akabislazy

Recently got stuck with this car and need to get it running reliably.....
I've gone over as much as I could and have had two different shops try and diagnose my over heating issues.
Neither one can pin-point the issue, and I'm too leary to take it to another shop(labor is expensive here in San Diego).
I'm always on a budget so I try to do these fixes myself.....anyway here's a list of things I'd like to note.

First and foremost the car has NO rough idle issues or anything at all.
Just runs REALLY hot unless at speed.
Replaced thermostat twice, once with aftermarket, again with certified Toyota t-stat since changing it didn't fix the issue, I figured the new one was a dud... odds that two brand new t-stats are bad are very unlikely......
Anyway, after changing them the car still runs hot in traffic, fine at speed.
When I park it it constantly pukes out the overflow.
Replaced both pressure caps twice now.
Water pump appears to flow water in and out just fine at speed so that rules that out.

I can't for the life of me locate the temperature sensor for this car to swap that out, but again, fine at speed, not at idle, rules that out.

Replaced the radiator and nothing changed.
Both shops were immediately trying to point to a blown head gasket, but both shops ran tests and nothing.

Never noticed any white smoke or any discoloration in the oil.

Power steering pump DOES have a small minor leak, but is always kept topped off.
No binding/kinks/rough steering issues at all.
Connector is plugged into the back of the pump as normal.



Now, I know it HAS to be something wrong with the fan speed since it does this mostly at idle, but I feel it has to be a combination of things for it to get SO hot, even on cold days in the winter time.
Regardless of ambient temperature it gets hot too fast.
The fan DOES stay the same speed at all times, with the ac on or off, or hot or cold.
I know this is causing it to overheat as well but I have no idea what to fix since the fan is ran off hydraulics :/

If I bypass and jump OP1 & E1 the fan does increase is speed as it should,
the connector is plugged in so I don't know why it isn't speeding up....that rules out my fan and pump.



Anyway, I'm at a total loss with this car and no shops around me seem to know what their talking about and I can't afford for the dealer to look at it.
Anyone care to shed some light on what is causing this crap?

Hayk

iTrader: (1)

So you're not losing any coolant and you're confident that it's circulating through the block, is that correct?

You might have an air pocket in the system due to the fact that it was open so many times. You need to run the engine without a pressure cap for about 20 minutes, to try and purge any air bubbles.

Kinzerhaus

It does sound like you may have a combination of things happening. I would start first with the suggestion of MrBooby and try to eliminate any air pockets. After you are sure there is no air in the system I would go back to the fan speed. If there are air pockets the sensors might not be getting hot and the fan will not kick up when it needs to.The fan speed should increase when the AC kicks on. If it isn't you need to track down the circuit that tells the fan when to kick in higher and look at the sensor for that. On my 96 I know of 2 temp sensors. One is on the left side of the engine just behind the fill neck the 2nd is on the right side close to where the bottom radiator hose enters the engine. I am not sure if the locations are different for your year.

akabislazy

I thought I clearly stated it was puking from the overflow.....coolant gets so boiling hot it surges out.
Besides that there are zero leaks.

Also, I've checked for pocket issues every time I go under the hood, that's not an issue.
Or a blockage, Ive flushed/refilled/changed practically everything.
I've checked the cooling ecu behind the box and everything checks fine.
There is not definite reason why the fan will not spin faster.
Everything checks out fine and there is no blockage.

Please don't reply with basic answers as I have already checked the common issues that are easily addressed......

randal

My '92 was just recently puking coolant too. And it was strange because the temp gauge never went past the half-way mark to indicate that the engine was overheating. But when I ran the A/C on a hot day and then park it...puke.

I just replaced the temp sensor and it has not done it since. Once removed, I check the old sensor with an ohmmeter and got "open circuit". It was really rotted from the years. The new temp sensor read 1800 ohms when room temp.

There appear to be two temp sensors and the sensor I replaced is just to the right of the center of the engine on an appendage of the intake manifold. Of course, there is another temp sensor right down by the thermostat but that one was ok. I will see if I can dig up a photo and put an arrow pointing to it if you are interested.

akabislazy

A photo would be handy, I've looked all over that area and all thats around there is my o2 sensor.....

LeX2K

You are having classic symptoms of either a bad water pump, or a blown head gasket. Start by inspected the water pump (you have to remove it to do this properly) and replace if needed. After replacing the water pump you still have the same problem, your head gasket is probably blown.

The hydrocarbon test is tricky to do properly, I've seen shops do the test and come up with a negative result, but the head gasket was indeed shot.

randal

Here is a pic taken while starting disassembly to replace a blown head gasket so some of the hoses and connectors are off but you should be able to put your finger on it. There is a mating green electrical connector and it is right of the intake manifold(as viewed from the front). This pic was taken from the drivers side fender position looking in.

After removing the sensor, you should test the resistance of the sensor with an ohmmeter. It should be around the 1800 ohm range at room temp and go down as the temperature goes up. If fine, you can leave it alone. I paid $12 for a new one.

akabislazy

Okay to be more clear with you, I replaced the timing belt about 12,000 miles ago, the water pump was in almost brand new condition. The car has an almost brand new top end on it with less than 20k. I have gone over the heads with a fine tooth comb and it was tested THOUROUGHLY at a HEAD shop. Stop trying to claim it needs a head job, everyone is saying that.
The issue that needs addressed is what is causin the fan to only run at one speed and not properly keeping the engine cool.
It speeds up when bridging the diagnostic port, and the harness connector is plugged into the pump, and I've checked out the cooling ecu behind the glove box and it checks out fine.


My question was what else controls the fans speed.
Stop thinking water pump/heads/radiator/thermostat. All are fine and daily new and all checked out

akabislazy

Thank you, this will be replaced regardless of if I need it or not.
You wouldn't happen to have that part number and who carries it would you?
I just called around real quickly and all the part stores are saying is "huh, what part do you mean? The thermostat?" lol its getting irritating.

Please don't tell me it's only available from the stealership either lol

randal

Got it at AdvanceAuto. Its a BWD brand, p/n WT653Z. Guess it was closer to $20.

Here's a link ->
http://shop.advanceautoparts.com/web...erature+sensor

Kinzerhaus

It is called a coolant temperature sensor. Pull yours out first I found out that at least for 96 models there is more than 1 variation even though the parts store only listed 1. Mine had a different plug then the 1 they had so I had to try another vendor. Got mine from the local Advance store.

GS4_Fiend

iTrader: (22)

Did you replaced the radiator cap with OEM? Some aftermarket will not work.

akabislazy

I went with aftermarket first then switched back, hence the reason why I replaced them multiple times along with the thermostat.

randal

I tried to replace my radiator cap with an OEM Nippon Denso and even ordered it from the Lexus dealer. But when it came in, it would not fit. Just a little too small and the spring is not even close to the same. I took the old one in and showed the parts manager the differences. He tried and tried but could not find any other part number. I had to return it. Still looking. I dont know if someone changed the radiator to something different and now the cap with my VIN does not match? It's a mystery.

akab, do you have an OEM p/n for the radiator cap?