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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078, 1995 M1079, 1079box for sale !!!
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5,857 Posts
Discussion Starter · #1 ·
I have two options while Im digging into my Mog. One is to use the tropical radiator that came on my Mog (small leak to be fixed) or two... use a radiator out of my spare 300D- if it can be made to fit. Last time I was on a HUGE - LONG upgrade (KY) I did almost overheat the Mog. I pulled over and shut down and let it cool, refilled w/water before moving on. Coolant mix may have been weak then to though.

Any suggestions?
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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I too have had issues with the rad on my 404 doka. But mine are a bit more severe. Or maybe I just drive a bit faster. I think mine is the trop version, but I would need a pic for reference. Both of my 404's have the same rad. After looking at the 300 rad, It is no better, and possibly worse. I am open to suggestions as well
 

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'76 406.145 Doka tug
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290 Posts
Getting a rad shop to rebuild the old one, mating your tanks to a thicker core might help, but more rows of core offer diminishing returns. Custom aluminum rads are unparalleled at cooling but ridiculous $$.

A close fitting rad fan shroud is very important for fan efficiancy at slow speeds as well.

In modified cars where space is limited I have Y'ed into the bypass circuit that supplies the interior heater core and installed another heater core, hot water valve and forced air ducting (ususally in front of the wheel well). In high-heat situations (sustained boost, or NO2 on) the hot water valve for the auxilliary bypass (that doesn't vent to the interior) is opened. Can be done real slick with an electric vaccum switching solenoid and vaccum operated hot water valve, or simply cable operated.

This 'on-demand' cooling works pretty well and when shut won't over-cool in the winter.

Another thing to consider is the relation of water pump pulley diameter to coolant flow rate. Too slow = insuficient flow and too fast will cause cavitation and insuficient flow as well. However it is quite involved to measure coolant flow rates especially when hot! and I'ld assume the stock design is well engineered.

I've never used a product like a 'water-wetter' that when added to the coolant mix increases it's heat-energy holding capacity, but it might help as well.
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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my heat issue is at high RPM, around 4000 or so . Ron davis makes a replacemnet aluminum rad but its $800, and is of course not guranteed to be the fix. Im considering buying a new water pump and polishing the impeller for less cavitation.
 

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1981 Ural 375 , U1300L 1988
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64 Posts
George -

I had a very similar issue with my diesel. Long hills would send the guage into danger zone. The monster Volvo truck fan I had on it would drap so much amperage I swear it sucked power from cars going by. It also worked just fine, but I felt like it was marginal. Here are a few things I found:

1. 300D stock radiator will not get you extra cooling capacity.
2. Adding rows/passages is an options I think the radiators in the mogs now are three pass I think you could add another pass but is $$$
3. consider a radiator with more cooling capacity. From a large truck with the same rough dimensions. $$$$
4. Large capacity cooling fan helps - you can buy the dual fans from many parts suppliers for under $150
5. Water Wetter - helps my truck run cooler in summer.


Good Luck and cooling running.
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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2,512 Posts
If you search 'aluminum radiator' on ebay, you'll pull up a list of aluminum universal fit rads. I haven't checked for one to fit a mog, but I've shoehorned them into lots of other swaps, sometimes for less money than a stock replacment. Once I had to have a welding shop tig a new lower hose connection on in the right spot, but that was only $40 or so. A good electric fan with a tight fitting shroud does wonders also. A popular junk yard fan with the swap-hotrod crowd can be robbed out of a Lincold Mark VIII. It moves a lot of air, but I don't know what clearance you have between the pulley and radiator, so it might not fit.
 

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UNIMOG, Gelaendewagen
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935 Posts
I know this thread is quite old, and I have been searching to see if there has been any update from anyone on this matter. I have seen no further info. So, has any one decided what would be a good after market replacement radiator for a 404? I have been having over heating issues that started to show their ugly head in Moab this spring. I currently have a tropical radiaor, but it has had a buggered up repair that is blocking a few rows. I have an other tropical that looks good, but the radiator shop says it isn't flowing very well and should be recored, at around $450. Does this seem like the way to go, or is there a better way to spend my money? -James
 

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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078, 1995 M1079, 1079box for sale !!!
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5,857 Posts
Discussion Starter · #8 ·
burqueDOKA said:
I ... I have been searching to see ...
James thanks for searching first.!

Im sure some folk will chime in soon
 

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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078, 1995 M1079, 1079box for sale !!!
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5,857 Posts
Discussion Starter · #9 ·
I have thought about increasing the radiator copacity with an AUXILIARY RADIATOR COOLER KIT. LIKE THIS ONE But I'm sure the price on this site is way off. They run closer to 90buks. Thought about adding a 12v cooling fan to it also.

 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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5,258 Posts
James, I have had mine rodded out here in burque, and it made a big difference. Other than that, if you are going the recore route, I suggest you pony up a few more bills and get the Ron Davis aluminum rad. It will make your truck run nice and cool minus any other cooling issues.

Does your temp guage read full temp under normal driving, or does it show high or low. Mine has a stuck thermo right now, and runs very cool under normal load, and then super hot when im working it.
 

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UNIMOG, Gelaendewagen
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Yeah I haven't eve looked at the thermostat yet, yeah I know it would be the easiest thing to start w/. I know my pulley set up is almost correct except for the two outer pulleys need to be switched. I pulled the radiator only because it has a buggered up repair job on the lower section that I'm sure is blocking a few rows and I figured I'd swap it out w/ an other one I have, but it is a little corroded inside. If I am driving and keep an air flow into it, it stays w/i normal ranges. If I just let it idle, it will overheat, and any slow trail rides w/ some work involved will definatley get her hot. It does not stay cool at all, so I'm pretty sure the thermo isn't stuck open, but mabey it's stuck closed. KC, who did you radiator work here in burque. A1 is worried that if they do what you were sugesting, it will cause leaks in the spots where the calcium is building up.
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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5,258 Posts
Their is a shaddy little rad muffler shop on San Mateo just north of Gibson. Cant remember their name, but they do decent work. They are on the west side of the road.
 

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Re: Radiator Dilema!

Well, Here's my experience. I took my stock 404 down to the local radiator shop. They inspected it and told me to replace the core. Which core I asked? They ordered a commercial style and said that for the diesel I would be very pleased. 4-core with the rods being double the thickness and very wide. Quite the difference. $764 and that was that. Also had the radiator cap mounted on the top so I can have some dash space.:)
 
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