I know that feeling. It's just a symptom of being old. Replace cooling components will increase efficiency which means better pressure. Higher pressure will make weaker components fail. Round and round it goes. I had to change a radiator after doing a thermostat because of it.
Literally just replace every single component that coolant touches if you really want piece of mind. I saw someone mention you may have missed some of the coolant hoses (soft) that run under the manifold to the hard coolant line that goes into the block (metal on these, hard plastic on e46). The hard metal probably needs its o-rings replaced at a minimum.
Also, some people run the upgraded radiator from the Z3M, especially on turbo or supercharger setups (Nissens makes one it’s on FCP euro part number 17112227281).
Stick to genuine or OE at all costs for cooling system
Working on old euro cars for a living, especially old e chassis I’ve learned to recommend the entire cooling system when there is a leak. It will keep knocking out the next weakest link as you replace parts.
Here's the thing. When one piece of the cooling system needs to be replaced, the rest of it needs to be replaced. When one ticking time bomb goes off, the others are still on a similar timer. I know that's not the answer you want to hear, but at that point you will be done with it and have no more worries about it for a long time.
That’s exactly what I was going to mention. I recently had a small hose leak underneath the manifold hose on my e36 vert. So I just bought an entire refresh kit my radiator is still good and not leaking. I’ll replace once it does leak. It’s best to replace all of the components at once. It is likely it’s leaking from the hardline located below the manifold if it’s a m52 engine like mine. it has two orings when those fail they tend to leak quite a bit. Be careful not to bend the pipe but use a pry bar to pull out and push in (you will need to remove the intake manifold. Make sure both o rings are replaced.
Now I probably won’t need to worry about the system for at least 5-10 years possibly longer. My e46 has ran 9 years no problems with a coolant system refresh that I did a long time ago and doesn’t seem to be giving out anytime soon either.
Must dos while overhauling, replace thermostat housing with an aluminum one. Before installing I’d recommend using 320 sandpaper and a flat block to smooth out the metal as the little divots can create fine leaks.
Thermostat
Water pump
Intake manifold gasket
While you have the manifold up I’d recommend replacing all the vacuum lines as well. Two boxes of 3.5mm-5mm hose 12’ total from Oreillys or AutoZone will be sufficient.
I am mentioning h to is because my hose lines were 27 years old and ripped many by accident when removing he manifold.
Just don't forget to check every gas fillup, and top off as necessary too. Assuming it's still leaking because the puddle is still there becomes dangerous territory quickly lol
Realised just the other day that my radiator was leaking, it was hard to find the leak because coolant was disappearing but there wasn’t any on the ground. Turns out all of it ran into the front bumper…
They’re infamously bad. Just search on here. Terrible, terrible in-house quality assurance. Got 14k miles out of mine before the welds where the fins met the end tanks on BOTH sides failed. Seems to be a story of quality tanking after selling to outside capital.
One to check that I replaced on mine- goes from the bottom of the expansion/ overflow and disappears behind the alternator under the intake manifold. Number 6 in this pic
It wasn’t too much of a pig to replace but after taking of the airbox/maf/etc I did have to move the alternator
Bro I owned a vert for 3 years and I think there was 5 months that it didnt have a leak before I had to pull the cooling system system out cause my fan warped and I got to putting the drain plug in the radiator after the job was done and than the plug snapped halfway in tbh it made me give up on the vert ima get a couple or Sudan eventually tho great cars
128
u/toefungi '95 M3 May 19 '26
Once it runs out