Radiator flush

[BradleyDP]

I just finished a rebuild on my engine. But it is running hot, 220�. Thermostat is not that old? Took radiator to get boiled and was informed not to. There were no leaks in it. But given it's age they think boiling would make LOTS of leaks in it. Which means new core.
SO what can I do to preserve my original radiator but get it flowing properly again. Flush it with and best way to do it?

[Matto]

You can check your thermostat on the stove top in a pan of water with a thermometer. You may also have a vapor lock in the top of the engine if your thermostat is not vented. Here is a link to a discusion on the old site that might help. Page two shows the differance between the vented and unvented thermostats.
http://cj3apage.proboards.com/index.cgi?action=display&board=Tech&thread=1567&page=1

[rocketeer]

Most correct thermos have just a simple 1/8" hole as a vent, that's all that's really needed. That would be the first thing I would check. Did it run hot before you overhauled the engine?

Here's some good info on thermos on the CJ2A page:

http://www.thecj2apage.com/forums/thermostats_topic4714.html

Larry

[Gunslinger]

I'm glad to hear your having that problem, as I've got the same one.  Engine ran cool before the re-build, same thermostat was put back in, now it runs at 220 F.  It seems that it takes a little longer each time I go out for it to get that warm, which makes no sense to me, and I have the hole in my therm to prevent vapor lock.  I just bought a new thermostat today and I bought some JB Radiator coolant to put in.  So I'll keep you posted, should know later tonight, however its 95 F out today, may wait till morning to drive it.

BTW, your rebuild looks really nice !!

[rocketeer]

Keep in mind that brand new rebuilds will be tight and run hotter than usual until broken in. That's normal as long as it doesn't overheat and boil over. Also, too lean a fuel mixture can cause running hot as well as running with incorrect timing.

Larry

[RussellL]

These old radiators used to be cleaned by having the tank unsoldered and removed.  Then they used brushes to rod out the tubes.   Maybe an older radiator shop that is still able to clean that way can help you better.  

On the other hand, if the radiator is really plugged and cleaning it is going to make it leak, maybe it is time for a new core.  Putting it off won't change that. I'd hate to be depending on some hardend calcium to keep from leaking all the coolant out.  

One final thought, any chance the thermostat got put in upside down?  

[BradleyDP]

Gunslinger- Yes please keep me posted.
RussellL - no it is not in up side down.
Would not mind replacing core with the original style honeycomb grid. Like whats in it now. BUT Shop quoted $600.
Mine has NO leaks. So I am using Preston flush and see if that helps.

I think it's part of the new engine thing too.

[Gunslinger]

Bradley,
The new threm didn't make much difference.  I added some JB radiator coolant, so I'm going to put some miels on it and see what happens.  I also bought a new Temp gage from Auto Zone.  I noticed a big difference between the reproduction OP gage and a sunpro gage, so I'll try that to see if I'm being lied to.  Then the only option I've got left is to pull the radiator and have it cleaned out.  My old block had lots of junk in it so after sitting for 6 months I guess its not unreasonable to think that maybe the rad has gotten blocked off in a couple spots.

Let me know how yours comes along.  What a challenge!!  I'm taking it to the Black Hills in a couple weeks to ride some trails, maybe I need to take it the Number 10 Saloon, perhaps a whiskey will loosen her up a bit !!!!

[Gunslinger]

New data on my radiator, I went for drive tonight to normalize the temp it was 82 degrees f outside. I did put in a new threm last week and I did drill a hole in it to prevent vapor lock.  My gage showed 215f, so I used my wifes digital meat thermometer and measured the temp in the rad at 206 f.  So now I know I can trust it.  Then I measured the temp in the radiator at 18 locations across the front by sticking the meat therm into the rad between the air fins, here's the data:

176    159    184    152    156    182
173    137    174    169    151    175
165    162    172    165    163    169

So it looks like row 2 and rows 4 and 5 have some blockage at the top to mid level of the radiator as they bare quite a bit cooler, looking from top to bottom most rows look Ok, hottest at the top cooler at the bottom, so guessing at the data I'm thinking I've got about 25% blockage- 30% maybe.  I talked to my radiator guy, he said that it can't be boiled out because no one does that anymore...not sure, at least he doesn't.  He said to drive it until its at least broken in, another 2-300 miles and then maybe do a radiator flush with preston radiator flush.  That sounds like a pretty complicated deal, anyone out there ever do that?

Todd

[Carls_jeep]

White vinegar dissolves calcium deposits and should work in a radiator. I don't know how much concentration it would take or how long it would have to be left in the cooling system but it does work. I have used vinegar to dissolve build up in shower heads and other things.

I have used the radiator flush chemicals and they seem to work sometimes. I think if you could find a shop that can remove the top and bottom tanks and hot tank the core it would be better.

If you have buildup at the top of the tubes I would try a 50/50 mix of vinegar and water for a week or two driving it several miles  each day and then try a radiator flush. If that don't work you will have to hot tank the core or replace it depending on how bad the shop says it is.  

[Gunslinger]

Bradley,
I talked tothe guys at NAPA, they sold me a flush kit to install on my lower heater hose, and a small jug of NAPA 1400 radiator cleaner, contrary to the instructions they told me to just dump it in on top of the anti freeze, run it for a bout 10 miles, let it sit over night and do another 10 miles the next day.  Then let it cool and flush the rad with a gardenhose.  I did that and I opened up the plug on the side of the block to flush that as well.  Nothting very noticeable came out, so I let it all drain and the re-filled with 50/50 mix of anti freeze, changed oil to a 15W 40 Rotella T.  Went for a drive last night, it was about 75 F out and the engine never got over 175-180 F.  When I looked at the RAD it looked cleaner so I think maybe that did some good.  How's your coming?

[Gunslinger]

�Then I measured the temp in the radiator at 18 locations across the front by sticking the meat therm into the rad between the air fins, here's the data:

176 � �159 � �184 � �152 � �156 � �182
173 � �137 � �174 � �169 � �151 � �175
165 � �162 � �172 � �165 � �163 � �169

Here's ther new map data on the rad, after I flushed it, took it for a drive tonight and again the temp gage only went to about 180F.
168   141   132   139    146    173
146   133   133   150    138    163
 152   130   135   145   158    159
So the outside edges are a little warm, but the center 4 rows are a lot cooler than they were before.  So I think this looks OK.