Compression Ignition Addict
Join Date: May 2013
Location: Yeah Right
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How many miles/hours on the rebuild? Have the rings been broken in yet? Why are you flooring a brand new motor? Did you just get it finished?
If the rings haven't seated yet, which can take quite a few miles, then you will have blowby. Did you stagger the rings so the grooves don't line up on the initial build? Did you break it in properly at a high rpm so the rings and pistons can get the initial wear pattern? If you didn't do this right, the rings can scar the cylinder or fail to cause the hatching pattern that basically rotates the rings around the piston and keeps them from sticking.
A lot here we don't know to make a decision. Regarding the glow plug connector, that just doesn't make any sense. If pressure was blowing past the glow plug to somehow pop off the connector, your compression would show it. Is this on all the glow plugs or just one? Is it always the same glow plugs? What glow plug/cylinder is this happening on?
Please give us more info.
Regarding compression, 6.4 diesels compression, in terms of blow-by, changes with rpm/heat. They have a bit lower compression at idle than at a sustained rpm. This is due to several factors. The main assumed factor is that during regens, the temps get very high in the cylinder and will expand everything significantly more than normal operation. To compensate, the compression is lowered by increasing the gaps on the ring to cylinder wall. However, anything with a turbo will already have lower compression. To understand this better, there is the compression ratio, which does not change and is based on the bottom stroke cylinder volume and top stroke cylinder volume ratio (topvol/bottomvol). Then there is compression loss due to blow-by. At low rpms/temps this increases (blow-by). When you do a compression test, you are seeing some pressure reading based on many factors. Assuming all things equal, this should be some number "P". When you have higher blow-by you will have some number "Q". Your loss is P-Q. Look up the numbers and see what is normal and compare to what you have. Remember, compression testing a cold engine will show 'Q' to be lower than normal.
Last edited by Expirobo; 06-19-2013 at 01:33 PM.