Radiator with twin fans

[NZurban]

Has anyone replaced the stock radiator in their diesel truck with a new aluminum radiator and double fans? My Suburban overheats at idle, fine on the open road.

 

[QBuff02]

There could be many causes to it overheating at an idle. Check the entire cooling system out first- coolant level, hoses, thermostat, radiator, fan belts, pulleys and fan clutch especially. It could even be related to rpm of the engine. But if you think most is ok, a slow turning fan clutch (that's failed or failing) will not draw enough air through the radiator at idle and can cause an overheat issue. What are the symptoms and when did it start?

 

[Arkansas_V8]

^Absolutely where I would start^. I Dont have a diesel, but I do have two 13" electric fans and a big diesel radiator. It made a big difference. I do alot of water crossings here in Arkansas, nice to shut the fans down when I need to. I got cheaper ones, so they draw a bit of power, so get some good name brand fans.

 

[Craig 85]

Two things to check is make sure the clutch fan is working correctly and maybe have your radiator rodded out. Maybe there's some build up in there causing a blockage.

I've never had a diesel square body, but on the 4 I've had with big blocks and a tow package, they've had this factory pusher fan IFO the radiator.

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[bucket]

Here's another vote for checking out the fan clutch. It's likely failing or has failed.

 

[Doppleganger]

My 85 has the pitiful 4 blade fan on it....doesn't cool much either. I have heard 85's were the last year for the 4 blade and that the later 5 (or 6?) blade moved alot more air. Course, mine's also the original 34 yr old setup too and has been bypassed and cobbled to beat the band. Going to go 3 or 4 core with 2 fans myself me thinks.

Have also heard the pusher's work better for AC. Dunno.

 

[NZurban]

I've had the Suburban a few months now, used mostly to tow our 5m boat. Out on the open road at about 55mph the temp gauge sits about 180, when we get into town and have to slow down to urban speed the temp quickly goes up to about 200-210 as we get closer to the dock, it continues to rise.

Once at the dock to unload the boat on the slipway it goes way up to 240 and coolant will "boil" out of the top house after the thermostat into the overflow bottle. I'ved swapped out the thermostat for a cooler one and also drilled a small hole in it to combat any air blocks in the system.

I had the radiator out of the vehicle a while ago and there was quite a bit of rust coloured gunk in the bottom that flushed with a hose. I've tested the water pump, it pushes a good amount of coolant around.

The radiator currently in the vehicle is an appropriate size but is not the correct one for the truck as there is no radiator cap on the left side. A previous owner has installed a piece of pipe with a radiator cap built in on the opposite side just after the thermostat.

So I'm happy the water pump is able to push coolant around at speed but as soon as there is less air passing through the radiator the temp goes up. The fan seems to spin ok, it only moves a little when spun by hand. How do I test the fan?? What is "rodding" the radiator?

I've done lots of searching online and it would appear something like the Spectra Premium 850 is the correct size radiator. I would like to get a full aluminium radiator but no one seems to make one that big.

 

[trukman1]

Be sure to check to see your timing is correct. Incorrect timing can cause over heating.

 

[Craig 85]

What is "rodding" the radiator?

Basically it's having it rebuilt. A radiator shop will remove the tanks and shove a rod down each tube to clear any blockages/corrosion. They make any other repairs, put it back together and repaint it. It cost me about $160 (California prices) to have mine done, but that included a new filler neck.

I know the diesel radiator is wider than mine (BBC 4 row). The diesel one should go to the holes with the threaded inserts you see at the bottom of my picture. I know @Frankenchevy has a diesel radiator in his truck. He might be able to post the correct set up.

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[Billy]

Has anyone replaced the stock radiator in their diesel truck with a new aluminum radiator and double fans? My Suburban overheats at idle, fine on the open road.

Google the square body Volvo relay mod. Works great for me

 

[bucket]

The symptoms scream 'lack of air flow'. All signs point to a bad fan clutch.

With the engine running warm, shut it off. Pop the hood and see how easily you can spin the fan by hand. If there's little to no resistance, the fan clutch is bad.

 

[Shorty81]

The symptoms scream 'lack of air flow'. All signs point to a bad fan clutch.

With the engine running warm, shut it off. Pop the hood and see how easily you can spin the fan by hand. If there's little to no resistance, the fan clutch is bad.

X2

 

[NZurban]

Anyone know the correct AC Delco replacement part number for the fan clutch? Down here in New Zealand they don't grow on trees. The wagon is an '84 K20 Suburban

 

[Craig 85]

ACDELCO 154911 {GM 19189703, GM 89001894} Professional Info
Standard Rotation; Severe Duty Thermal Fan Clutch

From Rockauto's web site for a K20 with a 6.2.

 

[NZurban]

I took the fan clutch off today, spun the bi-metallic strip round to the next hole to lock it manually. Going to see what happens next time I take it out. Hopefully it won't overheat and we'll see if the fan clutch is the culprit.