Help interpreting leakdown and compression test.

[squirrelchill]

So I have a 99 Limited with the 3.4, I bought the car last summer with 225k and have put about 5k on it. It had been feeling underpowered and the previous owner had indicated they had overheated it. I replaced the entire cooling system. I recently began noticing white steam/smoke out the tailpipe and it lost some coolant, so I assumed it was a head gasket or cracked head.

I performed a compression test and leakdown test, and the results have me a bit confused and I'm looking for some guidance in interpreting this, the results of the tests are:

Cylinder 1 - 19% pressure lost (73/90psi) | 180 psi compression
Cylinder 2 - 46% pressure lost (49/90psi) | 175 psi compression
Cylinder 3 - 44% pressure lost (51/90psi) | 180 psi compression
Cylinder 4 - 47% pressure lost (48/90psi) | 180 psi compression
Cylinder 5 - 28% pressure lost (65/90psi) | 180 psi compression
Cylinder 6 - 26% pressure lost (67/90psi) | 185 psi compression

I know the leakdown numbers are bad news, on every cylinder the only place I heard any air pressure escaping was the oil dip stick tube, and smelled some oil when the pressure initially was connected. There was no air observed escaping through the radiator, which seems to rule out a head gasket problem. I also thought I possibly heard a leak coming from the intake manifold but it was hard to tell. I've never done a leakdown test before but I followed [MENTION=120071]mtbtim[/MENTION] Timmy The Toolman's video exactly and used the OTC 5609. Any thoughts??

 

[gamefreakgc]

If you have compression, you have power. Those are decent compression numbers, a little tired but not terrible by any means.

Have you topped off the coolant lately or since you bought it? How much coolant are you losing? The fact that cylinder 2, 3, 4 are all low points to worn out piston rings or cylinder walls. Highly unlikely the gasket is blown on both side, in multiple locations.

I bought a 4Runner once that has all sorts of "issues". They were convinced it was a blown head gasket, some guy did this "tissue test" on the tailpipe and all that. I took it home, changed out the leaking water pump and changed the spark plugs and the engine was perfect again. A tune-up goes a long way.

 

[squirrelchill]

Have you topped off the coolant lately or since you bought it? How much coolant are you losing? The fact that cylinder 2, 3, 4 are all low points to worn out piston rings or cylinder walls. Highly unlikely the gasket is blown on both side, in multiple locations.

Thanks for your input. I replaced the radiator and hoses and flushed the cooling system when I bought it. It hasn't lost a ton of coolant honestly, but I also can't remember if I topped it off in the last couple months, I haven't been driving it really since January when I first started noticing head gasket symptoms. white smoke, rough idle on cold start, some coolant loss. I was afraid of piston rings when I saw the leakage numbers and could only hear air coming from the crankcase. But am also confused after the leakdown didn't put any air in the radiator from any cylinder. Is is possible that many rings all went bad together?

I also bought another 4runner in February, a 98 with the 3.4. It has noticeably better power compared to this one.

 

[gamefreakgc]

It is possible that the head gasket is leaking into an oil passageway and not a coolant passageway. Do you only get white smoke at start up or are there other conditions?

 

[LittleCaesar]

I would just change the oil, maybe to one weight heavier, and drive it. The numbers pinpoint to worn rings no doubt. Burning any oil?

How to do a leakdown test | Mobil™ Motor Oils

 

[Toyotayoda]

Leak down tests is as follows, once determined that cylinder leak down is excessive, where you hear air indicates the problem. You do a leak down test with the radiator cap off, the oil cap off, the intake hose off with the throttle open. Air bubbles from the radiator indicate a cylinder head gasket leak. Air leaking from the intake indicates intake valve or valves leaking compression. Air from the exhaust pipe indicates and exhaust valve or valves leaking compression. Noise from the oil cap indicates worn piston rings, or cylinder bore issue. It's that cut and dried. Compression numbers are really even, but they don't tell the whole story, how many revolutions did it take to make those numbers, there are also dry and wet compression tests. One usually does a wet compression test because the dry test was low, add a few CC's of oil to the cylinder, if compression improves you know you have a ring issue, if not you know your loss is in the valves. Engines are the same as they have always been, castings improved, ignition has improved, fuel control has improved, mechanical diagnosis is the same. White smoke during warm up can be normal depending on temperature, engines run rich when cold and the rich mixture comes out the pipe as white smoke in cooler temperatures, so don't go straight to bad head gasket when you see white smoke on a cool morning.

 

[thegipper]

You could also send an oil sample to blackstone lab's for analysis. If there is coolant in the oil, it will show up on the test.

 

[Kyngfish]

I only know leak down tests in reference to the Porsche air-cooled engines. A new engine will have sub 10% loss. Higher than 20% is considered rebuild time.

The benefit of the leak down is that based on where you hear the air coming out of, intake or exhaust side, you can try to pin down whether you just need to refresh the top end or rebuild the bottom. [MENTION=148927]Toyotayoda[/MENTION] 's advice here is on the money. I think also if you squirt some oil down in the cylinder and you do the leak down again and get better compression, you can diagnose the rings.

If they overheated it, my money is on your head being the issue, which is a pain in the ass, but totally doable, and for not a ton of money.

 

[gamefreakgc]

Leak down tests is as follows, once determined that cylinder leak down is excessive, where you hear air indicates the problem. You do a leak down test with the radiator cap off, the oil cap off, the intake hose off with the throttle open. Air bubbles from the radiator indicate a cylinder head gasket leak. Air leaking from the intake indicates intake valve or valves leaking compression. Air from the exhaust pipe indicates and exhaust valve or valves leaking compression. Noise from the oil cap indicates worn piston rings, or cylinder bore issue. It's that cut and dried. Compression numbers are really even, but they don't tell the whole story, how many revolutions did it take to make those numbers, there are also dry and wet compression tests. One usually does a wet compression test because the dry test was low, add a few CC's of oil to the cylinder, if compression improves you know you have a ring issue, if not you know your loss is in the valves. Engines are the same as they have always been, castings improved, ignition has improved, fuel control has improved, mechanical diagnosis is the same. White smoke during warm up can be normal depending on temperature, engines run rich when cold and the rich mixture comes out the pipe as white smoke in cooler temperatures, so don't go straight to bad head gasket when you see white smoke on a cool morning.

Yeah and these engines are known to straight up billow white steam in excess in the mornings. More than any other car I've seen and perfectly normal.

 

[phattyduck]

White smoke in January? That's probably normal.

Gasoline burning creates CO2 and H2O - and hot H2O is steam...

Unless that white smoke smelled like coolant, it isn't an issue. Might still have leaky valves or rings. Drive it now that the weather is better and see what's up. New plugs and wires might fix the cold stumble.

-Charlie