Does this head gasket look bad enough for no compression in Cylinder 4?

[RangerDangerr]

2003 2.3 180k

Lost compression in cylinder 4 and was low on coolant. I pulled the head and checked for warpage with a precision straight edge. Everything seems to be straight and valves appear to be seated...at least I think, I don't really know how to check the valves beyond visual inspection.

Does this headgasket look bad enough for no compression?

 

[Terry]

If you lost a head gasket, you should be able to hear it. Did you do a leak down test, how low was the compression?

Sent from my SAMSUNG-SM-G920A using Tapatalk

 

[RonD]

No compression and low compression are different signs of what problem may be.

No compression(under 40psi) is usually a valve issue, burnt or not closing(valve train issue)
It can be a hole in the piston but at your point of disassembly you would notice that

Low compression can be a head gasket issue, or cracked head
There is simply not enough space between head and block to lose all compression when the gasket fails, or a crack big enough to lose all compression.
Air can't get out fast enough for no compression.

And if a head gasket fails it is usually not visible on the gasket.
Pinch #4 cylinder ring and move fingers around it, you are feeling for a defect, an indentation or roughness.


You have a DOHC engine so 2 cams, one for exhaust valves and one for intake valves.
Did you notice any issues on the valve train for #4, could be a stem is bent and valve was sticking open, or broken valve spring

Yes, after finding no compression in #4 you should have pushed some air thru the spark plug hole and listened at intake and exhaust to see where air was going.
Same as a leak down test

 

[RangerDangerr]

I was out and about when it started missing real bad out of nowhere, got it home and changed the coil pack, the problem still persisted so I checked compression, all were 100-120 aside from #3 was 50. Then I tried to recheck and lost all compression on #4 literally a 0 reading.

Well the head is off now so I can't really push air through, and the cams are off so all the valves are closed and they seem to be seated properly. I have a gasket kit ready but I don't know what else I can do at this point. It all LOOKS fine but, obviously something is wrong.

 

[RonD]

What did timing chain look like, was it tight?

120psi is pretty low for that engine, above 160psi would be expected on cold engine, all spark plugs removed.

valve timing is the key to compression, a little off and compression drops quite a bit, 0 would be a stretch though.

 

[pjtoledo]

checking the valve sealing can be done with a liquid and compressed air nozzle.

lay head on side, ports facing up. pour liquid into port, enough to cover the valve.

point hi pressure air directly at center of valve, close up.
as the air hits the valve it turns and goes away. that creates vacuum around the edges of the valve and will suck fluid past valve.


I have a hi-mileage 2.3 that has never been apart, I'm concerned about valve lash.
do the follower buckets show any wear on yours?
valve lash is adjusted by replacing the buckets with a different thickness.

 

[RangerDangerr]

The chain looked and felt pretty tight.


The buckets are the spring covers? If so, they look brand new with little wear.
Wouldn't worn ones be thinner anyways, thus making the valves close earlier?

At any rate, I will try this valve test and report back tomorrow.

 

[RangerDangerr]

Alright, I did the air test on my valves. They were pretty terrible. A lot of air was coming through cylinder 4. Idk if it's enough to show 0 compression but it was pretty bad. I'm taking the head to get it decked and get a valve job.

Not much else I can do. I feel like the only way it won't have compression after this is if the block is totally screwed. I checked the block straightness and it can't even clear a .0015 feeler gauge. So I should be good.

 

[pjtoledo]

be careful when milling an overhead cam head!!!

the head surface and the cam bearing saddles must be parallel.
if the head is warped, then milled to true it the cam saddles are now out of line. that will put the cams in a bind and leads to breakage.

when removing the cams, keep track of those cam-follower buckets and where they go. the different thickness' set the valve lash. oops, a valve job will alter the clearances, you may have to buy all new buckets.