ALH TDI coolant leak from water pump? freeze plugs?

Fellas,

I have had a nagging coolant leak for some time now. I found a small crack on the expansion tank that I fixed, and one other small coolant leak from one of my other coolant hoses which is now fixed. Unfortunately those two leaks were very small and my issue appears to be elsewhere. It's to the point now that I am adding 1/3 gallon for every 57 miles I drive.

This past weekend I lifted the car up and found evidence of coolant leaking from the lower passengers side of the engine directly under the crank seal. Obviously it's from some component above the crank shaft like a water pump or something else. There are no other coolant leaks on the vehicle. I have checked all other possible locations(for instance the hard coolant pipe O ring) and found no other leaks. I did a full TB job 60K miles ago using very high quality parts from our trusted online vendors here so I'm having a hard time believing it's a bad water pump seal. I went ahead and ordered a new water pump(HEPU brand made in Germany w/ metal impeller) that should be here the end of this week. Only question I have now is if there are any freeze plugs on the TB side of the engine that have been known to leak? Any other areas I should be checking for leaks?

why not pop the timing belt cover off and look in with a flashlight? Dont need to worry about removing much to get that cover off.

Dang! Josh8loop, where have you been? Long time, no see!

Seems some of the WPs have a small plug that appears as a freeze-out plug. But, I've never seen one that appeared to be leaking!

elroy said:

why not pop the timing belt cover off and look in with a flashlight? Dont need to worry about removing much to get that cover off.

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I forgot to mention that I have already done that. Unfortunately it didn't turn up any visual indications. You can't really see the lower section of the water pump with the lower TB cover section still on.

AndyBees said:

Dang! Josh8loop, where have you been? Long time, no see!

Seems some of the WPs have a small plug that appears as a freeze-out plug. But, I've never seen one that appeared to be leaking!

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I know, it's been a while. Life has been very busy for the last few years. I have been lurking from time to time on the site. Maybe your right, I should look at that plug when I get things apart. I guess first thing is to remove the lower TB cover and the top TB cover so I can see the pump area better and see if that shows any more visual indications. It's been a long time since I've had the lower TB cover off-I will have to refresh my memory on how that thing comes off.

Remove the Serpentine belt
Remove the Harmonic balancer
Remove three 10mm head bolts and those two lower metal covers will come off.......

AndyBees said:

Remove the Serpentine belt
Remove the Harmonic balancer
Remove three 10mm head bolts and those two lower metal covers will come off.......

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Yes, indeed. Sounds like a reasonable place to start. I guess I don't even have to take out the engine bracketry to do that?

Look at your coolant flange right above transmission. Any type of red or rust color crystal like means its leaking there. Its a 7$ part.

erbilabuc said:

Look at your coolant flange right above transmission. Any type of red or rust color crystal like means its leaking there. Its a 7$ part.

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Nope, no leaking there. All the leaking is from the passengers side.

T-Stat housing? More likely your WP though. My T-Stat housing is leaking (slowly) and it took me a while to find the source. Coolant was evident on the front oil pan flange mostly though. None made it around to the crank pulley area. I'd be focusing on the WP for sure. Hoses in/out of the reservoir may be a source also.

Don't forget about the O-ring on the water pipe. That is on the backside of the block from the water pump. Mine only leaked there when cold.


http://forums.tdiclub.com/showthread.php?t=132193&highlight=needle+lift+sender

FlyTDI Guy said:

T-Stat housing? More likely your WP though. My T-Stat housing is leaking (slowly) and it took me a while to find the source. Coolant was evident on the front oil pan flange mostly though. None made it around to the crank pulley area. I'd be focusing on the WP for sure. Hoses in/out of the reservoir may be a source also.

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That is where mine was leaking from too. I originally thought it was the WP as the front (passenger side) of the engine was wet. I have replaced that stupid o-ring about 4 times and the housing twice. It stops for a little while, then starts again. I am not over torquing either.

79TA7.6 said:

That is where mine was leaking from too. I originally thought it was the WP as the front (passenger side) of the engine was wet. I have replaced that stupid o-ring about 4 times and the housing twice. It stops for a little while, then starts again. I am not over torquing either.

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You have to make sure that the mating surface on the block is clean and smooth... use a plastic scrubber ("Brillo" - type) pad...

Yuri

ymz said:

You have to make sure that the mating surface on the block is clean and smooth... use a plastic scrubber ("Brillo" - type) pad...

Yuri

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I'll try that as I'm about to undergo another replacement. Went to the dealer for an OEM housing and o-ring this time. Dunno if that's the problem (aftermarket) but I'm getting tired of adding coolant. Thanks for the tip.

The aftermarket o-ring I had gotten when I replaced my t-stat was thinner than the OE one. I ended up reusing the original ring until It started leaking. Then I got another one from the dealer and put that in. No leaks since.

FlyTDI Guy said:

T-Stat housing? More likely your WP though. My T-Stat housing is leaking (slowly) and it took me a while to find the source. Coolant was evident on the front oil pan flange mostly though. None made it around to the crank pulley area. I'd be focusing on the WP for sure. Hoses in/out of the reservoir may be a source also.

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I'll check all that again, but I'm fairly certain it's not gonna be that easy for me. I wish! Thanks for the suggestions.

3turboz said:

Don't forget about the O-ring on the water pipe. That is on the backside of the block from the water pump. Mine only leaked there when cold.


http://forums.tdiclub.com/showthread.php?t=132193&highlight=needle+lift+sender

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That one was a real pain when I replaced that a while back. Good thing is that I know it's not leaking there thankfully. Almost wish it was leaking instead of the water pump!

I'm wondering if there is a potential I have an overboard coolant leak from the head gasket on the passengers side of the engine. My coolant system is not being over pressurized so I know it's not leaking compression to the coolant system. What are the chances that the head gasket is leaking coolant overboard on that side of the engine?

Just for point of reference, the car now has 217K miles, and the PO refurbished the head following a TB failure at 100K miles just before I bought it. Supposedly a reputable FT Lauderdale company did the machining work to refurbish the head. I guess they must have done fairly well since I have put 110K miles on it after their work.

josh8loop, I am having a similar problem, and wondering what you found?