Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Wed Jun 29, 2011 4:46 pm Post subject: Opinion on double heaters?
I'm building not one, but two M38's with all the numbers and OD paint etc. I want a winter M38. No NDCC tires either----M+S. ( if you have ever driven one on hard packed snow or ice with NDCC tires, you will understand the fear of God!! ) The summer one is all planned and correct. The winter one is going to have a Koenig CJ3A hardtop painted OD with U.S.A. and hood # on the back top etc. I never liked the looks of the arctic hardtop due to the flat front windshield. It can always be just unbolted for the concours boys later. Now for the question: I have got two nice heaters for it, hot water type, two switches, I want one in the rear and one in the front. My goal is to drive with a T-shirt at 0 to 20 below. That way the chicks can still scope me out--- Since water will flow in the direction of least resistance, do I need to put like 3/4 inch to the rear and 5/8 to the front heater?????? Any seat of the pants experience with this double set-up? The winter one has a replacement motor etc. so it will look great, but not perfect like the summer matching # one. I do think that the OD paint is the only color that looks right on a M38 though. Hit me! John
Just curious, but where do you mount a heater in the rear? How will you connect the water lines for each to the motor? Will you install a Y fitting to split the water flow?
Your idea of larger lines to the rear is probably good, but you might still want to install valves so you can restrict one versus the other and if you are using a Y, you will want the larger size on the root connection from the Y back to the water pump.
Here in central Texas I barely need one heater. In fact I've never driven a jeep that had one. The A1 that I'm restoring will have one, but I look at as a luxury. I don't have a top either.
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Wed Jun 29, 2011 6:22 pm Post subject:
Old Salty, thanks for your thoughts, The hole exiting the the block is fixed. If I buy a elbow up to 3/4 it will be max flow. Water always flows out of the block, back to the waterpump. So, that is good. I'm glad you didn't say: "What did you do that for? ". That's the concours guys. Frankly, if I can't drive the toy or put oil in it-----forget it. I respect beautiful work and inovative toys. I don't like too far off the original design though, unless it is a field wreck that really isn't worth restoring. The idea of a adjustment to control the flow so they both put out heat is just what I'm thinking is a good thing. My Jeep was a FD Jeep and the holes in the rear floor gave me the idea. They had it set up to load a water tank with engine vacuum. Wierd, I know, but the Yankees were here. I like them. I named this Jeep "Herm" bought near the town of Hermosa. " Or" is the summer Jeep, all matching. Green Disease. John
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Wed Jun 29, 2011 6:32 pm Post subject:
The rear heater will be behind the passenger seat, RR but leaving room for the rear seat. I once put a Jeep wagon heater in a '48 CJ2A with a half cab. 20 below and T-Shirts was no problem. The good old days! John
John,One gas fired heater will do the job of 3 hot water heaters in a lot less space, not risk any coolant leaks and provide INSTANT heat! It will also leave your firewall and dash stock
It can be mounted on the right rear wheel house and suck outside air in thru a small 4" hole in your 3A top. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Hey, if I were riding around in a jeep in 20 below, I'd probably want 2 heaters too. I think the lowest temp I've ever even seen was about 5 below and I was on top of a mountain in New Mexico in January to see that. I wasn't in a jeep. I'm not afraid of a jeep that isn't totally original. I want to be able to actually use my jeeps, not just admire them. On the otherhand, I'm not going to change things just to be different either.
On the plumbing issue, I know you can't change the size of the opening into or out of the motor, but any part of the plumbing that has to carry the flow from both heaters should probably be increased in size unless that section is short. You don't want to add even more resistance to flow. With two heaters you are going to want all the flow you can get. Keeping that increase in size all the way to the back is probably a good idea too. It doesn't really matter which way the water flows.
I have to admire the ambition to take on restoring two jeeps at the same time. At the rate I am able to work, it will probably take me 2 years to finish the one I'm working on.
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Thu Jun 30, 2011 5:35 am Post subject:
I had two VW's that had the southwind gas heater option. The fumes from the exhaust and all the routing of things were not durable and the electric pump motor driving the gasoline pump had some problems. The worst of the matter was the rubber pump diaphram had a very bad habit of leaking raw gasoline inside right next to the combustion chamber. I had trouble even with new diaphrams constantly with the leaks, so I quit using them. I plan on making brackets that won't ruin the integrity of the original Jeeps dash and wheelhouse. Someone already cut the dash between the instruments and glove box, but I'm welding in new metal there, and the dash military data plate mounts over it also. My job allows me to work on the Jeeps while I man the door and phone, so I get lots done a little at a time. About a year and a half per Jeep to strip it to 0 and blast, overhaul, paint the whole thing. It's my retirement job. Blast facility right next to a restoration bodyshop. You can't have a better setup. 2 mechanic shops and two tranny shops 4 doors away. The front heater will keep my feet warm and defrost the window, while the rear will simply add BTU's to the space. I've got 50 bucks in both heaters and switches. The flattie engine already has the water taps in it cause the previous owner had a ugly pieced together heater laying on the floor out of a duece. I just tap and fuse power out of the first battery to get 12 volts. A shop about a block and a half from me sells new steel in all sizes so making a clean set of brackets that don't ruin the nice Jeep stuff is no problem. We need big flow and I like the idea of a adjustable valve to get the water flowing about even to both heaters. A 180 T-stat will be good. I put 160's in my other Jeeps, too hot in the summer at 180. Another thought: how about flow to rear heater, through it and then to the front heater, and then back to the engine? That would force it through both right??? John
Don't use the VW's as an excuse!! I owned two in the early 70's with gas heaters, a Type 3 Wagon and a Type 4 Wagon. Both performed flawlessly for years.
Those heaters in the VW's can't begin to compare with the quality of both the military truck Stewart Warners and the Aircraft Stewart Warners. These heaters are still manufactured today and used in thousands of vehicles and aircraft and operate on auto-gas, avgas, diesel and Jet A. Proper maintenance is the key to their longevity, reliability and safety. Periodic inspection is a must. The VW heaters suffered under poor to no maintenance and no periodic inspection and servicing. As with most car owners still today they leave spark plugs in their engines for 10 to 15 years and never flow check injectors on their engines and you can imagine how lax and inattentive they would be to the needs of a gas fired heater in their car.
Bottom line is follow the directions and they are perfectly safe to use, very reliable and definately provide more BTU's per pound of heater when compared to the how water types.
Plumbing your heaters in series will result in the first heater have hot water and the second heater will have warm water. Treat the water flow issue just like a hydraulic system. Pressure is equal in all directions and flow variations is generally not a real issue with auto heaters and can really just be ignored. You can run straight hose and tube sizes throughout the system connecting with "T"'s and she work just fine. I would use stainless steel tubing from the front side of the firewall under the tub and up thru the rear bed holes. Clamp the tubing securely to the tub about every 12". Then use hose from the tube ends to the heater and the tube ends to the engine. It will help to install a flushing "T" in each of the hoses at the rear heater. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Thu Jun 30, 2011 4:19 pm Post subject:
Thanks Wes! The tubing idea is good and much more durable. I'm not using VW's as a excuse, I just am acting on what experience I've had---twice. I have never been around a decent military gas htr. I do know they are very pricey. I have two Arvin type aftermarket heaters that I'm painting the same OD as the Jeep, so they will look the part to most people. I was thinking that one core may have more resistance than the other so balancing the flow based on feel of the htr. core temps might need a resistance valve on the feed of the free flowing one. Will definately be a experiment. Oh, I forgot to tell you, the cold one I had waiting for you--------I drank it. I'll have to get you another John
I mounted a modified military truck hot water heater behind the passinger seat. I ran the hoses thru the removeable panel on passinger floor along the tub beside passinger seat and then behind it. I did not cut the original panel. I used another piece of sheet metal and made a cut in it to accomodate the hoses. I put the original panel in the shop cabinet. I used some 2" pvc pipe painted OD to divert the air to the front between the seats. Which can easily be removed and stashed away when not needed. _________________ Tropical Veteran
35th Inf. Reg. "CACTI" 4th I.D. VN
Amateur Radio K5XOM
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Tue Jul 05, 2011 8:23 pm Post subject:
I will have to think about the hose routes , holes, wiring, mounts and brackets. The previous FD owners have already put holes in the rear floor. Whatever it ends up as, I will preserve all I can. Amazing how OD paint makes the wrong stuff look right. Since this Jeep has a replacement engine, I'm not as fussy. It will be nice though. Driving them and enjoying them is what it is about to me. John
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