Mercedes-Benz Forum banner

Radiator dripping

5K views 46 replies 9 participants last post by  richkay 
#1 · (Edited)
Install new rad but leave oil cooler in place??(Was Radiator dripping)

I noticed a small amount of fluid on floor up front under the SL.

On passenger side, it was just a small leak from hose that was fixed by tightening clamps.

On driver side, it was dripping off bottom of lower tank. (Tanks are brass on early cars). I moved fan shroud out of way and checked front as well, but no sign of fluid higher up. I dried off all signs of wetness and ran engine a bit. Then watched. Again no leak in core area, but wetness develops under upper lip of tank below core.

There doesn't seem to be any kind of seam that could leaking. Maybe a pinhole? Picture attached below.

I was going to take car to an MBCA event up in rural cottage country this weekend (about 2hr round trip) but decided to not chance it. Not sure just what I will do.

One possibility is to use a rad stop leak and see how it goes.

Other is to visit Pat's Radiator. They have capability of doing a repair, but may want to replace.

Not sure if brass tanked replacements are still available. (none of the usual aftermarket sites list one for a 72 350SL - Some list plastic tanked rads for 1973) Car also has an oil cooler which I recall was not available back when Lfedje was looking for one. If they have to remove rad for repair, perhaps they should recore at same time? Maybe eliminate oil cooler which later cars didn't have?
 

Attachments

See less See more
1
#3 ·
Based on where the leak is located( brass tank to fin array seam) I believe that it is mechanical/thermal stress related. Thousands of hot /cold cycles combined with chassis flex from being on the road. Based on my experience alone, I would avoid "stop leak" type products. At a minimum, these products will need to be " boiled out" ( thoroughly cleaned and flushed ) before the radiator can be repaired. A good radiator shop should be able to drain and resolder the seam often without removing the tank. I have previously done this successfully. Not on an MB but on several old GM's. The key is to make sure a wide area of the seam is well cleaned and to use good flux and solder. Good luck and travel safely. Tony V.
 
#13 ·
A good radiator shop should be able to drain and resolder the seam often without removing the tank. I have previously done this successfully. Not on an MB but on several old GM's. The key is to make sure a wide area of the seam is well cleaned and to use good flux and solder. Good luck and travel safely. Tony V.
You got me thinking about how these rads are put together and whether I could fix the leak myself. To solder it, I would need to pull the rad and invert it. Otherwise something like JBWeld might work although pressure could be a problem.

For a start, I am going to clean up that area with a fine brass brush and get a closer idea of where leak starts.

Saw video on Youtube on how these rads are assembled. This could be where my leak is and how it could be fixed.
 

Attachments

#4 ·
Ya know you are going to get it fixed. You are not going to put aluminum and plastic on a Classic. Leak seal is a band aid and "will" "F" up (clog) your heater core. ask me how I know. Find a pro, (an old timer) not just a guy who retired and bought a Radiator shop for something to do as a side line.

just my 2.8 cents
 
#7 ·
Ya know you are going to get it fixed. You are not going to put aluminum and plastic on a Classic.
You are of course right! I will go and see the rad shop. They used to be a small shop but the sons took over and they are now a bit too big for my likes. But they do know their stuff (so long as you own a Ford or GM :) )

Djenkas idea will probably work for me for a long time if I just drive around town. I just don;t want a breakdown out in the boonies!

Thanks to all for the input.

PS: I read Cush's thread - he had same rad as I have. Also recored.
 
#5 ·
More that 10yrs ago when i got my car, a good few African summer months later, she surprised me with a sudden temp spike . Missing 10l of coolant will do that. Luckily i did see it as it unfolded and no damage occured.
FFWD 10 yrs, the same pinhole is there, actually a few of them. It leaks only if temp approaches 100C deg and it dries immediately so little sign is there. Nothing to worry if you check the fluid level regularly and no major loss occurs between. Bit it ain't heartache to go better with time.
 
#6 ·
I had mine re-cored as I, too, have the brass tanks.
The advantage now, is the re-cored rad is more efficient due to more rows and more cooling fins.
In theory, they can be re-cored virtually forever.
Cost 10 years ago here in Barrie....$305.00.
Personally....I wouldn't use the "stop leak" products. Who knows where that stuff will get trapped and it really is more of a band aid or emergency product.
 
#9 ·
Well it is a very small leak and seeing car is not driven much, even less when parked with little pressure on leak.

I will get shop to advise, but I could remove rad as a Fall job and have shop do repair. On the other hand they R&R rads daily, so probably not much cost compared with me struggling with it and having to dispose of coolant.

One thing I noticed when I was under car - one lower bolt for the fan shroud was missing. I found a spare that was same as top bolt, but could not get it to screw into the clip. Are those bolts the same size (1972 model)
 
#10 ·
My radiator had a tiny leak that I lived with, but it did a very poor job in cooling, leaving the temp around 225 F (and up when stuck in traffic). I had been recommended to have the radiator rod-cleaned. But considering the cost of having someone restore it, and the logistics involved, I decided to pamper my car and just buy a new radiator. It was bit hard to find, and to negotiate a good price for the radiator (part 107 501 09 01). I think the new one, which is a Behr, is also brass (see photos), at least the bottom and the top, but overall it is a bit lighter than the old one, so maybe it is not brass inside.

The radiator is now installed, and my car runs at just over 175 F on long rides as in stop-and-go on warm days in the city. Given my car is otherwise in good condition, I felt it was worth spending the money, and be worry-free in cooling for the next 45 years. However, I kept the old one just in case.

I am told the oil cooler (on right side of the radiator) is no longer available as a new part.

Cheers,
P107
 

Attachments

#12 · (Edited)
But considering the cost of having someone restore it, and the logistics involved, I decided to pamper my car and just buy a new radiator. It was bit hard to find, and to negotiate a good price for the radiator (part 107 501 09 01). I think the new one, which is a Behr, is also brass (see photos), at least the bottom and the top, but overall it is a bit lighter than the old one, so maybe it is not brass inside.
A new rad would be nice considering old one is now 45 years old! Provided new one is as good as old one!

I have seen them listed on US OE parts sites, but they are expensive, especially when converted to C$ and shipped!

I found a source in Toronto that says they can supply a Behr 1075010901. But I could not find one on the Behr Hella site! Waiting to get confirmation and a price.

Re oil cooler, later cars don't have them, so I guess we could just put a bypass loop on and eliminate the cooler if they fail.
 
#16 ·
Could the supply of new radiators (1075010901) for the older 107's be running out? One supplier (Euro Part Imports) I contacted had it on the website, but it turned out none was in their inventory. Maybe your supplier in Canada bought up the last stock? I was told the radiator is a Behr whether in Behr package or MB package. I got mine from the Classic Center, as it was the only place I could find it. If indeed they are all the same, then going for the supplier with lowest price should be OK.

Cheers,
P107
 
#17 ·
Could the supply of new radiators (1075010901) for the older 107's be running out?
If the source I have found is legit, maybe I should buy one anyway!

After more checking, I confirmed today that the drip is from the seam just at one corner near the drain plug. Probably easy to repair once rad is out. I could probably fix it externally with JBWeld WaterWeld. https://www.jbweld.com/products/waterweld-epoxy-putty Good to 300F and sets in presence of water.
 
#20 ·
Of course, removing the radiator will make the job much easier, but I have successfully resoldered the exact seam location several times without removing the radiator. There are several key steps. The radiator must be completely drained. Any residual liquid will keep the tank from reaching the proper temperature to allow a good bond for the solder. Clean area for soldering is essential. Any contamination will compromise the joint. Top quality flux is essential. I prefer the paste type as it is easy to apply cold and you can watch the migration as it heats up. If you can find some NOS "lead bearing solder" ( the newer " no or low lead solders don't work as well in these applications) use that. 70/30 is best if you can find it. After you have cleaned the area, apply flux to the seam and about 1/4" around the are where the solder will be applied. Start applying heat about 1/2" way from the compromised seam area. Slowly move to the area of the seam and watch the flux migrate toward the heat. As soon as you see the flux start to be drawn into the seam by capillary action apply the solder to the seam. As the solder melts it will be drawn into the seam. As soon as it starts to drip or puddle remove the heat. Although it is easier to solder a leak on the bottom of a radiator if it is removed;capillary action will wick the solder into the seam even if the radiator is left in place. Good luck and I hope you are able to do the repair as it will save some time initially. Obviously, new or recore is the best long run solution. Regards to all, Tony V.
 
#21 ·
Thanks for the tips! I have done quite a bit of soldering in my time, but never good at it. Maybe because of the early plumbers alcohol blow torches we used back then!

I have bitten the bullet and bought the new Behr rad. Couldn't resist at the price C$390/US$285. Present one at 45 yrs old, probably due for retirement anyway! Seller tells me the rads they have are NOS.

Once out, I will repair the old rad and keep it as a spare.
 
#22 · (Edited)
Separating oil cooler and Rad

Been reading up on removal of radiator. So far just had a quick look at rad in car. I see those springs on side. Do they just pull back?


In a couple of earlier posts, it was mentioned that there are bolts that hold the rad and oil cooler together and they need to be removed before rad will come out. One post by heiferdust said that the A/C condenser is in the way on his 280SL and needs to be unbolted and moved forward in order to access those bolts.

Is this what others have done on early 350/450SLs?

heiferdusts pic
 
#24 ·
Can't help. I just loosened the cooler bolts pried the cooler over and pulled as one unit.
That is a help because that is how it works. The oil cooler bolt holes are horizontal slots that allow the oil cooler to slide closer to the radiator which relieves lateral pressure on the rubber mounting buffers in the frame.

The spring clips are common to lots of MB models. You push the tab down and they simply pop out.

Accomplish these two steps and you will be able to wiggle the radiator up and out.
 
#25 ·
Thanks Rowdie/Brad.

Brad. Do I understand that you too removed the rad & cooler as an assembly? Having had to disconnect the oil cooler hoses first.

I was hoping to leave the oil cooler in place , as Nobby, Peter 107's mechanic and heiferdust did. Hate to disturb those connections if I don't have to.
 
#29 ·
Thanks R & B. I will probably get the radiator this weekend, but because leak is very small, no rush to install. Just for fun I might see if it's possible to move the condenser enough to slide those bolts out. Probably not, so then back to plan A!
 
#30 · (Edited)
Got the rad today. Looked fine, except there seemed to be a repair on top tank. Looked like either a solder or epoxy build up. Not very well done and painted over satin black, some of which had run!

I started scraping build up with a knife blade (first pic) then with sandpaper and a bit more scraping (2nd pic).

Lo and behold, a star shining through the blackness!

Seems like I received a disguised OE rad! Elsewhere it says Behr and has the MB part number stamped in. Sticker in pics also has part number, plus some other numbers.
 

Attachments

#32 ·
The Classic Center told me that a MB OE radiator is a Behr, just packaged in a MB box. With the price you paid, seems you hit jackpot!

Let us know if your normal running engine temperature changes with the new radiator. On my car, it fell to a constant just-over 175 F, and it seems that my engine runs smoother at that temp.

Cheers,
P107
 
#34 ·
I do feel a bit like I hit the jackpot! But maybe not so much in that there is little wrong with my existing 45 yr old rad! Just that little drip!

My car currently runs quite cool. Might have something to do with our milder weather and lack of stop start gridlock in our smaller town. Only time I had high temperatures, was when ignition timing was retarded. I don't really expect lower temperatures with new rad.
 
#36 · (Edited)
Went out and tried to envisage how heiferdust got the condenser over far enough to allow access to those bolts. It is a different car and maybe the condenser is different. It looks like the aux blower would have to come off first, then all 4 condenser brackets. Then push condenser toward driver side and forward at passenger side. This 'might' just provide enough space to allow the bolts to be pushed back through the coils at end of condenser. But not so sure about that heiferdust's condenser looks different at that end from mine. (was going to post picture of mine, but little Canon camera just gave up ghost :( )
Tried unbolting a/c condenser and aux fan but could not get it to move very much. heiferdusts' 280SL must be different. Gave up on that idea! I will just have to disconnect the oil cooler lines. They show a little oil where the flex part is swaged to the solid metal part. Hope I don't need to replace those (C$200+)!

Once rad is out, I could eliminate the a/c condenser (a/c doesn't work) But it does keep bugs out of rad! What do you think?
 
#38 ·
The A/C condenser can't be removed unless the radiator is removed first. I was just trying to move it enough to get at the bolts that hold the radiator and oil cooler together.

Didn't work for me, which means that I will have to remove and re-install cooler and rad as a unit.

Have other stuff on my plate, so won't likely get to this for a while.
 
#39 ·
Today I received a post card in the mail. It was from our local garage. It said We miss you!

In a weak moment, I decided, what the heck, I will get them to install my new rad. I went as far as backing the car out of garage. Then thought, kids that were supposed to come this weekend have cancelled. Weekend is free! Need a project! Plus save at least $250!

Anyway, I started and so far have rad out!

Good tip from Brad to slide oil cooler toward rad before trying to lift it out.

I am going to replace the transmission cooler hoses and that is only problem I ran into. I can't get the back end of one of them off the hard line. Not enough leverage on open ended spanners it seems. Anyway, sprayed it with PBlaster and will try again on weekend. May need some heat, but hate to use open flame near engine.

Not sure if this happened after I removed rad, but oil cooler seems to have had something leak over lower exterior. The lower oil line always showed a bit of leakage and could have been spraying out. Hope it's not the cooler itself. They are NLA! I need to figure out how to do a pressure test.


Other thing I noticed, was how dirty the front of the rad was BEHIND the A/C condenser. That blocks effective airflow yet no way of accessing to clean other than removing rad!

I think, seeing A/C no longer works, that I will remove the condenser so that at least rad can be accessed for cleaning. Also wondering if some type of removable bug screen could be installed in front .
 
#40 ·
Found some odd things while doing this job.

First of all, EPC shown the "drain" plug at the top of the cooler. Manual says to disconnect lower oil line to drain?



I guess they must have changed their mind!

When starting to reassemble, I looked at the drain plug which I had put aside. Picture below. It had no washer. And EPC doesn't show a washer. Noticed it gets tighter as it is screwed in. Enough to be concerned seeing it is a steel plug into aluminum threads.

Anyone have a washer on this drain? Looks like it may rely on tapered thread for sealing. So maybe just some pipe dope on thread? (One of plugs in diff is like that). But why is it cut away just under the head? Almost looks like it is for an o-ring. But no such part on EPC.

 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top