Help!!! I have dropped a 70 model's 302 in my bronco 2 and it runs great, other than the fact I didn't know I needed to tear the tranny apart to put the A/A output shaft in, so I gotta rebuild it when I tear it down, sorry, blabbing, heres my other problem. I mounted the radiator on the rear tire carrier, and mounted a elect. fan. The radiator is higher than the engine. I can pull the plug on the thermo housing and fill radiator till water runs out up front. Now, It runs great and if its just idling, it doesn't even move the temp gauge. (oh and new thermostat). However if I start driving it around and it starts pulling on it, it just barely starts to warm up. Then it starts pushing cool cold water out of the radiator, then if you pull the cap off it spews like hell and then all the cold flys out and a little bit of extremely hot water is present. The cap is good... I tried several... I believe the water pump can't handle the distance, and the water is cavitating and not flowing properly. That their is a hot spot forming somewhere not near the temp sender and when you get on it, that spot warms up like crazy making lots of pressure even though the rest of the water is cool. Then if you release the cap, or it pushes past, most of the water comes out and then that last bit of hot is now back there. Thats even if its not running anymore. Should I give the water pump some more help, by removing the thermostat, I mean its carbed and I'm not using a heater with it. 4x4 only. I think that would help it tremendously as far as moving all that extra water and the distance. What do you all think??? Get rid of the restriction, I don't think it would hurt anything. Guess I could also install a inline pump, but that sucks literally and I don't think I should have to. I have had a similar prob with a mitsubishi and it was because the aluminum head was pitted real bad and pressure from the cylinders was pushing into the radiator and pushed all the water out. Thats without water in the oil, or water coming out the pipe. I fixed that, but I don't think that is my problem now. No aluminum head here, and I would trust the 302 over the 2 liter mits anyday.

 

I haven't been around a rear set up but a couple of ideas occur to me. I assume you have no kinks or bends that would allow a air pocket to form, and 2, how old is the pump? You can try removing the T-stat but I wonder if you need a high capacity pump to push the water.

 

From your description you pretty much determined found that water is not circulating through the radiator at all. A decent water pump should put out something like 10 psid which should push coolant to the radiator.

I would look at the suction side of the cooling system. All of the hoses between the radiator outlet and the inlet of the water pump need to be large in size and should not be crimped or collapsed. It is common to collapse a hose on the inlet side of a water pump especially with a long run of hose that does not have a spring liner to keep it open. This causes the water pump to cavitate and not pump anything.

It would be best to keep the thermostat in place. Removing it will make the cavitation worse. You could run a 160 degree t-stat if needed.

With luck, this will be a simple fix and will not require water pump replacement.

Lou Braun

 

Using some very stout hose. No kinks. I have tried real hard to make sure there were no air pockets, however I could be wrong. I too have also thought I might need a new water pump, and maybe a high output pump. I wouldn't think I would need anything more than stock though... The pump could be wore out on the impeller just not leaking out the weep hole. I still plan on a few more runs at it. Don't think it would hurt to replace the water pump though, its easy to get to now, with nothing really in the way... I understand it needs a little backpressure so the pump has something to push against and keep pressure going and water in the pump, but if the system is totally full and if the pump is struggling with the thermostat, I am gonna consider trying it without it, and possibly putting a small hole in it and or a washer setup to keep it flowing all the time yet still provide a little back pressure. Yeah it could make the cavitation worse, but somethings gotta work, even if it doesn't sound right.

 

Okay, fixed. That wasn't too hard. I just poured a little gas on her and threw a match and she was done, naw just kidding. I thought I was getting all the air pockets out... NOPE. I looked closer and there are a couple of spots that could hold lots of air. So... I stuck the sprayer on my hose and stuck it in the filler neck and let her fly. I then removed the plug in the thermo housing, and walked away. I let it basically pressurize the system a little from the other end. I did notice a few air bubbles at first comming out the front. After I let her sit I put my finger over the hole and removed and got a few more bubbles out then nothing but pure clean water. Plugged it while still pressurized, and then put the cap on and ran it pretty hard, going up and down one of my pond dams and threw some of my bar ditches. It again still didn't hardly raise past the cold mark, but the fan rarely kicked on and no water was pushed out the radiator. Perfect. So it is like I thought about one thing, all that extra water from the hose running front to back, 30 ft exactly was enough to really increase its overall cooling capacity, Some people told me the stock V6 radiator wouldn't be enough. I did originally use the F100 I got the 302 from for it radiator too. It ended up being rotten and wouldn't hold pressure. So I redid the mount for the smaller radiator, that also fits my black magic fan better and easier on the mount. Works great though, I believe it holds about 5 to 6 gallons of fluid. Not just that, but all that hose sorta releases some of the heat as well. Plenty for a stock V8.I'm a happy camper now. Just gotta rebuild the auto now. Missed a circlip on the new output shaft, the old one just slid out, so I didn't know one went inside. So figured I would rebuild it and put a shift kit on it if I had to dissassemble it. Using a TCI kit. Thanks...

 

Cool! Thanks for the update; you gotta love the cheap fixes.

 

Yeah, could have sworn I had done it good enough before, of getting the air out, but then again I had never messed with trying to mount a radiator on the back and having such long lines, so overkill was actually exactly what it needed. Now just that pesky tranny.