What Gives? Coolant Splatter

[RuskiE39]

Replaced what I assumed was a leaky upper rad hose 3 times and its still leaking exactly the same way, each time coolant splatter fluctuating in random intervals, am I looking at a bad thermostat seal somewhere? I heard as a possibility that bad engine mounts could cause enough engine movement to cause a broken seal in the rad hoses. Any ideas or experience?



And yes, this is an OEM hose from the stealership.

[edjack]

Is it coming from the small overflow hose that crosses the rad?

[BimmrMeUpSnotty]

Is it coming from the small overflow hose that crosses the rad?

Was thinking the same thing, had the same splatter pattern, but there was coolant on the upper rim of my expansion tank. I didn't have the factory clamp and used a generic hose clamp, which my brother who was helping me at the time, tightened the crap out of it and the hoses end split. I got the right clamp, cut the tip short, clamped it back on, no more leak, for now.... but we all know it's just a matter of time for a new leak, coming to a theater near you.

[auaq]

Yeah, check your expansion tank where the return hose attached to. See if you can gently twist the nipple and see if the coolant leaks.

[jclausen]

Check water pump look behind and into the back of the water pump pulley, if it was white stains on it it's the water pump

[crazy4trains]

Splatter tells me that it is either the water pump or the seal between the thermostat and the block. Once the coolant hits the pulleys there is not telling the source as it slings everywhere. It is very unlikely that it is your radiator hose as those are sealed with internal O-rings.

[BimmrMeUpSnotty]

I had the same exact splatter problem, and it came from the expansion tank dripping down to the belts, which splattered it onto the other side, which is pictured. No pump leak, no thermostat farts, no more splatter...

[gmak]

+1 It's likely being thrown there by either belts or fan.

[auaq]

If it is leaking from the water pump you would actually see dripping at the bottom of crank pulley.

[Porange]

I just had a similar issue. Initially there was splatter under the hoses and on other components, then the leak at the pump got worse enough that it dripped a noticable amount on the floor.

Sent from my SM-T800 using Tapatalk

[geargrinder]

Check water pump look behind and into the back of the water pump pulley, if it was white stains on it it's the water pump

Splatter tells me that it is either the water pump or the seal between the thermostat and the block. Once the coolant hits the pulleys there is not telling the source as it slings everywhere. It is very unlikely that it is your radiator hose as those are sealed with internal O-rings.

+1 It's likely being thrown there by either belts or fan.

+++ to All these. WP light failure can leak only when hot and driving and cause pretty mysterious and misleading spray. I replaced a buncha hoses prematurely only to eventually discover : water pump.

[auaq]

Never mind.

Wrong post.

[RuskiE39]

It's weird because I used a mirror to locate coolant drippage (not white dry residue) from the bottom of the top rad hose and assumed it was coming from a bad seal between the thermostat and top rad hose. I'll have to take a further look and take everyone's suggestions into account. Thanks a lot for everyone's input, i'll report back if I locate the issue.

[gmak]

Maybe the thermostat cover is cracked : especially if you're seeing actual leakage in that area.

[fullthrottle540]

It could be upper rad hose itself. Mine once had a pinhole leak, that only sprayed at high RPM's. Didn't leak at idle.

[RuskiE39]

It could be upper rad hose itself. Mine once had a pinhole leak, that only sprayed at high RPM's. Didn't leak at idle.

The weird thing is... I drove all the way to Seattle (100ish miles) and when I popped the hood I didn't have a single spot of coolant splatter. Then when I get home and did some city/town driving, here we go again! Splatter all over the air box.

[gmak]

The weird thing is... I drove all the way to Seattle (100ish miles) and when I popped the hood I didn't have a single spot of coolant splatter. Then when I get home and did some city/town driving, here we go again! Splatter all over the air box.

Could be temperature / pressure related. Cars run hotter in the city than on the highway. : ie a pinhole leak as 'fullthrottle' suggests.

[777300ER]

The opening on the expansion tank is warped. Happened to me. Have a look at the opening, make sure it is round.

[RuskiE39]

The opening on the expansion tank is warped. Happened to me. Have a look at the opening, make sure it is round.

I wrapped some tape around the exp tank cap to see if it was shooting out from there and it wasn't.

[gmak]

One trick is to put paper towel around the expansion tank. If it gets wet from driving - there is your answer.

I just used this on the return flow of a bypass oil filter going into the oil cap (on another model BMW) and it proved conclusively that there was no oil splatter from an ill-fitting cap.

You an do the same thing with non-moving parts of the coolant front end. wrap some around where you suspect the pin hole leak might be on the hose, and tape it in place at the ends. If it gets wet, bingo. If not, at least you have eliminated one more hypothesis.

[Ed CT]

Hey Ruskie - Were you ever able to locate the source of this Coolant Spray?

I've got the same thing that I've been chasing down for almost a year. Same spray on the AF Housing, very intermittent but now increasing in frequency, no evidence of leaks that I can see. I had assumed & R&R'd the T-Stat housing but no success. And have had the system apart a few times for other things with no sign of a leak. No major loss of coolant (yet....).

I guess the next step is dye and a black light.

[Dave Sal]

Hey Ruskie - Were you ever able to locate the source of this Coolant Spray?

I've got the same thing that I've been chasing down for almost a year. Same spray on the AF Housing, very intermittent but now increasing in frequency, no evidence of leaks that I can see. I had assumed & R&R'd the T-Stat housing but no success. And have had the system apart a few times for other things with no sign of a leak. No major loss of coolant (yet....).

I guess the next step is dye and a black light.

Just like you, I've also been chasing a mystery coolant leak for over a year. The spray is on the airbox, the power steering reservoir and goes the other way to the passenger side as well. I am pretty sure I found the leak last week. I noticed dried coolant around the bleed screw on the upper radiator hose and assumed that the bleed screw was the culprit. Waited till the engine cooled off and swapped it for a new brass bleed screw and went for a drive. No change, and I could still see liquid slowly oozing from the base. Looks like there is a tiny crack at the base of the bleed screw. I have a new upper radiator hose from FCP Euro arriving today so I have my fingers crossed that this solves the problem.

[motion]

Consider a pressure test, insure the system is completely full and as cool as possible. Pressurize from the bleeder port which will allow testing the cap. As always do as you feel is best.

[Ed CT]

Just like you, I've also been chasing a mystery coolant leak for over a year. The spray is on the airbox, the power steering reservoir and goes the other way to the passenger side as well. I am pretty sure I found the leak last week. I noticed dried coolant around the bleed screw on the upper radiator hose and assumed that the bleed screw was the culprit. Waited till the engine cooled off and swapped it for a new brass bleed screw and went for a drive. No change, and I could still see liquid slowly oozing from the base. Looks like there is a tiny crack at the base of the bleed screw. I have a new upper radiator hose from FCP Euro arriving today so I have my fingers crossed that this solves the problem.

These cars are fun, right???
Looks like on yours is that it seeps from the cracked hard-hose, drips onto the fan/belt, and then sprays in both direction. Be interesting to see if your new URH fixes it. As an alternative, you could always cut a piece of Powdered Toast Man off and duct-tape it to the hose to sop up the drip! (LOL That's a great sig avatar!)

I don't have any spray on the passenger side. Maybe I 'll take a mirror and light and look on the underside of my TStat housing for a crack & drip, but I would think that it'd be on the passenger side, too, but worth a look anyway.

- - - Updated - - -

Consider a pressure test, insure the system is completely full and as cool as possible. Pressurize from the bleeder port which will allow testing the cap. As always do as you feel is best.

Good suggestion and the most efficient way to test, but, yeah, I thought about that, but I'm fearful of blowing up some other coolant system component. Maybe I'll try it with a weak bicycle pump.

[sleuth255]

+1 on the bleed screw. My 530 had the exact same splatter. Bleed screw and upper rad hose solved it.