I have pulled #7 piston that was giving a 240# compression reading (on a recently rebuilt engine).

I am concerned about the condition of the bearings and also there is a lip at the top of the cylinder - although it is only around 60-70% of the cylinder wall.

So, here are my questions:
Are the bearings shot?
Why would this happen?
Why would there be a lip in the cylinder wall?

I do have some pictures of the cylnder head but will do that later as the sun is shining and the kids want to go to the park.

Does not look like a recent rebuild.Mabey just refreshed with new rings and bearings.All your bearings probably look the same and need to be changed.What happened to the previous engine?Were the oil lines and cooler flushed before new engine was installed?What about bearing clearances?

No point in measuring bearing clearances, they are shot.

Pictures with digital cameras almost always make things look worse than they are so I do not know how to comment on the cylinder. You should get it measured. Was there any visible damage or heavy wear on the piston or rings? You need to find out why that hole had low compression. Maybe you should get the head vac tested on the intake and exhaust ports, or at least remove the valves and see if the seats and valves are coencentric and sealing.

No point in measuring bearing clearances, they are shot.
I replaced a 2 piece crank for a 1 piece crank with new bearings in a 427. The old bearings with 150,000 miles looked better than those. Leo

Got a couple of questions.How many revolutions did you crank the engine to get the 240# compression?Not enough will give a low PSI.Did you check for a bent rod due to hydrolock?Check the rest of the pistons at TDC to be flush with the top of the block.

I cranked it for 8-10 revolutions and actually ran the test twice as I was surprised at the numbers.

What would cause the bearings to wear like that?
Oversize crank journal?
Undersize crank journal?
out of round crank journal?

I have to go back to the people who did the engine rebuild (9,000 miles ago) and I know they are going to deny responsibility.

Thanks

Those bearings don't look good, the pits / scratches are from debris in the oil but the one wore down to the copper looks like the rod may be out of tolerance worn in the top area like that. Cylinder wall dosen't look too bad though there's some ridge there. Get the rods re-manf'd at least, new bearings and maybe crank work/replace.
Don

No point in measuring bearing clearances, they are shot.

Pictures with digital cameras almost always make things look worse than they are so I do not know how to comment on the cylinder. You should get it measured. Was there any visible damage or heavy wear on the piston or rings? You need to find out why that hole had low compression. Maybe you should get the head vac tested on the intake and exhaust ports, or at least remove the valves and see if the seats and valves are coencentric and sealing.

x2. That does not look like a cylinder bore with just 9000 mile on it but picture can be deceiveing. Can you get your finger nail to click on the edge of the ring ridge? The bearing looks like alot of debre has been run or running threw it but this will not cause the low compression. Do the pistons have any markings on them to indecate if they are new after market or original. There should be a .0x0 stamped on them indicating the oversize. usually in the top. what markings are on the back of the bearings. they should have numbers indicating size.

What would cause the bearings to wear like that?
Oversize crank journal?
Undersize crank journal?
out of round crank journal?

A few possibilities are:
Dirt/debris in the oil,
Large end of connecting rod was not re-sized when it was rebuilt,
Incorrect p/n oil filter being used at oil change intervals,
Very cold weather starts starving the engine from oil,
Somebody forgot to install pressure bypass valves into block at last rebuild which would prevent oil from being filtered.

I would check the easiest and obvious first. Get the large end of that connecting rod measured for "out of round". Remove the oil pump, take it apart and inspect it for damage from dirt and debris. Remove the front main cap if you can get at it and check the bearing on it, it will likely be the worst one.

Is that cylinder head OK? I am curious to know why your compression is low in that cylinder.

Here are some pictures of the cylinder head.

The theory being proposed by the engine re-builder as to why #7 has 280lbs of compression is as follows:
Water or fuel seeped into the cylinder and caused a hydrolock resulting in a bent rod (how easy is it to measure a bent rod?).

The worn bearing is from the connecting rod side and I guess that the extreme force during this hydrolock pushed the bearing into the crankshaft and hence the heavy wear.

The cylinder head has severe pitting around the valves and I assume that some of the compression is sneaking past the valves – although I am not sure what would have caused this.

I know I have a cracked head or gasket from seeing bubbles in the cylinder head water but I could not see any damage to the gasket so I think the head has a small crack somewhere. The metal ring on the gasket for #7 has rust on there so I am thinking it is in that location. I have included a picture of one of the other cylinder head valve areas to show that the rest are the usual black color.

The bolt heads look as if they may have been re-used. Each of the flats has a small portion rounded off on the edge that would see the load during tightening. Would this condition exist on fresh bolts? I am thinking this could be contributing to the whole fiasco!

One last thing that I find intriguing is one of the cylinder head bolts from the back of the engine is covered in gritty gunky stuff – why would this be?

As always, thanks for your help - I would be floundering around helpless without this forum.

Got a picture of the inside of the exhaust manifold for #7 cylinder, or the exhaust port and the one beside it to compare? I bet it looks alot different inside than the rest of the engine.

The dirty head bolt is a non issue. It simply did not have enough sealant on the threads and some of the coolant worked its way above the threads and made a mess.

The bent rod theory would have been easily checked while it was still in the motor but you are past that. A hydrolocked cylinder can and does often cause a bent rod but the bearing wear your pictures show do not indicate anything other than dirt, debris or oil starvation. Bent rods will sometimes cause diagnol or irregular wear patterns on the rod bearings, not consistant wear from the pressure top side of the connecting rod as yours does. Your machine shops theory is not impossible but very unlikely.

A trick to check your head for cracks and valve sealing: Varsol. Prop the head up so you can pour varsol into the exhaust port. Make sure the valve is lower than the exhaust port and pour the varsol into the port. If the varsol runs freely through the valve you have a bad sealing surface and valve. A small amount varsol will escape through the valve guide into the area under the valve spring, that is normal. Your coolant has been entering that cylinder for a long time. The pits are from rust, the formation of the pits is greatly accelerated by the heat and pressure inside the engine. I would think that there is a very good chance that the exhaust seat in the head is pitted up with rust and that is where your compression is going.

The easiest way for you to check your connecting rod for a bend is by removing another rod and piston and doing a side by side comparison. You can remove the pistons and place one wrist pin through the tops of both connecting rods at once. A bent rod will be quite obvious, especially one that has been bent from a hydrolock. If not the machine shop should have a tool to check them.

Did you get it rebuilt or did you buy it that way?Just by the look of the pics there is no way the "rebuild" was done properly.Heads don't look like they were hot tanked.The coolant passages would not look rusty with-in 9000 miles.The head bolts are filthy.There should be teflon on the threads.Plus the bolts don't look like they have been replaced.They are to be replaced as they are a torque to yield bolt.This engine looks like it was just freshened-up with new rings etc.not a complete rebuild.If the rod is bent severe enough,you should be able to put it up and eyeball it.They usually bend just below the wrist pin.

Sounds like the machine shop is at fault. They should have seen that crack when they rebuilt the head. They also should not have reused those head bolts. The cylinder wouldnt look like that, either.

Those arn't quite as bad as the 220,000 mile bearings that came out of my 6.2L

I pulled #3 piston and the bearing is in the same condition as #7 (see previous pictures).

I measured both journals and they are at 2.3980/2.3985.

The bearings are showing as std - I would have thought a crank re-grind would have been part of the re-build.

Are these journals undersize and if so would it cause the heavy wear on one half?

Thanks

The top connecting rod bearing all ways wares the most. Because of compression and power stroke forces on it. The bottem connecting rod bearing is just along for the ride.
A lot of times I have heard cheap rebuilders don't resurface the cranks but I thought they at least replaced the bearings.
If they say std they are standard. I replaced the standard bearings in my truck with a new set of standard bearings and got about 15psi more oil pressure when warm.
You could get a new set of connecting rod and main bearings like I did for about $120 and toss them in.

I pulled #3 piston and the bearing is in the same condition as #7 (see previous pictures).

I measured both journals and they are at 2.3980/2.3985.

The bearings are showing as std - I would have thought a crank re-grind would have been part of the re-build.

Are these journals undersize and if so would it cause the heavy wear on one half?

Thanks

No they would not necessarily grind the crank on any rebuild if it was good. I do not have the spec here for the rod journal so I don't know if it is standard or not. It's been about 8 years since i ground a BB Chevy crank but that number looks really familiar. This said it is my understanding that the 6.5 has a nit rited crank from the factory and that you should never grind one unless you have it retreated. The wear on you rod bears was not caused by hydorlock and all of them will look pretty much the same since they share the same oil or lack there of.

Bill Heath suggested that it is due to anti-freeze in the oil as this is very corrosive.

About a week after the rebuild I did have a nice creamy mayonnaise substance for oil and the rebuilder said they “burnt it off” by running the motor for a while and “it is now good” I do not know what else they did but I never again had white oil on the dipstick.

Being the eternal optimist I am hoping that the head is cracked and I can replace the head and bearings and be back on the road.

I now have so much time and money into this thing that I can only spend more of both – even though there is an overwhelming temptation to push it off a cliff!

I have just returned from the engine rebuilder having shown him the condition of the bearings, pistons, cylinder head and cylinder bore.

He does not think the worn bearings are due to anti-freeze but are to do with the engine not being timed correctly – whatever. He then asked what I wanted and I just said that I would like a good engine in my car. So, he is going to build me a new engine and I have to switch the current one out. Of course, it aint over till it’s over but hopefully this latest engine will be a good one and I can move on to the next 6.5 project!

I want to thank all of you that posted a response as it certainly gave me some ammunition and even made me look smart when I was able to talk with authority about what had probably caused this condition.

God Bless you all.