31 AA Radiator Cap Blows Water at High RPM

[Mitch//pa]

[QUOTE=RustyWiring;1360187]@Dick: I torque when it's cool (thanks to reading the 'barn) but have only torqued three times in the 100 miles it now has on it.

@Ron: I will recheck compression. When I did it two weeks ago, it was 2-3lbs. I checked 1, then 2, scratched my head, did 3 & 4 and retested 2 and still got virtually no reading on the guage. 58-60 on the other three cylinders. I checked the head when I got it back from the shop - there were two hairlines about a half inch long around one the the bolt holes (probably the one that leaked early on). The machinist said he'd ignore them. I can't imagine all the compression would exit there without first registering something greater than 3lbs. Seems more and more like I screwed up the gasket installation.

So, now I'll set the compressor to 10# and grommet the air line to the #2 spark plug hole and listen/watch for where it goes.[/QUOTE]

Sounds good...make sure both valves are closed but u know that

[tbirdtbird]

you might have a valve that is too tight, i'd recheck the lash on #2

why is the water not blowing out of the overflow tube? Coming out from the bottom of the cap is kinda unusual

[joncrane]

Consider checking your radiator flow rate. A clogged radiator will backup with the water pump going at higher speeds. Disconnect the lower radiator hose and fill the radiator with a hand held over the outlet. Remove your hand and time how long it takes for the water to all run out.

[Mitch//pa]

Originally Posted by joncrane

Consider checking your radiator flow rate. A clogged radiator will backup with the water pump going at higher speeds. Disconnect the lower radiator hose and fill the radiator with a hand held over the outlet. Remove your hand and time how long it takes for the water to all run out.

"""A quote from Marcos barnyard"""

http://www.abarnyard.com/workshop/inlet-1.htm

""Don't be fooled by flow testing! Flow testing your radiator as suggested in several publications will only confirm EXTREME problems. You can block more than 1/3 of the cooling tubes on an original radiator and pass the flow test. The reason for this is the lower water outlet of the radiator is the restrictor. It is designed to limit the speed the water travels through the tubes. More time in the tubes equals cooler water.""

The fill, drop and count method is inaccurate on any radiator antique or modern..
Use your new thermal imager

[RustyWiring]

I think the radiator is in good shape:

The dry radiator had a thin, gummy layer over the top of the vertical tubes - as seen by staring into the mouth to either side of the baffle. This was over the summer. So, I had my local radiator shop clean it out ahead of final assembly. Working on faith, I accepted their word that it was 'clean as a whistle'.

Also, even though I drive for 20-25 minutes at a time, the only time I've seen the motometer register anything at all was right after I shut it off or maybe while idling after a 'long' drive. That was when I had the water level to the bottom tip of the motometer (yes, pretty much at the top of the mouth). The water level now is, obviously, much lower - I can just make out the vertical tubes.

The radiator seems pretty cool - I IR'd it a week ago. Forgot the values but it was in the 1xx range.

I tried a thicker o-ring last night. Had to work to get the cap down and rotated without rotating the whole assembly. No blow over. I suspect that that was just the exception to the rule and that I have a compression leak into the water system. Maybe another leak around the valves of #2.

I'll get to the leakdown this week and report back. I have another question about the (5-speed?!) transmission but I'll save that for another thread.

Thanks for all the warm support, folks.

[SeaSlugs]

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Originally Posted by RustyWiring

I'll get to the leakdown this week and report back. I have another question about the (5-speed?!) transmission but I'll save that for another thread.

Thanks for all the warm support, folks.

yea do this test asap as i highly doubt it has anything to do with your radiator.

your aa should be a 4 speed. 1st gear is granny low. 28/29 aas used the standard car 3 speed with a underdrive transmission behind that to achieve pretty much the same thing as your granny gear 1st gear.

[Veger]

Welcome Aboard Rusty! I lurk and learn a LOT from this site too. I'm a Model A NooB but i do know how to turn a wrench if need be and have a nice garage set up. Our AA does the same thing but not so bad once i get going up a hill or past 45 MPH i see a little bit of water coming out the cap. Not only that when i change the oil i seem to notice a gassy smell to it grrrrrr SO i keep fresh oil in it a lot for what little it drives any distance. Most the time its just from the back of the shop to the front of the business to show off. Anyways I just put up with mine cause it is just a tiny bit of water running over my pretty paint and just clean it up once I am at one of the few shows it goes to each year no biggie. One of these days i will know more to rebuild a engine maybe LOL. Good Luck and just LOVE the AA can't help but notice from the ONLY pic you got it almost looks like that is a hand crank for a dump bed? Again i'm just a NooB and it got me wondering LoL

Keep On Truckin!

[RustyWiring]

Hi Veger.

I, too, attribute pretty much everything I know about A/AA to this site. It has made the rebuild process so much less stressful (reading about the travails of others willing to share their experiences and being able to plan ahead for them). Les' red book has been huge, too.

My experience with any Model A/AA goes back to April of this year when I found this truck for sale in New York, took an 18' trailer through Canada, and brought it home to Michigan. I'd been looking for 'The Waltons' truck, on and off, for some time and this fit the bill close enough for me. I wasn't expecting to have to rebuild the engine but I find that sort of work enjoyable, as a hobby.

You said you drive your AA *PAST* 45MPH? I've got mine close to 45 once but really feel uncomfortable, RPM-wise, over 40MPH. I don't have a tacho so I just use my ear and my ear tells me to 'shift now'. Of course, I'm out of gears.

Yes, that is a manual crank dump/stakebed. My goal is to get a PTO and either change to hydraulic or build a contraption to spin the shaft from the PTO (without killing, crushing, impaling or decapitating anyone important). Hydraulic is probably the smarter choice. I'll take that topic to the AA forum one of these years.

I love driving that time machine. It's addicting - now that the kinks appear to be worked out...except for that dead cylinder, which I'll get to when I find where my kids put that rubber stopper for the leak down test. The real beauty of these machines, to me, is how simple they are. But I realize that it took TRUE genius to make them that simple.

[Veger]

LOL yea thats my bad Rusty what I should have said was 45 MPH going Down a BIG HILL with a HUGE wind behind me

Keep On Truckin'!

[Tom Wesenberg]

Running an engine for less than 30 minutes is bad for it because the oil doesn't get hot enough to boil off the condensation.

I wouldn't change a hand crank dump to a PTO dump. The hand crank is one thing that is unique to these old trucks and fascinates people at the car shows.

[Dollar Bill]

When you did the compression check, did your reading change any after adding oil to the cylinder? A leakdown test will give you a more definitive answer.

I respectfully disagree with the advice to load your engine by slipping the clutch. That's a good way to toast it.

[RustyWiring]

@Tom: Hmm. Never heard of that warning before. I began the break-in by driving a few hundred yards on day one, a mile the next day, two miles after that (distributor oil insufficient caused roasted points lobe). Then 4, then 8 then 10 then 20 last Sunday. 20 miles was about 20-25 minutes one way, with an hour break between, and that's the longest drive yet. I needed confidence that the old girl was going to hold it together. With 100 miles on it now, I'm pretty confident and will continue to drive longer and longer.

@Dollar Bill: I did the compression test after driving it the first few days. I wanted to do it before I got the engine all set the in chassis but it took me a while to create the adapter (spark plug butt welded below a 14mm nut) and my better judgement gave way to the excitement of getting it running. I did not add oil to the cylinder during the test. Sounds like a good way to confirm if the leak is minor.

One odd thing comes to mind, regarding the compression test: My son decided to put his hand over the plug hole while I turned over the engine. He received a HUGE hickey. That would have to be from the combustion stroke (as intake has the valve open), right? The valves look to be moving properly. The valves are closed from compression thru combustion and it has me wondering why, if I read an anemic 3lbs, was there any suction at all? I guess I had better test again tonight after work.

[RustyWiring]

Seems like I'm going in the wrong direction.

On 8Oct, I loaded up the bed with a few hay bale seats and drove my extended family (14 of us) to the nearby (1 mile away) cider mill and back. That went well enough, driving slowly.

A week later, I fired it up and it began to burn antifreeze - a white, sweet smoke screen a battleship would be proud of. Muffler was blowing water droplets, too. Checked torque and that was fine.

So, on Saturday, I pulled the head and replaced the head gasket because I was certain I was unkind to it while pushing it over the head studs a few months ago. This time, I removed a few studs to ease the installation. This gasket was Synder's top model, with silicon linings around everything. It said to use no sealant so I did not copper-spray it this time around. Fired it up and same result - big smoke screen and droplets coming out the end of the exhaust pipe.

Now, all that comes to mind is cracked head or cracked block. I closely examined the head when it was off. There was a crack from the jacket to an outside stud hole forward of #3 carb side. I don't think that this is a contributor. It was there before, too. I sort of figured that my 0-compression #2 cylinder would be the 'smoking gun' here but it was dry. Instead, I saw that #3 was quite wet. #3 plug wet, too. I did not see any cracks in the head that would cause this. I also inspected the cylinder wall. Nothing jumped out at me but, then again, I don't have magnaflux vision.

I guess the next step is to replace the head, or get it checked out (by a different machine shop this time). Failing that, I dread the thought of having to pull the engine again.

I would greatly appreciate any thoughts you have to share regarding next steps?

(As for #2 compression, I was able to push a 0.002" feeler gauge between the intake valve and it's seat but only around about a third of its circumference. Exhaust valve was tight. Would that gap alone account for 0 compression?)

[Mitch//pa]

Sounds like you could have multiple issues..
A leak down test will give you an indication of why there is no compression in #2 as well as which cylinder or cylinders is causing the coolant burn....this is something that I feel is an imperative step to be performed

[BILL WILLIAMSON]

"MAYBE" backflushing would help?? Rust flakes in the top of radiator tubes, is a COMMON problem.
Bill W.

[RustyWiring]

Hi Bill. Thanks for the advice.

I had the radiator, which was already in very good condition, professionally cleaned out over the summer. The block and head were also clean as a whistle.

@Mitch: I am pretty sure the leaky cylinder is #3 - that plug is wet and the cylinder wall had green droplets on it. When I removed the head, green liquid settled on top of the block surrounding #3 as though the cylinder was a swimming pool with liquid spilling over when the head was lifted. All other plugs are dry. I will do the leak test shortly on #2 & #3.

[Mitch//pa]

Originally Posted by RustyWiring

Hi Bill. Thanks for the advice.

I had the radiator, which was already in very good condition, professionally cleaned out over the summer. The block and head were also clean as a whistle.

@Mitch: I am pretty sure the leaky cylinder is #3 - that plug is wet and the cylinder wall had green droplets on it. When I removed the head, green liquid settled on top of the block surrounding #3 as though the cylinder was a swimming pool with liquid spilling over when the head was lifted. All other plugs are dry. I will do the leak test shortly on #2 & #3.

The test will show u why #2 is dead , which valve or other issue ...
Good deal

[tbirdtbird]

Given the length of this thread, which indicates at least 2 problems, you need to seriously consider the leakdown test on all 4 cylinders before you go any further, else you will be changing out heads and gaskets for a long time. What is lacking here is serious diagnostics. Instead there seems to be a lot of guessing. You can never be wrong with a leak down and they are quite easy to do.

You should not be able to get a feeler gauge under a closed valve...ie then it is NOT closed.

The so-called superior gasket with the silicone seal around the water holes has been the subject of numerous threads here and the consensus has been to avoid them, ie they work very very poorly. Most here are using the copper one without the silicone and using some spray-on copper coat. No one in our club (400 ppl) will use the silicone gasket, and I do not know of a single engine builder who will use them.

Be sure to never loosen number 8 (or any other nut for that matter) without lowering the coolant level, else coolant WILL leak into the cylinders. Many have stopped using the dizzy cable clamp for this reason. We trust that you are using the recommended torque sequence, also

Good luck and post your leakdown results so we can continue to help in diagnosis

[RustyWiring]

Well, I figured it all out. Yup, all of it. Pretty sure. Won't know for certain till reassembly.

1. Battle fleet glycol smoke screen. Crack in the head. Not sure why I didn't see it when I had the head off last week. It's a two inch seam above the piston on the forward side of #3. The good news - the cylinder was full of antifreeze since last week proving I installed the rings well (you'll see why that matters in point 3).

2. Blowing out the radiator cap at speed & puffing out the cap when starting hot (low fluid). Well, obviously, it's the crack on compression stroke.

3. Zero compression in #2. First, the intake valve is a poor fit. I had a machine shop install hardened seats and fit the valves. Seven are good, one was not. So, I will free that valve and lap it myself. Secondly, after seeing the pool in #3, I thought to verify #2 in the same manner. Glad I did. I filled it with an inch of gasoline which had then drained an hour later. I recall now that I let my son ring and install that piston. I thought I was paying attention. I guess I wasn't. But, doggonit, I watched him spin the ring gaps 120 degrees from each other and tap it carefully. So, now I will drop the pan and remove the piston and see what's wrong.

I guess the good news, to this point, is that I don't have to pull the motor...again. I'll report back once I have it back together.

Thank you for the input everyone

[SeaSlugs]

ring gaps orientation really dont matter - watch when you pull them out - they will be all over the place.

Other thing is make sure the rings are put in the right orientation (up and down) there is a top side to piston rings.

when you lap the vlave you will need to adjust its stem clearence again - if you have adjustable tappets then its easy - if you have stock setup you need to very carefuly grind/file a hair off the end of the stem.