M50 Rad issues

Post Wed Jul 19, 2006 7:52 am

Just finished my M50 convertion and got it straight through the MOT, so pretty pleased about that, but it seems to run HOT. Probably doesn't help to much with this weather but just had a question about radiators.

Right, my 525 rad had a hole in it so went down the breakers and got a 518 rad as it was the same size. Now what i want to know, although there the same size are the internals differen't? Differen't flow rates etc...?If that makes sense.

Checked the part numbers for a few rads and the 525 one is the same as the 328 ones etc.. and the 518 one had a differen't part number even tho it was the same size. Guessing theres a difference there somewhere?

The car seems to get hot when your driving along, but as soon as you pull over it starts to cool down. So the fans doing its job etc...

So i was thinking of changing the rad again to a 525, 325 328 rad, but if this isn't going to make any difference i'll try squeezing a bigger rad in. Just need some advise cheers.

Im guessing the rad is at fault as its the only thing thats changed since it came out the 5 series and that ran nice and cool then, altho it had a slight leak.

Cheers

Post Wed Jul 19, 2006 9:04 am

Have you checked out the M50 waterpump?

Post Wed Jul 19, 2006 9:16 am

Yeah it was the old plastic one so i changed it for a the metal one. Had the tested sticker on it so guess it was a good one? Put a lower temp thermostate in at the same time as well. When its idleing it all seems to work well gets to a certan temp, fan comes on cools it back down again, but driving along just seems to get hot even with fan on etc...

Post Wed Jul 19, 2006 10:16 am

6potwil6pot had this rad fitted

Dont think youd get one much bigger in

Post Wed Jul 19, 2006 10:19 am

Nice if he definatly managed to get that in then looks like i'll be replacing mine with that one. Any idea what car that was from?

Post Wed Jul 19, 2006 10:24 am

I think its on page 5 or thereabouts in the 'M50 developments' thread

He said its E36, although ive had a shallower one from an E36, and the one from my 525 was also smaller,

Post Wed Jul 19, 2006 10:26 am

Yeah i've seen a E36 325 one that big. All the others were the same size as my 525 one 440mm.
Take it he hasn't had any cooling issues?

Post Wed Jul 19, 2006 10:30 am

um is it an electric fan?

if so is it wired in backwards? (i did that

)

Post Wed Jul 19, 2006 10:30 am

The car is now track use only, so the cooling system is well tested

Post Wed Jul 19, 2006 10:33 am

Yeah check the fan is blowing the correct way. And does cool the car down if your just sitting there just driving along it gets hot. Thats why it makes me think the rads at fault. Bit backwards. The old RS loves to try overheat when its sitting there but fine driving along.

Used to run fine in the 5 series nice and cool, and the only real thing thats changed is the rad so thats what makes me guess its that.

Temp seems to get to just under 100degrees which im guessing is a bit to hot considering its just normal driving conditions i.e. not with my foot down

Post Wed Jul 19, 2006 10:45 am

Have you got the hoses on the heater matrix the right way around?
I did this on an M20 (got them backwards) and had the same problem

Post Wed Jul 19, 2006 10:51 am

Well i put all the hose back as they came off the 5 series. Are you talking about the heater matrix in the car? I could have got them the wrong way round. Doesn't the one on the right (looking at the car front on) go into the bottom of the rad and the left one comes out the head. Can't really remember without looking at it.
Wouldn't have thought it would make that much difference, but i don't know alot about it so might give this a try if it sounds like i got them the wrong way round!

Post Thu Jul 20, 2006 12:36 am

Im using my 318i E30 rad with no problems!

Post Thu Jul 20, 2006 7:21 am

Cheers argos, thats what i thought, the 518 rad can't flow as well. Altho you say a big rad will over cool the engine? Surely it can only cool to the level the termostate closes, which is ok running temp?

Stevetigger, i still got my original E30 318 rad didn't even think about using it cause it looked alot smaller than the other two i had. Might have to stick it on quickly and see how it goes, altho i should be getting some more bigger rads tomorrow.

Thanks for the replys guys

Post Sat Jul 22, 2006 12:24 am

Any progress on this?

Im using M20 radiator and expansion tank and even at 70mph the temp gauge dont want to drop below half way, the fan is on high speed constantly around town

Post Mon Jul 24, 2006 6:35 am

hi, yeah this weekend i put the earlier E36 325 rad in as its a lot deeper than the one i had, and it runs cool now, after a bit of a run and sitting in traffic i have to put the fan on but cools it down straight away. Got a new fan whilst i was at it not sure what its from but its massive and is the same size as the rad, only needs to be on for 5-10seconds to cool the car right down from 90degrees to just under 80.

Will post up some pics soon.

Thanks for all the replys guys.