[moliveira1981]

My car has been slowly leaking coolant and today I found the source. There is a slow leak coming out of the top of my thermostat:



It's definitely leaking here because when I wipe it off, the drop comes right back.

Is there anything I can do to repair this short of replacing the thermostat (and I assume the water pump at the same time)? My car only has 75k miles on it and this will be my second water pump!

[GoRomeo]

Second water pump already? Something is not right 🤔. Unless is defective?

[mainbearing]

Look into FCP Euro's Lifetime Replacement policy:
https://www.fcpeuro.com/page/lifetime-guarantee

If you decide to buy from them, then go ahead and replace both the thermostat and pump at the same time.

Also check to see if you need new hoses, especially with those problematic plastic connector ends.

[moliveira1981]

Originally Posted by mainbearing

Also check to see if you need new hoses, especially with those problematic plastic connector ends.

How do I know if I need new hoses? They all look to be in good shape with no cracks or visible leaks… but I am not a mechanic.

[moliveira1981]

Originally Posted by GoRomeo

Second water pump already? Something is not right 🤔. Unless is defective?

In fairness, I don’t think the pump I have now has failed but it does look like the thermostat has.

One big problem is that I don’t drive the car enough. Only 25k miles in the 10 years since the pump failed. The car (especially the battery) doesn’t seem to like that.

[ppointer]

This is what I use to keep my batteries happy during extended times of no driving:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[mainbearing]

The plastic connectors can turn brown and brittle with age and the o-rings inside the connectors can leak. If you are not seeing problems with those then just reuse the hoses.

Have you replaced the infamous "Mickey Mouse" flange connector by the oil filter housing? And checked the condition of the radiator vent tube to the coolant reservoir?

The water pump usually needs to be removed to replace the thermostat. If you replaced the thermostat without replacing the water pump before, then I suppose that was what you did. You can repeat it again of course, and when the pump eventually needs replacement then replace it at that time.

While I purchase mostly on Rock Auto, you can consider getting a thermostat from FCP. And later a water pump. Their lifetime replacement policy should help if you plan to keep the car longer term.

[mainbearing]

+1 put on a trickle charger if miles are that low. I do connect a charger from time to time just to "top off" the battery.

[moliveira1981]

Originally Posted by mainbearing

+1 put on a trickle charger if miles are that low. I do connect a charger from time to time just to "top off" the battery.

I really wish I could but I live in a condo with no garage and, unfortunately, no outlet that I can use near my parking space. My battery is less than two years old and starts complaining after just 1-2 weeks without starting... probably because I've had to jump it a few times already and also had it go very dead twice. Mechanic tells me the battery is ok but that doesn't sound ok to me. When I first got the car, I could go away for 3 weeks and come back and have it start right up no problem without any low charge warnings. Maybe I have some kind of parasitic draw? May need to have it tested next time I bring it to the shop.

[moliveira1981]

Originally Posted by mainbearing

The plastic connectors can turn brown and brittle with age and the o-rings inside the connectors can leak. If you are not seeing problems with those then just reuse the hoses.

Have you replaced the infamous "Mickey Mouse" flange connector by the oil filter housing? And checked the condition of the radiator vent tube to the coolant reservoir?

The water pump usually needs to be removed to replace the thermostat. If you replaced the thermostat without replacing the water pump before, then I suppose that was what you did. You can repeat it again of course, and when the pump eventually needs replacement then replace it at that time.

While I purchase mostly on Rock Auto, you can consider getting a thermostat from FCP. And later a water pump. Their lifetime replacement policy should help if you plan to keep the car longer term.

I didn't replace them myself but I just looked at the invoice from when I had it done and it says both water pump and thermostat. I'll have to take a look at the radiator vent tube.

In any case, I made an appointment today to do the water pump, thermostat, and swap out the plastic flange for an aluminum one. I will be ordering the parts from fcpeuro myself to have the mechanic install. Hopefully I get more than 25k out of this pump/thermostat but, if not, at least I won't have to pay for either one ever again (the parts, anyway). Maybe at that point I will finally bite the bullet and learn how to do it myself!

[Efthreeoh]

With all due respect to some of the posts here, the water pump does not need to be removed to replace the thermostat. Its the other way around, the thermostat needs to be removed to replace the water pump. The thermostat bolts to the water pump on the side of water pump. You can just replace the thermostat.

I do agree, if you have the cooling system opened and drained to replace the thermostat, because the mickey mouse flange fails due to age, it should be replaced as preventative maintenance. The hose the mickey mouse flange is part of is the main cooling hose from the cylinderhead to the thermostat, so it is detached from the thermostat during the thermostat removal. There are companies that sell a replacement hose with an aluminum flange instead of plastic. Have your mechanic replace the hose.

[moliveira1981]

Originally Posted by Efthreeoh

There are companies that sell a replacement hose with an aluminum flange instead of plastic. Have your mechanic replace the hose.

Good call. I was just going to do the flange but I might as well do the hose as well. It's a very small difference in price.

Is there a big difference in labor between doing only thermo vs. doing both thermo and pump? If not, I think I will still do the coolant pump. They have low miles on them (25k) but the components have been installed for 10 years now and I'd hate to have the pump go on me anytime soon.

[StradaRedlands]

Originally Posted by moliveira1981

Good call. I was just going to do the flange but I might as well do the hose as well. It's a very small difference in price.

Is there a big difference in labor between doing only thermo vs. doing both thermo and pump? If not, I think I will still do the coolant pump. They have low miles on them (25k) but the components have been installed for 10 years now and I'd hate to have the pump go on me anytime soon.

Tough call, but I would go ahead and replace the pump while there, just due to the age. Labor is probably going to be higher as it is more work for sure (extra bolts and hoses!). But probably just an increase, not doubling I wouldn't think. The pump is going to be a little pricey, but it's still cheaper than a car payment! Get Pierburg, they're the go to OE manufacturer.

[Efthreeoh]

Originally Posted by moliveira1981

Good call. I was just going to do the flange but I might as well do the hose as well. It's a very small difference in price.

Is there a big difference in labor between doing only thermo vs. doing both thermo and pump? If not, I think I will still do the coolant pump. They have low miles on them (25k) but the components have been installed for 10 years now and I'd hate to have the pump go on me anytime soon.

Your call on the pump. My BMW OE replacement pump has been in my car for 13 years and 275,000 miles. The original pumps die because of over-heating of the control electronics rather than age. The pump was redesigned in 2009 (new part number) and last much longer. I have a 2nd N52 in my 2008 Z4, which is on the original pump at 16 years now and 120,000 miles. If it was my car, I'd leave the pump alone.

The t-stat is held to the water pump with 2 bolts and just one hose (the U-shaped hose) connection to the water pump. There are 3 or 4 other hose connections on the thermostat.

[mainbearing]

If the stat can come out the side or top without even removing the pump that would be great. I changed the pump and stat only once. I fished both out between the radiator and subframe, for me the pump had to come out first. Live and learn I guess.

Anyway, if the stat replacement is that easy, then the stat and the Mickey hose should do for now. It will solve the current problem, which is a leak at the stat.

I do not know. Maybe an hour of labor max for the shop, whatever they charge per hour?

[moliveira1981]

Originally Posted by Efthreeoh

The pump was redesigned in 2009 (new part number) and last much longer.

Oh man, now I'm totally on the fence. I have a new question though...

Yesterday I replaced my HVAC blower because it had been making some squeaky noises. After I did that, I turned the car on to check if it was working. I got the "low coolant" light and immediately realized how much of an idiot I am because the thermostat is leaking (as we've been discussing) and I'm pretty sure the car is down to almost no coolant. (facepalm)

I turned the car off (it was running for < 1 min) and when I went to look under the hood there was a little bit of smoke. Nothing crazy - just trace amounts. I'd be shocked if the engine could heat up enough to cause the spilled coolant to smoke in that amount of time so now I'm worried that it was actually some kind of electrical smoke from the pump and I may have hosed that as well. The smoke came up from the left side of the engine.

My question is - can running the pump without coolant cause this and do you think I damaged the pump? If I did then I guess my decision about replacing it alongside the thermostat is an easy one.

[mainbearing]

My blower motor is squeaking occasionally. Some YT videos showed you can clean out the carbon brush powder and oil the bearing and make it run a good while longer. Otherwise I will just replace it with a TYC blower, as I did a TYC starter. Both carry lifetime warranty.
BMW's idea of leaving the brush area exposed is a stupid one.

Anyway, there is a coolant level sensor in the reservoir tank. Therefore if the light just came on you are not running too low. Wait for the engine to cool and remove the reservoir cap and shine a flashlight in there. See if you see coolant at the bottom.

When you say the "left side" is smoking, do you mean the pasenger side (left as you look from the front)? That may be oil leaks. Valve cover gasket and oil pan gasket are notorious on this engine. BMW should have paid Honda engineers to seal this engine.

I think a shop's "book rate" for water pump replacement is like 3 hours?? (even if they can do it faster)

[moliveira1981]

I will check the coolant and, yes, I meant passenger side. Forgot to mention that I had also installed a new interference suppression band (mine was in two pieces) before starting the engine. I really doubt that would be the source of the smoke but I wanted to mention it because it was coming up from that general area.

I hadn't noticed anything smoking any of the other recent times I had the engine running with the hood open so I really hope it's not an oil leak. I had to do the VCG once already. Also the blower I installed seems to be working ok during the short test I gave it but will keep TYC in mind if it happens again. TY