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1999 Jetta Coolant Leak Mystery


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Quercitin
Novice

Jun 29, 2013, 5:34 PM

Post #1 of 7 (1438 views)
1999 Jetta Coolant Leak Mystery Sign In

1999 Jetta GLS 2.0L AEG engine. Automatic transmission. 62,000 miles.

I’ve had a slow coolant leak from bottom of engine for several months. The leak accumulates to a visible droplet at the lowest point where the engine attaches to the transaxle, but the source appears to be from somewhere above this spot.

The leak rate has been the same whether engine was running or not. And the same rate whether the engine is hot or cold. And it had gotten no worse over these last months.

Two weeks ago, the vehicle began overheating, so I figured the leak was due to a failing water pump although that seemed unlikely given where the leak was coming from. I replaced the thermostat and water pump (and timing belt), which solved the over-heating, but the leak persisted exactly as before.

I jerry-rigged a coolant-system pressure tester (O’Reillys rental kit was for systems with radiator caps only) and have been able to get a few psi on the system. I continue to be unable to see where the leak originates. Of note, the rate of the leak appears less after the pressure test – perhaps I forced some debris into the source of the leak?

Thanks in advance for any feedback you all have.


Discretesignals
Ultimate Carjunky / Moderator
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Jun 29, 2013, 5:48 PM

Post #2 of 7 (1428 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

Without being there to look at it, can't give you an answer. You really want to pressurize the system to the rating on the cap.

Have you tried using inspection mirrors and high powered lights to help see the source?





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(This post was edited by Discretesignals on Jun 29, 2013, 5:49 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jun 30, 2013, 1:47 AM

Post #3 of 7 (1392 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

Get a pressure tester that fits where the pressure cap is no doubt on the recovery tank,

T



Quercitin
Novice

Jul 4, 2013, 12:49 PM

Post #4 of 7 (1352 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

Yes I've used a mirror and have a good insprection light, but can't find the source of the leak.

If I could figure out how to pressurize the system, it should then be fairly easy to find it.


Quercitin
Novice

Jul 4, 2013, 12:53 PM

Post #5 of 7 (1351 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

Any ideas on where to find a tester with the compatible fitting? I've tried both O'Reillys and Autozone, both of which have only the adapters for a conventional radiator cap.

The Jetta has a threaded plastic plug on top of the plastic coolant reservoir.


Hammer Time
Ultimate Carjunky / Moderator
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Jul 4, 2013, 1:29 PM

Post #6 of 7 (1349 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

You can buy an adapter for about $30 but you'd be better off just having a shop do it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 4, 2013, 2:24 PM

Post #7 of 7 (1339 views)
Re: 1999 Jetta Coolant Leak Mystery Sign In

It's nice when you can "rent" tools but if you can't then buy what you need or get it diagnosed with someone who does. You should have one to check that the fix worked after if found under pressure.

If leaking enough it's not holding pressure and will overheat again and just keeping a leaker full without cap on radiator can be a problem by itself and some are fussy no matter what.

You are risking your engine so attempting to save a buck if not too late now If you don't have the equipment then you may not even have tools to fix it anyway that would easily exceed having it done.

If you are lucky enough that it's just an external leak anywhere coolant travels without witnessing it it will be at the bottom unless car is left upside down or could be spraying to another spot so need to quick clean off suspect areas, perhaps blow dry it quick and watch it come back.

Hoses, gaskets, sensors into coolant, freeze plugs, radiator and more or it's also burning it up which is trouble already or mixing into oil or whatever. Waiting is costing you more than any free rental savings,

T







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