Help with radiator cap spray
 

I have had a reoccurring problem of spray coming under the radiator cap and decorating my hood. It occurs on longer pulls (up a hill) regardless of environmental ambient temperature. It does not occur with increased rpm. I have a moto-meter that works (tested it), and it indicates that my engine is not overheating.

The timing is dead on. I increase fuel and slightly retard spark when pulling a hill.

What gives? Where would you start? What would be other symptoms of a head gasket problem? Anyone think that could be it?

Thanks!

Re: Help with radiator cap spray
 

Make sure the radiator isn't brim full. Just fill to where the water or coolant is just covering the tubes by maybe 1/4 inch or so.

Same thing happens to me if I over fill it.

Re: Help with radiator cap spray
 

As suggested ^ don't over fill the radiator. Make sure your gasket is good and in place and check your overflow tube. You could also be missing the baffle in the top tank.

Re: Help with radiator cap spray
 

If the gasket under the cap is good you won't get any coolant out the cap. It would come out the overflow tube. Cap should be tightened snug on radiator neck. Is it the twist on cap or the threaded?

Re: Help with radiator cap spray
 

As a general rule , the model A water pump over pumps Years ago , Snyders recommended grinding off the tips of the water pump impeller to reduce the pumping action I think that about 1/3 of each impeller tip is recommended . Snyders offeres a cut down impeller . It has worked real good for me . None of our model A's run hot !!! I also agree with post#2 . The motor meter and quail radiator caps are the very worst to leak . I used red high temp silicone sealer under the cap gaskets when I run thermo quail caps and it helped . It has been said that the new repro radiators don't flow as well as the original radiators . Its not likely that the head gasket is the problem . I would explore every avenue before considering removing the head . I've seen way too many head studs wrung off in the block .

Re: Help with radiator cap spray
 

Retorque your head just to make sure that is not your problem. Otherwise, you are making pockets of steam at the hot spots in your water jacket. Your radiator is somewhat plugged. You are overheating.

Re: Help with radiator cap spray
 

Magicbox: Thanks. Definitely not full. It finds its own level below the top baffle.
Redmodelt: Thanks. Overflow tube clear! Gaskets.... Replaced them today. Will check if that's at least part of the issue when it stops raining here!
Eagle: I have the original cap (twist on) and a repop moto-meter. Allen wrench and twist top.

All: I have wondered if the gasket issue isn't sort of covering up an underlying problem. Or, do all radiators make spray, it just goes down the overfill tube?

Thanks again!

Re: Help with radiator cap spray
 

Do you have a “locking” cap?

My meter qual cap was spitting on the windshield on longer straights above 40. The gasket under the base was shot.

Re: Help with radiator cap spray
 

Purdy and Jackson: Original radiator, but completely re-cored with extra tubes. Only a couple thousand miles on it. I have always run a mixture of antifreeze and water so I don't believe it is rust/plugging issue. The completely rebuilt engine has less than 5000 miles. I will again re-torque the head. I had done that a bunch of times though, and the last couple I didn't get any more on them.

Purdy: I have enjoyed your posts over the years. Thx for a response. I have heard of the water pump fins being ground. I did not do that. It is a leakless from Snyders. I have always been suspicious of this though. Is it possible that the fins are only an issue when pulling a hill and not at higher rpm or at any other time? My common sense says "no", but as Samuel Clement said "Common sense isn't so common anymore"! :)

Thanks! Keep it comin'!

Re: Help with radiator cap spray
 

If all else fails, have your radiator rodded out to get maximum flow

Re: Help with radiator cap spray
 

Replaced that today! Will try it when the rain subsides to less than Hurricane levels around here!

Re: Help with radiator cap spray
 

I agree with Jackson. Re-torque your head. It won't hurt a thing to do so. You can not torque your head too many times... you can only torque it too much. Keep it at 55 lbs.

Even if your head does happen to be leaking your radiator cap should seal tight enough not to allow water to escape. It should only go out the overflow tube. At a minimum you've got a radiator cap gasket seal issue. Perhaps cutting an additional gasket out of a thinner material to supplement the gasket already in place. There are different thicknesses of cork gasket material available at most auto parts stores.

Re: Help with radiator cap spray
 

I agree as well.

its not an impeller issue - if it was sitting in neutral and revving the engine would cause it to spray - it needs the extra load (creates heat and pressure building) to blast into the water jacket to spurt out as your experiencing.

since you have a re-cored radiator unless its plugged up again with debris breaking free from the block id say you got a head sealing issue.

Yes if the radiator is plumb full it will come out and find its own level BUT it should for sure cover the tubes.

Check head nut torque to make sure its to spec and if you did have to snug a few up give it another drive and see what she does.

IF it still does it the easy way to find out is to get the engine warm, then do a leak down test with the radiator cap off. I bet it will behave like a geyser when you find the leaky offender cyl.

Re: Help with radiator cap spray
 

Cross-cut: Great info. I did just as you suggested, but have not tested it yet (extra gaskets).

Sea-slugs: The top baffle covers everything. Darned if I know how much water is in there. If I fill it to where I can see it (baffle), it definitely will spray out! :) How should I determine the level? Leak-down. I have seen that term used here on FB before, but don't know what it is. I will do some research and give it a try. Thank you!!

Re: Help with radiator cap spray
 

If it's a leaky head gasket, there will be combustion gasses in the radiator. It's easy to test. Auto Zone and O'Reilly's tool loan program includes this tester. You just buy the test fluid and the tester use is free if you return it unbroken.

Re: Help with radiator cap spray
 

Thanks 40 Deluxe. Good to know. Sounds like a good test even if I wasn't having this problem. btw Kuna is a great place!

Re: Help with radiator cap spray
 

I have a Motometer with wings below. The same thing happened to me on a hill with a long grade. After I reached the top, I pulled over to the side of the road and found that the cap was loose and I had to put in about a gallon of water.

We had gone to a car show in the morning. Before we left the show I check the water level in the radiator and it was ok. I used the wings to tighten the cap and I must not have tightened the cap properly. I had no problem driving on level roads, but about half way up the grade at 40 mph it started spraying water on the hood and windshield.

I bought a new seal and I'll make sure the cap is tight from now on.

David Serrano

Re: Help with radiator cap spray
 

if the allen screws are overtightened it is possible to distort the rediator neck so that the gasket surface is distorted making it hard for the gasket to seal

Re: Help with radiator cap spray
 

A friend had a similar problem. It only sprayed only while climbing up a hill and "pouring the coals to it". It was the water pump; somehow it would suck air through the shaft and only when stressed. No leaks on the straight and level. Go figure??

Re: Help with radiator cap spray
 

Put on a stock cap & see what happens. "Some" radiator gimmicks are more trouble than they're worth!!!---Why risk ruining an engine, just for LOOKS???
Bill W.

Re: Help with radiator cap spray
 

I've found that adding a capful or so of the anti-foaming liquid you can get where you rent carpet cleaning machines cuts down on coolant foaming. It's the foam that used to blow out my radiator cap.

Re: Help with radiator cap spray
 

I agree with Bill !!! I found an original cap for my roadster . I think that the original style caps look better . In my opinion the only thing that the locking caps are good for is to ruin the radiator neck and to leak . I had l;ots of problems with the thermo quail that I used on the coupe , my daughter liked it so I finally gave it to her . On the other hand if the radiator neck is damaged you may still have leaks . Even an original cap needs a good tight seal .

Every model A that I've ever owned would spray water out around the cap on a hard uphill pull under full throttle, Its a common trait of the model A . It can even happen on level ground under hard accelleration . Cutting down the impeller and getting a good seal at the radiator cap always solved the problem for me . An old partially plugged radiator or a new radiator with smaller or less tubes just can't handle the pressure that the water pump puts out . I guess that a cut down impeller could be called a band aid but if it solves the problem , so be it !!! If it wasn't common why would Snyders offer a cut down impeller . If the radiator can't handle the flow , the water has got to go somewhere . I can understand how a person would be reluctant to modify an expensive new leak proof pump . I'm not trying to tell anybody what they have to do . This has just been my experience .

Re: Help with radiator cap spray
 

I've found those MotoMeters are not at all accurate. It is true that over filling will cause coolant to come out. I always fill to cover the tubes and let the thing seek it's own level.
Are you running a thermostat? If so, it could be faulty. If not, a thermostat will close down the size of the hose and help control the flow of coolant. !60 degree 'stat for your location.
There is the possibility that rust chunks have washed into the radiator and blocked some of the tubes. Always a problem with all flathead Fords. Try back flushing the radiator. Never run plain water in these things.

Re: Help with radiator cap spray
 

As others have suggested, ck the gaskets..................Been There Done That.
Paul in CT

Re: Help with radiator cap spray
 

Purdy,

Those are both great ideas. My problem is getting the cap off. I think the Allen screw is stripped and it's so small it's going to be a pain taking it out.

I was thinking about cutting down the impeller but was worried that it would be unbalanced. I guess the vanes are too small to cause a problem even if they are unbalanced a little bit.

David Serrano

Re: Help with radiator cap spray
 

David , The nuts under the allen head screws could be turning , preventing the screws from backing out . You may have to drill out the screws if all else fails . I have had good luck grinding the tips of the impeller without getting things noticably out of balance . You could use the cut doen impeller that Snyders sells . The cut down impeller is on page A-140 of the Snyders catalog , part # A-8501-iM Price $8.50

Re: Help with radiator cap spray
 

Purdy,

Those are both great ideas. My problem is getting the locking cap off. I think the Allen screw is stripped and it's so small it's going to be a pain taking it out.

I was thinking about cutting down the impeller but was worried that it would be unbalanced. I guess the vanes are too small to cause a problem even if they are unbalanced a little bit.

David Serrano

Re: Help with radiator cap spray
 

Oops I double posted.

Purdy,

Thanks for the advice. I might just buy the one from Snyder's.

David Serrano

Re: Help with radiator cap spray
 

The water pump cannot pump more coolant out to the top tank than it pulls from the bottom of the radiator. Go to youtube and search: ford model a cooling system explained jack bahm

Re: Help with radiator cap spray
 

I haven’t tried to prove it, but I think it can. It’s siphening the water in the block.

Re: Help with radiator cap spray
 

Yo' David,
"Maybe" it's time to gently warm the neck, pop it OFF, remove the shell & solder on a NEW Filler Neck, available through the suppliers.---It can be easily done, IN THE CAR, with an inexpensive Propane Torch.
Bill W.

Re: Help with radiator cap spray
 

Its real easy to get the neck just a little off center . If the neck is a little off center it can cause the cap to rub the radiator shell and be difficult to get off and on . In worse cases, if it is more than a little off center the radiator shell won't fit over the neck, its happened to me. It can be a real PAIN to correct !!!

Re: Help with radiator cap spray
 

Not for the sake of disagreement , I figure the pump can pull as much coolant as it can push. As the pump pushes coolant out arround the cap and out the over flow tube the coolant level drops . Just my thought . I won't try to prove anything .

Re: Help with radiator cap spray
 

Nobody's just trying to be "RIGHT", just trying to HELP!
Bill W.

Re: Help with radiator cap spray
 

Right on bro , I'm not the best at soldering radiators !!! an experienced radiator man would have no problem .

Re: Help with radiator cap spray
 

Chief worked part time at Orville Mannings' Radumator Shop & lurned me some of the BASICS.:D I could "possibly" Solder on a body panel! These skills also helped me be a "pretty" good Body Leader. I can still smell the BEES'WAX!
When burning cars for scrapping, at the Wrecking Yard, I'd collect BIG "cow patties" of lead, under the car. Then melt it & form sticks of it, in an angle iron "mold" & some went to a Friend, that made Fishin' Weights, along with savin' wheel balancing weights for him. Chief taught me the value of "exotic" metals.
Bill Stucktight

Re: Help with radiator cap spray
 

Imagine an engine running a little hot, say 185. Maybe there's a hot spot in a little shielded corner running 200 degrees. You punch the gas and the pump spins up. The flow makes the pressure highest at the exit of the pump and lowest at the entrance to the pump and in-between pressure in between. All you need is for the pressure to drop in the block by enough to boil 200 degree water and you'll pull a steam bubble in the block. Then the top tank will fill by the same size as the steam bubble. Too much , and it overflows. So yes, the pump can push more out than it draws from the radiator. It draws from the block.

Re: Help with radiator cap spray
 

Bill,

I'm tempted to try but I'm really a rookie. If my father-in-law was still alive I'm sure he could have done it. He grew up on a farm in Hanford in the 1930's and he would tackle anything mechanical just to see if he could do it.

In WW II, the Army put him in the Civil Engineering Corps building bridges in France after D-day. He was stationed in England first, and he said the pub keepers would get mad at the GIs because they would come in and drink all the beer. Beer was rationed and the pubs were only allowed a couple kegs and they had nothing left to sell to the locals. The locals generally nursed a pint all night.

The Early Ford Store recommended a Radiator shop in the San Gabriel Valley that still works on old radiators. Most radiator shops today just want to replace the plastic or aluminum radiators with new ones. Even I can do that.

Thanks guys,

David Serrano

Re: Help with radiator cap spray
 

Simon, good analysis. The steam bubble is the key. Without a bubble, the pump output is controlled by the radiator outlet.

Re: Help with radiator cap spray
 

Good point, makes cleaning out rust/gunk behind cyl #4 even more important. But in this particular posters case he says he has a recored radiator and rebuilt engine - i would hope whoever rebuilt the engine dunked and cleaned inside the waterjacket.

This is where one of those thermal cameras would be great to use to detect hot spots in both block and radiator.