(I posted this a few weeks ago but still haven't cured it)
My 1990 E150 van with a 351W overheats after about 15 minutes of driving. It rises to the midpoint after about 5 minutes and stays there until I get to about the 15 minute point. then the gauge goes slowly almost all the way over. Then when I park and turn it off, in a few minutes the pressure cap begins pulsing and releasing water & steam. Blows less than a half gallon of water off. Van has 68000 ORIGINAL miles.
I have already done the following:
New thermostat.
New radiator cap
New serpentine belt, and roughed up the pulley surface on the water pump pulley.
New oxygen sensor
Put on a known good fan clutch from another van w/351W.
Put on a known good radiator from same.
Flushed out the block & radiator with a garden hose, in both directions.
Used a block checking kit (The NAPA one with the blue fluid) to check for head gasket leaks.
Today I took off the water pump, and it is in perfect shape- impeller just like new.
In addition, I changed the plugs, wires, cap & rotor before this problem started.
Wouldn't be the first time I've seen that either!. Most of them come with a picture of how to install it, but, us real men usually ignore specific instructions like that. We are mostly more accustomed to following our wife's instructions!
It would probably be a good idea to just bite the bullet on the Tstat and replace it again anyway - not a hard job just to make sure.
If you installed it backwards, upside down, or it was defective out of box, this could still be a problem.
I'd not expect this to be a problem unless the main issue was that the radiator does not seal.
You probably erred in roughing up the surface of the pulley. This is hazardous to the long life of the belt, but would not cause the problems you are reporting.
This does not play into your problems at all.
The Fan Clutch would cause a symptom of overheating at idle -- heavy stop-n-go traffic -- but the overheat would go away at sustained speeds above about 40-ish.
This would not play into the symptom set you describe UNLESS the engine is running poorly too, in which case you can have a wire or two crossed, and the timing is out of whack. I'd expect you to report poor running as the main problem though, with overheating as a sidebar.
Given the symptoms and repair steps already attempted, I'd be looking at the t-stat again. You did not say if the water pump was new or not, but your motor is from a time when some versions had serpentine belts and some had V-belts. The waterpump is different, depending on the belts used. The serpentine belt type very often runs in reverse of the V-belt type.
Also, if the serpentine belt is installed incorrectly (and still fits) then the water pump can be spinning backwards. The pulleys of the accessory items on a serpentine belt are ribbed and smooth. The ribbed pulleys ALWAYS make contact with the inside surface of hte belt, and the smooth pulleys ALWAYS make contact with the outside surface of the belt. This is always true. It should be impossible to put the right belt on wrong, or the wrong belt on right, but one might be able to put the wrong belt on wrong. This is a possibility you are facing. Check the routing of the serpintine belt.
If you replaced the water pump, and got the v-belt type, then logic says you should have had trouble putting the pulley and fan on, but this is not always the case, and you are left with a pump that looks good but the impeller vanes do not spin in the proper direction and circulation is poor at best, but possibly non-existant.
Worst case is a blown head gasket. You can have a blown head gasket that allows water and oil to mix, but still keeps the combustion gases where they belong. If this was true in your case, you should have a very heavy build up of sludge in the coolant, or water on the dipstick. Pull the dipstick while the engine is running and look for bubbles. (This is not conclusive unless there are bubbles, but it's a good check to make, and it's easy.) You can also drain the oil into a catch pan, then SLOWLY pour the oil into your Recycle Container and check the catch pan for water on the bottom. Water sinks in oil, so it will be on the bottom of whatever is holding it. With the engine running, the water will appear as droplets on the dipstick. With the engine off, the water will sink to the bottom of the pan, and not appear on the dip stick at all. If you're good, you can drain some oil into a suitable clear container, then put the drain plug back in, then let the container rest for a while and look for signs of water forming at the bottom. (Lots of bottled water companies use clear plastic bottles in the 1 gallon size that you can cut the top off of and collect a pint or so of oil into.)
read it all still reminds me of a stuck thermistat....installed backwards... spend another few bucks and change it even though its new ... Iv'e had them be bad out of the box before ...also had one where the poor guy was doing it at home but not watching his kid closely and when he got done he had this problem... his 10yr old decided to help him clean it and left a peice of a rag in the hole... at lest thats the story he gave me a couple days after I fixed it for him... john
Ashton, Thanks for the reply. I do intend to try that, since I think the leak is very small. I bought a bottle of K&W Nanotechnology Head Gasket & Block Repair this afternoon. They recommend finding the leaking cylinder first and disabling its injector and remove that spark plug before doing the treatment. I'll try it next Saturday & see what happens.
Looking back now, I flushed out the whole system back in February because I wasn't getting much heat. All kinds of gunk came out, brown rusty crap.Got plenty of heat after flushing, but this problem might be because I flushed out or loosened something that was plugging the gasket leak. But I have had the van for 3 years already so I can't complain. We'll see what happens
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