Coolant Reservoir Leak

[emerydc8]

What I thought was just a loose hose clamp turned out to be a hairline crack in the stem where the metallic reinforcement tube is located. This reservoir was replaced in the last ten years for a crack in the same area. Based on its location, I'm thinking about trying some JB Weld or PC-7 and moving the clamping point further towards the middle of the metallic reinforcement tube. Aside from the sediment under the crack, the loss of coolant was insignificant. The stem seems to be the weak point in the reservoir. If sediment is present like in the picture, don't assume the hose clamp needs to be tightened--better to pull the hose off and look at the stem for cracks.

 

[nocfn]

Good find. I think the bigger issue is that the tank is pressurized so if there is a leak then there could be a contribution to the effectiveness of the fluid flow. As things heat up and expand, there is the overflow tank and the absence of a vacuum there may potentially be an issue with effective system cooling.

 

[JC220]

That's unfortunate but really just renew it again as no patch could be relied upon and sudden coolant loss could trash your engine as you know.

 

[kwontumspeed]

Mine did the same, twice. Granted that was within 15 years. The third time I added a constant tension/spring clamp instead of a mini perforated and it seems to hold up much better.

 

[gerryvz]

Honestly, I think I'd just replace the reservoir and be done with it. As I recall from a couple of years ago, they weren't too expensive to purchase new.

 

[TerryA]

I replaced a perfectly good original reservoir due to the yellowing with a new from MB OE one which failed after a couple of years. I’m on a second one now.

I don’t think the quality of the MB OE replacements is the same as the original units.

 

[emerydc8]

I replaced a perfectly good original reservoir due to the yellowing with a new from MB OE one which failed after a couple of years. I’m on a second one now.

I don’t think the quality of the MB OE replacements is the same as the original units.

Out of two W124s, I've replaced three of these reservoirs in the past ten years for cracks in the same place. The replacement reservoirs don't have time to turn yellow--they break first. This will be the fourth reservoir. At $75 (actually more like $150 including the sensor and shipping), they're not that expensive, but you wouldn't think a reservoir would be considered a rotable part. I agree--The replacement reservoirs are junk.

 

[emerydc8]

Honestly, I think I'd just replace the reservoir and be done with it. As I recall from a couple of years ago, they weren't too expensive to purchase new.

Okay. You and @JC220 have shamed me into it--I've ordered a new one. Also ordered a new windshield washer reservoir with all the hardware, including those cool windshieldwashernozzleheatergrommets that often get installed upside down. The reservoir I'm replacing is only a few years old and already has a crack on the top extending out from the cap threads.