LordKarnage17

So I have a small leak somewhere near the coolant expansion tank because I see occasional pink drips accumulating on the bottom of the engine, and over the course of a month or 2 I have to top it up. The other day I was visiting family about an hour away so I checked my fluids before leaving (recently did an oil change and wanted to make sure the oil level wasent dropping because of a leak somewhere)
The coolant was a bit low so I topped it up with a bit of distilled water. Long story short, I didnt initially realize the G12 coolant from the dealership was a concentrate so the concentration of the coolant is higher than it should be, so I've been adding distilled coolant to dilute it out to what it should be at for the colder temperatures here. One the way back home, I was noticing the heat wasent at the level it it used to be at, and the engine was taking longer to heat up than normal. It was cold outside but not much colder than it had been the past couple weeks. I checked the coolant today and noticed it had quite quickly turned from the pink to a brown color.
I've read that this could be from cross contamination in the oil cooler, so what would be the best way to check for this?

A1EK

Couple of points here.

Adding a higher concentration of coolant will not affect the function of the car, it will just give you a greater protection at a lower temperature, however over time some engines have issues with the seals if coolant is incorrect.


If your coolant colour is brown is it just on the surface put still pink underneath if you move and look? IF so then the brown colour you are looking at is more than likely your engine oil floating on the surface in a sludge. Don’t despair it is very likely just your oil cooler as you stated that has failed, if you look at the right side of your engine above the oil filter you will see an aluminium square, that is your cooler.



To remove:

1. Twist off oil filter and use a rag to catch oil drips.
   
   
2. Use a deep 27mm socket and undo the thin nut that holds the cooler in place, (You cannot see the nut unless you are underneath)
   
3. Slide cooler down and off.
4. Replace rubber O-Ring with a smear of oil or a complete cooler if you bought one and connect to hoses.
   
5. Tighten the 27mm thin nut, but DO NOT overtighten as this will damage the seal, it should be 18ft lbs or 25 Nm Torque.
   
6. Top up engine oil to correct level.
7. Flush or drain old coolant and clean out expansion bottle (take off the car and use washing up liquid or a little spirit).
   
8. Top up coolant with new G12 and remove any air blockages
   
   

It’s not a difficult job and should only take about 30mins, the oil cooler is cheap and it may be good to buy a new one if you do not know how old the current one is or if it has failed internally.


Good luck.

LordKarnage17

Is the oil cooler fragile? Now that I'm thinking about it, I did just replace the oil less than a week ago. Would be a mighty coencidence that the oil cooler just happened to start leaking after I replaced the oil filter days prior.

I didn't feel like I was more physical than I had to be. I did need to use one of those oil filter removal tools so maybe that torqued the oil cooler in a funny way?

I'll go have a look at what the oil looks like.

LordKarnage17

I went and checked the coolant and it seems pretty homogeneous, and dosent look to have any oil particulants changing the color. I did check this while the engine was running however so maybe the water pump mixed everything up again.
The oil didnt show any signs of having coolant in it either, however since all these symptoms are fairly recent, I woudn't expect it to.
The engine reached operating temp reasonably quickly (in the span of a 5 minute drive) so I'd imagine the thermostat is good, however heat in the cabin is essentially non existent now, almost like the temp setting is on low, even though its set to like 20C.

A1EK

Looking at your photos the colour does not look quite right and also the coolant is not clear as I can't see the bottom of your header tank. It may be possible that you've mixed different coolant types and it's emulsified however it does look that there could be still an oil contamination issue as well.

A couple of points :
Was the coolant very low when you went to top it up?
As for checking the engine oil for signs of water, if the cooler was leaking you wouldn't tend to see any signs of water inside the engine and if you did this would suggest the head gasket is leaking.

It may it may be possible that when you removed the oil filter you have disturbed the cooler o ring seal ever so slightly.

With all of the above said even if your oil cooler was leaking oil into your coolant system you should still get heat as my car when I bought it was a thick brown sludge but the heater worked fairly well.

To break the problem down, the first thing that I would do is flush all your coolant out of the car and replace with plain water. Then run the car for a little while and check the coolant tank to see if there is any signs of oil after you've driven it for a bit.
If there is no signs of oil then your cooler is not leaking and it may be just that you had a mixed contamination of engine coolant, so if your heater inside the car is working again then drain the water and replenished with the correct G12 coolant ratio.

If you do find that there is oil in the water then the next step would be to remove the oil cooler and replace it or you could try replacing the oil seal first but this is all time consuming. You can check the oil cooler by putting a pressure gauge on one of the pipe outlets and blocking off the other to see if the gauge drops over a period of time or just buy new cooler.

Lastly do you have heat when you drive that car but it then goes when you're so sitting at the lights if this is the case you may have an air blockage which you need to release, I can explain more about this later.

I've attached photos of my coolant, it's night time here now and -7c but you can see the coolant is pink and clear.

LordKarnage17

The coolant was low enough to trip the sensor, but there was still coolant in the bottom of the expansion tank. Before I got distilled water to dilute out the coolant I did use a bit of tap water to top it up and get me to the stores. Could the minerals in the tap water have caused this reaction?
Is there a drain plug on the bottom of the rad? or would I just pull out the ECT down there. During my drive today I noticed the the coolant level increased a bit in the expansion tank which I would assume to mean that coolant somewhere in the system got replaced with air.
My drive this morning was quite short so I didnt every go above 3k rpm but I didnt really notice any warm air coming from the heater core at any points of the drive. before I flush the coolant, I might try pulling out the top heater core hose a bit to expose the little bleeder hole in the tube to see if there air stuck in the heater core.

A1EK

Adding a little tap water would not cause any issues and besides the emulsified look of your coolant, you should still get warm air. As a guide, if I drive for 2 mins even at low revs of 1500 the car heat at vents gets warm, if you select the vents that face you via the climate control they will not open until the temperature is warmed up to avoid blasting cold air, unless you over ride the climate control manually.

The expansion tank by definition will allow the coolant to rise as it heats and pressure builds so this is normal, the usual height of the coolant when you open the cap when cold is around the top of the four lugs that you can see in your photos.There is a drain at the bottom right of the radiator as you stand in front of the car, however it is a pain to open and often becomes clogged, so an easier option is just pull the sensor out next to it, it is only held in place via a C-Clip and rubber O-Ring.As I mentioned I would try draining your coolant to start with and see if the heat returns as well as also seeing if there are any traces of oil contamination that you may see in the expansion bottle. Then you should also try clearing your heater core, via disconnecting the inlet and outlet pipes at the bulk head that go into your cabin, place a garden hose on the inlet and see if any gunk come out of the outlet and it should be a strong flow through it with no restrictions, if possible connect the hose to your hot tap it makes a world of difference to clear the pipes. Then back flush by connecting the hose to the outlet pipe and see what comes out of the inlet. You can do the same for the hoses that you disconnected from the core to and allow the garden hose to force out the dirty coolant for a few minutes. Once you have flushed, you can then check for trapped air as you mentioned via the small bleed hole on the core outlet pipe and also via the nut on the metal pipe at the top of the engine to the right.

LordKarnage17

Tried bleeding the heater core yesterday using the little hole in the pope, but it was one there pretty good and I'd didnt want to damage the barb that the hose goes into.
One thing I did notice is that during that drive, when the engine was above around 2.5k there was coolant getting through the heater core, and there was a good bit of heat in the cabin, but as soon as the rpms droped, the coolant flow went back to basically 0.
Would that mean a clogged heater core, or trapped air?

With the weather outside being sub 0 throughout the day, I'm a bit hesitant to flush the coolant and fill it up with water because the of the small risk of it freezing in the block, so I'll wait until I can go over to my friends place thats got a garage.

A1EK

You've described common symptoms with both points.
The hose can be difficult to remove from pipe, but try again as when you know the method it's quite easy, so here's how. Push the hose further onto the pipe first give it a twist this will break the seal, then try pulling hose off pipe. If this doesn't work buy or make a hose release tool as attached, slide the hook between the hose and pipe and work around , the hose will come free.

As for having heat when moving but not when stationary this is something I had, it could indicate a blocked core, however if your heat was fine before than it could likely be trapped air .

Try releasing the hose again there should be a steady stream jet of coolant when warm that spray's out. Also use the air release nut on engine pipe.

John535is

going back to your initial post, did you ever find the 'small leak'.
Reason for asking, one symptom of the water pump failing is the drop off of water flow at idle, but picks up when revving which you noticed.
second symptom is there is a little weep hole on the water pump, when the seal is failing it will have a small drip. Check around the lower front of the engine for any coolant stains.