Cooling woes -- fixed - PeachParts Mercedes-Benz Forum

LUVMBDiesels · #1 07-27-2007, 05:42 PM

The SD was running hot with the temps going up to about 95 degrees. I did two citric acid flushes and each time the temps would go down to 85 for about a week and then climb back up. I purchased and installed a 75 degree thermostat and was filling the system again when lo and behold the radiator sprung a leak. I guess all the citric acid finally removed the rust that was holding the radiator together

Well to make a long story short, I ordered a new radiator from radiator.com ($200.00 for a 300SD radiator) and it came today. It took all of 34 minutes ro remove and replace the radiator. Talk about EASY! If I had know it was that easy I would have replaced the darn thing and forgotten about the citric acid flushes.

The old one was completely dirty and clogged up. Now the temps are nice and cool. I am thinking about putting the 80 degree thermostat back in.

If you are running hot, don't worry about replacing the radiator. It had to be the easiest thing I have done so far. I think MB made them that easy because they KNEW they would fail.

Uncle Possum · #2 07-27-2007, 08:23 PM

My 82 SD runs up to about 95 here in Vegas with the AC on and 115 degree heat outside. I had thought about flushing, changing thermostats, etc. but if you can replace the radiator for $200, that sounds like a much more reliable fix.

I went the website, and the Online Chat person couldn't find an exact match for my car. Do you happen to have the part number you used?

LUVMBDiesels · #3 07-27-2007, 09:01 PM

The part number for the 300SD is 473PL Description is MERCEDES 300 SD 1981 I-5 3.0L 183ci 81-85

I spoke to Tony Alimenti 215-969-8838

Hope that helps

P.E.Haiges · #4 07-27-2007, 09:28 PM

Uncle,

If your temp only goes to 95*C in 115*F weather, there is nothing wrong with your cooling system.

If it ain't broke, don't fix it.

P E H

#5 07-27-2007, 09:40 PM

Quote:

Originally Posted by P.E.Haiges

Uncle,

If your temp only goes to 95*C in 115*F weather, there is nothing wrong with your cooling system.

If it ain't broke, don't fix it.

P E H

I agree, I have a new radiator and that's about what mine would do in 115F. I don't think you are going improve it much more.

LUVMBDiesels · #6 07-28-2007, 11:23 AM

I have been running on the new radiator with no thermostat to see what temperature the engine would naturally go to. Even sitting in traffic the temps NEVER got above 75 degrees. My suggestion to everybody is to replace that radiator. After 20 plus years they are just not going to do the job anymore.

I am going to put the thermostat back in today and see what happens to the temps.

tangofox007 · #7 07-28-2007, 12:04 PM

Quote:

Originally Posted by LUVMBDiesels

I think MB made them that easy because they KNEW they would fail.

Or they knew that a high percentage of owners would not maintain their cooling systems properly!!!

P.E.Haiges · #8 07-28-2007, 01:07 PM

LUV,

If I have no overheating problems or leaks, why should I replace a perfectly good radiator?

If is ain't broke, don't fix it.

Was the replacement radiator copper or aluminum?

P E H

a2t · #9 07-28-2007, 03:57 PM

its not THAt easy on my OM603 but I do agree with repl a 20yr old rad. Glad it was easy task

Ive heard (on my model, anyways) only to use Behr unit as some aftermarkets are not very good. What brand did radiator.com sell? I bought one from them for my 92 Corrado SLC and its still working great, wasnt OEM brand though.

And do put that t-stat back in(new one!). Engine needs to be at 80-90C to perform correctly. Seems like with all that front area, enough cooling air is present. I can run my Corrado without one since there isnt much frontal area to cool, and that radiator looks more like the benz trans cooler than a coolant rad!

PE - some of us do preventative mtc on our cars since we drive wife/kids on 3 hr + trips. Better to be safe than stranded at 1am in backwoods of redneck GA. I seem to recall our discussion about changing out fuel prefilters regularly, you had same "if it aint broke dont fix it" stance. You'll be happy to know since my Frybrid install the clear filter went bye bye. Sorry I didnt save the old, clogged ones for you though

Douglas.Sherida · #10 07-28-2007, 04:58 PM

Congratulations on solving your problem.

After a month or so of troubleshooting I also solved the cooling problem on my 84 300TD turbo. It turned out to be the new OEM thermostat (Behr 80 C).

I had done a thorough descale and checked everything (down to pulling the waterpump for inspection). Throughout the process I also managed to produce a leaky radiator, but in my case replacing the radiator didn't solve the cooling problem. I only mention this because the radiator is the most expensive part of the cooling system. The full story is here: http://www.peachparts.com/shopforum/showthread.php?t=193569

You are absolutely correct, in that anyone who knows which end of a screwdriver to use can replace a radiator.

LUVMBDiesels · #11 07-28-2007, 05:09 PM

The replacement radiator is a Nissen. it is aluminum with the plastic tanks just like the OEM, except that the neck is supposedly stronger. It has a lifetime warranty from rad.com.

As far as PM goes... I bought the car two years ago and have replaced:

Fuel filters - both of them every six months
Oil filters - Every month
Oil every two months synthetic
Air filter - every six months
Brake fluid flush once a year

etc.
I run about 160 miles a day in commuting and do not want the car to break down 80 miles from home

The PO ran the car on green coolant so I had replaced the water pump, all the hoses, etc. I also connected a pipe to the drain plug and did multiple flushes. It was after the second citric acid flush that the radiator failed.

If you have the complete history iof your car and it has only run Zerex or MB coolant and it has been citric acid flushed every two years and it is running at 85 degrees then I guess you can keep your 20 year old radiator.

You can also keep your old oil filters, etc after all if they are not completly clogged you can still filter some oil with them...

I was letting people know how quick the swap was and that it was not something that you need to go to a shop for.

I will be installing the thermostat once I verify that there are no leaks and will refill with Zerex G05 at that time. I bought the coolant some time ago, but did not want to put it in until I had the system running as well as it could.

Uncle Possum · #12 07-29-2007, 01:41 PM

The PO ran the car on green coolant so I had replaced the water pump, all the hoses, etc. I also connected a pipe to the drain plug and did multiple flushes. It was after the second citric acid flush that the radiator failed.

My car also came with Green coolant. The PO pointed out that he had the radiator flushed not long before he sold it to me. Now I wonder what he used, and if he did more harm than good.

What color is the Zerex G05?

P.E.Haiges · #13 07-29-2007, 01:59 PM

a2t,

The original radiator in my '80 300SD is 27 years old and working fine. Of course it has a copper radiator not AL.

AND it has Evans waterless coolant in the cooling system with the radiator cap kept loose so there is no pressure.

I believe this is a greater preventative of a breakdown due to coolant loss than a new radiator. It costs less to.

P E H

P.E.Haiges · #14 07-29-2007, 02:07 PM

LUV,

I consider your maintenence schedule ridiculous. Even MB doesn't recommend changing filters and oil that often. What a waste of good synthetic oil.

Have U figured the yearly cost of your excess oil and filter changes?

Douglas.Sherida · #15 07-29-2007, 03:47 PM

Quote:

Originally Posted by Uncle Possum

What color is the Zerex G05?

Yellow, sort of like rusty water.