560sl clogged radiator
 

I have a 1986 560sl (170K). It has been running at about 95-115 degrees unless I am going above 50mph. Two different shops have put the temperature gun on the radiator and showed me that it is hot in some places and cold in other places and diagnosing a clogged radiator. Since the radiator is only a few months old and was a new Behr, I took it back to the guy who installed it and told him what was going on. Problem, he refuses to admit that the radiator might be bad ("Behr doesn't make defective radiators, ever) or clogged. He is checking the thermostat (he put a new one in when he did the radiator), then said he was going to check the fan clutch (OK, can't hurt) but seems really resistant to check the radiator.

Does anyone have any experience with clogged behr radiators? I have heard that they cannot be rodded out because of the "turbulators" in the core. Can they be checked for flow rate without taking off the side tanks?

Any thoughts?

I have yet to see a defective behr out of the box. Seeing as the temp is order when you are moving I would look to the fan clutch. Did this guy flush the system/heater core before he installed the new rad?

Jonathan

560sl clogged radiator
 

Thanks for your reply.

He did flush at installation. Is this clog something that could have developed after installation? I really only started noticing it in January (two months after new radiator installed). What about the very hot and very cold spots on the radiator, does that make any sense?

Also, the car used to run at rock solid 80, now, even at speed, it is more like 90-95, so it is not really normal in any situations.

I'm just surprised to see it happen is all.. Were this in my shop this would be the first Behr that failed so soon in it's life. The unit should still be under warantee so it's not like your guy will have to pay for another rad.. I realise double work is never much fun, but it's not that bad a job. You may consider offering to work w/ him a bit on the labour the 2nd time around..

You can check the fan clutch your self, it should give you a decent bit of resistance when moved by hand. If it spins rather easily it's getting tired.

Jonathan

Could the clog have been from an incorrect installation? Could it be related to needing a valve job or something like that? I really appreciate your answers.

The clog can be caused by chemicals used to seal radiators,

Joyhn Roncallo

After I did some major work on my car my temp is higher than it was before. I'm worried that I disturbed the yin and yang going on in the fan clutch. It does warn in the manual to keep it upright, which I did virtually all the time - maybe if yours was left flat on the ground when (I assume) it was removed during the radiator installation, some "stuff" settled in the wrong place or leaked out. My clutch is 19 years old...maybe time to get a new one, but ouch on the price...

Although Behr makes an excellent product, I have gotten a couple of defective Behr radiators right out of the box. Based on the info you provided I'd say that that is what's going on with your ride. The shop that installed the rad should do the whole job at no cost to you. I'm basing this post on the experience of having installed hundreds of radiators. I'm not a DIY. Check my bio.


Post Script: Fan clutches are often mis diagnosed. There is a little pin and bimetalic plate on the front of the clutch that moves and ports viscous fluid in the clutch when the temp starts to rise. This makes the fan turn faster to cool the engine better. If the radiator is clogged, there is no hot air from the flowing coolant so the clutch doesn't sense a rising temp and doesn't speed up the fan. Mant mechanics see the fan isn't spinning fast enough and blame the fan clutch.

Good luck,
Peter

It is so funny that you should say that. My mechanic refuses to even touch the radiator to see if it is hot in some places and cold in other places when the engine is up to temperature. He just keeps saying it is impossible for a radiator installed in November to be clogged. And then he told me that I needed a fan clutch for $600+. We just had a screaming match on the phone and I had to threaten him to at least touch the freaking radiator with his hand to see if it was clogged. Whew!! I am one unhappy customer.