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On cylinder #2 when I was adding pressure it pushed my cylinder down a little. It did it twice and that was the only cylinder that did that.
I did run the test on a cold engine. But I can't imagine it would make that much of a difference.
Any tips on finding the source? There is a lot of air noise, I'm not sure how to pinpoint the location.
On once cylinder near the dipstick, I pulled it out and felt a little air. I will study some, but would appreciate some expert advice.
Here is cylinder #4. This one had lower compression when I tested that a long time ago. I can do that as well again. I need to run the leak down test with a warm engine.
Is this on a engine that is in running condition and is being used ?
In my shop days the percentage of leakage (maybe wrongly) was not a big concern, the differences between cylinders as a diagnostic tool was, so as to determine a problem.
And especially for coolant to cylinder leaks / head gaskets / cracks / burnt valve. It was normal for the air pressure to push a piston down.
Why were you doing this test, what is the problem you want to solve ?
The trans should be in gear, e-brakes on, piston at TDC, for the test. The engine shouldn't be able to rotate. Are you sure you were at TDC on the compression stroke? (verify by looking at rotor position)
Do the instructions for the tool say what air pressure to use? 100 psi seems pretty high. But like Old F1 says, differences are what you look for. You might try a re-test after adding a bit of oil to each cylinder before testing.
Testing at TDC puts the rings into the most worn part of the cylinder (just under the ridge), and these older engines typically have a lot of wear there.
This engine is running fairly well. My main concern is that I'm burning about a quart of oil every 125 miles.
I will try it warm and see what that does. I hadn't thought about looking at the rotor. I removed the valve covers and watched the intake valve close and bumped the engine until the cylinder was at the top.
The instructions and all the videos I have watched say 100 psi for the test. I haven't found any Y-Block specific info.
If you’re burning a quart every 125 miles you’d probably see oil foul on your plugs and have a blue-ish exhaust. Do you have that? Any wet spots on the engine? 100 psi sounds like a lot on an older lower compression engine. Do you have a Ford factory shop manual? We bought the reprint of one off Amazon for 30 or 40 bucks and they have a lot of great information in them. Getting heat into The engine will help your numbers, because your pistons will grow faster than the block and clearances will be tighter at temperature, but the rings are designed to handle that expansion and contraction so it shouldn’t make a huge difference I wouldn’t think. What weight oil are you running and what is the ambient temperature where you live currently? Also on a leak down test you don’t really know if it’s valves or pistons leaking. If you have pressure coming out of the dipstick tube that’s a pretty good indication it’s piston, but I remember a test procedure saying to squirt some oil in the cylinder and test. The oil you put in the cylinder should prevent leak down through the pistons.
I actually have black on the tail pipe and when I start up after sitting for a little bit it will leave a nice black spot on the concrete from my exhaust. I do have leakage elsewhere as well. I see oil on the engine, but if I stop and park I get very little as far as dripping oil.
I will dig into the shop manual and see what I can find. I'm bad about not looking at it.....
Temperature was in the upper 60's yesterday.
I'm running Rotella 15-40W oil.
I need to look a little closer at my plugs but most are pretty black.
Rotella 15-40 should be good. You won’t get much out of going to 20-50 in my experience. I believe black smoke coming out of the tail pipe is more indicative of over fueling (rich condition). If you were burning motor oil it would be blue. Constant blue smoke indicates rings. Blue smoke only at startup indicates valve seals. White smoke indicates a head gasket leak. You could be over fueling and fouling out spark plugs and leaving excessive carbon deposits on cylinder walls. I would pull the plugs and have a look. Also Bluetooth borescopes are like 20 bucks on Amazon. You could pull a plug on a cylinder you suspect is damaged and check for cylinder wall scoring or excessive carbon deposits.
As temperature changes your carb will need adjustment, because air density at different temperatures is different. Also Air density at different elevations is different. So when you take a road trip to the Rockies you may have to adjust your mixture on the carburetor. These are naturally aspirated engines meaning atmospheric pressure drives air into the cylinders on the intake stroke. Density of air will mean less or more oxygen entering the combustion chamber, because pressure is constant (assuming a similar altitude). So basically if you run your engine at freezing you will need more fuel, because air is more dense and more oxygen is entering the cylinder. As the temperature warms up you need to lean it out. This is the disadvantage of a carburetor.
Great advice guys. I have a borescope....if I remember where I put it when we moved. Last time I looked the cylinders looked pretty good.
I remembered I saved the video of #4 which has the lowest compression. This was from 2017 though. Lots of driving since then I will check again.
I bet I am running rich. I will do some adjusting. Sometimes it takes a bit to get started. I'm sure that puts a lot of fuel in the cylinders as well.
I went out and took a picture of my spark plugs. Lots of black on them. I will adjust the carb when I get a chance this week.
A couple look good though. If I was running rich wouldn't they all be black? Or I guess the question is what would cause some to be black and not others?
They are black but dry because I haven't run the truck in a couple of weeks. So they have had plenty of time to dry out. Man....I should be driving it more...
1 and 6 look pretty good, but the rest are pretty rough. I’d go ahead and get a new set of plugs. At a minimum I would clean them up before putting them back in. If you go the cleaning route swap your good plugs with a bad plug, run them and see if they clean up. Also look at your leak down data for the good looking plugs compared to the rest of them. Maybe you can see something there. It’s hard to tell if they are oil fouled, but I still go back to your previous statement of black soot coming out the tail pipe to say it could be over fueling. Once you get the carb set change the oil, because it could be fuel contaminated.
Oh, I hadn't thought about the oil being fuel contaminated. I will do that after I get the carb set.
I recently changed the oil, but I forgot to put the copper washer back on the drain plug. This will give me the opportunity to put that back as well. I found it in the drain pan when I was transferring the old oil to my used oil jug. Cussed a little when I saw it.
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