Compression and Leakdown Results, Answers?

[greekgodchaos]

Hot&Dry
Cyl1: 110
Cyl2: 110
Cyl3: 125
Cyl4: 125


Hot&Wet (Oil added)
Cyl1: 132
Cyl2: 133
Cyl3: 128
Cyl4: 133

Gapped plugs to: 0.029

Leakdown Results:
Cyl1: 60% Leak to Cyl2
Cyl2: 61% Leak to Cyl1
Cyl3: 65% Leak to Cyl4
Cyl4: 60% Leak to Cyl3


*An Ultrasonic Leak Detector was used to pinpoint where the air leaks were located.

*A U.S. General (Harbor Freight) Leakdown Tester was used for...well, the Leakdown Test.

*There is no blue or white smoke coming from my exhaust. Unless I push almost 18psi then white smoke comes out.

*No oil in the coolant.

*No coolant in the oil.


...Ideas?


UPDATE: I spaced that Cyl2 was probably on its Exhaust TDC so I cranked it again and retested 1 and 2. No leaking out of the valves, just between Cylinders.

 

[greekgodchaos]

Anyone have any clue? Could my HG really be leaking between cylinders on both sides but not in the middle? Again, my leak down test showed that the only leaking that was happening was between Cylinders 4 and 3 and 2 and 1, but not 3 and 2. The car has overheated a total of maybe 3 times over the past year, and the coolant level never seems to drop whenever I check it every other day.

 

[delta448]

Sure it's possible. It only takes one overheating episode to warp a head. Sounds like you already know what you have to do. Good luck.

 

[t4-teg]

On the leakdown test, where is the air leaking from? A leakdown test shows you if the cylinder is leaking or not, but its your job to trace where its leaking from. You need to pull the IC piping off the intake manifold and listen for air, you need to preferable pull the exhaust manifold off and listen for air. Air out of either of these places usually identifies leaky valves. Air bubbles in the cooling system during leakdown tests shows a leaky headgasket. And, air from the dipstick tube or oil fill hole in the valve cover shows leaky rings.

Judging by your wet compression numbers, you most definatly have a ring sealing problem. Compression numbers going up, as You already know indicates a ring seal issue.

Time for a rebuild...

 

[97gst_spyder]

I'd at least try to re-torque the headstuds. Then re-test.

It worked for me.

 

[t4-teg]

^ Either way, he still has a ring sealing issue that will need to be addressed.

 

[Diehardmitsu]

Considering the wet and dry tests when the motor was hot, you gained over 20 psi on Cyl. 1&2. If its was a head gasket problem, wet/hot and dry/hot compression test shouldn't have such a big difference. Usually adding a cap full of oil or 2 to the cylinder only brings up the compression about 1-10 psi in a good motor
I think you might have some scoring on those cylinder walls or just worn rings.
How may miles on the block?

 

[greekgodchaos]

On the leakdown test, where is the air leaking from? A leakdown test shows you if the cylinder is leaking or not, but its your job to trace where its leaking from. You need to pull the IC piping off the intake manifold and listen for air, you need to preferable pull the exhaust manifold off and listen for air. Air out of either of these places usually identifies leaky valves. Air bubbles in the cooling system during leakdown tests shows a leaky headgasket. And, air from the dipstick tube or oil fill hole in the valve cover shows leaky rings.

Judging by your wet compression numbers, you most definatly have a ring sealing problem. Compression numbers going up, as You already know indicates a ring seal issue.

Time for a rebuild...

Cyl4 leaks into 3, 3 leaks into 4, 2 leaks into 1, and 1 leaks into 2. No bubbles are in the coolant when I do the leakdown test, so Im thinking that the HG just damaged across cylinders and not the coolant passages. No leaking out of the exhaust or intake valves and No leaking into the crank case. (16psi = fine and dandy, 20psi = SpyHunter ploom of white smoke and never popped my dipstick, which is unmodified.)

I'd at least try to re-torque the headstuds. Then re-test.

It worked for me.

Ill definitely do that tomorrow, I'm getting my valve cover power cleaned under the baffles because I'm paranoid like that haha


Thanks guys for the fast replies I really appreciate it, I'm just wanting to get all the questions answered so I can jump on repairing this since its my DD and my jeep leaks and terrifies me whenever I drive it

 

[delta448]

I think I should expand on my first post just a little.

• The rings are shot. The 6 bolt service limit is about 120psi compression IIRC, and you're about there.
• That you're seeing cross cylinder leaking says the headgasket is also damaged. This is probably a result of overheating and the different expansion rate of an aluminum head on an iron block. Depending on the headgasket material, it's usually fine up to at least 240F coolant temp, but after that I would begin to expect problems.
• The white smoke show at 18+psi of boost is also headgasket related. The coolant to combustion leak is only showing up here because you have low static compression and you aren't taxing the seal until your dynamic compression (boost adds combustion pressure) rises enough to follow the damaged areas of the seal and push coolant. I bet if you go out right now and drive the car hard for any more than a couple full-boost pulls you'll see a puking overflow bottle.

So basically, it's time to rebuild this engine. It needs new rings and a new headgasket in the least.

 

[laserspeeddemon]

The rings are shot. The 6 bolt service limit is about 120psi compression IIRC, and you're about there.

Low compression numbers could also be a result of the Head Gasket. And considering his wet test wasn't far off from the dry, I would almost certainly point to the head gasket before rings.

 

[delta448]

Low compression numbers could also be a result of the Head Gasket. And considering his wet test wasn't far off from the dry, I would almost certainly point to the head gasket before rings.

I do respect your opinion Sean, and usually I'd agree 100% with your assessment but I still suspect these rings deserve replacement. He's still on the stock 6 bolt bottom end.

If you're going to tear the head off for a new gasket anyway, it would surely suck to find out you still have low compression after it's replaced. A wash, hone and new rings shouldn't break the bank, and new bearings are also cheap insurance. That's roughly $6-800 at most if you do the assembly yourself.

 

[laserspeeddemon]

Good point, but I was merely saying both could be true.

 

[greekgodchaos]

Update: Finally removing the engine this week, doing a full build on my DD

Resurfacing the head
Evo 8 Pistons w/ my 1g Rods (Getting the block cleaned up, resurfaced (if needed) and some new rings as well)
Stock 6-Bolt Crank
BSE Kit
OEM MLS Headgasket???
Evo 8 Valve Springs/Retainers
ARP Head/Rod/Main Studs/Bolts
ACL Main/Rod Bearings
All New Gaskets and Seals
Mighty Max Oil Filter Housing

Anything I'm forgetting?? Also I cant figure out what Head gasket I will go with, either an OEM MLS, OEM Composite, Fel-Pro, or what.

 

[BogusSVO]

you need to decide what HG you will use BEFORE you take the block/head to the machineshop to be surfaced, You need a much smoother surface for a MLS than you do a composite.

Make sure that neither the head or block will be surfaced on a belt surfacer.