Water Pump/Radiator Questions

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Fitz68

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I haven't been able to get my 68 Dart 318ci to cool properly and after doing two drain/flush and replacing the thermostat, I'm now replacing the water pump. When I did the drain/flush I replaced first with all 50/50 Peak coolant and then again with about a 70/30 mix (mostly water) plus a container of water wetter to help with the issue. Still overheating...

First question, I need to get screw in ports for the top of the water pump and wanted to run it by here first whether I measured these correctly. The smaller one on the right measured 5/8in where the hose would connect and the one on the left measured 7/8in at the end where the hose would connect. Does anyone know which fittings I should get?

Second question, should I go ahead and replace the radiator at the same time since I'm doing the water pump to rule that out as the source of the problem? When I was troubleshooting everything it seemed as if the radiator was working...and I burped the system by waiting for the thermostat to open when it heated up enough and filling up the radiator.
 

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You can get such fittings at NAPA or a hardware store; they will be hose-to-pipe thread adapters. Take the pump with you to get the right sized pipe threads (unless someone speaks up with the sizes).

Can you give some more info? Under what conditions does this overheat? Be as exact as you can in the description. Are you determining it is overheating by the stock gauge, or have you used a infrared temp gun or thermometer in the rad opening, or???

What other steps have you taken? Did you get a lot of crud out of the engine in the flushes, and did you pull the block drain plugs out in that process?
 
I converted the front drum brakes to power disc and after completion noticed that I was overheating. I did a lot of adjusting, etc to the brakes to make sure they weren't dragging and I feel pretty good it's not due to the brakes because I can overheat literally running the engine for five minutes and driving around the block a few times. Next I flushed the system completely with water and then refilled with the Peak Coolant. I don't think I burped the system properly though so I had to go through the process of trying to burp it. Still overheating, so I changed the thermostat and refilled with Peak. Still overheating so I drained about two quarts and then refilled with water and water wetter. I live in Florida so it seems like I should have more water...according to what I read on here. The water wetter helped a little, but still the engine overheated on a grocery run. The real problem seems to occur when I'm sitting at red lights. I did convert from single exhaust to dual exhaust (turbo mufflers) due to a rotted out exhaust y pipe. I don't know if somehow that could be causing the engine to idle to fast...which I've read in my manual is another possible cause of overheating. At this point, once I change the water pump I'm thinking I'll take it to someone next to see if they can diagnose the issue.
 
Would this be an /6 to V8 swap with the /6 radiator still in use?
 
I would take your radiator to a good old school radiator shop and have it flow tested. It will more than likely need to be rodded out. I just took mine that I thought was clean as a whistle to a shop only to find out it needed cleaning. Made a BIG difference. Also I drill a 1/8" hole in the flat part of my thermostats before I install them. This prevents a air lock. Iwas taught this by a old mechanic years ago.
 
-If your engine is overheating at idle or very slow speeds, then the system is just not shedding heat or the engine is creating too much heat for the system.
-Under these conditions the fan has to draw air through the rad. So#1 the rad has to facilitate this. ie, the fins have to be clear, and if A/C equipped the condenser fins too have to be clear, as in not mudded up or the fins all bent. #2, the fan has to be aggressive enough to pull air through the rad. This usually requires a well-fitted shroud and a core seals,and if clutch-equipped; the darn thing better be tight, #3 the belt has to be tensioned properly and it has to fit the pulleys properly,cuz it drives by the flanks.And of course #4,the rad has to allow the water to flow freely from top to bottom. Even a 6cylinder rad should be able to handle this, at slow speeds. And finally #5,the pump has to move the coolant through the system. Water is the best coolant. The pump seal needs a lubricant.An additive package is usually installed to help combat electrolysis if straight water is used. The other helps mentioned above all apply.
-There is not much that can create too-much heat under these slow speed/short duration conditions. Save a blown headgasket, or faulty circulation. Faulty circulation can be a failed pump, a stuck stat, plugged coretubes, or a collapsed lower hose.A blown headgasket usually manifests as coolant spewing everywhere, ruptured hoses, continual loss of fluid, bubbles in the rad when the throttle is blipped, and/or a stinky gas issuing from the open water neck.
A process of elimination will find the problem.You are already well on your way to solving the problem, with a new pump and stat.
 
Thanks everyone! Really appreciate the help pointing me in the right direction. I cannot believe how expensive those fittings are! 69_340_GTS: how could you tell the HO-968B is the 7/8 fitting? I looked on Jims auto parts and that one says "fitting that screws into front of manifold " with no size. I REALLY appreciate the help and just want to make sure I order the right ones.(especially with how expensive they are!)
 
Look at Mancini: $16 for this pair; not sure it is the exact ones needed:
http://www.manciniracing.com/19lasmblheho.html

And I'm tellin' ya... out local NAPA carries these.

And if you don't mind me asking again... did you pull the block plugs just above the oil pan rail? If not, it will leave a lot of crud in the bottom of the block. That can go into the rad....
 
I tried everything imaginable to stop my rebuilt 318 from running a bit too hot. New radiator cured it. We tend to try all the less expensive remedies first.
 
Fitz68 said:
Thanks everyone! Really appreciate the help pointing me in the right direction. I cannot believe how expensive those fittings are! 69_340_GTS: how could you tell the HO-968B is the 7/8 fitting? I looked on Jims auto parts and that one says "fitting that screws into front of manifold " with no size. I REALLY appreciate the help and just want to make sure I order the right ones.(especially with how expensive they are!)
Click to expand...

The ones that the bypass hose attaches to (one in manifold and one in water pump) are 7/8" nipple x 1/2 NPT.
 
nm9stheham said:
Look at Mancini: $16 for this pair; not sure it is the exact ones needed:
http://www.manciniracing.com/19lasmblheho.html

And I'm tellin' ya... out local NAPA carries these.

And if you don't mind me asking again... did you pull the block plugs just above the oil pan rail? If not, it will leave a lot of crud in the bottom of the block. That can go into the rad....
Click to expand...

Ok, I checked out that link and that might do it. I also just received the new pump and am slightly confused that they included some kind of adapter(see the pic). Thoughts on why they would include this?

I haven't pulled the plugs. Can I pull them and get them reinstalled without any special tools? Frankly I haven't researched what is involved with pulling the plugs.

I did look into a company that's local (St. Pete, FL) that said they can maint/clean my radiator for $85. It seems like a pretty good deal to try that first before purchasing a new radiator. They also guarantee if it fails they put the cost of the maintenance towards a new one. So I figure I can get the radiator addressed at the same time as I figure out how to get these ports for the water pump. Homerun would be to figure out how to get any gunk out of the block!
 

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Over the years, Mopar has used a couple of different sizes fittings for the bypass. In about 1970 they enlarged them. So your new pump is set to use whatever size of fitting your intake calls for, and it's matching bypass hose
Similarly, Mopar has used two sizes of heater hoses at that second location. Install whatever fitting matches the heatercore.

On the otherhand; it may just be a repair part if it's a rebuilt pump
 
The block plugs are just pipe plugs, with a square head. Just put rust penetrant around them for a day or so, tap them a bit with a small hammer, and take your time. An 8 point socket is best to use. Reseal with teflon tape.

Ask the company doing the rad work for $85 if that includes 'rodding' the radiator. Probably not. They may just boil it out, which often does not get all the blockage out. Not sure how careful they would be with rodding out if they want to sell you a new one; the older rad tubes can get thinned out and are easy to punch through if not careful. Is this a very old rad shop, like from the 60's or earlier? If so, I would trust them to do it right and if they are good and the rad core is shot, then they can re-core it, but that will usually run $300 or more.

And down there, I would use distilled water in the cooling system. FL water in your area is pretty full of minerals and that will cause some corrosion and crud havoc in any cooling system, old or new.
 
For the same tubes in my 383, I used threaded brass pipe from Home Depot. That was into a cast-iron water pump housing and I recall removing them at least once and finding no corrosion.

First, do a complete flush on your block, using your old radiator. Recover your new coolant first, since probably still fine. One pass w/ water isn't enough. At least use water w/ Prestone Super Flush or such. The store flushes have gotten more wimpy, so I bought pure citric acid (powder) on ebay (also at food supplies) and use 1 lb. Run with it for several days, then drain. You probably needn't worry about freezing solid in St. Pete until Jan. For sure unscrew the block drain plugs (1 each side, 1/4" NPT plug I recall). You will be amazed at the crud that comes out, and may need to free it w/ a screwdriver. I used a GM knock sensor for one plug (future plans). Refill and run several times w/ water to clean.

You can clean & test your radiator yourself. Pull it, turn upside down and use a hose in the "bottom" port (now at top) to back-flow crud out. I went further and rigged an adapter to seal my garden hose to a radiator hose. I block the "top" port (at bottom) w/ my hand (w/ cap on) and build pressure, though not the full 60 psig of my water supply. Release hand quickly to get a pulse out that helps knock rust balls loose. Repeat many times. Might also help you find core leaks. I first cap the tranny ports (SAE flare, 5/16" I recall, Ace hardware), since water in the tranny is bad, though I also blow those out with air when done. Finally, put radiator upright. Fill w/ water (cap off) while blocking the bottom. Remove hand and judge if it flows out fast under gravity. If it dribbles or glugs out, you probably have plugged passages. It should flow out fast and steady, filling ~1/2 of the bottom outlet tube.
 
At operating temp., shoot the temps at the rad inlet/oulet,, and if there less than 40* difference,, start shooting (the tubes - mine has a laser) across the rad 1/2 way down, checking for cool/cold areas/tubes,, the more cold areas/tubes,, the bigger area blocked..

If it's losing 40* or more,, I'd be looking elsewhere.. jmo
 
If you flush the block with chemicals, be prepared to replace the coreplugs. Sometimes the only thing keeping them from leaking is that crud. Changing them is not hard, except for all the stuff that's in the way; like exhaust, starter, engine mounts, steering box, etc.
 
AJ/FormS said:
If you flush the block with chemicals, be prepared to replace the coreplugs. Sometimes the only thing keeping them from leaking is that crud. Changing them is not hard, except for all the stuff that's in the way; like exhaust, starter, engine mounts, steering box, etc.
Click to expand...

After doing this one time, I would definitely pull the engine to do again.
 
That is exactly why I posted
Changing core-plugs in the chassis is a very major PITA. So I leave the chemicals on the shelf. That silt in the bottom of the block in a DD teener is of no concern to me. Dig it out when the engine is on the stand or send the block out to be tanked.
 
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