when to replace a radiator
 

A change to Zerex fluid in my 84 300 SD and all of the flushes prompted a bunch of leaks in my original (I am guessing) cooling system. I have replaced the gasket on the water pump housing, the water pump and its gaskets, the thermostat and its gasket, a couple hoses and the auxiliary reservoir, which had a hairline leak.

Now, when I look at the back of the radiator (which does not yet leak) the metallic grate on the back of it seems to be disintegrating in spots. Is that a reason to replace the radiator? I am guessing yes, but would appreciate other thoughts.

Also, I was having some challenge purging the system - engine was getting very hot in just a few minutes. Any tips on that? Thank you!

You already know that you're on borrowed time with most likely the original radiator. So, the only decision you need to make is whether you don't mind a leak developing when you're 100 miles from home.............??

The other determining factor is whether the old radiator can maintain engine temperature with 100F. ambients?

To cure the air problem, remove the upper hose and fill the head with coolant right to the top of the hose............reinstall it to the radiator quickly without spilling any coolant............

radiator
 

Thank you, Brian. You confirmed my thoughts and great advice on filling up the system,too!

Dan

which radiator to buy?
 

I saw that PeachParts has 2 radiators for sale, A nissen ($291) and a behr ($433). Any suggestions on which to buy? I could also get mine re-cored for $300-$400.

this is for the '84 300SD...

Firstly, check APE for the best prices on that component. The general consensus is that Nissens makes a fine product and it will go the distance.

I recently bought a Nissens off of this site, exact one you mention above. It works great, absolutely no complaints. That and Phil somehow got it to me (in PA) within 24 hours. :thumbsup2:

I wouldn't waste time or money re-coring one of these old plastic-tank radiators. Not unless you want to gamble on 'broken-neck' syndrome!
I've seen two W126 radiators - an '84 300Sd and '87 300SE - as well as other cars with plastic radiators, where the plastic radiator neck, attached to the upper radiator hose, broke off the tank without warning.
In 2008, I happily replaced the radiator right after I acquired my '84 300TD. It was original, and had some visible traces of past seepage in one corner. But more important, I certainly didn't want to worry about the neck breaking on a long trip!

Happy Motoring, Mark

I replaced both mine a couple of years ago, the neck on the 300D broke when I tried to tighten it and the 240D was running a little hot. They both were original and looked pretty tough when I pulled them out.

The Nissens is supposed to have fiber reinforcement in the necks.

now, to purge the radiator system
 

OK, I replaced the radiator (A nissen), having already replaced the water pump and gasket, the water pump housing gasket, the overflow tank, several hoses, and the thermostat and its gasket. It was one leak after another and now it seems sound...

However, am still having problems purging the system. Probably b/c I run WVO so I have hoses going to my auxiliary WVO tank. I have been trying to pull my car up the driveway frontways, drive it around and back it up, etc. to force out any air bubbles, but the hot water still is getting blocked somewhere around the heater, I think. My aux. tank and the hoses leading to it remain cold. I did follow Brian's suggestion earlier in this thread - that hose is heating up, but not my auxiliary hoses for the WVO...

Shall I keep backing my car up and down or does someone have any other suggestions? One slight complication (maybe) is that my climate control fan is dead, but I should still be able to open the switch and have heat flow out the vents, so I am hoping that is not an issue - just another future project (and I have many on this car!). I am so eager to use this car again!

Thanks.

Dan

Drill a small hole in your thermostat, this will help it burp out quicker too.

The 617 engine already has a bleed passage built into the thermostat housing.

radiator bleeding
 

Thank you for your replies.

So, is it worth it for me to drive up and down my driveway, perhaps using ramps to get a greater angle, until the system self bleeds?

If you filled the head, as instructed............just take it for a 15 mile drive and the system should eventually purge itself of any excess air.

Thank you, Brian. Its just that the temperature was getting pretty high a while back when I drove it (granted, it was before I filled the head) and I get nervous about overheating far from home. I will start with shorter drives to see if the temp stays manageable.