Coolant Leaking Onto Serpentine Belt

M

mrsweetness09

Greenie N00B Member
Greenie Member
Hey everyone! I got home from work this evening and noticed some vapor coming from under the hood. Popped the hood and sure enough, the smell of coolant hit me immediately. The leak seems to be on the left side of the bay and is getting onto the serpentine belt, which is then flinging it everywhere. The most concentrated portion of coolant was sitting on the front portion of the belly pan closest to the radiator.

My thought process is that the two most likely suspects are the water pump and the radiator. The area around the water pump looks completely dry with no coolant staining. The side of the radiator and the foam piece next to it do not, but this is in the path of the coolant fling from the serp belt.

Are there any common coolant failure points on this side of the engine bay that I should keep a look out for when I pressure test and get under the car tomorrow? Any ideas or help would be appreciated!

2013 MS3. Cobb intake, Damond street trinity, auto tech HPFP internals, action stage 2 clutch and single mass, BC BR series coilovers. Freektuned at 20psi.

Image of suspicious spot on radiator and vid of water pump attached, not the best but best I could do.

Also should add:
85k miles
The plastic block that connects to the block that people seem to like to replace with a metal one is dry.
 

Attachments

Last edited by a moderator:
The overflow vent for the coolant res is, actually, inside of it. Unbolt that fucker and look directly under it; perhaps it vented during an overheat, spraying coolant everywhere, or perhaps you have a head gasket failure.
 
Enki said:
The overflow vent for the coolant res is, actually, inside of it. Unbolt that fucker and look directly under it; perhaps it vented during an overheat, spraying coolant everywhere, or perhaps you have a head gasket failure.
Click to expand...
Sorry, forgot to add more context to the post. A couple days ago my friend mildly overfilled the tank claiming “that’s what we’re were taught to do with P1 Volvos and they have the same coolant reservoir”.

Regarding head gasket failure. I would think in the event of an external jacket failure on this side of the bay, it would leak into the timing cover causing milkshake. I checked for milkshake on cap and dipstick and my oil looked healthy. I’m going to get the coolant to the correct fill line and pressure test it and go from there.
Will keep the thread posted

Also, there was no overheat on my drive home from work. I monitor my anxiety port closely lol.
What I find strange about the idea of it being the coolant overflow is that the coolant was filled like two days ago. Not sure why it would take so long to dump all the extra out
 
Last edited by a moderator:
I do believe that there is a secondary method of head gasket failure, in which combustion gasses are pushed into the cooling system.
An alternative test would be to wipe everything down and add some of the fluorescent dye to the coolant, then fire it up and check everything with a blacklight.
 
Enki said:
I do believe that there is a secondary method of head gasket failure, in which combustion gasses are pushed into the cooling system.
An alternative test would be to wipe everything down and add some of the fluorescent dye to the coolant, then fire it up and check everything with a blacklight.
Click to expand...
Okay, update this morning. About 1-2mm has leaked from the reservoir overnight, and the reservoir is now below the max fill line. If this much fluid was leaking into the combustion chamber with no pressure on the system it definitely would have overheated or would have been noticeably burning coolant on my drive home yesterday, so head gasket is most likely out of the question. I’ll put a combustion leak tester on it just to be safe this afternoon when I get the car off the ground and put a pressure tester on it. My bet is on radiator right now, but will update later this afternoon.
 
Was it cold when you checked last night? If you checked when warm 1-2 mm is well within the expansion - contraction of coolant
 
Easter Bunny said:
Was it cold when you checked last night? If you checked when warm 1-2 mm is well within the expansion - contraction of coolant
Click to expand...
Excellent point. Yes it was warm last night and cold this morning. Thank you. I think what I will do is check for HG failure and pressure test it tomorrow. If it passes both I’ll run it and chew out my idiot friend who probably just didn’t want to admit he overfilled it and he thought it would be fine.
 
Alright, so I believe my problem is solved.
Combustion leak test showed a good HG.
Pressure test showed no leak.

I believe the coolant reservoir dumped the excess coolant onto the frame rail, which then will run and fly directly onto the serpentine belt assembly and get absolutely fucking everywhere. So Enki and Easter Bunny, your guesses of it being the overfilled coolant were correct.

I will continue to monitor my coolant level. images showing where my frame rail took a coolant bath and coolant staining on the bottom of the reservoir will be attached.
 

Attachments

  • IMG_2880.jpeg
    IMG_2880.jpeg
    1.2 MB · Views: 4
  • IMG_2879.jpeg
    IMG_2879.jpeg
    1,019.9 KB · Views: 4
Further update, inspected what I could on the water pump again and found a wet spot on what looks like the weep hole. Went ahead and ordered a new water pump, serp belt, and idler pulley.
Goes to show that these water pumps can fail prematurely despite it being rare I guess.
 
You must log in or register to reply here.
Back
Top