The Stovebolt Site Forums The Shop Area Engine Shop Truck radiator boils over :(

Not full strength. I let it drain from the engine block petcock while filling the top of the radiator while the engine ran for 10 or 15 minutes. It was probably pretty cleaned out of acid but I had my mom put a half box of soda in it and run it for a few minutes.

I can’t get my head around around what would cause the symptom you’re describing in the first paragraph. I’m not doubting that you observed what you observed, it’s just weird.

I would think you could do the combustion gas test at Mom’s house without many tools. Perhaps that’s a place to start.

I don't understand it , either especially since I spit in the filler and the spit just stayed put.

If the head has to come off due to a potential gasket leak, the water pump has to come off anyway. I may just pull the pump off to have a look at it.

Just as a point of comparison….if I have the cap open and watch fluid moving once the thermostat opens….there is a LOT of flow.

Nope- - - -neither the old nor the new design engine (high or low water pump) needs to have the pump removed to pull the head. All the water pump bolts including Dave's relocator plate type are in the block. Pull the pump if you wish, but it's not necessary to change the head gasket.
Jerry

That's funny. Without the vehicle in front of me I can't remember how it's put together!

Here’s a pic showing high-mounted water pump, outlet housing and thermostat housing configuration on an early (1954-1955.1) high pressure 235 truck engine. Outlet housing bolts to the cylinder head, water pump bolts to the block. Believe a 216 will look about the same.

I can confirm that a 216 is set up the same as a 235 as far as water pump mounting.

Whether it is a 160 or a 180 has no bearing on what your maximum temperature will be. One just opens sooner than the other.
Water jacket crud, radiator crud (internal or external), bad water pump vane (never heard of that on a Stovebolt), air pocket in the head, and incorrect timing are what can cause extreme high engine temperature.

I am sure you know better than I but that was not what I encountered when swapping 160 to 180 and back again.
Temp at the radiator was 175 w/a 160.
The temp at the heat riser stayed the same though, very hot.

BD, T stats do not control engine operating temperature. An engine will run at whatever temperature it's designed to run at regardless of T-stat rating assuming all systems are operating at factory specifications.

The T stat enables the engine to get up to optimal operating temperature more quickly than if no T stat exists. It stays closed to help heat up the engine and then opens when the rated temp is reached to allow the engine to cool itself as designed.

The size of the radiator and its condition determine where the temperature will stabilize once the thermostat opens. A clogged or corroded radiator will let an engine overheat no matter what the thermostat setting is, or even if there's one installed at all. Another source of overheating would be an exhaust gas leak into the coolant- - - -leaky head gasket, cracked cylinder head, a pinhole in a cylinder wall, etc. It doesn't take much exhaust gas at 1,000+ degrees and hundreds of pounds of pressure to overwhelm even the best condition cooling system. Compression/combustion pressure alone can force coolant past a pressure cap, even without the coolant itself getting over the boiling point. "Test- - - -don't guess!"
Jerry

52Carl- For sources of extreme engine temperature, add:
Hot combustion gases entering the water jacket through cracked cylinder head, cracked block, or leaking head gasket.

Have you disconnected the lower radiator hose and put a garden hose in the top of the radiator to check flow? With a 1/2" garden hose running full blast your radiator should be able to dump it as fast as it's going in...if it fills up and overflows out the filler neck then the radiator is clogged. You can also see now clean/dirty the exiting water is.

Mike B

Yes. Radiator is clean and shiny inside and flows right out the bottom.

You'll notice in the picture above where the water running out of the engine block petcock is clean and clear with engine running and fresh water filling the radiator.

What was the ambient outside temperature that day? The reason I ask is that on a cold day, the thermostat will close at whatever it's rating dictates in order to maintain a hot enough engine temperature for maximum performance in cold weather.

Being Otto`s thread , I should not go into detail. But it was recently. Both 327 have 160 degree stats and run cooler
at the radiator than 180. IDK. I have gun to check temp. All I can speak to is what I have in front of me.

A 160° thermostat only limits the lowest temperature, not the upper limit which is controlled by the radiator’s ability to cool. That would also include the fan. If your cooling system could cool the coolant to at or below 160°, your thermostat would keep it at 160.

Otto - have you had a chance to do any of the head gasket tests yet?

Side note - On a very hot day, my truck will creep up around 200 degrees if idling at a long stop light. Back to 180 as soon as I am moving. I consider that normal behavior for my setup.

It sounds like that’s roughly what you are experiencing, but it’s not the way your truck typically behaves….is that right?

No, I haven't had a chance to do any tests. The truck is 40 mi away and I can't get out there after work.

Yes, my truck runs at straight up 180 all the time, even in rush hour stop and go in the summer. Only a couple times has it approached 195 or so.

On Saturday it was an actual "boiling over" event. Water was in a rolling boil and blowing out of the overflow reservoir. 4lb rad cap.

After all the cleaning and flushing, a couple drives around my mom's area saw the temperature start moving up toward 200+ before I stopped. Not what the truck normally does.

Was the temp creeping up to 200 even whilst the truck was moving?

Yes.

Can someone give me the diameter of the heater hoses on this truck? I forgot to measure them before putting everything back together and the truck is 40 miles away.

I need to make the contraption HRL described to attach a garden hose to the system to pressurize the cooling system without the radiator.

1951 216 w 1941 radiator.

I know the upper hose is smaller diameter than the lower hose.

Otto, IIRC the original 1951 heater hose inner diameter was 5/8". On my '51 with a '54 235, I use 5/8" and 3/4" as the later water pump hose nipple is durn near impossible to get the 5/8" hose on. Get about a 6' length of each and you can cover all potential size issues. Oh and some new hose clamps may be in order depending on how yours are.

Thanks, my mistake. I actually need the diameter of the radiator hoses upper and lower. The upper one is smaller than the lower one .

If you trust Rock Auto….

Your upper hose is roughly 1.2” ID

Your lower is 1.5” ID

Alternate idea: buy one of the universal coolant flush kits. It will include a fitting that adapts a garden hose into your heater hose. Splice that into your looped heater hose to provide the inbound pressure. The t shaped fittings in this kit:

https://www.walmart.com/ip/Prestone-Automotive-Flush-N-Fill-Kit/16817507

Buy a couple cheap PVC pipe caps, the male threaded kind, and deadhead the radiator hoses into those. Maybe buy a few different male OD to make sure you can match your radiator hose IDs.

Clamp tight and you should be able to hold that 20-30lbs pressure Jerry referenced earlier.

Otto, A recheck of the upper and lower radiator hoses for your 216 and '41 radiator should be - Lower: 1-1/2" ID both ends Upper: 1-1/4" ID both ends

A litte searching through Stovebolt and the web comes back with the following Gates hose #s:

Upper: Gates 21942 - 1-1/4" ID both ends and formed correctly (a NAPA alternative is 8632)

Lower: Gates 20230 - 1/1/2" ID both ends and formed correctly

Note: Others have reported some minor trimming of length may be necessary

2nd Note: JW beat me to the post button on the dimensions.

Didn't know that flush kit existed- - - -now it's on the "gotta have" list! Thanks!
Jerry

Super cheap, and handy for many things!

Otto - This thread has gone in a lot of directions and this may have been already mentioned, or otherwise eliminated as a possibility during one of your tests.

Make sure you have a functioning radiator cap that isn’t leaking pressure. Just a little bit of air in the system creates a snowball affect. Air is compressible, system will burp fluid, which creates a bigger air gap, and so on and so forth.

I “know a guy” who learned this lesson.

Jw, it has a 4 lb pressure cap and doesn't appear to be leaking, but I guess if it's just drawing in air you wouldn't see anything. Would that still cause the rolling boil that I had last Saturday when the water was boiling out of the overflow reservoir?

A bad radiator cap COULD cause that sort of symptom. Can’t say whether or not it actually was/is your problem.

You can rent a coolant system pressure tester at the parts store. It’s expensive, but you get it all back upon return. It will allow you to test your current system, your current cap, and the new cap which has a 50/50 shot of being bad out of the box.
Almost anything could leak in your system. Even just a hose connection that isn’t 100% tight.

I had multiple issues. A leaky heater core that was getting some air. And a bad cap. I bought an NOS cap from eBay because I distrust modern parts that much.

Might as well round up the tester, a new cap, along with the other stuff you’ll be dragging 40 miles to Mom’s house.

Hahah! Yep!

Does anyone know where I can buy a 4lb cap that will work with a recovery reservoir? That's what I have now and I figure I'll stick with what's been working rather than change to a zero pressure cap.

This one looks like it's got the suction disc that allows the recovery tank to empty on cool-down.

www.ebay.com/itm/335305035910?

Or this one:

www.ebay.com/itm/386867258617?

Jerry

Is today the day, Otto?

Well, this morning I rounded up $40 worth of plumbing fittings to hook up a garden hose to the heater hoses and block off the radiator hoses/outlets. I also borrowed ($310 deposit) a cooling system test kit.

I intend to test the radiator cap. On a zero pressure system, what is the max pressure allowed in the radiator. Since I have a 4lb radiaot cap. I assume I can pump it to at least that.

Heater core is new and is out of the equation until this is sorted out.

Nobody had any of the radiator flush kits. I saved assorted pieces from previous kits but the connector I found is for 3/4 inch heater hose insted of 5/8 inch.

With some extra pushing and stretching, or some extra tightening of a hose clamp, I wouldn’t sweat the difference between 3/4 and 5/8 on an exercise like you’re performing.

If given the choice, I would probably prefer to tighten a 3/4 hose on a 5/8 fitting, rather than stretch a 5/8 hose over a 3/4 fitting. But you will figure it out either way.

Yeah the hoses are 5/8 and the fitting was 3/4. There was no way that that hose was going over that 3/4 fitting. I had a leftover sample from the actual hose that's on the truck and no amount of forcing was going to make that fitting fit

Anyone who can squeeze a 5/8 braided heater hose over a 3/4 hose barb is a better man than me.