got bad overheating cant find problem, need help bad, getting to much pressure at reservoid new intake gaskets, pump, flushed sys, new temp stat 195, by passed heater, engine does not miss,no water in oil, no water at exaust, new fan clutch,this is a 93 4.3 vortex

 

Welcome to the forum. You probably noticed this isnt where you originally posted.

When does the truck over heat? While idling? Driving in town? Highway driving?
How do you know you have too much pressure? HAve you put a guage on the radiator? If you have and pressure is building very quickly when you start the struck, I would suspect a blown head gasket.

What is the history of this problem?

 

i found the problem 4 dirt dobbers nest on back of radiator , also the water pump seal i believe was pulling air into the cooling system an not leaking water i could not find any sign of leak. cleaned off dirt dobbers nest test drove done good all day ran at 195-200 . i hooked up heater hoses an it ran hot not as bad so i taken it up on hiway ran it up to 75 an pulled off road an the pump seal started leaking for about a minute an stopped,i added a quart of water, then came home an replaced pump doing fine now.

 

sorry about the post getting in wrong place, new here got to find all the controls. every thing fixed now. except oxygen sensor missing from exaust need wiring diagram showing the plug in location.

 

The plug for the oxygen sensor should be hiding up between the transmission case and the exhaust pipe. You really have to reach around up in there to find it. That said, it's always possible that someone has "modified" the oxygen sensor and/or its wires. On my wife's '93 Jimmy a previous owner cut the wires to the old oxygen sensor and welded a nut onto the exhaust pipe to install a new one further back. They made a crude splice to the wires to extend them far enough back to reach the new sensor location. I made better splices and put it in properly. You'll just have to look around under the truck to find out what the situation is.

Good luck!

 

thanks i found the plug going to weld up the nut to exhaust when rain clears out
maybe i get a little more gas milage now only getting 15 city.an not any on highway much better all new tuneup. basically no o2 sensor .also found trans not in over drive till 50 miles a hour , this truck has been sitting since 2003 only got 153,000 miles , also detent cable has been repaired get a pinch bolt on it could it bet not long enough now or too long do i need to open throttle wide open an set it fully pulled out an tighten pinch bolt back this is a 700 r4 trans

 

I found my '91 got MUCH better mileage by just changing the o2 sensor. The mileage was terrible, & with all I had done tune-up wise, the sensor was the only thing I could think of. Went from 13 mpg to 20 (wife driving - for me I'd have to knock 3 mpg off that).

So if you have all the original injection stuff in place, I'd run the o2 sensor. There's no real benefit to disconnecting it.

 

thanks smitty: i thout the sensor was gone but when all these storms moved out of here i found the sensor is still there hard to see it. it has a 3 wire plug an goes up beside the passenger side frame. going to check it tomorrow this thing gets bad gas milage about like yours 13 complete tuneup been done in last 100 miles.