1992 3 vzfe overheating quick????

[dill38]

I bought this car knowing it had overheated and needed head gaskets (hydrocarbon in the coolant) the car still ran good and didn't overheat unless put on the highway, I milled the heads, replaced the gaskets, flushed the radiator and replaced both caps, installed new water pump and two different thermostats, new timing belt. when started up the car started to overheat within 1.5 mi. I assumed trapped air in system so drained and refilled several different times, finally after giving up I pulled the thermostat and have driven the car for the last seven thousand mi.
now that the weather is getting cold I would like to revisit the problem and install the thermostat and be warm for the winter, so I reinstalled the thermostat with the spring toward the engine cavity "the only way it will fit" and had the same result (overheated in less than two mi) I would sure appreciate any help?

[Yuko]

Are the cooling fans running? If I remember correctly, 3VZ-FE's fans are hydraulically power by the power steering pump. (Something like that) The guys with the 3VZ can chime in. My guess is that the without the thermostat, there was a higher rate of coolant flow to the radiator to cool it down. But even when the thermostat is fully open, the coolant is restricted by the assemble itself.

[BMR]

Yuko's correct, the radiator fans are powered hydraulically off the power steering pump, which is actually two pumps pancaked together. They share the same fluid reservoir, but on the pressure-side of the two systems, they're separate.

So, like Yuko asked, are the fans running and it's still overheating?

Did you use aftermarket caps?... the aftermarket crap is notorious for being defective right out of the box. Best to use Toyota parts.

This engine is really fussy about having the cooling system pressurized properly. Mine start having some temperature spikes with just a small hairline crack in the upper radiator end-cap, which is a very common failure mode for these crappy plastic rads. So if the fans are working properly, look for pressure leaks.

They're also fussy about air in the system. The best way to burp it all out is to remove the cap at the 'stat with the engine cold. This is the highest point in the system, so air tends to collect there. Start the engine, and as it warms up, it'll burp up air; top it off with coolant as it does that.

[dill38]

thanks for the responce, i have read read read this and other forumns about this problem and tried i think all the normal stuff.
yes it is a hyd fan, that seems to be working properly, i tested by jumping relay under hood and by unplugging temp sensor at thermostat. the engine does start to overheat long before the fan gets to ful lspeed, although it still overheats when i jump the fan to run continuous at high speed. this tells me its not related to the fan?
they are aftermarket caps that did seemed to help, but judging by the diameter of the hoses when it gets hot the caps are holding more than normal pressure.
the weird thing is how fast it overheats before the thermo opens (stove top tested at 180)? ive never seen an engine get this hot in less than a mile of slow driving. yet without the thermo struggles to get the temp gauge to half way even after my normal 30 mi highway drive to work?

[dill38]

i understand the whole air in the system thing and im confident im getting it all out by idleing the engine and by getting "all" the same fluid back in

[mazdaverx7]

what i would do at this point is to either replace the radiator or have it professionally dipped by a radiator shop. store bought flushes are not that great for removing calcium deposits..which may be blocking coolant flow in the radiator. use only a Toyota brand thermostat and cap. running the engine without a thermostat is not good and should not be done. this can cause overcooling which is harmful to the engine.

when the heads were milled, did you have them checked for corrosion around the combustion chamber?

[dill38]

i removed the radiator to flush but wasnt plugged, rad full flow of water hose with no restriction.
heads were dipped and then milled, but were not pressure checked,
they assured me "no cracks"

[Yuko]

Since everything sounds good, was the jiggle valve on the thermostat aligned correctly in the housing? On the 3VZ-FE, it should be at the top of the thermostat. If not, it can cause air to be trapped in the system.

[mazdaverx7]

i'm wondering if there's a blocked coolant passage in the engine around one or more of the cylinders..

fwiw, the jiggle pin should always be facing the 12 o'clock position

[dill38]

yes, the jiggle valve was in the correct position.

i was very careful to keep all passages clean when doing the head gaskets even vacuming out the the passages.

i used felpro head gaskets and tried to research any problems related to passages with them but didnt find anything related.

because i used an aftermarket water pump i was wandering if anyone has ever heard of them having trouble with the pumps not putting up enough flow?

[Stillrunning]

Originally Posted by dill38

the weird thing is how fast it overheats before the thermo opens (stove top tested at 180)?

There's your clue. The thermostat is not allowing coolant to exit the rad and cool the engine. Is the lower rad hose hot? Are you sure you have the correct thermostat?

[dill38]

when i said "overheats quick" i mean in like the first 5min of run time, the engine should not get hot enough to open the thermo in that short of a time in 60 degree ambiant weather from a cold start

[Stillrunning]

Originally Posted by dill38

the engine should not get hot enough to open the thermo in that short of a time

Are you sure the "overheat" is not just on the gauge and not actually in the coolant?

[dill38]

yes, it boils over

[Stillrunning]

I think you'll have to see if your system has a by-pass to circulate coolant even when the thermostat is closed. Maybe the new water pump or it's gasket has this blocked off, which may explain why no hot water is flowing to the engine side of the thermostat enabling it to see engine temp and open. Maybe a Toyo dealer parts counter can show you an exploded view so that you can understand how your system flow is controlled.