Coolant Leak at Block Head Junction

padam · Apr 21, 2024

I was doing some work on my 413, and discovered that I have a coolant leak that seems to be coming from the block-head junction.
I noticed a little coolant dripping occasionaly on the rear outside of the block last year. Today I was getting ready to install new pusrodsand saw a puddle of coolant inside the block on the lifter area of cylinder 8.
I pressurized the coolant system and am getting a dribble of coolant on the inside and outside of the area shown in the photo.

For reference these are 906 heads that have had .100" milled off the decks.
I am using steel shim head gaskets around .020"

I am going to do some more checking before I start tearing into things, just wondereing if this is a known area for problems.

493 Mike · Apr 21, 2024

Not really. Chrysler used the same style gaskets through out the B engine production. Did your machinist finish for the steel gaskets or composition type gaskets?
Mike

padam · Apr 21, 2024

493 Mike said:
Not really. Chrysler used the same style gaskets through out the B engine production. Did your machinist finish for the steel gaskets or composition type gaskets?
Mike

I told him what I was using, but really don’t know if he applied any special finish. He’s pretty old school

pnora · Apr 21, 2024

About the simplest thing you can do is go through the torque sequence. I would loosen each bolt and torque each one in sequence.

snakeoil24 · Apr 21, 2024

90 percent of machinist have no clue about finishing for multi layer vs steel shim

padam · Apr 21, 2024

Above link is to a video of the leak with about 9 psi in the cooling system.
I don't think it would have been this bad last year, I would have seen coolant in the oil.
I guess the heads will have to come off.

EDIT:
Not happy with the link so I will post it to youtube.
EDITt 2:
Link fixed

moparedtn · Apr 21, 2024

Is that a "ding" in the head or a gasket pushing out?

padam · Apr 22, 2024

moparedtn said:
Is that a "ding" in the head or a gasket pushing out?

I think it is just where the coolant is bulging out before it runs down.

I'm going to try to get the head off after work today.

padam · Apr 22, 2024

I got the head off today.
I don’t see anything obvious that looks like it is the source of the leak.

I'm uploading a bunch of pictures. If you guys can take a look and tell me if anything jumps out at you I'd appreciate it.

In the mean time I think my best step forward is to install a new gasket and pressure teat the system again.

padam · Apr 22, 2024

more pics

RemCharger · Apr 22, 2024

A few questions..
What brand of gasket was it?
Has the big slots.. industrial?
Did you use a sealer?

My street 383 would blow a little out in the burnout box for years. Finally leaked internal. Always attributed it to the fact that I never sprayed the gasket, just installed dry

padam · Apr 23, 2024

RemCharger said:
A few questions..
What brand of gasket was it?
Has the big slots.. industrial?
Did you use a sealer?

My street 383 would blow a little out in the burnout box for years. Finally leaked internal. Always attributed it to the fact that I never sprayed the gasket, just installed dry

These are Superformance gaskets. As far as I know it’s the only one they make, and it’s the only thin gasket I could find in the spring of 2021.
I sprayed these both sides with Copper Coat and you can still see it on the block heads and gasket.

There is rust pitting around some of the gasket openings. No doubt from running straight water in the summertime as tracks require. (I won’t do that again. )

The head bolts all clicked the torque wrench at 70 ft/lbs.

Last night I picked up Fel-pro 8519 PT-1 gaskets. They are .039 vs the .022 of the steel shim gasket so I will lose a little compression. But that’s ok since I will gain a little PV clearance which will make me more comfortable, my switch to Crane adjustable rockers is giving me about +.010” lift.

I will try to get this side head on this evening and pressurize the system.

dvw · Apr 23, 2024

First of all nobody checks for anti-freeze. I always run some. The cut on the surface looks pretty rough. Looks like it was done with a Storm Vulcan cutter. I'd clean the pits real well. Scrape some JB weld into the pits with a razor blade so it's flat. (dont laugh it works at 15-1 comp). Then a little RTV around the water ports, very little. I use Ultra Grey. When torquing the head, loosen each bolt in sequence after 10 minutes or so and retorque to full value in one sweep. Garanteed the bolt will turn further the 2nd time.
Doug

padam · Apr 24, 2024

dvw said:
First of all nobody checks for anti-freeze. I always run some. The cut on the surface looks pretty rough. Looks like it was done with a Storm Vulcan cutter. I'd clean the pits real well. Scrape some JB weld into the pits with a razor blade so it's flat. (dont laugh it works at 15-1 comp). Then a little RTV around the water ports, very little. I use Ultra Grey. When torquing the head, loosen each bolt in sequence after 10 minutes or so and retorque to full value in one sweep. Garanteed the bolt will turn further the 2nd time.
Doug

Thanks for the advice Doug, sounds like you’re familiar with this situation.

I installed the head last night before I read your post. The JB weld thing sounds intense and don’t think I would try it with the engine in the car like this.

I checked block and head with a straight edge and car only barely get a .001 shim under it a couple places, so they are flat. But the surface finish on the block is rough. Too rough for my liking. I don’t know what machine he used. It looks like one tooth of the cutter was down farther than the others. Like I said my guy is very old school.

I did use your method to torque the head bolts I had seen in an older post.
I pressurized the system last night and no leaks this morning. So that is encouraging. I hope that the newer tech of the Fel-pro gaskets will hold up better.

padam · Apr 27, 2024

Always one step up and two steps back.

I was making pretty good progress the last few days. Both heads are on. A few of the lifters had coolant in them so I took them apart and cleaned them. That took awhile.
I got the rockers on and adjusted.
Then I got to looking at the headers and noticed a little hole and a crack in one of the tubes.

padam · Monday at 8:41 PM

Took it for a spin today,all seems good.
I am going to try to make it to the track this weekend.

PRHeads · Tuesday at 5:54 PM

I’m late to the party on this one, but I agree the deck surface is quite rough.
Too rough for a steel gasket imo.

You made the tight call by going to the composition gasket.

padam · Tuesday at 8:10 PM

PRHeads said:
I’m late to the party on this one, but I agree the deck surface is quite rough.
Too rough for a steel gasket imo.

You made the tight call by going to the composition gasket.

Yes, it’s kind of deceiving. If you run your hand over it it feels good. But my fingernail catches it, so seems like the tool had too sharp a corner.
The head surface was much smoother.
Both gaskets also looked like they were starting to fail between the middle cylinders. So I guess I really reached the limit on them.
I hope the composite holds up better, according to Fel-pros info they are supposed to be more forgiving for imperfect surfaces.

Lessons learned?
I really shouldn’t have accepted the surface finish on the block. The guy that owns the shop is a friend and well known as doing good work and being a real car guy and racer. He is getting older though, and I don’t know about the guys that work for him. I know his equipment is very old also.
If I build another engine I will use a different shop.

I also think it makes sense to take advantage of newer technology when it comes to stuff like gaskets.

When I rebuilt this engine in 2021 I only expected to use it until I could put a stroker together. I ended up putting so much work into my chassis and drivetrain that the stroker never happened. I will re-evaluate the engine situation after this season, hopefully it gets me thru.

Coolant Leak at Block Head Junction

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