Coolant Leak; mk4 ALH

[DaveLinger]

I've had a coolant leak for a while now; it started by leaking just a little, but now it's to the point where the reservoir will be empty within a few days of filling it.

It leaks out of the right (passenger) side, where the expansion tank is located. I've been advised that the only thing that would leak on that side would be the expansion tank/reservoir. I unbolted it and removed the upper hose, but didn't have anything large enough to compress the lower hose clamp, so I couldn't completely remove it for examination.

It had some dried pink reside around it, but no major leaks. The system holds pressure. I'm still planning on replacing it and hoping for the best, but what are other culprits on that side of the car?

 

[steelmb]

Water pump is on that end of the engine. Is it coming off the engine or fender?

 

[DaveLinger]

Fender area. I've seen coolant on the tire, FMIC piping, etc.

 

[DaveLinger]

Also I've recently removed the timing belt cover to adjust timing and didn't see any liquid anywhere - would a leaky water pump leak around the pulley? Where would the coolant come from in a leaky water pump situation?

 

[steelmb]

I'm thinking it would come out the bottom of the timing belt cover.

 

[DaveLinger]

That's what I was thinking; so if all of that was dry and it seems to be leaking from the fender area, I can safely assume it's the expansion tank or a cracked hose?

 

[steelmb]

Ya I suppose. I would get it on ramps and remove the belly pan ASAP to identify where it is coming from. It sounds like you have had fair warning to do something about this.

 

[jayb79]

my NB was leaking around the water pump, but it wasn't that the pump went bad. The o-ring got pinched during the install, it didn't leak until it had about40k on it. I put the o-ring from the old pump on and it was fine for another 80k. yes, i put 120k on my TB, lots of highway.

 

[Dimitri16V]

either the cap does not hold pressure and the coolant overboils or the expansion tank has a crack . what could be bad is if it leaks in the coolant level connector, coolant will find its way on every cable

I would bet it's the tank though, crappy plastics these days

 

[PeterV]

It is NOT the WP.... Acutally you have a bad headgasket. The resivoir is pumping extra pressure into the coolent tank and adding extra pressure to the tank & cap. We just had this same problem. ID parts had all the parts we needed. NOTE: the overflow tube leaks down the fender rail. You are running some pretty aggressive mods so expect some weakness in the head. You could drive to Red Lion, Pa and have Jeff do the work.

 

[DaveLinger]

Unfortunately, PeterV, I think you're right. That would explain why the tank DOES hold pressure and seems to leak more after aggressive driving and why it just started leaking when I replaced the turbo actuator and added 10psi. Well damn. How could I verify this? Are there any immediate dangers of driving in this condition other than having to add coolant all the time? My oil isn't milky.

I'm assuming it's a fairly expensive job to have a head gasket replaced?

 

[Dimitri16V]

you need this

http://www.harborfreight.com/catalo...tomotive+&+Motorcycle&q=cooling+system+tester

 

[Jettascuba]

Diagnosed a cracked coolant reservoir on a Jetta 3 yesterdag by pressure testing the cooling system - just put some low air pressure in via the overflow nozzle (use a bicycle pump if you don't have other sources of air). Check the seam specifically - leaked at 2 places. Also check the reservoir cap, the o-ring holder on my A4 broke apart a month ago. Also check the windscreen sprayer pump seal and coolant hose.

 

[PeterV]

I think that the verification is in doing the gasket. Your mods do put stress on everything. The gasket is the weak point...

Also do you smell any G12 in the cabin? The heater core is a weak point too. We had to do the core last year.

you are washing the pistons and walls with G12. Although you might be able to drive many more miles you could be looking at a larger repair bill if you abrade the head or block away at the leak point.

 

[DaveLinger]

Jettascuba,

I'm confident that it's not the reservoir because it DOES hold pressure. The o-ring is present on the cap. When I remove the cap, even an hour after shutting the car off, there is still some pressure.

PeterV: No, no coolant smell in the cabin, only outside and only sometimes. It seems to only leak when I beat on it (run very high boost). Is it possible that if I got the boost reduced or drive carefully and not run high boost that the leak will slow or stop until I can have the head gasket replaced?

 

[PeterV]

In order to save the possible high dollar items cost I agree a lower boost will help and a lighter foot. The benefit of a lighter foot will be fuel savings allowing you to get the fix done quicker.

By the way how many miles are on the TDi?

Our hamsterdiesels '99 Golf has 190K, My '00 Jetta has 250K. We did not go with the big turbos just RC, nozzies, clutches & suspensions.

We did not use the ARP head studs on the gasket job just the stock ones.
ps: get an extra stud or 2 incase one stud is not to spec.

 

[tstdi]

This is currently happening to me as well. Drive the car and the system seems to get overpressurized and blow the coolant out of the globe. Idle theres no problem. Temp stays dead center. Replaced globe and cap with no change. I just had the head gasket changed and I'm wondering if they didn't torque everything down correctly. Good luck with finding your leak and please let us know when you get it worked out.

 

[DaveLinger]

PeterV, the car has 140k miles. I bought the car at ~125k and "new head gasket" was listed on the seller's page for the car.

tstdi, sounds like me. The car NEVER overheats and my coolant level seems to stay at "just a little in the bottom of the tank". I hate to just jump in and replace the head gasket if it's possible that it's something easier/cheaper, but it seems like that's my only choice right now.

 

[steelmb]

You might try something like this to test for a head gasket leak.

http://buy1.snapon.com/catalog/item...&group_ID=1505&store=snapon-store&dir=catalog

I'm sure there may be cheaper alternatives out there but I figured this would give you an idea of what to look for.

 

[rangercap]

First UOA on 2000 Jetta TDI

Deleted...

 

[rangercap]

Deleted...

 

[Genesis]

If coolant gets into the oil (and it will if you have a cylinder head gasket leak) it will destroy the mains in very short order. Do not tolerate this problem; it's a known and very reliable killer of engines.

Pull an oil sample immediately and do not drive the car until you get the results back. If there's coolant in the oil you've got trouble.

 

[rpaull3]

coolant leak here too >.<

I have a coolant leak as well. I put stop leak in to get home after buying the car and it overheating on me on the way home... it made it home without another overheat, and it seemed like the leak was gone, but my dad said i should flush that stuff out. So I did, and It is leaking again. It appears to be leaking from the bottom of the overflow/fill tank. There is black in the coolant now after a warm up and hard drive around the block. I'm thinking the black is residual stop leak because that was the color of it and i didn't yet do a second drain and there was stop leak in the bottom of the fill tank when it was empty. But I'm slightly worried that I might have a bad head gasket. I will be removing the tank tonight and giving it a good look over as well as a hose check in the same vicinity. Will update on findings.

 

[DaveLinger]

I have a coolant leak as well. I put stop leak in to get home after buying the car and it overheating on me on the way home... it made it home without another overheat, and it seemed like the leak was gone, but my dad said i should flush that stuff out. So I did, and It is leaking again. It appears to be leaking from the bottom of the overflow/fill tank. There is black in the coolant now after a warm up and hard drive around the block. I'm thinking the black is residual stop leak because that was the color of it and i didn't yet do a second drain and there was stop leak in the bottom of the fill tank when it was empty. But I'm slightly worried that I might have a bad head gasket. I will be removing the tank tonight and giving it a good look over as well as a hose check in the same vicinity. Will update on findings.

If the coolant is leaking out of the bottom of the overflow tank, it's probably due to the system overpressurizing, as that's where the pressure release is.

The problem is... if your coolant system is overpressurized and you're not overheating, it's probably a bad head gasket. Combustion gases getting past the gasket and pressurizing the coolant system. It could also be pushing oil or burnt fuel/carbon residue into the coolant, which could explain the discolored coolant.

 

[rpaull3]

bad head gasket!

So I did some more research to find proof positive that it is indeed the head gasket. I found the coolant system pressurizing after a few moments of being started, I found oil in the coolant, and the oil level, which I just changed after purchasing the vehicle, was lower after a single drive around the block. Thusly I am now researching how to replace the head gasket.

 

[\/\/0J0]

Do not attempt this job unless you have the timing belt tools, a good set of triple square bits, and access to vcds.

 

[antonio2001]

Can amyone give some advice? i noticed my coolant level was low randomly. thermostat never opens here were in winter with -30c temperatures. i cannot find the leak ANYWHERE. system is never fully pressurized. maybe because coolant never gets idealy to normal op. temp. cause of the cold. brand new thermostant and coolant. change it everyyear before winter. not headgasket cuz its brand new. so shouldnt be. and not waterpump either. not even that dreadful steel pipe that does the turn of the world around the engine. any advice to where to look?

 

[Stan TDI]

Here is a long shot but it happened to me. Coolant was at the passenger fender closer to the front of the car. Ended up the side skirt had been pushed up against the coolant hose. The hose then was slightly rubbing against the accessory belt. It ended up with a slight cut that would leak coolant.

 

[antonio2001]

hey thanks. so far no more leaking. ill keep on eye on that thanks alot man.