Jump to content
HybridZ

(75 280z) Cooling questions/Radiator suggestion....


Recommended Posts

So my car seems to have a overheating problem.. It seems to be losing coolant somewhere and I've replaced the main hoses and I'm not seeing any leaks when I park in under the card board... The car doesn't have a Reservoir tank so I'm not sure if its just evaporating and going out of the outlet hose that just drips on the ground..

 

As of right now I'm just using distilled water I've replaced some parts for the cooling system

 

Upper and Lower Radiator hoses

Thermostat

Water Temp Sensor

Flushed the system as well

 

 

So basically this is what happens, after a couple days if I run the car and I idle for awhile the temp raises about 3/4 to full now if I'm there for awhile it will go all the way to almost red but as I drive it goes right back to the middle...

 

 

After a week the Radiator needs to be filled with over Gallon and Half of water then I let it run for 10 mins with no cap on and squeeze the upper hose to try to bleed any air out...

 

Now sadly my heater doesn't work at all since I bought the car so I don't really know if I can bleed the car properly with out it or is there another way to bleed it??

 

Radiator Suggestions???

 

So I've saved up to buy a new radiator and I'm thinking of going with the Koyo Race 

http://www.koyoradracing.com/news.asp?id=61

 

It is pricey and I don't plan on doing any track but I do want an Aluminum radiator from a reputable brand..

 

Do you guys have any other suggestions for me that would just be better for daily driving??

 

Thanks to all that responded!!

Link to comment
Share on other sites

If you're strapped for cash, a cheap eBay champion one will normally work.

 

That being said, if you're loosing coolant at more than a gallon a week then there is something seriously wrong with your cooling system. I'd guess a deformed head gasket that is letting water into a cylinder.

Link to comment
Share on other sites

 The car doesn't have a Reservoir tank so I'm not sure if its just evaporating and going out of the outlet hose that just drips on the ground..

So basically this is what happens, after a couple days if I run the car and I idle for awhile the temp raises about 3/4 to full now if I'm there for awhile it will go all the way to almost red but as I drive it goes right back to the middle...

 

After a week the Radiator needs to be filled with over Gallon and Half of water then I let it run for 10 mins with no cap on and squeeze the upper hose to try to bleed any air out...

 

Now sadly my heater doesn't work at all since I bought the car so I don't really know if I can bleed the car properly with out it or is there another way to bleed it??

Why guess when you can know?  Strap an old milk bottle in there for overflow, drive it for a week and see what's in the bottle. 

 

I had a headgasket that leaked from the passenger side rear.  Coolant only, all external.  I've read of others with the same problem.  You'd probably see a rusty, coolant washed trail down the back of the engine if you had the problem.  And my 76 280Z has never needed "bleeding" or burping.  I think that might be an early 240Z cooling sytem issue.  Finally, if your cooling system doesn't work you might have the core bypassed.  Apparently this can cause problems by changing the coolant flow path through the engine.  Read up on bypass versus block-off of the heater core.

Link to comment
Share on other sites

Look at the weep hole of your water pump...that amount of coolant can leave while it's running....and since you are running pure water evaporate without leaving any traces whatsoever. In your case you may get lucky and see signs at the weep hole.

 

My 260 without a reservoir would burp a little after each highway run and stop. In 3,000 miles it lost 1.5 gallons, based on additions afterwards. I added water wetter to stop post shutdown spiking and burp over...and it stopped. Added a reservoir from a 78 and haven't needed to add coolant in years, just PH check twice a year.

 

Running straight water is not wise, it boils easily and affords absolutely no anti-boil properties...if your radiator cap is not 16 or 24#, chances you are running nothing more sophisticated than a Model-T Ebullient Cooling System, and adding water is what is required. Batch at least 20% glycol and the anti-boil properties improve quite a bit. Water wetter helps as well.

The dash gauge "at 3/4" is about as useless a quantification as you can get...you need a meat thermometer in the fins or a Non-Contact I/R temperature gun to nail down what your temperature is really doing.

Link to comment
Share on other sites

The dash gauge "at 3/4" is about as useless a quantification as you can get...you need a meat thermometer in the fins or a Non-Contact I/R temperature gun to nail down what your temperature is really doing.

Even better is a temp gauge with a sensor exposed directly to the coolant.

Link to comment
Share on other sites

You might also consider replacing your radiator hoses. I mean you can pull them off to inspect them, but if they're old and bulbous you may have blockage inside. I've had that happen. as tony said, some antifreeze will make a big difference. maybe your rad cap is rusted out and not holding pressure.  a radiator shop should be able to diagnose cheap.

Link to comment
Share on other sites

Bathed sensors aren't necessary for basic diagnostics. A meat thermometer from Wal Mart, or an Autozone $29.95 IR heat gun will work just fine to diagnose problems, if one actually exists.

 

If you span the gauge, 190F is NOT dead center like everybody thinks! 3/4 is at most 210F if that is really the reading, and with a 190 thermostat that is a NORMAL reading in some cases!

 

It's why I say run the 160F... Unless you ate very careful the nucleat boiling starts above 180 thermostat housing temperature...and then it's all over buddy!

Link to comment
Share on other sites

I would try to clean the radiator out by having it boiled and rodded out. Unless you know how long it has been since this service has been done, its pretty likely you would benefit from it. I had overheating problems and replaced one engine, two thermostats, rad hoses, rad cap, a belt and three head gaskets before i figured this out. It ran cool after the rad service. My rad was pretty much not flowing at all. Cost around $100.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...