Compression Test Results
Butt-Head
Joined: Apr 2004
Posts: 9,415
Likes: 2,910
From: Reed Point, MT
This is what one typically finds when taking apart a higher mileage 7.3. The intake valve seat surface is completely worn away and the valves sink really bad.
The one on the left has 180K miles of poor air filtration and the one on the right is out of a 40K mile engine that ate a valve.
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
Cleatusr12: You are the man! But everyone here already knew that.
I had poor air filtration because I could never get the air filter box to close properly and was impatient. And when I would close the clamps down, it would warp the mating surfaces on one side of the air filter box.
My van only has 166,000 miles on it. But, I am ashamed to say, was apparently poorly maintained by me.
Unless you have other suggestions, I will post pictures of block after I raise the body and remove the heads while the engine is still in the vehicle.
I had poor air filtration because I could never get the air filter box to close properly and was impatient. And when I would close the clamps down, it would warp the mating surfaces on one side of the air filter box.
My van only has 166,000 miles on it. But, I am ashamed to say, was apparently poorly maintained by me.
Unless you have other suggestions, I will post pictures of block after I raise the body and remove the heads while the engine is still in the vehicle.
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
BTW, when I checked the oil, on the dipstick I had more "oil" in it that it should have had.
When I drained the oil, the first liquid which came out was yellow - so it was either diesel or contaminated water.
So I can know know what to look for and where to look:
1. Assuming it was diesel, how did it get there?
2. Assuming it was water, how did it get there?
(I felt it and it felt like oil to me, but it did not have that diesel smell.)
When I drained the oil, the first liquid which came out was yellow - so it was either diesel or contaminated water.
So I can know know what to look for and where to look:
1. Assuming it was diesel, how did it get there?
2. Assuming it was water, how did it get there?
(I felt it and it felt like oil to me, but it did not have that diesel smell.)
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
Coolant was regular green. Whatever (oil or water) which drained out of the engine oil pan first (before the black oil) was golden and clear.
I drained the radiator water out into a bucket and took out the radiator to access the crank shaft/harmonic balancer bolt to turn the engine by hand per Cody. There was no oil in the coolant, but I guess there could be coolant in the oil. But the clear golden color is wrong. I guess it could be rainwater if the closed hood leaked rainwater onto the engine. I had the valve covers off for seven years... Does engine oil float above water as I think it does?
Can poor compression be due to a bad injector?
Can a bad injector introduce diesel or water into the crank case?
Since cylinder No. 1 is up front and easy to remove, I am going to remove it and take pictures.
I drained the radiator water out into a bucket and took out the radiator to access the crank shaft/harmonic balancer bolt to turn the engine by hand per Cody. There was no oil in the coolant, but I guess there could be coolant in the oil. But the clear golden color is wrong. I guess it could be rainwater if the closed hood leaked rainwater onto the engine. I had the valve covers off for seven years... Does engine oil float above water as I think it does?
Can poor compression be due to a bad injector?
Can a bad injector introduce diesel or water into the crank case?
Since cylinder No. 1 is up front and easy to remove, I am going to remove it and take pictures.
Hotshot
Joined: Mar 2014
Posts: 10,750
Likes: 1,065
From: Douglassville, PA
Yes oil floats on water. Do you still have that liquid that you drained out? You'd have to be careful (painstaking even) but you could find out what's down there. I'm thinking it almost has to be water or coolant.
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
No. To me at least, it is a very uniform cranking sound. (I wonder if I can take and post up an audio recording...?)
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
I am planning to pull the head on at least the passenger side to look at the No. 1 cylinder with 185-180 lbs compression.
Has anyone had success looking at the top of the piston with an inspection camera? I have tried 3 of the cheap Chinese because they were "small" but the resolution is not good. (I know Cody and others are thinking to themselves, "Just pull the head buddy!")
Butt-Head
Joined: Apr 2004
Posts: 9,415
Likes: 2,910
From: Reed Point, MT
Actually, I am spoiled and have the facilities to do much more major repairs. There is no way that I would pull just a head in a pickup or a van. For me, it's a no-brainer to just pull the engine out because it takes very little time. Again, I realize that not everyone has those luxuries though.
Banned
Joined: Dec 2018
Posts: 3,541
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maybe it has to be dead-dead (like 0 psi) for it to do that. 180 is only half dead. I would be tempted to just change the oil and observe how it runs on 7.5 cylinders as far as blow-by and oil consumption. And cross contamination between the oil and coolant. If there is water in the oil pan and lots of white smoke that would suggest a head gasket issue wouldn't it?
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
Likes: 52
From: Sacramento Delta, CA
Will a crack in a nozzle be apparent under a microscope? Or will it require pressure for a hairline crack to open up?
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Joined: Dec 2018
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I think the only way water gets in through the injection system is if a cup is cracked. I would pull the injectors out first and have a look before doing anything more drastic. The bad cups usually show up as fuel contamination sitting on top of the coolant bottle. (Fuel system is under higher pressure than the water at least while the engine is running. When it shut off I am not sure what happens.) There is a way to test the cups with the injectors out. I think the cooling system must be pressurized.