As you may recall or read on my previous threads, I've replaced every hose, clamp, gasket, thermostat, and water pump on my cooling system because I was looking to make sure everything in tip-top shape. I even installed RealGauge. However, despite all my efforts in preventive maintenance, I was still losing coolant, except that now there were no visible leaks on the ground, no smell of coolant, and no coolant in the valley. I was now fearing the worst, a head gasket. I looked for the pathognomonic signs of a head gasket and none of those symptoms were present.

Today I stopped by my local Advanced Auto rented their coolant pressure test kit. I pumped it to 15 psi. I was expected pressure to drop like a rock, but it didn't. It lost about 3 psi and held steady at 12 psi. Still. that's enough to confirm a leak somewhere. After some searching I found it. The radiator is leaking at the right side plastic coolant tank seams at the top, just slightly below the level of the top radiator hose at the plastic to metal joint. I quickly checked my usual sources and found that Rockauto has the best price, at $182. Both of these is the same Nissens radiator. The forum sponsors have the OEM radiator available in the range of $700 - $855, and Dave Roche has it for about $353.75. The price disparity is rather large for what, at least in the pictures, all look to be the same part.

Given this situation what are my options? Should I:

• Buy a new radiator (probably the Nissen's from RockAuto)?
• Have a custom radiator made entirely out of aluminum? ($$$)
• Attempt a rebuild? Perhaps crimping the seams of the radiator with the pliers could solve it?
• Aftermarket upgrade radiator if such a thing exists???

It doesn't matter what repair attempt I do, that radiator has to come out of the car. There is no way to attempt to crimp the tabs in-situ. If the radiator is coming out, that means I will have to disconnect the transmission cooler lines. Is there a way to limit the amount of transmission fluid lost? Is the amount of fluid that will be lost negligible, or am I forced to top up the transmission? I did a transmission service not too long ago and would hate to have to go through that again.

Any thoughts?

 

I did the Rock Auto Nissens replacement and it was a good fit. I pulled my radiator out in sections in order not to open up the AC system. If I had to do it again I would pull the ratiator out with the condenser attached. Make your life a lot easier.

 

I also don't want to open up the a/c system. Was it really that tough to separate the radiator from the a/c condenser? I know the space is tight to remove those two bolts. I think I would rather remove the front bumper if it helps me with that.

 

I ordered the Nissen's radiator from Rockauto. With the potential catastrophe that a bad repair job of the radiator could cause by attempting it myself, I would rather be certain that the part won't fail in a few months. I am not going to attempt to crimp the radiator joints.

Is there a way of minimizing transmission fluid loss from the oil cooler lines?

 

Slightly different arrangement as mine is the 5HP, but I disconnected the upper trans cooler line and left everything to drain for a day or two. Probably works best from hot after a run.

I only lost about an eggcupful from the lower union. You can probably put a container underneath to catch what comes out as a measure, but at worst it's only the content of the cooler. Make sure that you plug the hose open ends, and you can top up any missing fluid via the upper hose when you put everything back together.

It definitely worked for me as I forgot to do this when I later changed the cooler hoses and had a messy puddle of fluid to mop up as a result

 

I replaced the radiator in my 2003 4.2 a few weeks ago with a Nissens unit bought on eBay. Somewhere on this forum I read that typical loss of transmission fluid is about 150cc, so I added this amount to tthe upper hose on reassembly using a turkey baster. As a previous poster has noted, you don't lose much when disconnecting the hoses.

I did not remove the AC condenser or the front bumper; I don't see how removing the bumper would help. If you have AC charging apparatus it would be a bit easier to remove the condenser with the radiator, but it's not at all necessary. Some of the fasteners are difficult to reach, but patience is your friend. The worst of it was manipulating the steel panel on the right side so that the condenser would clear the radiator. I think you can remove this panel somehow, but my solution was to rotate it clockwise (seen from above) until there was clearance.

I carefully removed the foam closing strips from my old radiator and affixed them to the new using 3M weatherstrip adhesive.

I've driven the car several hundred miles since the replacement and everything seems happy.

 

Yes if you take your time its not that hard, just time consuming. Regarding fluid loss it was very slight only a couple of onces. Before I secured the top oil cooler line I put in the loss amont with new fluid. My only problem was I did not tighten the oil cooler lines enough. Also I did not replace all of the radiator seals that are on the sides of the radiator. I did this because I wanted to get more air flow into the engine compartment. I spoke with Nissens and they said as long as the fan shroud is in place no loss of cooling. My car runs about 200 F.

 

Mine leaked int he same spot a few years back and I went the Nissen's route - did not have to open AC system either. One word of caution - the radiator will come with a small port on the upper left next to the upper transmission cooler line. The older MY XK's had a bypass tube running to the expansion reservoir but from 2000 on do not - so you will need a small gas line cap and a zip tie to seal that off - see pic below