Radiator Replacement

[johnnie]

Sorry to resurrect an old thread but it's relevant to my current problem.

i now own James Midas and have experienced a similar issue to the original post.

The car ran perfectly cool for 150 miles back to mine from James and only done a few trips with no issues before standing up over winter. I've just dragged in out for this season and given it a oil and plug change and topped up the coolant which was a little low. Its been on a gravel drive and I've not noticed any drips but when it was put into my mates unit we did see a few water spots under it. I retopped the coolant to about half way in the expansion bottle and ran it and there seemed to be quite a puddle forming at the front for a little while which then stopped. I felt all round the radiator which seemed dry and I couldn't find any leaks on any pipework. I thought I may have over filled it and have driven it over the last few days with no problems (around 60 miles).
Tonight when I drove it it suddenly started running hotter than I've ever seen before (3/4 up the gauge) although to the best of my knowledge the fan didn't cut in. I stopped and it took a couple of litres of water to get it back to half way up the expansion. I then done a 10mile test and it ran cool as you like.
I plan to pull the front off and change the rad this weekend along with the thermostat.

A few questions

Does anybody know what Rad James fitted in the end? I have a MG Metro rad in the shed and it looks similar so am hoping that will fit.
Is there something I'm doing stupid when topping up?
Are they prone to air locking (clutching at straws perhaps)
Are you still lurking on here James? Any history / quirks / tips would be appreciated.

[kelvink]

I've an idea that he may have used an MGF rad but I could be wrong

[lankyjames]

Mgf radiator - bought as bottom mounts lined up but never fitted! Since sold to Jon. Original radiator is allergro, but a metro should work too so long as the input output are the same side.

Remember also the front collects water quite badly, there are a few drainage holes that get blocked up with stones (ballast!)

[johnnie]

Oh that is annoying the metro is opposite corners.
Looking at MG tf on the interweb they look to be the same. I take it you were planning some pipework mods?

Alegro seem pretty rare. Anybody on here got one they want to sell?

I did wonder if the problem was just water collection but last nights hot running seems to have knocked that on the head

[lankyjames]

I had bought a bunch of pipework to make it cross-flow, silicone, solid pipe and fan switch (mg tf doesn't have one built into the rad) again all since sold on now. Makes sense to upgrade rather than stick to old tech plus allegro and mk2 metro rads are hard to find!

[johnnie]

Yeah I think it'll have to be converted now, things got decidedly worse today.
I tried to take it to a friends unit to check it out. Dropped some K seal into the Rad and managed a few miles before the temp rapidly climbed so had to stop! Ended up stuck on twisty little Norfolk lanes stopping to let it cool down and then doing another mile or so. The engine was hot but the rad was cold, suspected the thermostat but when i eventually made a house where I could blag a watering can full of water it drank the lot, then ran the 15 miles or so to the unit just above the blue and sat there not leaking a drop of water!!!!!! Arhhhhhh!!!
I'm going to change the stat, the water pump, flush through the block and heater system and try to fit the later metro rad. That should be easy enough to do I just need to source a 180 degree u bend water hose preferably with an expansion bottle take off. I have a steel pipe from the Metro that should run across the top of the rad to a short 90 degree to the stat housing. Bottom hose should go straight on.
Three weeks to the first club run of the year and as club president I HAVE to be there, Best get cracking.

[sherwood-ranger]

I had a similar thing happen in a Morris Minor, it would run fine for a couple of days then just overheat an loose all it's water. It turned out to be a blown head gasket. If you can't find any other cause it might be worth pulling the head.

[johnnie]

I'm hoping it's not that. I've got no other symptoms, starts well, pulls well, no smoke and the oils clean.
The puddles under the front convince me its a rad leak problem at present, I might compression check just to be sure

[midasnut]

Sounds like an air lock. Make sure the heater is fully on and flush the system. Once that's done top up the system from the highest point. On the two mark 3's I've had that's was the top hose for the heater unit. I even needed to jack up the near side of the car to make sure the air didn't get trapped. At one point on my first mk 3 about 16 years ago I had to change the head a couple of times and had to go through this four times in as many weeks before I found an air line crack down the edge of a valve guide. If you get an air lock the water won't circulate properly, the rad stays cold and every now and then the water appears to vanish from the system. Basically the water in the block boils off.

[johnnie]

Air lock is one of the things I was wondering about? We'll see how it is with the new rad set up