What is cylinder liner protrusion on Y485?

[Tim Berframe]

I have a 2007 Yangdong Y485. Head gasket will not seal. I have compression in the water. I measure the liner protrusion to be 36 thou above the deck. All liners are in plane with each other. The deck is flat. The head surface is flat.

I cannot find a spec for this engine ( Cat and Perkins and others all seem to be less than 10 thou). Perhaps one of the dealers on here might know? With such a huge protrusion, it seem doubtful to me that the skinny gasket will seal?

 

[Bob Rooks]

Disclaimer: I'm not a dealer.

Measure the thickness of the head gasket at the metal ring. It should be greater than the liner projection (the amount the liner projects above the block deck). If the measurement is not greater the liners may be: 1) Shimmed too high. 2) Wrong liners. 3) Liner bore not undercut enough. 4) Wrong head gasket.

 

[Tim Berframe]

I measured that wrong. The fire ring crushes on the larger ring around the outside of the liner. Those protrude about 1.5 to 2 thou above the deck. There appears to be complete crush on the fire rings for all cylinders. The soft part of the gasket appears to have crushed about 10 thou around the fire rings so I think it has sealed OK on the deck and liners. Must have leaked on the head side of gasket.

Took head to machine shop. They magnafluxed it and no cracks. It is flat with no warp. Two of the fuel injector inserts had pitting around the perimeter and they were proud of the surface by 5 thou. They flattened those and I put it together. Blew another head gasket before it came to temp. Same symptom - pressure in the coolant.

I will try to find a diesel compression gauge kit to rule out an over compression condition from the new rebuild parts. Running out of thoughts and patience...

 

[Bob Rooks]

Injector tube pitting is the smoking gun I believe. Aren't they copper? The fact that they project above the surface means the seal has been compromised and need to be replaced. Perhaps originally not installed correctly. Another possibility is a cracked liner if it's a wet liner engine. Very unlikely that you have too much compression - how would that happen?

 

[Tim Berframe]

Heres what it looks like. You can see the start of water pitting in the #3 & #4 cylinders. It looks worse in the photo than it is.

The injector inserts are very hard steel. Much harder than the head.

These are dry liners and brand new. They did measure identical to the old ones.

I wanted to rule out over compression because I changed pistons, liners, rods. They are supposed to be the correct replacements but wanting to rule out one thing at a time.

I just found a spec for liner protrusion. It says 0.07mm to 0.15mm (2.75 thou to 5.9 thou). Mine were 1.5 to 2 thou as best I could measure with feeler gauge. So, that would crush the soft part of gasket more and the metal part less. I think its leaking between head and metal gasket overlapping the injector insert at #3. Would shimming the liners up 2 thou make enough difference?

 

[Bob Rooks]

What I found peculiar in that pic is that the pitting seems to begin at #2 cylinder and grows progressively worse to #4.

 

[Rgladden]

If you don't mind my butting in; you said blew a head gasket. Where? Compression in to the coolant? Coolant into the compression chamber? Not likely, water does not compress and would bend the rod.

 

[Tim Berframe]

Itç—´ all described up the thread and in another long thread. Compression in the coolant. Not enough water to hydro lock and bend rods. I think the water is pressurized and when shut down, pressure pushes back into cylinder and takes drops with it.

I changed pistons and rods. The rods had same center to center measure so strike shouldn稚 have changed. The pistons were switched to 4 ring pistons because they were cheap and I couldn稚 buy the 3 ring set I needed. They are not identical so perhaps they displace slightly more? Just want to check

It came from factory with #3 valve lash tightened down so far that I believe I ran on three cylinders for 5 years. After changing that to spec, it ran hot with a lot of blow by for a few hours before the camshaft broke due to unrelated quality control issue. Upon disassembly, it was apparent that it was leaking between head and gasket between 3 and 4. Rebuilt last fall and gasket blew within 10 mins. Just had head ç´*ixed last week and same failure within two mins

 

[Rgladden]

Your theory has merit for sure and a tiny bit of H2O could increase the combustion also. Just my 2 cents but I believe I would be suspecting a casting flaw in an area the MagnaGlow could not be seen under that #3 valve. Exhaust
or intake?

 

[Bob Rooks]

Tim,
Was the top of the three ring and four ring pistons identical? Top of #1 ring land to top of piston?