D8H D342 Blowing Water out Rad

Fill your radiator over full,start engine and check for bubbles.
Bob

Fill your radiator over full,start engine and check for bubbles.
Bob

Probably low liner projection or sometimes a precombustion chamber can have a pin hole or bad chamber gasket at the chamber seat. But not all is lost the block can be counterbore and shims installed under the liners. Just alot of work.

Yep, I think you're gonna have to pull the engine down and have the counterbores re-cut and put shims in to get your liner to the proper projection. It's common on these types of engines for that to happen. I had a D339 in a D7E to do the same thing and that's the same engine as your D342 minus 2 cylinders.

Now, there are O-rings and and a steel washer on and under your precombustion chambers that can pressurize the radiator too if not sealing right. You might want to pull all of them and reseal them just to start with the simplest. Check your pre-com chambers for pinholes in them too when you pull them. You have to have a special splined tool to remove them. The dealer usually keeps them in stock, they're about $50 new.

what year is your 46 a my dad and i had 4 46A s mid sre nos we had a lot of trouble with hair line cracks in the heads we up dated then to real late ser no heads and never had any truoble with them after that we ran 24/7 365 working in a Diatomaceous earth mine you mite check with cat or a good eng shop on the heads

First make sure it is not something daft like the radiator pressure relief valve not working, it should hold around 14psi. if it holds pressure, put a hose on the relief valve and into a pint bottle full of water, with the engine running at full temp, flip the bottle upside down in a bucket of water and check how long it takes for gas from the radiator to displace all the water in the bottle,anything less than 30 seconds means you have a problem, and, as others have said, these engines are notorious for the liners dropping in the block. I am also sure that many engines have been pulled apart when there was not really a problem, that's why i would check the rate of leakage first .

Plenty of ideas here and all are Valid. ,Having run a small fleet of H's K's for years We always with a heat problem checked Heads with a Laser heat gun First. if it is a cracked head that Cyl will show a higher reading . Can save a lot of work and expense pulling Both heads . Also a piece of advise , if you do remove a head ,replace manifold joining rings with Cat only . Non genuine are too soft . LJ

Hi Max

I had the exact same problem with my D6C.:noidea: Found out the bypasses around the thermostat were plugged. Both of them. This created a boiling situation in the block until the thermostat warmed and opened and then she blew her top. It didn't matter how tight the cap was.:eek2: The bypass in the thermostat housing was plugged with crud and the 1/8 inch tube from the water pump to the upper tube with a piece of "O" ring material. I cleared those two passages and no more problems. This was an inexpensive fix. Check it out!

Casey