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nmehdikh

Weird coolant / over heating problem

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Ah, usually it goes more along the lines of changing the water pump and while you are in there changing the thermostat and coolant. For me I never seem to be able to save the coolant so I end up buying more so I only want to buy once if I can help it.

 

What miles says is true, a belt can silently slip. I don't recall the stock routing, but I think if it was slipping a lot wouldn't the voltage drop? I thought they were on the same circuit. 

 

Couple things here.

 

1. It could just be a big bubble being trapped somewhere

 

2. It could be engine related, cracked or ripped head gasket, warped head, or a really bad tune (lean AFR's will make an engine run hotter)

 

3. It could be a bad pump, once you start accelerating the engine does generate more heat. A bad pump wouldn't circulate the fluid as well.

 

4. It could be your gauges are off. As mentioned a car can run about 210 without boiling, it should actually be able to run 220 without boiling with a good sealed system, the problem is that if it doesn't come down you are going to have a problem.

 

5. This just came to me. Have you checked the location of the sender? If the sender was drilled in somewhere or installed somewhere different it could be reading something not as reflective of the overall temp.

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Google "how to test a thermostat"   Also, YouTube has videos on this.  You will need a thermometer for this test.  Go buy a digital thermometer. 

 

A belt can slip with no noise.

Got a thermometer and the thermostat out. Testing is on tomorrows agenda.

 

Ah, usually it goes more along the lines of changing the water pump and while you are in there changing the thermostat and coolant. For me I never seem to be able to save the coolant so I end up buying more so I only want to buy once if I can help it.

 

What miles says is true, a belt can silently slip. I don't recall the stock routing, but I think if it was slipping a lot wouldn't the voltage drop? I thought they were on the same circuit. 

 

Couple things here.

 

1. It could just be a big bubble being trapped somewhere

 

2. It could be engine related, cracked or ripped head gasket, warped head, or a really bad tune (lean AFR's will make an engine run hotter)

 

3. It could be a bad pump, once you start accelerating the engine does generate more heat. A bad pump wouldn't circulate the fluid as well.

 

4. It could be your gauges are off. As mentioned a car can run about 210 without boiling, it should actually be able to run 220 without boiling with a good sealed system, the problem is that if it doesn't come down you are going to have a problem.

 

5. This just came to me. Have you checked the location of the sender? If the sender was drilled in somewhere or installed somewhere different it could be reading something not as reflective of the overall temp.

Got the cooling system drained and ready to change the waterpump, and I may have found the issue. The radiator had a lot of large particles clogging the smaller pipes that lead to the fins. So this is what was restricting the flow so much. Going to try and flush it all out if I can, if not, a new radiator is on my list. Going to change the waterpump while I can as well. Regarding the waterpump, MSA couldn't get me the cast impeller kind, any risk running the stamped impeller?

 

You are right regarding the routing, on my car the alternator and waterpump are on the same belt.

 

Thanks for all the help guys, I'll report back if cleaning out the radiator clog fixes the issue.

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Posted (edited)

You can get the Cast impeller type from other sources. Do not buy a stamped steel impeller. Beck Arnley are good OEM brands. Often original Japanese manufacturer parts. Rock Auto usually carries them.

 

Edit: Rock Auto has cast impeller style in stock.

 

AISIN, which is an OEM supplier to Nissan $22.79. And Beck Arnley for $31.79. Both should be cast impellors and both are good quality. You could call Rock Auto and ask them to double check. 

 

http://www.rockauto.com/en/catalog/nissan,1973,240z,2.4l+l6,1209170,cooling+system,water+pump,2208

 

Edit: Regarding MSA. They cannot get you their Premium W/Pump # 16-7021 which comes with a cast impeller according to their site? It's a pretty common part. Costs more than Rock Auto though.

 

http://www.thezstore...ssic15t/16-7021

Edited by Chickenman

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Posted (edited)

If the W/pump has a cast impeller and is not leaking, there is no reason to change it. Good idea to take it off and check it, but no need to change if it's still good. A new gasket is dirt cheap. On the other hand, if it has a cheap stamped steel impeller, then chuck it. 

 

Your plugged Rad is the likely culprit....

Edited by Chickenman

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Edit: Regarding MSA. They cannot get you their Premium W/Pump # 16-7021 which comes with a cast impeller according to their site? It's a pretty common part. Costs more than Rock Auto though.

 

http://www.thezstore...ssic15t/16-7021

I was in their store on Wednesday and that's what they told me. They said they used to be able to get them, but their supplier fell through.

 

If you need to replace the radiator Arizona Z Car sells a bolt-in aluminum radiator for Z cars.  It is good quality and it is my understanding that it is a Ron Davis radiator with Z car mounting brackets. Keeps my SBC 350 cool in the summer.

 

http://www.arizonazcar.com/radiator.html

Thanks for the link!

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Well that could surely be the problem, inhibited flow and blocked passages could cause bubbles to flow as it generates turbulence.

 

You should see what a local radiator shop charges to do a clean before you go replacing the radiator. I've heard the stock ones are good units and good to use if their condition is good on the outside.

 

If you go aftermarket I would say to source one that has a fan shroud. Also make sure to duct the radiator to improve at speed cooling. The fanshroud will help with stand still cooling.

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Well here is just a small sample of some of the stuff I managed to get out of the radiator. Going to do my best to get everything cleaned up as much as possible, and switch out the waterpump. Pretty sure this was the culprit, I probably wont be able to test drive it until Sunday/Monday to see if it still heats up.

Thanks for all the help guys

post-54134-0-48123300-1489817485_thumb.jpg

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Posted (edited)

That is scale from inside your engine. 

 

Most likely you will find that scale inside the water pump as well.  Heater and heater hoses too.  Pull the heater hoses off where they connect to the engine and inspect for scale.  Don't take the hoses off at the heater because they are a bitch to put back on.

 

You might be able to flush the block and heater core out before you put the new water pump on.

 

The radiator will just plug up again if you don't flush out the block.

 

Maybe one of the L6 guys will know how to flush out the block.

Edited by Miles

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That's a lot and if that radiator was installed that means someone changed out the old one at some point. I wonder if someone was running straight water at some point.

 

I imagine the water pump is going to be quite beat up.

 

Not sure how you would get rid of all that other then flushing until nothing comes out. If I recall I think Tony? Mentioned a method where you run a women's stocking pre radiator to filter out some of the bits and check and replace that often until none come through.

 

The problem is that it has mass and will just settle and kind of knock around in the water jacket if you just try and flush it out. Short of pulling the block and having it tanked I guess you just have to try and get as much out as you can. Maybe consider some kind of evaporust treatment to keep the block from deteriorating any more.

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Holy crap, that's horrible.

What about rigging up a garden hose with some kind of adapter and reverse flushing from the thermostat housing (thermostat removed). You could flush everything from the head out the hole in the front case from the removed water pump. After that's done, you could flush again from the block drain towards the removed pump.

Don't be surprised if the head gasket leaks when you're all done, or shortly thereafter.

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Posted (edited)

^ That's the method I used to use. Worked quite well. Especially after you ran a really strong flush agent through the engine.

 

Edit: I just used a garden hose and a rag to seal the Radiator neck. Remove the thermostat top housing and stat. Then stuff hose down Rad filler, wrap a rag around it and turn water on full blast. When it starts coming out clear, reverse the setup. Hose into stat housing. 

 

Be prepared to replace both the radiator and possibly the heater core. Sometimes the scale and rust is the only thing keeping them from leaking. That's a lot of corrosion. 

Edited by Chickenman

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How about this:

 

1. Remove the thermostat and replace the thermostat cover

2. Remove the the top (return) hose from the radiator

3. Remove the bottom hose from the radiator and secure a garden hose up inside of it sealing the hoses with duct tape.

4. Turn on the garden hose full.

5. Start the engine reving it to pulse the water going through the engine.

 

This way no scale enters the radiator  and the water pressure/flow is increased by the water pump.

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Posted (edited)

^ That'll work.

 

On second thought's, considering the amount of scale that you've found. I'd use the garden hose flush method first. Then run some HD Chemical Rad flush through the engine. Then repeat the garden hose flush a second time. Make sure that the heater temp switch is closed on the first hose blast. You don't want to plug it any worse with loose scale. Then turn the Heater core to full hot with the Chemical Rad Flush and second garden hose flush. 

Edited by Chickenman

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I did the garden hose flush method, without the radiator connected. Pulsed the motor a few times. Kept it up until it clear water was coming out. Then went about changing the waterpump.

Not much crud came out of the motor, and the water flows great through the block. Changed the waterpump as well. The waterpump was in decent condition when I pulled it out. Cast impeller and no visible pitting or anything.

Still haven't had a chance to test drive it as the rear suspension is currently in pieces. But I had another question, regarding the gauge sending unit. It is currently tapped into the thermostat housing, on the bottom side. So on the "hot" side of the thermostat. Doesn't that mean I'll get varying temperature readings based on load, regardless of what the radiator is doing? As the motor is revving, and producing more heat, the coolant takes that heat, directly past the sending unit, then to the radiator for cooling. Then after its cooled, it flows through the block to be heated and then back to the temp sensor. So no matter what it's seeing "fresh" hot coolant. Or am I missing something here?

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I did the garden hose flush method, without the radiator connected. Pulsed the motor a few times. Kept it up until it clear water was coming out. Then went about changing the waterpump.

 

Not much crud came out of the motor, and the water flows great through the block. Changed the waterpump as well. The waterpump was in decent condition when I pulled it out. Cast impeller and no visible pitting or anything.

 

Still haven't had a chance to test drive it as the rear suspension is currently in pieces. But I had another question, regarding the gauge sending unit. It is currently tapped into the thermostat housing, on the bottom side.  It is right where it is supposed to be.  The concern is with the aftermarket Temp Gauge - did the PO install  the sending unit that came with the gauge (correct) or did he just hook it up to the stock Datsun sending unit (wrong)?  This is why we asked for the temp readings.  So on the "hot" side of the thermostat. Doesn't that mean I'll get varying temperature readings based on load, regardless of what the radiator is doing? You are over thinking this, and falling down another rabbit hole. It is where the engineer designed it to be.  As the motor is revving, and producing more heat, the coolant takes that heat, directly past the sending unit, then to the radiator for cooling. Then after its cooled, it flows through the block to be heated and then back to the temp sensor. So no matter what it's seeing "fresh" hot coolant. Or am I missing something here?

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