So this is bad...

[Paul_G]

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?

 

[33 IMP]

Worst would be butted ring gaps from the heat, and busted ring lands/pistons.
I think you've got a warped head or two, and a bad head gasket. Surface the heads, new gaskets, redo compression check. ( 210-215 is a BUNCH of compression pressure for pump gas!)

 

[67charger383]

If it's too much compression then convert to E85

 

[Paul_G]

Worst would be butted ring gaps from the heat, and busted ring lands/pistons.
I think you've got a warped head or two, and a bad head gasket. Surface the heads, new gaskets, redo compression check. ( 210-215 is a BUNCH of compression pressure for pump gas!)

The goal was 10.5:1. Engine ran great. 32° of timing. I thought there might have been some pre ignition, turned out to be leaky exh man gaskets.

If it's too much compression then convert to E85

Tried that. I was running an E30 blend. There are apps to get the blend very close. Dont think it will be necessary.

Now, if he has to mill the heads a little, how much is too much? Can the difference be made back up with thicker head gaskets?

 

[33 IMP]

Your compression pressure is also a function of cam selection. Since you are already high on the pressure (in my humble opinion), get them surfaced the minimum to get them flat! and then only if they need it.
And yes, you can use a thicker head gasket to adjust static compression ratio, but a thicker gasket will affect quench if you used some.

 

[440Coronet500]

First, never run a motor over temp for an extended period of time. Could be a few things fron head gasket to rings. Take your time to figure it out. 440'

 

[dvw]

Sounds like a blown head gasket between 5 & 7. Did the cylinder pressure raise coolant pressure enough to push core plugs out? Seems unlikely. How hot was hot? How do the cylinder walls look? I think if it were me I'd pop the pistons out and take a look. For sure every core plug would get swapped with a good look at the core plug holes.
Doug

 

[PRHeads]

Likely a head gasket.
Very carefully inspect the deck of the block in the area the gasket failed.
Especially if it had MLS gaskets.

The cranking pressure test numbers being high can be misleading with a hyd cam.
If the motor sat for any length of time, the lifters bleed down which raises the cranking pressure numbers.

After the motor is back up and running, pick a cylinder where the plug is easy to access and test that one immediately after running the motor to see if the number changes.
Then, let it sit for a while and retest it so see if the number starts to go up.

There is really no reason that combo of parts would have the cranking pressure that high if the lifters were pumped up.

If you really wanted to test it, you could do a cranking pressure test while someone was running a priming tool so the oil system, and lifters, were seeing full pressure.

I’m basically in the same camp as Doug.
I’d probably pull it apart and look it all over.

 

[Paul_G]

Here are some pics. Is this head trashed or repairable? Deep groove in the aluminum between 3 and 5. The block had some carbon burn in the blow out spot. Most of it scraped off the block, and smooth out when sanded with some 150 grit and a sanding block.

 

[33 IMP]

A competent heliarc welder can fix that .

 

[PRHeads]

This is a situation where by using a “better” component, I’m 99% sure you wouldn’t have had to be pulling that head.

I’m talking about the head gaskets.
The 1009’s, which is what it looks like you have there, can be problematic in high heat situations.
After you get past the armor........It’s just paper and rubber.

Cometics only for me on that type of build.

That one bore looks pretty sketchy to me, and it looks like a small area of the piston started to melt in the area of the burn through.

There is also a little mark in the valve pocket, but it might just be a reflection or something.

 

[Paul_G]

I am talking with the machine shop on Monday, taking the heads to them. They built the short block for me and want to see the heads. Two of the core plugs they installed came out, thats what started this failure. They used Dorman 565-068 brass plugs. Is that a standard replacement core plug? The Milodon core plugs I put in are much beefier.

How much of this damage, if any, should be their responsibility?

 

[justcruisin]

You don't see many people running one but I have always run a low water probe in my cooling system for this very reason. If you loose your coolant the temp gauge wont always tell you but a buzzer or warning light will.

 

[Paul_G]

First, never run a motor over temp for an extended period of time. Could be a few things fron head gasket to rings. Take your time to figure it out. 440'

When a core plug comes out on the road the coolant is out of the engine in a matter of seconds. If all the liquid goes under the car, which mine did, and you dont see it your screwed. With no coolant circulating in the engine the cylinder temps sky rocket, and on top of that there is no hot coolant on the temp sensor so the dash gauge does not show it hot.

You don't see many people running one but I have always run a low water probe in my cooling system for this very reason. If you loose your coolant the temp gauge wont always tell you but a buzzer or warning light will.

Excellent idea. The radiator has an unused plug in the lower tank. I might figure out a low coolant warning of some kind.

 

[Paul_G]

I got a straight edge. 1/4" by 1" piece of aluminum stock. Not a machinist straight edge, I want to check the deck on the block with it. I sanded the deck surface clean with a block and sand paper.

Is there a tolerance for how much clearance is allowed across the block surface? With the straight edge firmly against the surface, i can see some light from a flashlight in a few places between the straight edge and deck surface. But just barely.

 

[Paul_G]

That one bore looks pretty sketchy to me, and it looks like a small area of the piston started to melt in the area of the burn through.

There is also a little mark in the valve pocket, but it might just be a reflection or something.

View attachment 998064 View attachment 998066

Good eye Dwayne, I looked closely at that piston, i can feel a little roughness over the burn spot.

 

[Paul_G]

After spending the weekend moping around like a lost puppy, looking at the broken engine and crying in my beer, I decide to take the engine out for a bottom end tear down and inspection. This is like starting the build all over again.

 

[Bee1971]

But with Piece of Mind

You did the right thing

Hopefully your machine shop can come through on the customer service side

 

[BDF6]

I sure hope this gets fixed in your favor quickly. I can't hardly stand down time & hope you are back on the road ASAP.

 

[PRHeads]

But with Piece of Mind

You did the right thing

Hopefully your machine shop can come through on the customer service side

Agreed.

It sucks big time that it happened, but it’s just one of those things that can happen in the car hobby.

Cams go bad, rear seals leak, valves stick, transmissions don’t shift, lifters fail....... the list goes on and on.

The freeze plugs blowing out is a pretty rare one though.
I think the next ones would get the green loctite treatment if it were mine.