Remedying a warm 300D Before Atlanta Summer - Page 3 - PeachParts Mercedes-Benz Forum

BillGrissom · #31 03-24-2018, 05:06 AM

If the radiator physically fits, you could use it. The pressurized reservoir seems a bad idea anyway. Ebay has blingy overflow bottles.

MongooseGA · #32 03-24-2018, 04:50 PM

Quote:

Originally Posted by BillGrissom

If the radiator physically fits, you could use it. The pressurized reservoir seems a bad idea anyway. Ebay has blingy overflow bottles.

Mount an over-flow and ditch the expansion tank altogether?

Well, now that I think about it... I guess that would work.

What's the point of an expansion tank vs overflow tank anyway?

leathermang · #33 03-24-2018, 06:49 PM

Quote:

Originally Posted by MongooseGA

Making sure I follow:

If the system is sealed and under pressure, it will raise the boiling temp of the coolant? So theoretically the pin holes would lower the boiling point?

Correct.

leathermang · #34 03-24-2018, 06:54 PM

I am not sure..
but be sure to check on the overall design of the radiator ' over flows'
as some may come off the cap tube...and some may come from lower ..
the best system will allow coolant to be pulled back into the radiator when the system cools....much will depend on the placement of the pressure ' gasket' on the cap... if the route to the catch container is above that spring loaded gasket it is just an overflow system.. and can not suck coolant back into the system to fill it up.. having no air in the coolant system greatly improves the cooling performance. ... The catch can will need to have a pressure cap for the system which allows the coolant to be pulled back in...

BillGrissom · #35 03-25-2018, 09:05 AM

Like leathermang said. Many U.S. cars thru the mid 1960's just had a tube which vented coolant to the ground, if it overcame the radiator cap set pressure. They later added an "overflow bottle" or "catch can". In most I have seen (thru today), the overflow has a tube which goes to the bottom of the reservoir, which lets it suck coolant back into the radiator. Thinking about it, there must be a check-ball in the rad cap to allow that. In these systems, you need fill new fluid only in the reservoir, though I still open the cap to check the radiator itself. Verify the purty Chinese aluminum reservoirs on ebay are plumbed similarly.

MongooseGA · #36 03-25-2018, 11:46 AM

Well, I gave this a shot. I'm familiar with the overflow tank as my LX470 uses one. Simple design.

I went to fit the new rad yesterday and found that dimensionally, it is identical, however the post and drain plug on the bottom, and the tabs to secure the rad to the front crash bar (the little clips) are all shifted like an inch from where they should be. To make it work, I'd have had to cut off the tabs that are used to clamp the oil cooler to the rad. It's just barely off enough that it won't work. I'm not looking to start cutting up on vital components.

Bummer.

So, I just ordered a new, correct Nissens. They're a thicker core anyway so now I'll just consider it an upgrade.

I also replaced my fan clutch with a know good one from ebay. They both had pretty similar resistance in the hand, so we'll see.

strelnik · #37 03-26-2018, 09:27 AM

Quote:

Originally Posted by MongooseGA

Well, I gave this a shot. I'm familiar with the overflow tank as my LX470 uses one. Simple design.

I went to fit the new rad yesterday and found that dimensionally, it is identical, however the post and drain plug on the bottom, and the tabs to secure the rad to the front crash bar (the little clips) are all shifted like an inch from where they should be. To make it work, I'd have had to cut off the tabs that are used to clamp the oil cooler to the rad. It's just barely off enough that it won't work. I'm not looking to start cutting up on vital components.

Bummer.

So, I just ordered a new, correct Nissens. They're a thicker core anyway so now I'll just consider it an upgrade.

I also replaced my fan clutch with a know good one from ebay. They both had pretty similar resistance in the hand, so we'll see.

I made a quick run-though of all these posts and no one mentioned or suggested any kind of flush. Has a regular or a citric acid flush been done on this car?

MongooseGA · #38 03-26-2018, 06:18 PM

I have not flushed it, no. I have looked into it. I hadn't planned on it, but it's an option.

leathermang · #39 03-26-2018, 10:13 PM

On the thicker core...
given that you are worried about the working temp rising
the thicker core is a MUST....

MongooseGA · #40 03-30-2018, 03:38 PM

New Nissens radiator arrived yesterday and within 20 minutes I had it dropped in. Today was her first day back on commuting duty. All was well on the way in, usually it's the warmer afternoon that brought on higher engine temps. New fan clutch, new rad, new thermostat, new expansion tank, new rad hoses, and monovalve delete. I hope we're in good shape!

vstech · #41 03-30-2018, 06:00 PM

All sounds good.

Now may be the time to perform a citric acid flush.

You could get a pump and circulate between upper and lower hoses so you don't need to acid dunk or particle fill your new radiator...

MongooseGA · #42 03-31-2018, 07:48 PM

Quote:

Originally Posted by vstech

All sounds good.

Now may be the time to perform a citric acid flush.

You could get a pump and circulate between upper and lower hoses so you don't need to acid dunk or particle fill your new radiator...

I'm still undecided on the flush. I'm reluctant after reading stories of the flush ending up being detrimental, springing leaks etc. I know it only shows to point out an already-bad system but...

The car did fine yesterday. Operating temps stayed 85-90*, and when in rush hour traffic it came up to maybe the upper 90s. Seems like that's about spec for what these should be running.

leathermang · #43 03-31-2018, 08:22 PM

If you are worried about the citric acid...
think about just doing clean water flush....
then put in your new and properly mixed water and antifreeze....

My Stuff Owns Me · #44 04-01-2018, 01:20 PM

Quote:

Originally Posted by MongooseGA

Hey all,

I've been daily driving my '85 300D for a few months now after a bunch of work done.

Lately, I've been noticing the engine temp creeping up over 100* when sitting in Atlanta traffic. When the car is moving, temps stay right where they should around 80-90*.

I have deleted the monovalve and aux pump with the Klima Design Works kit (highly recommended, I'll do a review later), replaced the coolant reservoir, replaced the thermostat. I did not 'burp' the coolant after the most recent drain and refill, not sure if air in the system can work its way out or if that would be a factor here.

When the temps creep up, blasting the cabin heat does in fact help keep the temps from climbing much higher. Unfortunately, this is a terrible option when the outside temps are hitting 90-100*F+

I did notice a tiny tiny pin hole at the upper hose neck of the original radiator. I have a replacement BEHR to go in but hadn't swapped yet as there hadn't been a need. Guess I'll be doing that now.

I am unable to get out of the car to check if the AUX fan is spinning when the engine temps are climbing and have yet to reproduce it in my driveway. I'm an idiot when it comes to testing electricals but I do have a multi-meter. Any thoughts as to how I can test my fan or its connections? I'm thinking I'll oven/hot water test the new(installed) thermostat when I drain the coolant and swap the rad. Any other thoughts?

I realize that I am late to the party but wanted to add my two cents worth.

You don't say if the AC is on or what the ambient temperature is.

I'd say that 100 deg is not too unreasonable but that that depends on the above.

My Stuff Owns Me · #45 04-01-2018, 01:26 PM

Quote:

Originally Posted by MongooseGA

Probably a dumb question, but would that mean that it would only turn on if the AC compressor is engaged?

Another dumb question: I flushed the original radiator out of the car and stupidly left the nipples for the trans cooler uncovered allowing water in. I just had the trans rebuilt, definitely not willing to risk that $3k job over a $200 rad. Could I flush the trans cooler with some DEXIII before hooking the part back up while I wait for the new unit?

The compressor on and refrigerant temp (receiver/drier metal, actually) above 62 C. If you are using R-134a then that is too high for good cooling. Lower temperature switches are available. These can be swapped with out refrigerant loss. The fan will run after the compressor is turned off until metal of the receiver/drier where the switch is mounted drops below approx 62 C.