I replaced my oem 16" fan with a better one from ebay rated at 2700 cfm I had to reverse the wires, but other than that it looks and spins correct. The only problem is that it wont turn on when the engine heats up. I have removed the viscous fan for now and when running in hot weather, the fan never turns on. I jumpered the relay (30-87) and it turns on. I jumpered the two connections on the lower right (drv) side of the rad with relay in and it runs, so I am thinking that the thing that sticks out of the radiator on the lower right side (temp switch) is faulty. I have removed the a/c and all assoc components (comp, cond, etc) and the fan is mounted right up against the radiator. How often do those switches fail? Does this mean I need to replace my thermostat and this temp switch? Will this require me to drain the coolant? The coolant I have is fresh and was recently drained and flushed during my rebuild. Thanks, Borys.

 

The switch on the radiator completes the circuit for the fan so both wires at the fan and the fan side wire at the switch (on radiator) should have 12 volts whenever the ignition is in the on position. If you have the 12 volts and the ground is good, then your switch is bad or the coolant isn't getting hot enough to trigger it. Removing the switch will drain most of the coolant. It can be reused if uncontaminated.

Dennis

 

I think the switch is bad. I know I have 12v there because the fan runs when I touch the two wires together. I really do not want to drain the coolant out of the radiator. What would cause the coolant to not get hot enough?

 

If the thermostat was stuck in the open position, switch is the 82 C variety, and flow throught the radiator is good it may not need to come on. Is the gauge showing it's hot?

Dennis

 

If the switch is shot it won't matter what temp the coolant is. It won't work. I think you will probably have to drain the coolant and possibly pull the rad to get the switch out. I have never done this so I don't know if the switch can be changed with the rad in the car. If the switch can be removed while in the car you could probably leave the coolant in as long ask you are quick to plug the hole with your finger or something until the new switch is ready to go in. keep the rest of the system closed up so there is no vent to let the coolant flow more quickly.

 

You would need very big fingers, Jim.

Borys, I'd say count on draining the radiator. I don't know exactly how you would work around the front spoiler if you have one, but I think you could remove the front grille and get in there to change the switch. I replaced mine at the same time I put in a new radiator so I didn't have to try this... but I think it could work.

If you do have to pull the radiator, get the right size wrenches for any oil/trans cooler lines and CAREFULLY counter-hold at the tank fitting as you remove the hoses. If you just put a wrench on the fitting nut and twist it you may be sorry...

 

I changed my lower front rad switch through the front(after removing grille slats), and lost minimal coolant - just have the new switch with gasket all ready (in other hand) to screw straight in as the old one comes out. YMMV
jp 83 Euro S AT 49k.

 

JP,

You must be really quick and accurate. Whenever I try that, I end up wearing or inhaling half of it. LOL

Dennis

 

Dennis, With the grille bars out, and good easy access to the switch, it should only take a few seconds to get the new one started, and as long as there is no air inlet at the top of the system, you shouldnt lose much coolant...IIRC its only about a 15mm,5/8" hole. Maybe I was just lucky.
jp 83 Euro S AT 49k

 

JP,

Murphys law ALWAYS kicks in when I try stabbing something like that. Now I just figure that the bottom of the radiator needs the crud flushed out of it anyway. 8^)

Dennis

 

Well, I got my power brake bleeder and bled the brakes properly finally! I have other problems now. The cooling fan still doesn't work, but since the brakes work I decided to go for an extended drive. I added a quick switch via the cooling fan relay so that I can turn it on as needed. Here is a list of problems I think I have:

1. The brakes work, but I have to apply a lot of pressure to get the car to stop. Probably need a new booster? I rebuilt the calipers and added stainless steel brake lines.
2. The car still runs warmer than what I am comfortable with. I'm sure that I oriented the blades on the cooling fan correctly and it's mounted right against the radiator, but I will post a pic soon to verify. When driving, the guage is just barely over the white line. When I stop at a light for a while, like when wainting to turn it moves up to the second white line with the fan running! Could just be a bad thermostat, but I am scared it might be the water pump. I didn't change the pump since the prev owner had receipts showing it was changed a year before I got it, and the pump still looked new
3. When in Drive and stopped idling at a light, the idle is rock solid at around 800, but the oil pressure drops to about 1 bar and the idiot light comes on alond with the red light at the bottom of the oil pressure guage. Maybe need to retension the t-belt? When I put it in park the idle moves up to about 1000 and idiot light turns off. Maybe the tensioner is not tensioning properly when fully warm engine.
4. I changed the odometer gear, but the odometer still doesnt work. The old gear was in one piece, but as soon as I touched it, it felt very soft and fell completely apart. Maybe the odometer itself is bad.
My budget is starting to run low.
5. I am going to need to put new rear cv joint boots on soon.
I'm just feeling a little bummed since I just tore this engine apart and rebuilt it back up. Just the tought of having to go back in there to put a new water pump makes me feel like

 

If your cooling fan looks like the pic below.... it probably just isn't doing the job. Mine wasn't, even with a new radiator. My heating up at idle problem disappeared with an improved fan. Someone else around here told me theirs was up to the task.... maybe there was something wrong with mine. Maybe the same thing has gone wrong with yours. Just a thought...

Also, the light on the dash is complaining of low oil pressure, not T-belt tension. What oil are you running? Also, while you were in there, did you replace the oil thermostat? You say you just rebuilt the engine.... what were your bearing clearances? Any chance that oil is leaking internally between the block halves?

 

Verify that you have vacuum at the booster, that the check valve is working there. If your brakes worked before the engine was out, no reason to think that the booster suddenly went bad. Don't know about the earlier car, but my S4 has a little venturi boster in the vacuum line at the point where the booster hose comes in. Make sure your connection there is good and the part isn't cracked.

The thermostat would cause the engine to be warm all the time, not just at traffic lights, so you can probably eliminate that as a possible cause. You are looking at either low air flow or low water flow at idle. If the car is idling at all rough, look again for that vacuum leak that's causing the brake problem. Also, check to make sure the vacuum hoses to the distributor are hooked up right. Check the timing too.

The oil pump is driven from the toothed side of the belt, so it would take more than just a loose belt to cause low oil pressure. If both the gauge and the light are telling you low oil pressure, you have low oil pressure. What did you overhaul inside the engine? Bearings directly affect oil pressure. I don't know if your car has a check valve in the head for drainback, or restrictors that help maintain bottom-end oil flow. Any funny noises from the engine that might point to baering noise of valve train rattles? Oh... Is there plenty of the right oil in the engine? 20W-50 per spec?


No clue.


This is one thing time and money will cure on their own. A liberal dose of both will do the trick. Don't lose focus now when you are so close to done!


This is a nice calm, relaxing job that doesn't cost a ton of money to do.

The problem won'yt be the water pump unless there was a problem with the water pump before you started. The sudden failure mode for water pumps is 'leak'. They don't just suddenly wear out. Heating problem is more likely a fan problem. How is the mechanical fan doing? Fan clutch OK? There's a very important warning about storing the fan and clutch in their normal position when off the car to avoid losing all the silicone fluid in the clutch. If you stored that fan in the face-up or the face-down position while rebuiolding the engine, it's likely you lost the fluid from the clutch and the mechanical fan isn't helping any. Do a search on 'fan clutch' and 'silicone fluid' to get the skinny on recharging your clutch with some fluid from the Toyota store.

 

I replaced the oem fan with a fan I purchased from ebay rated at 2700 cfm. Maybe the fan is spinning the wrong way. I have removed the belt fan because I have been unable to find the right size belt to drive it without the smog pump. I replaced the head gaskets, cam gaskets, rear cam seals, oil seperator gasket, all vacuum hoses. I installed an oild control kit from 928 motorsports upon reassembly. Maybe its just that the oil is low. I have no idea what a bearing clearance is. I should say that I rebuilt the top end of the motor, I didn't actually have room to pull the engine out in order to dig into the block. I also replaced the oil pan gasket and I have found no leaks so far.

 

How can I verify the vacuum at the booster? I have a mityvac. I did make sure the check valve by blowing into it etc.. and I made sure that I oriented it the correct way. I also checked that the venturi piece (3-way piece??) wasn't cracked.

The car idles well, its just that the oil pressure is low. I think that the car is warmer than it should be at all times, it's just that it gets worse at idle.


I overhauled the top end of the engine. I am going to check the oil level tomorrow and take some pics.