Here it is, I have this 89 250 van with a 318 that was running fine until a hole was rubbed on the top of the radiator when the oil intake was bouncing against it. something that was overlooked by the previous owner. I followed my bros advice about using radiator sealant to fix it since it wasnt a big hole at the time. I was idling it like it said and watched my radiator squirting out for about 10 mins without it slowing so I stopped it and let it sit for about an hour. I refilled it and starting driving home only to see the heat guage peg out....I stopped, it dumped the entire contents of the coolant on the ground and ive been having trouble ever since. I did get the hole fixed properley btw:P now for the good part... its been boiling over into the overflow for the last few weeks, I took out the thermostat, replaced the waterpump, flushed out the system and its still boiling over. should I look for a new radiator or is there something else I should be checking?

 

Maybee your lower radiator hose is old and collapsing. Some have a coil like spring in it to prevent this. Could be your radiator has a bunch of internal blockages. What did your flushings look like?
My 89 b250 once had a stuck thermostat and ran hot. I replaced it on I-10 in west texas in the summer with a 185 t-stat and it ran too cool and my mileage suffered.

 

had a bunch of gunk come out but. the lower hose doesnt appear to be collapsing but I will keep that in mind when I do my next replacement.

 

If you're lucky the sealant clogged the radiator. If you're unlucky the head warped and blew a headgasket when the engine overheated.

Is your temperature gauge sitting at normal when the boiling over into the overflow starts to happen or does it climb upwell before that?

 

the temp guage read about 1/3 up with barely noticeable boiling at the minimum point, the last time I took it out on the freeway it was about halfway up and it lost about 1.5 inches of water from the boiling.that was a 20 mile drive

 

After I had to change my stuck thermostat in west Texas, I could tell I didn't run quite as smooth. Less power/ economy. When I got the engine rebuilt 9 months later It was discovered one of the heads was cracked. I can't be sure but I think it happened in Texas, and my temp gauge was reading just under 2/3 the wayup the gauge, when it normaly ran just under half.

After the rebuild it ran a quarter way up the gauge. I thought the rebuildersput in a 185 and went to change it to a 195 and discovered it was a 195. With the rebuild I got a new radiator. It lasted less than 2 years. The cooling fins would disintegrate at the slightest touch, but the engine still never ran hot, nor did it leak, before I replaced it.

One more thing you could check is the viscous fan coupling. It could be worn and slipping full time, never getting up to full speed. I think when cold they spin freely by hand, when warm you should feel some resistance. I read somewhere that when you have them out of the vehicle you must store them in a certain position or the clutch fluid will leak out.

I hate to say it but if your temp gauge got pegged, Alloro's hypothesis( warped/cracked head, blown head gasket)could be the most likely. What does your exhast look/ smell like? Any freeze plugs weeping?

 

no weeping from freeze plugs, no leaks I can determine. the exhaust appears normal. and I havent noticed any smells to it arent supposed to be there.I dont know much about those fans you mentioned tho. I know I have one but no clue if its working properly. also ive seen no evidence of any fluids in the oil.

 

Your engine fan has a viscous clutch. The hotter it gets, the more the clutch locks down and spins the fan faster. With a cold engine go spin the fan by hand. There should be little to no resistance. When hot, shut off the engine, and spin the fan by hand, it should be much harder to spin. I don't think this is your problem. If you are losing coolant and there are no leaks, you are burning it in the combustion chamber. Blown head gasket. Coolant in the combustion chamber can wash oil off the cylinder walls. Don't drive it, unless you'r planning on a rebuild soon anyway.

 

If it were a plugged radiator your temp gauge would climb right up and peg itself. Since the coolant is coming out the overflow without overheating, then you have to go with compression getting pumped into and over-pressurizing the cooling system and forcing the coolant out. Looks like you're going to have to pull the heads.

 

thanks for the help but pulling the heads arent an option so I guess I will be without.:/