Leakdown test results not good - Some thoughts needed

[RC211V]

Hello,

I have a friend who is attempting to purchase a ' 96 Integra with only 87K and after performing a leakdown and compression test, we are concerned about a few things.

Compression are about 15 points from each other.

However, the leakdown was far worse. Here are the Results:

Leakdown
#1 = 22%
#2 = 30%
#3 = 45%
#4 = 12%

My questions are:
1. What is the worst case scenario down the road with worn rings? Power? oil consumption? If its engine failure, then I will tell him to avoid it.

2. If oil consumption and power are the worst issues, then I plan on running Auto-RX to hopefully help in re-sealing the rings. Is this a lost cause?

3. Possible causes? Lack of oil changes creating deposits and sludge?

 

[seotaji]

Engines in good condition will have leakdown percentages of 2-4% but percentages as high as 10% are considered acceptable, as engines get older. If your engine is leaking 10% or more, you will probably be able to hear the air escaping the cylinder. There are three ways for the air to escape, the valves, the rings or the head gasket. Listen at the intake ports and exhaust ports/header for leaks from the valves. Listen to the oil filler neck for leaks past the rings and there is not a good place to listen for head gasket problems, but air might show up in the cooling system if you have a bad head gasket. Of course you can also look at your oil for signs of water in the oil also for bad head gaskets.

Several percent leakage past valve seats is not uncommon in worn heads. Culprits are bent valves, dirty seats, out-of-round seats or burnt valves. If you hear leakage past the intake valve in a port, take two screwdrivers and pry up on the retainer to see if seal is improved. If seal improves and then returns to previous leakage rates when you let go, you probably have a bent valve stem. Another possibility is that the valve train is not adjusted, keeping the valve from seating properly. In general, 1-3% leakage across all intake ports is considered OK. If you hear any leakage in the exhaust port, you should plan to rebuild the head(s) as the exhaust valves will continue to be undercut by leaking exhaust gases.

Ring seating and end gaps normally produce the most leakage in a cylinder. In small bore engines typical values are 8-12% with large bore engines producing 15-20% after rings have worn. The ring end gaps open (.010 new - .030 worn) as the rings and cylinder wear. Detonation can also break a ring causing increased leakage. A new engine may show high leakage until the rings have a chance to seat on the cylinder wall. Ring leakage greater than 20%-30% means it's time to rebuild.

 

[TheLoneRanger]

I would suspect the vehicle has more miles on it than 87K. Those leakdown numbers point to simple engine wear.

I would remove a sparkplug and examine it, and also take a look at the tailpipe opening. This will tell if the car's using oil and how much.....

 

[Gary Allan]

Leak down tests can sometimes be misleading. In school we lossened the valves on one cylinder and performed the test. It indicated a bad intake valve (high numbers ..could be heard out the carb). Performed the exact same test on the ajacent cylinder ...it indicated a bad exhaust valve (high numbers ..could be heard out tail pipe.

Neither valves were bad. The head gasket between the two cylinders leaked (no coolant leaks ..just combustion gasses). When one was being tested ..the ajacent cylinder's (intake or exhaust) valve was open ..providing the "evidence". When the head was pulled the head gasket was discovered to be the cause.

Seeing that your reading indicate the highest leakage on ajacent cylinders reminded me of this event.

I had cylinder leakage so bad due to JUST valves that when I hooked up air to the cylinder ...the ventury action in reverse blew a decent stream of gas out the carb (1600 Champ Mitsu). This was straight shop air. The cylinder walls and rings were in excellent shape. Now the thing would idle fairly decently ..but any load would show you that you were running on two of the four cylinders (different ones) at any one time. A trip to the local machine shop and $135 for the valves and related work and it was good as new.

With numbers this high ..I would think that it would be apparent with a test drive.