Hi All, I've had an annoying coolant leak for a little while that I can't seem to figure out. The overflow tank will slowly go down little by little after drives. I have filled it several times so it doesn't go dry. I never see any liquid on the ground or in the engine bay. I added some uv dye and looked carefully with a uv light after my last drive a coyple days ago. I took many pics and a video afterwards. Looks like it has sprayed in many places so it's hard to determine the source. Hopefully the images show the uv fluid clearly enough. I also took a video buts mp4 so it won't load. Maybe someone can see something I'm missing to nail this leak source. Any insight is much appreciated.

 

Pressure test it.

 

if I'm interpreting those pictures correctly it looks like it has gone everywhere. I've heard of waterpumps leaking and the pulley spinning the coolant about the engine bay which may be the culprit

Agree pressure testing is useful and not expensive

do you see bubbles in the overflow tank when running? Any major coolant work in recent times? I had air trapped in my new vortec engine for awhile and took quite a bit of burping the system to get it all out - in the meantime the coolant level was going down (whilst air was being replaced with coolant)

 

Thanks for the feedback. I did pressure test it prior to adding the uv dye and discovered that a capped low coolant level port on my Dewitt's radiator was leaking. I tightened it and retested and pressure was holding so I thought it was ok. Then more leaking so I did the dye. Good suggestion and I will pressure test it again. It does seem like it's splattered all over. I didn't see anything by the water pump. I'll pressure test again and circle back.

 

^^^ This ^^^

When the seal wears out, coolant comes out of the weep hole(s), and drips onto the back side of the pulley, which then slings it in a fine mist EVERYWHERE, coating the inside faces of other accessories (alt, AIR pump, PS pump, etc.) and the front faces of all the components behind the front of the motor.

Also, an obvious shortcoming in all those pictures is, they're all taken looking down from the TOP. [insert obnoxious buzzer sound here] Coolant is heavier than air, therefore goes DOWN when it leaks in liquid form, not UP. Get up underneath the car and LOOK UP at it. In particular, look at the lower rad hose. Coolant will literally run down the BOTTOM side of it (toward the ground) when the seal leaks, and drip off at the radiator end of the hose. If you see coolant there, you need a WP. You might also want to check the bottle and make sure it's not cracked where the hose goes into it, at the BOTTOM. Doesn't look like that's your issue, since it doesn't fit the fact of coolant coating the inward-facing surface of the AIR pump and whatever all else, and therefore isn't likely to be "the right" explanation (see my signature), butt is a fairly common thing to happen anyway, and as such, deserves to be checked.

 

Thanks for the good comments. There's no bubbling in the tank but the engine was rebuilt about 6 months back and the water pump wasn't replaced at the time as it was working fine. This leak has been happening since, it has been more minimal it seems at some points since vs others and since I haven't seen any liquid really anywhere I've just continued to periodically refill the overflow reservoir. Not a good long term solution.

Tonight I got under the car. A tight squeeze as I don't have jacks or a lift yet, and tried to see what might be happening there and take some images which are included here. There is evidence of it all over the pully. I didn't see anything on the hose connection to the water pump. So, it seems like it likely is coming from there although it's slow and must be very fine.

I also did a pressure test. Started at 15 and after 10 minutes it was at about 14. No liquid was observed anywhere while the pressure was added. Leads me to believe that if it's only leaking slightly while the water pump pulley is moving this may well be the culprit, spraying it all over which I can see and as was mentioned by Sofa.