

If they are essentially the same as before then you have valve issues.

If they are significantly improved then you have ring issues.

I did that right after my initial compression test, and then pressured up each cylinder to confirm.

1-90/96
2-89/120
3-76/90
4-9/16
5-78/88
6-45/55
7-65/89
8-86/96

Posted on: Today 16:01

53 Cavalier

Re: Manifold colour & gaskets

#46

Home away from home

Quote:

TxGoat wrote:
It doesn't seem likely to me that the rings could be that bad. The piston in the picture looks good and the rings appear to be a good fit in the ring grooves. Were the cylinders honed properly? Ring gaps checked and set? Is it possible the timing chain has slipped? Could some of the valves have possibly hit the spark plugs? Could something have fallen into the engine, like a screw from the carburetor or a broken spark plug insulator or a dirt dauber nest? Hydraulic lifer issues? Head gasket?

-Pistons were good
-Honing is a definite possibility
-Ring gaps checked and all within spec
-Even if the timing chain had slipped a leak down test would produce the same results............wouldn't it?
-No valve/spark plug contact
-I don't think something falling into the engine is too likely. If it was only one cylinder, and the rest were okay, I think that would be a more likely possibility.
-No dirt dauber in our part of the world, and really no similar creatures.
-Hydraulic lifter issues would be more like a collapsed, either fully or partially, lifter. That should present as a noise I think and the leak down test shouldn't give the results it did. Every cylinder indicates the valves are holding and that the pressure is bypassing the rings.
-Headgasket. No pressure or contamination in the cooling system. If it were blown between two cylinders I would get similar readings for both those cylinders wouldn't I?

Posted on: Today 16:24

TxGoat

Re: Manifold colour & gaskets

#47

Home away from home

With compression near zero in one cylinder, it shouldn't be too difficult to determine where it is going using compressed air in the spark plug hole and bringing the bad cylinder to TDC on the compression stroke. The air is going to go out the exhaust, or the intake, or it will spew into the crankcase, the water jacket, or one of the adjacent cylinders.

Posted on: Today 16:32

53 Cavalier

Re: Manifold colour & gaskets

#48

Home away from home

Quote:

TxGoat wrote:
With compression near zero in one cylinder, it shouldn't be too difficult to determine where it is going using compressed air in the spark plug hole and bringing the bad cylinder to TDC on the compression stroke. The air is going to go out the exhaust, or the intake, or it will spew into the crankcase, the water jacket, or one of the adjacent cylinders.

Ya missed the picture on reply #40

Results are the same on each cylinder.