sixOHfour

Hey everyone!
Long time reader first time poster. Heres my problem:
I have a 1990 Toyota Pickup 4x4 5 speed with the 3vze engine and we just did the head gaskets, water pump and thermostat. I had a cracked head so I replaced that too. I just got it about a month ago so I did basic stuff as well like cap, rotor, wires, plugs, fuel filter, K&N CAI and coolant flush.

Anyways, all is good except for my stupid temperature gauge!!! It will idle all day long and run at perfect temperature but as soon as I drive it for more than 20 minutes the needle starts climbing. It will go slowly until in the red and the cutoff will kill the truck. It is NOT actually overheating and I am 100% positive of that, but the computer thinks it is so I cant go anywhere. The thermostat opens up as it should and I am not losing coolant. When the truck "thinks" it is running hot it starts to run like a pile of.....low low idle, around 400rpm! Timing is dead on. Heater works well so it isn't a blocked core and my rad flows perfectly.
How often do the coolant temp sensor and sender fail? someone told me today I should have done my knock sensor but I don't see how this is connected

I should mention as well that my fuel mileage SUCKS!!! Im getting about 160 miles to a tank driving like a grandma. It dosent help that I'm running 33'' BFG M/T's with a 6'' suspension lift but everyone else gets alot better mileage than me.

Please help I am going insane trying to figure this one out!

shaunneuhaus95

there are 3 temp sensors in that engine, 1 for the guage on dash, 1 for the ecu, and one for (i think its called) the cold start injector.

shaunneuhaus95

on my 94 runner i had a bad gauge sensor and it would show that i was overheating 30 seconds after i started the yota on a cold morn. but if u run a search for (coolant temp sensor) theres a thread on ur issues

Zinek

Make sure that the housing that the three sensors mount to has a good coolant flow through and the small hose is not clogged. drain the coolant disconnect the hoses going to that housing and blow compressed air from both directions. It sounds like there is a partial blockage because it doesn't happen at idle when there is a low heat and circulation. But as soon you start driving bigger load creates more heat and therfore you need more cooling, but if there is a partial clogging, you will see a rise in temperature

sixOHfour

Ok, I have a 1990 Toyota Pickup 3vze 4x4 5spd and we are struggling with temperature issues.

I blew a head gasket and had the heads/gaskets replaced with a new water pump and thermostat with a 1/8th'' hole drilled at 12 o'clock. Today we replaced the coolant temperature sender and sensor. The truck will idle all day and the temperature gauge stays normal however after about 15 minutes of driving (speed does not matter) it starts to climb near the red and will hover between normal and very hot. The lower rad hose is cold and the upper rad hose is hot....in fact the entire water pump area remains cold as does the bottom of the radiator. The hose does not collapse. When we had the rad out we ran a hose through it and it seems to be flowing properly. When we did the hg's #6 cylinder had a crack in the head so we got a new one and had it tested and the valves adjusted.

I keep throwing money and parts into this thing and to no avail. Has anyone else had these problems? Its almost as if we are getting no coolant flow through the bottom end. There are no air pockets as we have burped the truck extensively.

Please help!

BigSwole

Are you sure the thermostat is working properly?

peow130

Fan clutch in good working order?

sixOHfour

Im fairly confident that it is. We just replaced it, but it could be a bad one from the factory I guess. Should I have drilled it with more than one 1/8'' hole?


I think so, but I'm not 100% sure. The fan is always spinning away if that helps.

We are going absolutely crazy!! Its quite the puzzle.

drmix

Did you jack up the front end of the truck when you filled up the coolant? When I replaced my thermostat and radiator there was a huge air bubble stuck in the cooling system. What I did was lift the front end and squeeze the lower hose while it was running with the heater cranked on high. Never overheated after that

BigSwole

I'm thinking the thermostat might have been bad from the factory. Your pin hole is getting you by at idle but with the added heat of driving the pinhole can't keep up with the thermostat not opening. I think you can boil it to test it. Or just pick up a new one.

sixOHfour

We are having hot starting problems with my dad's 1992 4runner w/ 3vze 5spd.

The truck will start and run perfectly when cold and can run all day long. The second it gets up to operating temperature and you shut it off it will not fire back up again. When you try and start it while its hot it wont even crank, it almost sounds like the battery is dead, but it is not!

He put a brand new battery and and a new starter in it today and is still experiencing the same problem. Alternator is good as well providing 14.2v @ the battery. All of the dash lights/exterior lights come on, but still no cranking when hot. The truck cannot be jump started when hot either, but can be bump started hot or cold.

Have any of you experienced this same problem? and more importantly, how did you go about fixing it?

Thanks!

MrPeepers

Hey, not sure if this is relevant to Toyotas or not, don't wont to lead you down the wrong path. But I had this same exact issue in a Honda and it was the main relay. May want to a google that to see if you see anything related until someone else gets back to you.

sixOHfour

He fixed it today, turns out it was a bad ground from the main relay! haha nice one mrpeepers

sixOHfour

Ok guys and gals I am at my wits end.

I have a 1990 Toyota Pickup 4x4 3VZ-E 5 spd that is driving me around the bend. I have recently done the following work:
Headgaskets w/new head bolts plus ALL top end gaskets replaced, valves checked & adjusted @ machine shop
Water pump
Thermostat
New Radiator & Cap
Coolant temperature sensor
Coolant temperature sender
Timing belt
Plugs, Cap, Rotor, Wires
Throttle position sensor
Fan and alternator belts.
Various vacuum and heater hoses.
Fan Shroud

It was throwing a code 41, so I replaced the throttle position sensor and adjusted it as per the guide. The resistance is well within tolerance and adjusted properly. Problem is even after reset the code goes away for a while then comes back. It has a hard time holding a steady idle, the hotter it gets the lower it drops until it stalls. I also cant get the RPM to drop when the timing jumper is installed. So obviously the timing is close, but off enough to cause me other problems. It overheats on the highway, I dont know why...ive done everything except the heater core. Hopefully its the timing...It isnt air, there is NO way it has any left in there.

I have also noticed that my temperature and battery voltage gauge tend to sway quite wildly, especially the voltage! When you sit at a stop light it moves back and forth pretty badly, but when driving it it stays up higher.

Im getting really sick of throwing money at it and technicians are scratching their heads..

Any input?

TylerH

I had a friend that had that problem. It was a coolant or temp sensor, you sure you replaced all of them? I dont know much about 3.0 or i would give you more info. Just passing on past experiance.

Wrenchinjoe

So I am guessing that this problem presented itself after all the engine work?? How did the engine run prior to tearing it down to the block? Assuming the engine ran ok before the top end rebuild, I would be inclined to search for a vacuum leak. Also make double sure that mess of vac lines on the passenger side were installed correctly, as it is easy mix a couple of them up. Jiggle the wiring harness and connectors at the various connection points to see if that makes your idle better or worse, as that old wiring can be brittle, and you had to disconnect every sensor and contort the entire harness out of the way to do the engine work.

If you don't find anything, go back and triple check that the timing marks all line up and that the distributor is installed correctly.

alil2cul4u

For the overheating, did you check the fan clutch? If I remember right, when you spin it, it should have some resistance. I'm pretty sure a bad fan clutch could cause overheating!

dropzone

iTrader: (6)

MultiPle threads merged and retitled...

sixOHfour

Since it really only happens on the Highway I don't see how the fan clutch would cause it.

Checked the truck today, no vacuum leaks.