Thread: TD5 Leaking Radiator Question

Today, after a short drive of my 2004 D2a TD5, I found a little puddle of coolant on the ground directly under the passenger side of the radiator, not the inlet pipe but the plastic tank itself. I removed the top cooling fan cowl and found coolant leaking out from under the cooling fan lower cowl top piece that is held in place by a screw into the top of the tank body.
Radiator lower cowl top piece and mounting screw.jpg

At first I thought that the small plastic nipple for the expansion tank hose was cracked as it is quite vulnerable to being knocked but after removing the lower cowl I saw that it was intact. The inlet hose pipe was fine as well and the hose joint wasn't leaking either. The whole top of the plastic tank and the tank to aluminium fins joint was wet with coolant. Leaking tank joint?
I dried the whole area with compressed air and covered the front of the radiator (I had removed the viscous fan and lower cowl earlier). I ran the motor up to operating temperature but no leak to be found ! Dry, nada ! I ran the motor for well over half an hour and the Nanocom showed the coolant temperature was 89.5^oC so should be up to pressure but still no leak...mmm?

I lightly screwed the lower cowl top mounting screw a couple of turns into the top of the tank screw hole then bingo !
Coolant leaking from screw hole in PS radiator plastic tank.jpg Cooling Fan Lower Cowl Radiator Screw.jpg
Coolant started streaming out. Yeah, I found my leak but why did it leak??

A few weeks ago I had removed the intercooler for a flush which necessitated the removal and refitting of the cooling fan lower cowl. I am sure that the two self-tapping screws I used to fit it were the same screws that came out. The screw hole in the top of the tank is only 16mm deep and the screws are 18mm long but the lower cowl top piece the screws goes through is 2.8mm thick so in theory there should be 0.8mm screw clearance to the bottom of the hole...not much. Perhaps some dirt had gotten in there as It wouldn't take much to cause a problem. I am pretty sure I didn't over tighten the screws as that could also squash the soft cowl plastic 0.8mm. I am also pretty careful to always re‑use the same thread in plastic when using self-tappers but it is hard to tell so maybe I cross threaded it. Lastly, and I think most likely, the plastic is old and brittle and the stress of the self-tapper just cracked the screw hole sides.

OK so my question is...are the two self-tapping screws the correct part to screw down the lower cowl to the top of the radiator plastic tanks? They look original and they were on the vehicle when I got it but maybe a previous mechanic had changed them. Part #9 of the Land Rover website Parts List shows these should be an M6 x 12mm flanged bolt and there doesn't appear to be a self-tapping screw part number listed in any of the variants. However, the flanged bolt doesn't look like it would fit under the cooling fan plastic top cowl. What do other people have?
Land Rover Parts List - FS106127L Radiator Screw.jpg FS106127L Flanged Head Screw.jpg

Originally Posted by AK83

I just used some RTV type goo to help seal it. Let it sit for a good day or two. Still holding after a good hot summer and 10 months later.

Originally Posted by Campaspe Man

A couple of years back I managed to badly crack that plastic nipple you mention, that connects to the expansion tank line on the upper passenger side. To my surprise, I was able to fix it using JB Weld using their 2 part PlastiWeld (yellow coloured tube). It took some patience but it didn't seem to have trouble holding the pressure or temperature. It was good for about 2 years.

Originally Posted by discorevy

gas thread tape should hold until you find a replacement radiator.

These are all good to know emergency repairs and speak to keeping some backup repair material in the going away tool box. I did decide to bite the bullet and fit a new radiator in the name of long term reliability. I bought a GM branded OEM which wasn't tooooo bad price wise and looks to be the goods.

Originally Posted by AK83

I fitted a new rad and knowing about the issue, I cut the thread down on the screws that someone had used so it didn't dig in too deep.

Looking into the screw holes of the new radiator I noticed that they were actually quite a severe conical shape with no thread which meant that the stress on the plastic increases as the screw goes deeper. So I did as you have done and cut the screws down to 13mm long under the head, making sure I graduated the initial screw thread.
P1150702.jpg
This still left 7mm of screw down thread which is more than adequate and will hopefully reduce the stress on the plastic in future years.