Radiator Removal/Cleaning?

[Strife]

I just removed my 560sl's radiator for cleaning at a shop (it doesn't leak, and has the copper insert in the neck fix). The upper hose was super hot and pressured, the lower not so much - and my cooling isn't as good as it was. I've done the usual things (thermostat, right mix/right MB/Zerex G-05 stuff, no water pump/overflow bottle leaks, new pressure cap (tried 120 and 140, etc). Removal wasn't very difficult and now I know why pro mechanics remove radiators before working in this area (too bad previous owner's mechanic didn't, more bent fins towards the back than I'd like to see, none contrbuted by me). The front of the radiator was buggier and dirtier than I would have thought possible, given the condenser in front. The tanks aren't bad in terms of gray stuff, goo, or scale but who knows what's going on in the aluminum parts (PO used green Prestone for who knows how long).

A few questions:
1. What exactly does a rad shop use in terms of equipment or chemicals?
2. Does straightening the fins help (I'd say that maybe 1-3% of my fins are bent). Is straightening risky?
3. Do you think the shop can give me an assessment of the radiator in terms of an improvement before I try it?

[Strife]

I should add, that my symptoms are gets towards 100 at idle after highway driving and stays there, creeps up in highway driving at temps >85 F, which leads me to think it's a capacity issue. My fan clutch is newish (<1 year old, and has good turning resistance).

[GSMITH]

Strife,
Our 560sl's are the same year and have most of the same problems.
I had to replace my rad because the core was weeping coolent.
I only noticed it after topping of the resivor tank twice in one month.
Only had to add about a pint each time. I thought it was my bad
radiator cap. Never experienced this in 30+ years of DIY.
Funny thing was when I removed the upper hose part of the plastic neck
stayed with the hose. It was broken at the clamp and was somehow
staying in place under pressure. I consider myself very lucky.
Not so lucky was it looked like tranny fluid was getting into the coolent.
It took a few flushes till I got it cleaned up.
Now if I can only figure out where the overflow hose goes to after it
enters the fenderwell. The overflow hose is cracked so until
I figure this out I hooked up a hose to drain to the road instead of the
engine compartment. That reminds me I need to fix that.

Your "symptoms" are what I get with the same car with a new Rad.
It is mainly because of the excess load of highway driving and the
aux fan does not kick in till 100.

Now to try and answer your questions.

1. What exactly does a rad shop use in terms of equipment or chemicals?
They would need to remove the plastic tanks do an acid bath then run a
rod/brush thru the core. Acid is not really good for the aluminum and
finding tank seals would hard.

2. Does straightening the fins help (I'd say that maybe 1-3% of my fins are bent). Is straightening risky?
1-3% is not that bad. Not really risky but try to only bend them once.

3. Do you think the shop can give me an assessment of the radiator in terms of an improvement before I try it?
None of the rad shops I know of will even try to give an assessment.

I have a question for you.
My valve covers are black. Were yours???
Yours are very bright and shinny now.
Looks great. Wish I had them.

Gary

[Strife]

I did get it cleaned, but my radiator was in fundamentally good shape and the shop didn't think it needed cleaning very badly. But removing it gave me an opportunity to clean everywhere else. I've found virtually no effect on temps after cleaning.

I put in a copper pipe in the neck with plumbers epoxy and so far, this has been fine. Note that some, me included, think that breaking this neck may have to do with bad motor mounts, where the torque movement of the engine pulls on the (really tight when hot) hose and pulls on the neck, breaking it. I've replaced my mounts.

The overflow hose goes into an overflow bag between the fender and the plastic fender wheel well liner. The wheel well liner is very easy to remove and reinstall with the wheel off. There is a rubber seal involved. It's a good opportunity to clean the liner, under the liner, and treat the rubber seal while everything is off. I'm not sure if pre-86 SL's have this - I think it's one of the anti-corrosion improvements in the 560's.

The hose is a European diameter so it isn't going to be directly replaceable from a local car store - I ordered a direct replacement by mail from an aftermarket supplier.

The valve covers are the same as yours, except I removed the paint, sanded them, and buffed them. It's a lot of work and is somewhat time-consuming (the castings aren't that great) and a drill mounted buffer isn't really good enough to do this with-I have a somewhat underpowered, but cheap homemade buffing machine. This makes the car "unoriginal", (along with the other stuff I did did) but I really like the effect! If you want dress-up engine parts for this car, you have to make 'em yourself.

[GSMITH]

Well the summer heat is probrobly the problem.
Thanks for the info on the bag.
I will check the engine mounts when I fix the hose.
Did the replacement hose have the braided cover?
What do you mean by rubber seal?
Are you talking about the one the hose goes thru?
Mine is an 86 like yours. I have not had it as long as you so all of your
posts are very helpful. Thanks for documenting all of your hard work.
This winters project will be getting the AC vents to work so I can take
the stick out of the center vent and remove the towel that is cramed
in the defrost vents.

All of the polishing may not be original but looks great.
Wish I could see it in person but I hardly ever get out of Florida.

[Strife]

No, the braid is from a kit kids use on ricers to make their hoses look like very expensive quick-release racing hoses, I think it was $20 or so for the whole kit and I used only a few pieces from it.

The plastic piece in the wheel well has a rubber weatherstripping seal between it and the actual fender, it's important to reinstall it right to keep moisture away from the metal fender.

It's very difficult to check the motor mounts for crushing or damage without actually removing them; MAYBE an experienced shop mechanic could see the engine gunned or run with the brakes on to see if the engine moves more than it should. It seems like it should be possible to check for crushing with a ruler against a "known good" car. One of my mounts was completely broken, and the other was crushed; the car at the time was 18 years old, had 83k miles on it, and had been driven by "little old ladies" before I got it (so I don't think there was drag racing, stump pulling, etc in its past).