Could bad Glow plugs give low compression

[ak diesel driver]

wouldn't that hydrolock the IP?

 

[Nowaydude]

Wet compression test turns the oil you are using into fuel and the cylinder ignites blowing compression gauge up like hand grenade. You have to be able to do it with liquid that cant combust if doing wet comp test.
Otherwise, do leak down (100psi is how I learned it) dry and wet- very rarely you can tell the rings/walls are bad that way but worth trying if unsure.


Blocking off injection line and running engine is like unplugging spark plug wire and injector on a gas engine. It will fight the other cylinders and not just loose power from itself not working but make the other cylinders work harder. Your turning the v8 into v7 with power of v5. It is taking life out of the engine faster. Not a great long term option but sometimes ya do what ya gotta do. But if soon to be rebuilt/ replaced anyways...

Ok thanks, thats why I asked, don't want to explode anything!!! So if I do leakdown 100 psi at tdc of the low cylinders on compression strome and don't hear any air coming from the dip sick or lower end its probably just heads or gaskets? Thanks Mike

 

[WarWagon]

Could be a broken valve spring. Oh wait: the broken spring on mine was the highest compression cylinder.

With this many "low" holes and a confirmed leak it's real clear this engine was revved past redline and smacked a few valves on the pistons.

My engine was destroyed when the governor failed during a SNAP emissions test. It still ran with more cracked mains, galled camshaft lobe, broken valve spring, bent valves giving low compression, and 8 cracked pistons.

Ask yourself before you bother pulling the heads "if it's worth it" to drop an engine in it. Maybe you get a short time out of rebuilt heads and then the bottom end requires repair/replacement. With the noted lifter problems IMO your odds are not very good to avoid yanking the engine for an overhaul. And then cracked mains mean you are looking for a, cheaper than a 6.2/6.5, 454 gasser to drop in.

 

[Will L.]

wouldn't that hydrolock the IP?

I cant remember if i have ever done it to one of these pumps, but I have similar ones that use pop injectors with no problem. True, better to not risk it and run a dedicated return line back to the tank if needed.

I am saying this as option only to buy a little time being under the impression you ABSOLUTELY have to stop the smoking because it’s bad enough you can’t drive it and have nothing else to drive. I am with WarWagon in expecting a soon rebuilt or replaced engine.