Cat c15 Sdp rebuild help

Thinner spacerplate brings liner protrution to .006. Mic the new spacerplate also. I have had to go through a few new ones till I found one in spec.

 

You need to clean it to get true measurements.

 

ACERT pushing coolant and you've found a spot on the gasket where you believe the combustion gas is tracking to the coolant gallery? usually the ferrule in that coolant gallery will also be burnt/slightly melted from the combustion gas.

I preach this to so many people regularly and often get blank looks in return.

very very seldom will a 3406E/C15/C16 blow a head gasket or bypass the fire ring unless the clamping load is removed from the fire ring. this can ONLY happen if either the head is lifting on compression/power strokes or the liner is dropping. I've never seen a cat head lift but sure as the sun will rise tomorrow I've seen multiple dropped liners.

measuring liner heights with the hold down bolts at 75ft/lb will not show you if one section of the deck below the liner flange is worn away. hold down bolts will not depict a void under one corner of the liner flange. hold down bolts don't flex the flange they only seat the liner.

when the engine is running that liner swells up like a balloon expanding the bore from pressure during the power stroke. anything that increases cylinder pressure causes the liner to expand a greater amount. higher comp ratio, exhaust back pressure, excess fuel, boost leaks, high inlet air temps are all things that can contribute to cylinder peak pressure.

the liner expanding obviously means the flange is moving slightly too. its under load when the liner and liner flange are deforming from the cylinder pressure that the clamping force squashing the fire ring onto the liner flange can be taken away. the combustion gas can track straight into a coolant gallery.

generally it will only be one corner of the liner that has a void under it.

if you can be certain you can see where the combustion gas has bypassed the fire ring and the ferrule from that gallery is charred and burnt its time to do the following.

clean the head and look very very closely at the face correlating to were the fire ring section that has been bypassing sits. when the clamping load goes the fire ring will fret ever so slightly into the head face. you'll barely see it unless looking very close but you'll feel it by running a seal pick over it lightly.

if this is the case than you'll have to remove the liners. remove one or all liners. clean the deck. use your height gauge for liner protrusion on the deck surface. 0 the gauge and then slide it to the area where the suspect liner flange seats. you'll likely see 0.002"-0.004" recession shown on the gauge. move it around all 4 corners of the flange seat area and you'll start to see that 1 or 2 corners have small voids under them.

fix for this is counter bore and line shims, new liners because the flange will be fretted and worn slightly and get the head faced to remove the mark where the fire ring has fretted into it.

installing the "magic fix" 0.335" spacer plate is a masking option. you're not fixing the issue. you're simply adding another 0.003" protrusion resulting in greater fire ring clamping. the material recession is still present and will keep developing. however you have just brought yourself the timeframe it will take to wear 0.003" more material away and you'll start pushing coolant again.

I have seen SO MANY guys do 2 or 3 gaskets justifying it by saying the liner protrusion was within spec. look at the bigger picture prove how its happened and why.

 

The straight edge you are using also doesnt appear to be a machinist quality straight edge. Usually the straight edge will be certified to x amout of thou in x inches and the edge is about a 1/4 inch wide.
Common steel rulers can easily be out 3-4 thou in a couple inches.

I will also 2nd cutting the block rather then the thinner spacer plate. Every time a customer has cheaped out and wanted a thinner plate installed, the engine has been back apart to cut in a year or 2.

 

In no way did i suggest just using the thinner spacerplate to fix the issue if that is what is implied. I suggested using the thinner spacerplate after the deck of block has been leveled and head deck leveled so there is a uniform protrution on all cylinders. I prefer .006 if there is high hp involved. Just cleaning up the deck and replacing gasket is going to not last long before it happens again.

 

if they're cutting counter bores and fitting liner shims you should be able to use a standard spacer plate.
if the guy cutting knows what he's doing he can give you your desired protrusion with the standard plate.

with my tool if I cut to 0 or the shim thickness protrusion on standard plate comes up between 0.003" and 0.004". cutting to 0.002" less than the shim will return a liner protrusion of 0.005" and 0.006" with standard 0.338" spacer plate.

with genuine cat 5.40 liners running 0.007" or more liner protrusion will likely end in liner flange cracking and once again you'll be pushing coolant.

I usually run 0.004-0.005" protrusion within 0.001" variance over the entire deck and no more that 0.0005" variance between adjacent liners. haven't had an issue with 15's and 15 ACERTS up to 700rwhp everyday workers with that. if further gasket failure occurs at that protrusion you have a cylinder pressure issue. be it continual high inlet temps, turbo back pressure, incorrect compression ratio etc.