Radiator cooling capacity is dropping

[bartsscooterservice]

My oem radiator is not cooling enough, especially on the highway when driving above 75 mph for longer than 5 minutes it gets to hot, the needle on the dash goes almost all the way to the right.

I want to keep the Original radiator instead of an aluminium one, I have found a good radiator shop, but they charge 350 EURO for re-coring ex tax. Would this be worth it ?

The better aluminium radiators including shipping will be the same price or more, only the cheaper aluminium aftermarket radiators would be a cheaper option right now.

What would you guys advice ? Or is there anyone here who has a good oem 240z radiator for sale willing to ship overseas ?

Gr Bart

[siteunseen]

The orange car I recently bought was reading too hot for my comfort zone too. I read a older thread that Carl Beck commented on about putting a newer 280 radiator in 240s, said he started using them when they first came out in the late 70s. I bought one and already had a shroud and fan from a '79 ZX, couldn't get the ZX fan figured out though, the hub is recessed unlike the 240s which is all the way up front. Anyway, Blah blah blah and it cools great. Maybe get one and keep the original for later, that's what I did. Pictures soon.

http://www.classiczcars.com/forums/parts-swapping-s30/52672-easy-fit-new-radiator.html

amazon.com has one, Amazon.com: Ready-Rad 0433634 New Radiator: Automotive

Edited July 17, 2014 by siteunseen

[240260280z]

Is the pump working correctly. Sometimes the timing cover erodes behind the pump vanes.

[bartsscooterservice]

Yes the pump was replaced last year, everything seemed fine on the inside.

[tlorber]

I would first yank the thermostat, and see if you have the same results. Then check if your radiator needs to be rodded out. If you are saying that it worked at some point, that something has changed within the system. A full shroud will help at idle, but at 75 mph you should be moving enough air to cool adequately.

[Zed Head]

Don't forget head gasket and bad gauge as potential causes. Stuck thermostat is a good possibility. If you've been using modern antifreeze formulations with clean water it would be odd for the radiator to get fouled.

[EuroDat]

Hi Bart,

A simple test to check if its a blocked radiator is to drive it and when it gets hot again open the heater fully and fan at maximum. You should see the temperature drop suddenly and remain a little lower. Thats the extra cooling capacity in the heater.

Other checks would be to lossen the belt and check the pump turns freely. Check belt tension.

Another check is to drain some fluid from the radiator enough to expose the tubes. Check how many appear blocked. If more than a third appear blocked, you're not going to have enough capacity in the weather conditons we are now having here lately.

Some old shops will pressure test your radiator and if it appears ok, they can remove the bottom tank and clean the core. I have done it with a friend on his 1971 ford capri radiator. He used it for 6 years without problems and that was in 40degC summers.

Good luck

Chas

[siteunseen]

How free spinning is your fan clutch? Too easy isn't good.

[jonathanrussell]

I was chasing a "running too hot" problem with my dad's 78 280z. Since we were getting it running again after sitting for several years, I was willing to replace multiple parts while chasing the problem. I replaced thermostat, water pump, fan clutch, and radiator cap. Still, the car ran hot, though not quite as hot as what you described. My dad's car is very original with low miles so I wanted to try and save the radiator. the fins were all straight and visual inspection when looking into the top tank showed nothing obvious. Here is what I did that solved his problem.

I pulled the radiator. I plugged all hose holes except the cap. I filled the radiator with muriatic acid and let it sit full for 45 minutes. At 45 minutes, I emptied the acid into a bucket and rinsed the radiator for several minutes with water. I filtered the muriatic acid using a towel stretched over another bucket and re-used the acid to repeat the above process three more times.

Next, I re-installed the radiator, filled with 50/50 anti-freeze and water. His car no longer runs hot, even on 95 degree days in traffic.

Not saying this is your problem but if you have access to muriatic acid it is something you might consider trying. If you do try this, use gloves, wear sleeves, wear eye protection, don't pour water into a big bucket of acid (acid into water is fine), etc.

[Stanley]

If you warm it up with the cap off and see a good flow of coolant when the thermostat opens, you can rule out thermostat, water pump and radiator blockage.

Tried flushing it? I flushed the old brass one and plenty grit etc. came out of radiator and engine. Finally dumped it though.

I like the Champion Aluminum 3-row from MSA, not too expensive, looks good, and keeps it cool on the road. Plus it weighs a lot less, which affects shipping charge.

Edited July 18, 2014 by Stanley

[bartsscooterservice]

@ jonathan: my dad said about the same thing yesterday, flush the radiator with acid.

@ Stanley: I will have a look

@ Zed head: the oil pressure reads ok.

@ Chas: going to check the radiator today

Thermostat was changed last year, but it could be. I'm going to check a few things today.

Yesterday was a hot day around 28c, and on idle the needle basically got all the way into the red, only when driving on the highway it got a bit cooler, but still very hot like a little over 3/4. When the engine is running idle, I can feel the fan sucking the air when I hold my hand in front of the radiator, I assume the fan is working properly ? My first thought would be radiator, because simply it hasn't been replaced either flushed so far..

Edited July 18, 2014 by bartsscooterservice

[bartsscooterservice]

I would first yank the thermostat, and see if you have the same results. Then check if your radiator needs to be rodded out. If you are saying that it worked at some point, that something has changed within the system. A full shroud will help at idle, but at 75 mph you should be moving enough air to cool adequately.

Yeah.. it does cool best so far when driving at higher speeds, to me that looks like a radiator problem. I'm going to try to flush it out..see what it does.