Hey... I am a newbie to this forum, but I recently purchased a 1988 E150 with a 351 in it and the van has a over hearting problem. If I start up the van it will run great and not over heat. When I go to drive it I get a few miles down the road and it starts to over heat. One day I was looking at the van and when you give it gas the bottom radiator hose will start to close and the more gas you give it the more it will close. Any clues? Thanks.

 

Coolantintake circuit is blocked solid. Could be bad pump, blockage in lower hose, blockage in engine block orblockage in radiator.

 

I already replaced the water pump, I also dont have a thremostat in but I dont think that would casue the problem. How could I tell if the system is blocked? If I go to flush the system will it not run all the way through? Thanks for the help.

 

No thermostat COULD increase pump suction on the intake side. Or maybe simply - someone bought a hose that didn't have a spring coiled in it where the original had a spring coiled in it. The spring prevents hose collapse. I wonder if you could have extra suction though by a broken head gasket, etc. to the engine intake system (bad gasket or cracked intake). I'd start by draining it and looking at the hose. I'd add a 140 degree thermostat for longer engine life. Flushing the coolant system could also help. Look for white smoke out the tailpipe on a warm day (firing coolant). Hope this wraps it up for ya'.

 

yeah I think im going to flush it out tom.....I really dont think its a head gasket cause no smoke and the coolant is clean. I ll also put a thremostat in it too and look into gettin a springed hose. I only paid $300 for the van an the odometer says 98000 and the title didnt say the odometer is off so i really have no loss no matter whats wrong with it.but thanks for the advice.

 

If no smoke out the exhaust I'd leave the head gaskets for last - but instead I'd check for coolant in the oil the next time I changed it. If the thermostat aggrivates the problem - it may help you also track it down easier. Honestly when an engine hits around 100,000 the lifters are usually shot anyways. The dome on the bottom of them wears right off - of course yours being newer might have roller lifters - in which case the roller pin usually lasts longer in place of the dome. A clogged converter or two could really also be the culprit and sometimes pushes high pressure leaks everywhere. If it's a catalytic converter the exhaust will not have enough pressure to pop your hand off the tailpipe (when it's cold and you start it).

 

the thermostat has two functions
one two stop the water flow at start up to allow engine to warm up
faster.
and two it slows the water down so it stays in the radiator longer.
with no thermostat the water pump blast the water through the system,
suckin the intake hose closed, hello, and causin engine to overheat.

gotta have mrthermostat in
gweedo

 

I don't think you're gettin' that I RAN engines without them (thermostats). They do slow the flow a little when open - not that much though - the pressure is still there and flow should equal regardless in a good system. And they also stop flow to heat up the engine faster on startup. Really the only thing that would cause the intake (lower) hose to close is if the radiator couldn't handle the flow fast enough - maybe that's what we're searching for here (blocking it with a thermostat likely will only add to the problem of not having enough flow but read on). Without the thermostat the radiator is too small for the system and doesn't allow enough coolant flow through the radiator cores at higher speed and with the absence of coolant a vacuum forms and pulls the hose shut. Could also be radiator cap and system in general can't handle enough pressure to keep the coolant in causing a general loss in pressure. Maybe coolant isn't filled high enough over the cores to start. Maybe I should ask now - Is this the correct radiator (from a good company like modine,etc.) or a low grade replacement that just happened to fit and was in stock? At any rate I mentioned a while back to try the 140 (to 160)degree thermostat. I do understand it's not really a race engine and the radiator is a newer factory turd. That's why I prefer 60's and 70's stuff (and even earlier). You'll never know what you're missing. By the way if the radiator is a retrofit from where a 6 cylinder radiator was bolted in - you sometimes have to cut away the sheetmetal in front of the radiator where the sides of the cores should be exposed. This will help it to cool. Check if your motor is stock -in other words.

 

sorry took so long to respond ive been busy but I got a different radiator and put a stat in and the problem is no longer there, thanks for all the help!