Coolant leak...all I did was pull the radiator and put it back.

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Coolant leak...all I did was pull the radiator and put it back.

Post by Blue Shadow »

Working on the install of new condenser and pulled the rad for the removal of the old condenser. Put the rad back in and filled the system. Got the low coolant light a while later and put a quart or two in the reservoir. Did the 20-round trip multiple stop errands run and the coolant light comes on again. Didn't see much, added coolant and verified all the hose clamps.

Today, fired it up, found the leak below the top rad hose. I had already reseated the hose and clamp in the old, compressed groove. Had room to add another hose clamp closer to the end of the hose and that seems to have stopped the leak. Might be the first time I have this kind of problem on a clean hose connection and a good, flexible hose. Sure, those corroded metal hose connection can be a problem when putting things back together but the rad hose bib and hose were in great shape.

One more issue solved, I hope, too many to count left to tackle.
austin8753
Posts: 1444
Joined: May 16, 2010 1:37 AM
Location: Portland, Oregon, USA

Re: Coolant leak...all I did was pull the radiator and put it back.

Post by austin8753 »

you might try replacing the clamp, perhaps it's been overtorqued too many times. 47-54mm at the upper and lower radiator hoses, if you've an M30 powered car, should my memory serve me correctly.
Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Re: Coolant leak...all I did was pull the radiator and put it back.

Post by Blue Shadow »

That is the correct size. The clamp torques up just fine. I don't know for sure but maybe the hose or rad had a booboo in the area under the clamp. I'm happy the second clamp seems to have resolved the issue for now.

I'll be going in again before winter with a complete flush and fill. My coolant is weak and old, time to but in the G-05
austin8753
Posts: 1444
Joined: May 16, 2010 1:37 AM
Location: Portland, Oregon, USA

Re: Coolant leak...all I did was pull the radiator and put it back.

Post by austin8753 »

for sure, at least it stopped the leak temporarily.

i had an issue, similarly, with my M5. when i had the engine out, i replaced anything i could buy, including all the cooling hoses and radiator. the new radiator is the brass/copper style, unlike the original unit with plastic end tanks. well, whoever did the braise job at the radiator plant, did not do a good job, and where the lower radiator hose neck met the end tank, the braise failed and it leaked coolant. i thought it was the hose, but after careful inspection with the pressure tester fitted, led me to the failed braise job. i even installed a second hose clamp on mine, since there was plenty of room, but after a couple days, the leak came back. the crack probably enlarged from the second clamp.

anyway, to make a short story long, you might inspect for a failure around the neck.
Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Re: Coolant leak...all I did was pull the radiator and put it back.

Post by Blue Shadow »

I looked for that on the rad input and the overflow. I have an overflow repair nozzle if needed. Both looked good. I repaired a clean new rad input crack with JBWeld years ago in the pits. Worked well. Don't know if a radiator that has coolant impregnated plastic will take to JBWeld. Hope I don't need to find out.
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