31 AA Radiator Cap Blows Water at High RPM

[CYB4]

Rusty,

I had the same problem, at high rpm and also heavy load uphills I lost a lot of coolant thru the radiator cap. It was a non visible crack in the head, the shop found, which wanted to machine its surface. I installed a Snyders 5:5 head last winter and I am happy now; the coolant stays there, where it should and the engine feels stronger.

[RustyWiring]

@SeaSlugs - Thanks for the advice. Fortunately, I installed adjustable tappets this summer for that very reason. I don't have that kind of patience. Recalling a bit more, I remember my boy tapping the piston down and it stopping at one of the rings. So, we tightened the ring compressor further and in she went. I'll bet now that we broke a ring. I do recall paying special attention to the (top?) ring orientation so I think we got those right. But, I'll find out.

@Chris - Thanks for the backup. I, too, have the Snyder's 5.5:1 in the basement, painted and awaiting the water pump studs from the old head.

[CYB4]

Rusty,

I got these water pump stuts http://www.snydersantiqueauto.com/pump-mounting-kit. If you ever have to change the water pump, you don't have to remove the radiator

[Tom Wesenberg]

Three piece oil rings with the two thin rails are the trickiest to move from the compressor to the cylinder, and hopefully they didn't get damaged. If a ring broke, the ends can wear a groove into the cylinder.

Be interesting to see what you find for the zero compression.
As I recall, you did not do a leak down test on that cylinder, right?

[RustyWiring]

@Chris: Is it odd that I was able to remove the pump, with fan attached, without damaging the radiator? It really came off quite easily. The radiator, on the other hand, was a BEAR to remove and put back. The fenders were in the way.

@Tom: Correct. I did not perform a leak down test. Once the head was off last week and I saw the poorly seating valve, I didn't see a need. With the valve providing such an easy path to exit, I'm not sure I would have noticed anything getting by the cylinder.

[SeaSlugs]

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Originally Posted by CYB4

Rusty,

I got these water pump stuts http://www.snydersantiqueauto.com/pump-mounting-kit. If you ever have to change the water pump, you don't have to remove the radiator

I agree with these, for as cheap as they are its a nice thing to know its easy to change out.

Still have to use some rtv on the threads or it will seep out the threads....

[CYB4]

Rusty,

May be my radiator is closer to the fan than yours. I pulled the water pump together with the head, so I was able to leave the radiator in the car.

[RustyWiring]

I lapped enough to burn a national forest. Barely tightened the gap. The valve is uniformly ground but the seat is not. I will contact the machine shop that performed the work originally and see if there is a better way to do this job short of towing the truck to him.

Removed the piston. The rings are fine; installed correctly, nothing broken, cylinder perfect. Maybe gasoline can pass by the rings faster than water/antifreeze and my previous test was worthless. Maybe the lack of compression is solely due to the valve gap of 0.002-0.003 around a half of the intake valve circumference.

I plan to reinstall the piston as-is. I wonder what the compression would be if I put some plumbers putty around the valve and stick the head back on. If it was good, then the leak is solely the valve. If not, then I have some other mystery and maybe I'm destined for three cylinders . It ran great on three initially.

[Tom Wesenberg]

There are hand cutters that can redo your seat, but I prefer the stones driven by an electric motor.

At any rate, I don't consider it a valve job if all three angles aren't done correctly so you get the correct width of contact and spacing to the valve face.

[tbirdtbird]

"Maybe the lack of compression is solely due to the valve gap of 0.002-0.003 around a half of the intake valve circumference."

that is where the money is

how did the guy mess that up

[katy]

Maybe the lack of compression is solely due to the valve gap of 0.002-0.003 around a half of the intake valve circumference.

Suggest that you check the valve, to be sure that it's not bent. Found that one time.

[RustyWiring]

Got the piston back in and had some time soooo...I had a lap dance with the valve again. And, yes, I feel dirty

Took another hour of fire starting but it seats now as well as all the others. I sure hope I got all the grinding compound off the engine.

The pan gasket arrives tomorrow so I expect to have everything back together on Saturday for a restart.

@Katy: Thanks. I checked the valve stem and it's good and straight. It's only been a 100 miles and 3 months since they were new so I wasn't expecting them to be bent but always good to get other ideas and check them out while it's all apart.

[john charlton]

Do you have a known good clear radiator ??? Waterpump grease over the years normally block the centre third tubes . The waterpump is designed to flow through a clear rad . If the rad is partially blocked the pump can overwhelm the top tank and hence water out of the overflow .

John in lovely sunny day Suffolk County England .

PS You should have the AA rad which has an extra row of tubes .

[RustyWiring]

@John: I had the radiator cleaned out at our local, highly-reputed radiator shop before installation. And, yup, it's the bigger rad. Thanks for the input.

[tbirdtbird]

someone mentioned trouble with ring compressor/getting rings into the cylinder....

for the past couple years we have been using the wrinkle-band type compressor made by Lisle instead of the more traditional sleeve type compressor

https://www.amazon.com/Lisle-21700-W...ing+compressor

We feel it works way better/way easier. My sleeve compressor went into the trash

[Mitch//pa]

Originally Posted by tbirdtbird

someone mentioned trouble with ring compressor/getting rings into the cylinder....

for the past couple years we have been using the wrinkle-band type compressor made by Lisle instead of the more traditional sleeve type compressor

https://www.amazon.com/Lisle-21700-W...ing+compressor

We feel it works way better/way easier. My sleeve compressor went into the trash

Agree Thats what i use for all engines.... works better and cheaper...
never really have an issue of the rings getting caught on the block using it...

[100IH]

I hope I haven"t missed a comment along the way. Here is what I see. You are trying to get valve contact when it is almost closed by lapping more and more. That won.t work. That .002 lift off the seat is how much the valve is being held up from contacting the seat in the block. The valve needs to go down to zero clearance and then the lifter below the valve needs to be adjusted further down an additional .013 to provide valve lash or clearance so that when the valve gets hot and expands (lengthwise), it won't hold the valve off it's seat. Lapping when there is negative clearance would be very difficult because the valve then should have spring tension and be difficult to turn for lapping purposes. If you could turn the valve for lapping purposes you would only increase the gap, .002 to a larger gap of .003. Picture this, There is only one thing to consider when talking gaps -the one between the bottom of the stem and the lifter, the valve lash. If the lash is correct, .013 and the valve is off it's seat completely around its seat, the stem is tight in the guide or the spring tension is not enough to close it. If that is the case you would be able to push the valve down to contact the seat. If the valve face is open on one side, the valve is bent or the seat is not concentric with the center line of the guide.

[RustyWiring]

@100IH: It's the latter part of your final sentence: The seat was not ground concentric with the centerline of the valve guide. The valve is perfect.

That being said, it's ok now. It just took two hours of grinding.

The remaining gaskets showed up today. I'll report back this weekend with what I pray will be the final chapter of this saga.

The moral of the story is 'trust but verify' your machinist's work...or find a better machinist. My mistake was my eagerness to get my first Model A running and not confirming the work done was done well.

[RustyWiring]

So, yesterday, here in southern Michigan, it was 70 degrees. Today, it's 34 and snowing! Guess which day I had available to finish reassembly? Yup, today.

Anyway, Al is back together and fired right up. I mean, I didn't even have to reset the timing. I have similar compression in all four cylinders now and the smoke screen is gone. Purrs like a happy kitty and maybe I can smoke the tires in first and second with this newfound horsepower.

Thank you very much for all the generous help. Now, it time to shut 'em down for six months.

[CYB4]

Rusty,

Let us know next driving season within this threat, if you A is now ok during driving conditions.