1984 running hot

[robcgray]

Replacing water pump, hard to identify which hoses I might want to have for the job:

On a colder day a few weeks ago I made a road trip, about 2 hours. About half way there, when I got off the interstate to use the head, the engine heated to the top of the scale, not in the red.

It's been more frequent ever since. I did not hear the clutch fan running as it should with such high temperatures, so I replaced the aftermarket with an aisin.

There was no improvement, and now there is a humming noise coming from the general area of the fan clutch. Engine still hot (running the heater brings it back to normal) and fan still not turning on as expected for such high temps. This has me thinking the water pump impeller is shot, and not circulating coolant. Clutch fan not running because temps of air through radiator aren't that high?

Anyway, I have ordered a new water pump and gasket, and the install kit that ToyotaMatt puts together. I am also going to replace the radiator cap, the thermostat/o-ring, gasket and bolts. I also ordered a new water bypass hose. Matt's water pump replacement kit also comes with a hose.

What hoses am I missing?

Thanks,
Bob

 

[John McVicker]

Sounds like you are covered. You might consider even a different new fan clutch…fj80 FCT 049. I replaced my FCT 017 with the 049 & it helped.

 

[OSS]

Radiator

 

[OzarkMtnCruiser]

I'd replace every hose that touches the WP. There is a small hose that connects to the oil cooler line at the bottom of the pump- OEM 90910-05155 But this hose works you just need to cut it down to size.. and cut it a little bigger than you think you need. Gates 21739. There is a spreadsheet on this site that has all the pn ome and alternates for the cooling hoses.

 

[robcgray]

I'd replace every hose that touches the WP. There is a small hose that connects to the oil cooler line at the bottom of the pump- OEM 90910-05155 But this hose works you just need to cut it down to size.. and cut it a little bigger than you think you need. Gates 21739. There is a spreadsheet on this site that has all the pn ome and alternates for the cooling hoses.

Thanks.

 

[Tennessee80]

My ‘85 was also running hot when I first got it and it was the thermostat. Replaced that and all good since then.

 

[bcolvin]

city racer has, I believe, all of the coolant hoses. Great business.

 

[Seth S]

have you verified that the coolant is actually over temp? Are you boiling over or have you taken some readings with an infrared type heat gun? The stock gages dont have the best track record for accuracy and can suffer grounding issues.

 

[robcgray]

have you verified that the coolant is actually over temp? Are you boiling over or have you taken some readings with an infrared type heat gun? The stock gages dont have the best track record for accuracy and can suffer grounding issues.

It's not over temp, just much hotter than usual. Engine behaves differently: Oil is disappearing. Doesn't want to stay running after hot shut down. Smell of gas is significant. Will get into normal temp range if heater is on.

 

[robcgray]

My ‘85 was also running hot when I first got it and it was the thermostat. Replaced that and all good since then.

If it weren't for the humming noise, I would say this is a good bet. If thermostat isn't opening, no hot coolant to radiator to activate fan clutch. Running the heater would still help reduce temps.

 

[Tennessee80]

It's not over temp, just much hotter than usual. Engine behaves differently: Oil is disappearing. Doesn't want to stay running after hot shut down. Smell of gas is significant. Will get into normal temp range if heater is on.

What carb are you running? I have a Weber and the PO had the thing running rich, smelled like gas also. I turned down the fuel mixture and it really helped…

@Bama4door any ideas here?

 

[open country]

Re: stopping after a long drive, it's normal for temp gauge to increase as the truck heat soaks at a stop. Mine does this and gauge crawls back down once I start the engine and the fan moves air back through the system.

Also my gauge runs about 2/3 to red at all times during normal driving, I've always assumed this is normal and never seen other signs of overheating. I have a new radiator, FJ80 fan clutch, thermostat, and all hoses with fresh coolant.

 

[robcgray]

Engine runs cooler, but still having clutch fan issues. Fan runs loud and clear on each start but doesn't run any more after that. Thought maybe the belt was too loose, so I tightened it. That wasn't it. I am thinking I managed to replace a bad fan clutch with another bad fan clutch, so am going to install another new fan clutch. If that doesn't work, back to water pump, but with correct part.

I finished installing a new thermostat, but failed on the water pump. Bought the wrong part. On city racer website, I didn't see the questions to ask yourself and bought a unit without the proper flange for the clutch fan.

Took the old water pump apart and it seemed in good order so I reinstalled with new gasket.

Removing radiator wasn't as bad as I thought.

 

[robcgray]

Engine runs cooler, but still having clutch fan issues. Fan runs loud and clear on each start but doesn't run any more after that. Thought maybe the belt was too loose, so I tightened it. That wasn't it. I am thinking I managed to replace a bad fan clutch with another bad fan clutch, so am going to install another new fan clutch. If that doesn't work, back to water pump, but with correct part.

I finished installing a new thermostat, but failed on the water pump. Bought the wrong part. On city racer website, I didn't see the questions to ask yourself and bought a unit without the proper flange for the clutch fan.

Took the old water pump apart and it seemed in good order so I reinstalled with new gasket.

Removing radiator wasn't as bad as I thought.

Changing fan clutch did not fix the noise.

This is a link New video by Robert Gray - https://photos.app.goo.gl/FF67BhPNQ2oGpTx78 to a 2-second video of the whirring/humming noise that is prevalent after normal clutch fan noise stops. Anybody recognize this noise? Weird, but I don't think I can hear clutch fan and whirring noise at the same time.

Like I said earlier, engine temps are completely normal. I may have had more than one issue. Bad thermostat and bad original fan clutch, but why this new noise after replacing the original fan clutch? Any chance it is the air pump, which shares a drive belt with water pump (not really where the sound is coming from)?

Coincidence, or not, but after the original trip where the first temperature spike occurred, the air conditioner stopped working. Blue light comes on, heater and blower still work, but compressor does not kick on with button press. When I researched this there was discussion about manifold pressure, and I was unsure if that is the same manifold pressure that the air pump maintains.

Thanks for any help.

 

[2mbb]

I'm not sure where you are located, but in winter the fan clutch may not kick in under normal operation. Mine works when it get above 80 deg ambient temperature, I think.

Regarding the AC system, the "manifold" is a manifold gauge which is used to check the hi-side and low-side pressures of the refrigerant. This is not related at all to the Air Injection system. There is a pressure switch that prevents the compressor clutch from engaging is the pressure is too low (too little refrigerant). Based on your explanation of what works and what doesn't, it could be low refrigerant, bad pressure switch, bad thermistor, compressor clutch not working or engine idle is too low. For the last one there is the AC amplifier under the dash that has a blue knob to adjust the cut off RPM. Or your AC idle up for the carburetor may not be working.

 

[John McVicker]

@robcgray 2 things to comment on.

1) new fan clutch…what did you use? FCT 049. Or FCT 017
2) borrow or buy an IR Gun to verify your ACTUAL temperature. You can NOT trust the OEM gauge in your situation.

Also do some searches on adding silicone oil to your fan clutch. This has helped many people.

 

[robcgray]

I'm not sure where you are located, but in winter the fan clutch may not kick in under normal operation. Mine works when it get above 80 deg ambient temperature, I think.

Regarding the AC system, the "manifold" is a manifold gauge which is used to check the hi-side and low-side pressures of the refrigerant. This is not related at all to the Air Injection system. There is a pressure switch that prevents the compressor clutch from engaging is the pressure is too low (too little refrigerant). Based on your explanation of what works and what doesn't, it could be low refrigerant, bad pressure switch, bad thermistor, compressor clutch not working or engine idle is too low. For the last one there is the AC amplifier under the dash that has a blue knob to adjust the cut off RPM. Or your AC idle up for the carburetor may not be working.

View attachment 3210401

Thanks for this.
I am in Florida, and it has been warm ever since the cold front at Christmas.

Drove it around yesterday and now I do hear both sounds at same time.

I am planning to replace the water pump for real this time. Going to try to do it without removing radiator this time. Man was my back aching after the first try.

 

[robcgray]

@robcgray 2 things to comment on.

1) new fan clutch…what did you use? FCT 049. Or FCT 017
2) borrow or buy an IR Gun to verify your ACTUAL temperature. You can NOT trust the OEM gauge in your situation.

Also do some searches on adding silicone oil to your fan clutch. This has helped many people.

Thanks.

I used FCT-017. I have 2 brand new Aisin ones, so I doubt silicone oil is the issue.

I think I will get an infrared gun to double check gauge readings.

I have identified the water pump as non-OEM, and am hoping the humming is just a sign that the bearing is starting to fail. I don't want to get stranded with a seized water pump.

When I had the water pump out, everything turned smooth and there was no lateral wiggle, but I did not check for axial looseness. Right now, there is no play in the fan axially, and there is no weeping.

 

[OSS]

Engine still hot (running the heater brings it back to normal) and fan still not turning on as expected for such high temps.

Ok-I’m thinking out loud here…
The heater source of coolant is the Tee fitting right next to the temperature sender at the rear of the head.
The heater core (heat exchanger) inside the cabin isn’t a particularly big radiator. It certainly isn’t up for the job of providing much real cooling to the engine.

When the heater valve is opened, (heater slider control pushed into the red in the cabin) the flow is opened up through that rear tee fitting, and LOTS of coolant now flows through the rear of the head since there’s now another open passageway.

Just the fact that there’s so much more coolant now flowing through the back of the head when the heater valve opens, cools down the coolant back there a lot since it’s flowing faster…
When the heater valve is opened, the back of the cylinder head cools down a bit simply because the flow has increased- and the temperature sensor detects it — But its fake cooling.

The overall temperature of the entire cooling system doesn’t change much when the heater is opened up, only the way it’s getting measured has changed. (Increased flow past the temperature sender).

If the water pump really was at fault, opening up the heater wouldn’t suddenly cool down the engine.
I don’t know why your engine was getting hot, but I suspect it has nothing to do with the water pump.

 

[robcgray]

Ok-I’m thinking out loud here…
The heater source of coolant is the Tee fitting right next to the temperature sender at the rear of the head.
The heater core (heat exchanger) inside the cabin isn’t a particularly big radiator. It certainly isn’t up for the job of providing much real cooling to the engine.

When the heater valve is opened, (heater slider control pushed into the red in the cabin) the flow is opened up through that rear tee fitting, and LOTS of coolant now flows through the rear of the head since there’s now another open passageway.

Just the fact that there’s so much more coolant now flowing through the back of the head when the heater valve opens, cools down the coolant back there a lot since it’s flowing faster…
When the heater valve is opened, the back of the cylinder head cools down a bit simply because the flow has increased- and the temperature sensor detects it — But its fake cooling.

The overall temperature of the entire cooling system doesn’t change much when the heater is opened up, only the way it’s getting measured has changed. (Increased flow past the temperature sender).

If the water pump really was at fault, opening up the heater wouldn’t suddenly cool down the engine.
I don’t know why your engine was getting hot, but I suspect it has nothing to do with the water pump.

Thanks, I like what you're saying here.

I wasn't sure how much running the heater effected actual engine temperature. I also wondered about flow if the water pump is working well. (Even considering convective flow when the heater is on. Hotter fluid rises and cooler fluid sinks, but I cannot picture the relative arrangement of source and sink in that situation).

I do believe there was more than one issue: possible bad fan clutch, possible bad thermostat and even an improper coolant fill (I found a brass ferrel in the coolant reservoir drain that was clogged).

None of this explains the whirring/humming that began after I replaced the first fan clutch.