Paul_G
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New engine build 505ci, TF PP240 heads. Had the short block done at a local machine shop using the 440 Source stroker kit. Finished assembly of the engine myself. Took almost a year to get the engine finished and in a car. Been running for a couple months now.
Then about a month ago this happened, blew out a freeze plug while on the highway. The machine shop installed them. Engine got real hot before I figured it out. Replaced the one freeze plug.
https://www.forbbodiesonly.com/moparforum/threads/freeze-plug-blew-out.199096/
Last week another freeze plug blows out at speed on the highway. A lot of speed. Again, engine gets super hot before I see it. Hot to the point of smoking the engine oil out the breather. Get the car home and replaced the remaining freeze plugs installed by the machine shop. The engine ran again but did not feel right.
This time called the machine shop and told them what happened. He said to do a leak down test, or at least a compression test. The compression test showed 210 to 215 PSI across the right bank, 2,4,6,8. Left bank, 210 on cylinders 1 and 8, but only 175ish on 5 and 7. He asked about the condition of the engine oil and coolant. Both normal. He said to run it.
Today I had the car out for an early drive before it gets too hot. We are in the 110°'s here in Phoenix right now. During the drive the engine is down on power, getting worse to the point of having to limp it home. Oil pressure was normal, coolant temp normal. Get home, pull a plug wire off dist cap terminals one at a time while engine is running. Cylinders 5 and 7 are weak. Pull the left valve cover, all looks good in there. Did another compression test. 5 and 7 are 30 PSI, the others are still the same as the previous compression test. Backed off the rocker arm adjusters on 5 and 7 cylinders so all four valves are closed. Put air pressure in cylinder 5 and can hear and feel it coming out the spark plug hole on 7, and vice versa.
Called the machine shop. He said to bring in both heads on Monday so he can check them for flatness. These are aluminum heads.
So at best a blown head gasket right? What is the worst?
Then about a month ago this happened, blew out a freeze plug while on the highway. The machine shop installed them. Engine got real hot before I figured it out. Replaced the one freeze plug.
https://www.forbbodiesonly.com/moparforum/threads/freeze-plug-blew-out.199096/
Last week another freeze plug blows out at speed on the highway. A lot of speed. Again, engine gets super hot before I see it. Hot to the point of smoking the engine oil out the breather. Get the car home and replaced the remaining freeze plugs installed by the machine shop. The engine ran again but did not feel right.
This time called the machine shop and told them what happened. He said to do a leak down test, or at least a compression test. The compression test showed 210 to 215 PSI across the right bank, 2,4,6,8. Left bank, 210 on cylinders 1 and 8, but only 175ish on 5 and 7. He asked about the condition of the engine oil and coolant. Both normal. He said to run it.
Today I had the car out for an early drive before it gets too hot. We are in the 110°'s here in Phoenix right now. During the drive the engine is down on power, getting worse to the point of having to limp it home. Oil pressure was normal, coolant temp normal. Get home, pull a plug wire off dist cap terminals one at a time while engine is running. Cylinders 5 and 7 are weak. Pull the left valve cover, all looks good in there. Did another compression test. 5 and 7 are 30 PSI, the others are still the same as the previous compression test. Backed off the rocker arm adjusters on 5 and 7 cylinders so all four valves are closed. Put air pressure in cylinder 5 and can hear and feel it coming out the spark plug hole on 7, and vice versa.
Called the machine shop. He said to bring in both heads on Monday so he can check them for flatness. These are aluminum heads.
So at best a blown head gasket right? What is the worst?
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