• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

    So with that I ask that anyone with a question about one of our build ups or a general tech question to please use the forum as it was intended. I am absolutely available by telephone to answer your questions as well but at times may direct you back to our website to better field your question or questions. Most other private messages I will be glad to answer for you.

    Thank you for your understanding.

    Jeff Ismail

C Series/Round Body Heater & Components Overview/Repair

This thread is more an offer up of what I've found than a tech question per say, I invite others to add what they know as well. I will cover #16739 inside and out, so if you've been inside either of the other two and have pictures and tech know how or conversions to more comon parts, post it here.
I am aware there were two versions of this heater, and one other available:
(#16739 Fresh Air Standard Capacity(This one))
(#16640 Recirculating(simplified version of this one))
(#16655 Fresh Air Super Capacity(the one I've been told dual functions as a portal to hell))
For the sake of IH newcomers, I'll explain a bit more in depth on a couple things, some forum users may want to skim read as this might be alot of things you know already.
The #s referenced above, are a two part code found on the left side of your LST (line setting ticket) the 16 is the section in the parts manual, the next three didgets are what will distinguish what type you have(of course swaps and conversions over the years may have changed that) As far as I can tell from what I've seen online, for sale, and at salvage yards, the #739 is the most common version. Looking at the parts manual, some of the parts of 739 can apply to 640 as well. There are a couple diferent motors, and other small variations within each but for the most part the one I will cover seems simple enough. Sorry, this was the best pic I had before I tore it apart :D


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Step One: Identify the problem(s)
There are a number of reasons to savagely rip apart your heater, everything from non functional frozen controlls to leaking coolant all over your passenger's feet. For my purposes, it was all if not most of them. I found heavy rust about 3-5 inches up from and all over the bottom of the housing. The valve was bypassed and another manual valve spliced into the line under the hood. Being those were jerry rigged, I'd be willing to bet money that the rust represented the amount of coolant sloshing around inside the bottom of the housing.

In this pic you can see the residual coolant from a very slow leak.

The rust is also in the bottom of the motor access area, evedent that there was enough coolant in there at some point to overflow into it.

All the rust will be removed.
Here I found an interesting variation, in the heater core. It is not the same part as the one in the parts manual, as that one lacks the lengthy tube.

I'm not certain if this was the factory core or not. The core was a loadstar part, and I did manage to find a brand new replacement. The original type, I could not find, though I didnt look around too much before I found this one.

The new core will fit just as the old one did, however there are a couple things that make me question its originality. The first is that there is definate evidence the PO was in there jacking with things, and his track record for fixing things correctly is 0 for 10000000 attempts. The core as I'm sure you can tell, has a fair bit of jb weld, as well the rust flakes from the rotting vent above clogged most of it. In addition, here you can see some less than professional cuts to allow clearance for the loadstar core:

The different hole locations are all factory cut on the fire wall, the thing that makes me wonder is the fact that there are only two holes in the back plate and not three.

Could it be original? Theres an old assembly line worker out there somewhere who might know, let me know if you know one :lol:
Fortunately for me, the blower motor and rotor are in excelent condition and won't require too much work.

For those interested in the loadstar part, I bought it from an ebay vendor brand new, a couple weeks before this post for right at $100 free shipping. Heres the lable:

Next up, I'll go through what I've learned about heater valves, and then go through the control assembly. Later we will work on individual components and eventually sand and paint the body.


The factory heater valve was still in place on my heater, however given the bypass and rust I think it was likely the culprit of a fairly serious leak.

Fortunately it wasn't so rusty as to render it unidentifiable. The IH part # as I'm sure most IH enthusiasts are used to, didn't lend well to finding much of anything. Ranco H16 however proved very usefull. The type H16 was used in a large variety of post ww2 autos, in about eleventymillion diferent configurations. Naturally, atleast to my knowledge, none of these are still made. They ARE however, rebuildable. New seals are available at NAPA for about $10. Amazingly my store had one on the shelf, however I'm not certain I will be using it just yet. All of these valves, as far as I can tell, work the same way, and use the same small parts. Here is a link to a rebuild proces, unfortunately a diferent varient, however the method of replacing the seal is similar. http://www.pbase.com/czechman/ranco here is another link to a usefull rebuild process in pdf form, again diferent variation: http://packardinfo.com/xoops/html/modules/article/view.article.php?253 Unfortunately my valve is a bit far gone to be used again, however I ABSOLUTELY WILL NOT THROW IT AWAY, nor would I recomend you do so either. It can easily be dismantled for useable parts, parts that I may use to rebuild the one in my parts truck for more content here. I got uber lucky and managed to find one NOS for an afordable price.

The Ranco type H 16, for our purposes in IH light trucks, what is important are these numbers:

I have yet to determine the point of the second number beyond guessing that its just another part#, however the first one is what determines the configuration, ie, this is a Ranco type H 16 4459. Basically its the equivalent to a model # for the part. These numbers were not readable on the old valve. Here is a picture of a new seal from a napa kit:

I'm not sure I can legally post the included instructions, so I wont, but on the back under Application Summary, we find IHC 1950-1975. So it likely services any ranco h16 in an IH within that year range, and also likely would've stopped the original leak in mine, rather than cutting off the inlet and bypassing. :mad2: The possibly exists, that I may be able to sleve and solder it back on, but being that its cut where it's not particularly round, it will be dificult at best.
For those who's valve may be hacked up as in my case, repair not within skill level, or missing entirely, unless you find a NOS item, your best bet is to convert it to another valve. Keep in mind that the direction the cable accesses it from and the direction that turns it on/off are important. You may end up with a valve that is on when your control says off. There is another thread where this is discussed, in this case we find a Ranco H 16 variant that was adapted. At the end of the thread we see another case of a loadstar core: https://forums.ihpartsamerica.com/showthread.php?t=9444&highlight=Heater+core
For the record I tried really hard to find the Mac truck part# available with no results, but you get the idea on how the swap would go. I have also seen an inline splice under the hood with the control cable rerouted there and ziptied to the hose. As far as I could tell, it looked like it would work fine. As a last note, be careful with the copper coils on the ranco valves, they apear to be alcohol filled type thermo-regulators, and once cracked, I don't know of a way they can be repaired. Its a similar tech to a mechanical temp gauge of the period. Its also remotely possible they be filled with something other than alcohol, fumes from wich are likely hazardous even in as small a quantity as is present. This is unlikely but still it's always best to be cautious.
Lastly next up will be a quick look at the control assembly, later on I think I will disassemble my original valve and do a mock seal change. Given its condition, it wont matter too much if I screw up, and I can demonstrate how to take it apart.


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A bit on the control unit, there really isnt much to it, or at least there shouldnt be, if it werent for previous owners. At some point he took it apart and it obviously wasnt right. The first clue was the fact that it was coated in bearing grease, followed by being dropped in a freshly dug flower bed.

The next clue it was poed was the fact that two of the leavers were scraping on the edge of the face plate slots.

Disassembly went quick and easy, a set of parallel jaw pliers and a tiny cresant wrench are a nice combo. The knobs come off with a 5/64 allen key.

In here I found what might explain the screwy po fixes. He liked rolling his own fixes, he also literally rolled his own...

I'm not gona smoke it to find out, but I'll give po the benifit of the doubt and say he was high while fixing from now on. Benefit? I've somehow gotten to the point where this is normal for this truck. :sosp: This friction washer removes easy with pliers and wiggling.

After a good cleaning via standard screw driver, degreaser, sonic cleaning and leaving it infront of my shop radio while playing ACDC on full blast for good measure, I could see wear patterns that were obviously wrong, and others that didnt make sence because the parts weren't aranged properly. There are washers that have a certain order and purpose, and I reengineered it as best I could. There are 5 large washers and 2 small ones present in my unit, the two smalls get sandwiched by four larges in these two curved tracks in the top plate:

So the small washer is in the track itself like a roller on the respective pin. This pic shows the layering of top washers then the knob leaver, then the secondary leaver:

The bottom leaver for temp gets the remaining large washer between it and the bottom plate for proper spacing in the face plate slot:

The rear washer sandwich gets the friction wahser:

All the nuts I tightened till flush not even snug. Lastly I lubed it up with what only a gunsmith would, his favorite firearms grease: Lubriplate SFL-0. The leavers now move effortlessly smooth and with the cables lubed up and the components on the other end maintenanced it should work as well as or better than new.


H 16 heater valve disassembly
I took apart the "junk" valve last night for curiosity sake, the first step is to free the capped end of the copper coil and undo these four tabs:

Using a sharp ish old wood chisle that I rarely use for what its intended, I lightly tapped untill the tab just started to come up. Throughout the process I gave areas vigorous brushing with a brass brush. Once straight the mech starts to slide out with light tapping and remains attached to the push rod but otherwise loose:

The mech can then be simply "poped" off by pulling it upwards, as it is retained by a cupped area over the ball shaped end of the push rod, and the pictured spring clip:

The clip pops off to the left and reveals a thin brass cup afixed with a small wire clip:

Wich in turn are also easily removed:

The next step to access the seal will test your patience. In order to remove the valve plumbing from the front plate, these four tabs need to be straightened, and let me tell you, those brass tabs, were harder than the steel face plate. Anealing them carefully is probably a good option. I came up with a cleaver short cut, straightening three of the tabs and popping it out part way, then only altering the 4rth enough to allow clearance for full removal:

The technique involved my chisle, various pliers, and the thin 5 inch long craftsman standard driver that no one ever uses to drive screws. Notice, that in order to access the lower tab, I carefully bent away the flange, wich I then straightened ala anvil and ballpein:

Next the seal comes out, here it is next to the napa repair kit seal:

Lastly here is the cut up plumbing. I will atempt to repair it by making a sleve out of a 5.56 nato casing and soldering it back together, but wont have a way to test it for a while:

Last note, I put the thermostat mech infront of a nice toasty fire for a few minutes, but I didnt see the plunger protrude. This could mean that the seal has failed and depressurized the coil, or it didn't absorb any heat for its small surface area. I will test it one more time with a heat gun to confirm this, but if it doesnt extend then this valves thermostat function is likely toast.
Part 2 of this adventure coming soon!


Oof, this got shelved for a while due to some life stuff, I'm just gonna ignore smooth transitioning and gear-clutch back into it. :icon_xp:
-The main case
First up, I took the case with me to IHPA on a parts run, I had bought some parts online for a scout by mistake and returned them in exchange for a brief blasting of the heater body; enough to get the PO roll brush paint and some of the rust off. From here is where the project got benched. I put the body in my heat pump closet where it was nice and dry. Fast forward: here we are and I have a 5 gallon bucket of evapo-rust. Presto:

A few soaks later in different directions the body is fully rust free and has a coat of evapo-rust to prevent rust untill paint, at wich point it will get cleaned, and primered with red oxide. Next up will be the same process for the back plate. It will eventually be finished with a close to original gloss machine grey color.
-Seam sealant
The main body consists of several panels spot welded together with a sealant in the gaps and areas where air shouldn't pass through. This will be covered in detail before primer.

This should've been higher up in this thread, I've only just realized it was missing.
Removal of the heater assy is fairly straight forward, and can be done with one person but better with two. The first step is to disconnect the hoses to the water pump with the vehicle facing down hill slightly, you will loose some coolant here, it may be best to drain some out at the drain valve and contain it for reuse. Once the hoses are dealt with (they can be connected together) the next step is to find the two control cables on top of the body, follow them back to the control knob assy and disconnect. Next there is a two wire lead for the blower motor, assuming your wire isn't hacked it should unplug. Lastly, there are three studs on the back plate that go through the firewall and are secured with nuts in the engine bay. Loosen them up with a buddy to lower the heater to the floor.

*DISASSEMBLY TIPS the backplate screws are usually rusted in place, but are often quite soft. Pliers can be used to grip the head perpendicular to the screw and rotate. Often the head will snap off if it doesn't unscrew normally. The shaft can be removed once the back is off by grasping it from the inside and tightening it inward. The shaft will pull itself through. I and others have used this technique with surprisingly consistent success. The front cover reveals the motor, wich simply pulls out with a few screws along with the mouse wheel (rust can stick the motor mount to the duct). The heater core pulls straight out but can be glued in place by rubber mounting material and or rust/PO goobers, there is often no other way to remove it other than brute force.