The Stovebolt Site Forums The Shop Area Interiors Why is my heater dripping?

The 1954 Harrison AirFlow heater in my '54 3104 occationally drips a few drops. Enough to make a small puddle on the floor mat. The water drips from the heater case. Doesn't happen every time I drive the truck. I pulled it out today. Can you help me diagnose the problem and guide me toward a fix?

Here's my two-part diagnosis. What's your opinion?
1) I believe that the leak is at the pipe on the core that connects to the hose to the Ranco valve. The pipe has a crush-dent in it. Perhaps the leak travels down the pipe to the core and falls into the heater case, then drips onto the floor mat.

2) I suppose that the rebuilt Ranco valve is randomly opening to supply water to the hose and to the crushed pipe. Don't know if the valve is defective, or if my 160deg thermostat doesn't warm the water enough to the valve for normal operation. The heater doesn't blow hot.

>>> How can I make the crushed pipe(s) round again?
>>> What is your diagnosis of my dripping heater?
>>> How can I test the core and the Ranco valve?

I saw the crushed pipe when I cleaned and painted the heater a few years ago, but "hoped" that it wouldn't cause a problem. I can't see any traces of antifreeze in the core. The water/antifreeze in the engine and radiator is completely clean. No rust at all.

PHOTOS:
> PIC - Crush-dent on Heater Core
> PIC - Both pipes, top view
> PIC - Both pipes 3/4 view
> PIC - Pipes and Core side A
> PIC - Pipes and Core side B
> PIC - Ranco Valve

Thanks for your guidence.

you most definitely need to round out both those pipes on the core, rad shops have fittings they use for that, you could see if someplace will do it for you, or find something [like a socket] that fits snug inside the pipe size and gently tap it in - a pair of needle nose pliers pushed in and twisted will usually round the opening enough to get the socket started .... the Ranco looks good, but if it's leaking it should show

also, as you say it doesn't put out much heat, might be the amount you run the engine with only a 160 stat doesn't usually build up much pressure in the system to push water out more

Bill

Bill -

I took your advice to repair the bent / crushed pipes on my heater core. It was too easy! Thanks for giving me the encouragement to make the repair.

I gently drove a deep 3/8" socket into the pipes to round the ends and to remove the dents. Then pecked on the pipes with the socket inside to finish the job. I polished up the tips to make sure that nothing was hiding under the oxidation. I sat the heater core in a pail of water and puffed a little air pressure into it. No bubbles.

I'll connect the hoses to the pipes with flat spring clamps instead of the gear driven clamps that I used before. The spring clamps are in the pics below. Not looking for a lot of heat with my 160deg thermostat, but at least antifreeze won't be dripping onto my wife's foot.

These pics are a pretty dramatic change from the pics in my original post:
> Crushed pipe repaired
> Pipes repaired end view
> Pipes repaired
> Pipe repair in progress

better than new I've found the heater tubes usually need to be tweaked a bit because they're such thin material that just getting old seized clamps and petrified hoses off messes them up

Bill

Lonnie, Great job on straightening the pipes.

A 160 thermostat is probably too low for the correct operating temp of the motor.

I would recommend a 180 to bring all temps closer to factory specs. They actually run better when run hotter than 160.

Hi, Wayne -

If it ran any better with a 180 deg thermostat, I don't think that I would be able to control the powerful beast!

I'm not sure how to interpret the factory specs ... "starts to open at 148-156 deg F. fully open at 176 deg F"

I don't need the heater very often and it doesn't boil over in the Orlando summer heat. Figure I'll leave well enough alone and keep the 160-deg thermostat and 4# cap.

Thanks for the info on operating temp and thanks for the compliment on my newly found brass working abilities.

Lonnie, If you still have the heater apart, look at the control valve diaphragm real close under a magnifying glass.
How old is it? If you see any cracks in the rubber, I'd repair it.
This is what failed on mine even after I tested it, I didn't see the cracks. It could also have been the source of your drips, even though the pipes were suspect.

hd4unm -

Thanks for the suggestion. However, the heat control valve on my AD truck is not mounted in the heater like it is in your TF truck. It is mounted on the firewall separate from the heater and would not cause the leak that I am experiencing.

> CLICK - Ranco valve on passenger side of firewall. You can see one hose from the engine to the heater and one hose from the engine to the Ranco valve, then another hose from the valve to the heater.

HELP! I'm looking for suggestions to fix my problem.

I still have the leak - only now it's worse. The heater would drip less than an ounce at irregular intervals before I removed it and straightened the crushed in/out pipes. Today I reinstalled the heater, Ranco valve, and hoses. I refilled the cooling system with water so that I could go for a drive an test my work. When I got into the cab, water was dribbling out of the heater at a pretty good pace - more than it ever had. Never even started the engine. So it's out of the truck again and back on my bench.

Don't know if the old heater hoses are causing the problem. They are about three years old. I cut an inch off of the end where the gear clamp was attached and installed new flat spring clamps. I'll install new heater hoses when I reinstall the heater.

I used the Stovebolt Google search for "heater leak test." I saw similar problems posted. Most of the responses advised to use low pressure when testing an AD heater core. So I tested with lung pressure. Couldn't find any leak. Water or air should be gushing out of the core based on the amount of water that was dribbling from the heater case.

> I clamped a couple of feet of heater hose to the pipes, filled the core and hoses with water, then held one hose and blew into the other. No leak.
> I emptied the core, sprayed it with soapy water and blew into it. No leak.
> Then I used my patented Party Balloon Leak Test to fill the core with constant low pressure. I emptied the core, blew up two party balloons and attached to each tube, then sat it into an ice chest full of water. No bubbles.

Pics:
Party Balloon Leak Test
Party Balloon Leak Test 2
Pipes after removing crease New flat spring hose clamp in pic.
Core before pipe repair
Heater in truck Old pic.
Ranco valve and hoses

Thanks for any advice that you can give to me.

well, must be the hose connections if it was leaking with no pressure in the cooling system, I'm not real keen on those spring clamps, prefer wide screw clamps .... you could take the core to a rad shop and have them check it to positively eliminate that - also could use a compressor regulated down to 10-15psi [as a shop would] for a better leak test yourself, with a piece of hose on each tube using those clamps

Bill

The advice I was given was that testing the core ot 10-15 pounds would kill it. The 54 core is tough to find. The earlier version is being reproduced.

There is a fair distance between the heater core and the Ranco valve. Where does the water drip from?

Bill and Greg -

Thanks for your fast replies.

The water is coming from the joint between the two halves of the heater case, near the back where the hoses are attached - but that could be because that end of the case is lower than the front.

I felt the hoses where they attach to the pipes. They feel dry. And the back of the case at the holes for the hoses feels dry too. The hoses do not go inside the case, but they do butt up pretty close to it. So water could trail along the pipes and fall inside the case if there is a leak between the hose and the pipe. I can't see how the Ranco valve could be causing the problem. The hoses leading to it are dry on the outside.

My 235 has a 4-lb cap. That's why I used lung pressure and balloon pressure to test the core. Still reluctant to puff in too much pressure. The leak today occured with only the pressure of gravity. If I don't find a leak, then I may be forced to pump in 6-10 pounds of pressure.

When I did my lung test of the core, I used two pieces of heater hose clamped to the pipes with the flat spring clamps that I used when I installed the heater. They hold tight to the pipes. I had used gear clamps before. I was leary of crushing the pipes again. So the leak has occurred with both types of clamps.

I cut off an inch of the heater hose at the core in case the insided was deformed while the pipes were out-of-round. I'll remove the hoses to the heater tomorrow and inspect them. I'll buy new ones to be safe.

I don't see any tracks of Prestone on fins in the core. Seems like it would be stained if the leak was in the passages. The cooling system is perfectly clear - no rust. So there probably wouldn't be a rust trail if the passages are leaking.

I'll attach the core to the back of the case tomorrow and leave the front open. Then I'll do my lung pressure test again while it is out of the truck. Next I'll put on the front and test again. Maybe the case is flexing the core. Also, I wonder if the core is being flexed when I bolt the case to the inner cowl??

My gut tells me that the problem is a deformed hose, or a stress crack where the pipes attach to the core. It has to be significant based on the size of the trickle of water that was leaking out.

Keep me in mind. I'll give you an update when I know more.

- Lonnie

What about putting some sort of sealer on the inside of the heater hoses where they connect to the heater core? That would fill any possible leaks there. You would most likely have to split the hoses to get them off the next time but beats a wet floor.

As you mentioned, not much inside the heater other than the core. The real connections are exterior to the heater housing.

when i test mine i only pressurize them to what the cap is rated for. the heater in my 40 is a arvin type and not original to the truck. i had the same issue as yours leaking between the case. i narrowed it down to the connections where the hoses attach. they were out of round to the point where the clamp couldnt pull the hose tight around the fittings and it would leak and runinto the truck. i got some bar stock of the same dia. and tapped it in the connections to make them round again and that did the trick. since the 40 is an atmospheric system (not pressurized) i didnt have to smoke the clamps to get them to seal once round.

Lonnie,

Since you are set-up with a test tank why don't you test it like a radiator? Take and block one hose put a fitting on the other for a quick connect and use a compressor. I agree with your figures on pressure just adjust it to 5lbs and watch it close. If you don't see that core bubble anywhere after say 2 minutes it is the hoses. If there is a bad spot on the core 5 or even 4 lbs of pressure will show. You can also try testing it in a couple different orientations, you never know?

Good luck! I have been following this with interest.

No more drips, plus the heater is working, too!

Each of you correctly diagonosed the cause of the drip from my heater ... the hose connection to the in/out pipes on the heater core. 51 ashton, I straightened the crushed pipes on the core last week.

I removed all of my old Thermold heater hoses today and replaced with new Gates Premium (NAPA #H-153.) Although both are 5/8", the Thermold hoses are noticably larger ID than the Gates hoses. Easy to tell just by poking my finger into each. I ran my hose test on the core last night with short pieces of Gates Safety Stripe hoses. Everything held tightly. But today when I bench tested the core with my old hoses connected - it was like blowing into the wind.

So I mounted the heater and installed new heater hoses today. I used gear clamps instead of wide flat spring clamps to connect the hoses to the core as Bill suggested. Then I took it for a two hour shake down cruise. After a few minutes, the temp gauge pegged on "H", which I expected as air was purged from the block and the thermostat opened. I shut down and waited a few minutes. When I restarted, the gauge immediately fell to the usual position - a little below center.

And then best of all ... the heater works now. Blows hot even with a 160deg thermostat. It didn't heat before I installed the new hoses. I'm wondering if air was trapped in the heater core thus preventing hot water from circulating. Perhaps it was sucking air through the leak between the hoses and the in/out pipes on the core. I ain't gonna speculate much; I'll just enjoy the new found heat.

I'll drain the straight water and refill with Prestone tomorrow morning.

Thanks to everyone for your interest and your help in fixing my dripping heater.

Any chance one of the old hoses is plugged? I think the air theory of the heater not working is a stretch? If a hose was plugeed, there would have been no circulation=no heat and the water pump would have really been pressuring the other hose?

I didn't find anything plugged - hoses, core, or Ranco valve.

there can be an airlock happen in the heater, I think it has to do with which fittings on the engine go to 'top' or 'bottom' of the heater, makes a difference on the TF heaters

Bill