Help: Coolant Leaking again, Oil Leak & Mixing in Reservoir

[Anthony3o55]

so i replaced my 2nd waterpump last monday and it started to leak coolant in less than a week causing the coolant light to come on again. My original water pump lasted me 95k miles and man do I miss it but unfortunately it leaked last year in December 2023. I then repalced it to an OE one from FCP euro and it dies in September 2024. Replaced it with an OEM from VW and leaks again. That same day I got the car back fixing the 2nd waterpump with OEM driving home had the CEL about the intake manifold getting stuck closed and a sensor issue. All plugs and connections are there so I bought an OE one from FCP. Car is 500 miles shy from 120k.

What could cause it to leak so quickly? bad installation? remove and install back on? is the seal ruined?

(stupid question) is the upper oil pan above the waterpump causing oil to leak down and mess up the seal?

Little bit of oil been mixing with the coolant for a while. I flushed it at least twice within a 1.5yrs. Last year I replaced the accessory bracket seal and the oil cooler seal.


I purchased an OE oil cooler today for $74 from O’reily locally due to high mileage. Fingers crossed.

I live in south florida so seals should go bad from multiple heat cycles maybe? This is my daily.

Looking at it all over again and replacing the oil cooler & the manifold as well.

any experiences or tips would be appreciated

thanks in advance as always

 

[DSC808]

If you replaced it this month I doubt its the thermostat/water pump, it's probably installation error. Maybe the union is not seated flush, pinched gasket, doubled up on the gasket etc... If your doing the oil cooler might as well buy all new gaskets (intake manifold gasket, thermostat/water pump gasket, oil cooler gasket) and reinstall. If you had it done at a shop have them look at it. If they took off the IM to do the thermostat/water pump it sounds like it might be related to your manifold CEL.
Also did you check the 3 plastic connections to the pump? I thought I had a bad water pump and replaced it a month ago, but it was more than likely a hose had backed off the plastic connector and started to leak. While doing the water pump I removed the plastic connector and cleaned off the residue and reattached. If you look at my pic you can see there's about a 1/2 in gap from the bottom of the rubber hose to the plastic connector. Inbetween is coolant residue/gunk. This is the middle connector.

 

[Anthony3o55]

If you replaced it this month I doubt its the thermostat/water pump, it's probably installation error. Maybe the union is not seated flush, pinched gasket, doubled up on the gasket etc... If your doing the oil cooler might as well buy all new gaskets (intake manifold gasket, thermostat/water pump gasket, oil cooler gasket) and reinstall. If you had it done at a shop have them look at it. If they took off the IM to do the thermostat/water pump it sounds like it might be related to your manifold CEL.
Also did you check the 3 plastic connections to the pump? I thought I had a bad water pump and replaced it a month ago, but it was more than likely a hose had backed off the plastic connector and started to leak. While doing the water pump I removed the plastic connector and cleaned off the residue and reattached. If you look at my pic you can see there's about a 1/2 in gap from the bottom of the rubber hose to the plastic connector. Inbetween is coolant residue/gunk. This is the middle connector.
View attachment 310271

I didn't do the work myself. I used a $30 boroscope from amazon and looked for anything odd and didn't see nothing but a leak and oil build up. Hoses looked fine looking from above.

Dropped off the car to get looked at tmrw. Doing oil cooler and new seal hoping that resolves the coolant and oil mixing. Regarding the coolant leak won't find out til tmrw night on what it was. Will bring it up to the shop. Installing Oil cooler and new oil cooler seal, new intake manifold and new manifold seal. I unfortunately do not have new seals for the waterpump. Waterpump was done 6 days ago. I do know someone at VW so if its needed I have it there or advance auto nearby.

 

[BudgetPhoenix]

Since you just had it done last year im guessing your accessory bracket or oil cooler seals were compromised and failed. Idk maybe surface wasnt cleaned well enough last time.

 

[Anthony3o55]

update: did a pressure test on the coolant system with the manifold off and coolant is spitting out the waterpump. Waterpump crazy enough has a crack leaking the coolant. Oil leak looks like its coming from the accessory bracket. Need to get a second opinion before I replace the seal to confirm it.

 

[Samb]

Hello,
Need advice please.

Golf R recently had its water pump and thermostat replaced, and I’ve driven less than 500 miles since. The coolant level stayed steady until yesterday, when it dropped just below the sensor. I topped it up slightly above the sensor with water to track any further loss.

Within 30 hours (<50 miles), the low coolant warning came back. I noticed the area near the driver’s side headlight, below the washer fluid reservoir, was very wet. Since it’s been raining heavily, I’m not sure if this is a coolant leak or just rainwater. There’s no coolant smell, and the rest of the engine bay is dry. The wetness seems to be much more than the actual coolant loss.

I suspect there might be an airlock because I hear bubbling sounds after switching the car off following a 15-minute drive. The noise is more noticeable when I accelerate hard once or twice during the journey. The car heats normally at lower fan speeds (1-3), but the air turns cooler when I set it to full blast, even with the temperature on high.

The car hasn’t overheated; the coolant temp holds at 90°C, and the oil temp rarely exceeds 107°C. Vehicle is generally healthy returning 27mpg+.

The diagnostic scan shows error code “P16C700: Heater Support Pump Locked”.

This code was present before the water pump and thermostat were replaced, but I didn’t have heating problems back then. Any thoughts on whether this could be an airlock or something else? Also, does the pressurised coolant system need to be driven to clear air pockets? If so, I’ve driven enough for it to have worked itself out by now.