Losing Coolant

My 1996 Passat TDI that I've owned since new has started losing coolant. Runs fine, has not overheated but loses about 16 OZ of coolant every 400 miles or so, then the low coolant warning light starts blinking. There is no evidence of an external leak. No coolant smell in cabin.

Here's my dilemma. This is my beater/work car and the body and interior is very rough. It has about 320K miles on it and I only need to get about 25K more miles out of her before I retire and no longer need to make my longish commute. I'm thinking that Bars Stop Leak might be worth a shot to get me to the "finish line". Is this even worth a shot? I REALLY don't want to spend much money on this old ride.

If you don't want to fix it for 25,000 Miles then just keep adding the two cups.
That's 62.5 fill ups of 8 oz water and 8 oz of coolant. Grand total of 500 oz of coolant. Or about 4 gallons of coolant and 4 gallons of distilled Water


So do we want to assume its consuming the coolant and being blown out the exhaust? Do you smell that caramely maple syrup? What's your reservoir look like? Oil not getting sludgy ?

kooyajerms said:

If you don't want to fix it for 25,000 Miles then just keep adding the two cups.
That's 62.5 fill ups of 8 oz water and 8 oz of coolant. Grand total of 500 oz of coolant. Or about 4 gallons of coolant and 4 gallons of distilled Water
So do we want to assume its consuming the coolant and being blown out the exhaust? Do you smell that caramely maple syrup? What's your reservoir look like? Oil not getting sludgy ?

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Reservoir looks O.K. Coolant is green (I know, I know, but I've been running regular green coolant for 15 years with no ill effects). I guess the coolant is going out the exhaust. No sludgy oil. No syrupy smell that I have noticed.

Also, yes I have considered just adding coolant/water as needed but I am concerned that the leak could suddenly get worse and that maybe a stop-gap "quick fix" may prevent that from happening.

wish easy way to tell if heater core or not, hot summer days is when they spring a leak... but if not it id assume the headgasket is seeping between the layers into the combustion chamber.. yup seen it with cars with the pink coolent.. and green corrodes vs pink supposedly.. so limp it adding stop leak is never a good idea if you do not know whats leaking.. will plug up orfaces in the cooling system.. but some black pepper is my turn to stop leak... get it from any quicky food joint free..

imo... do a valve job as the guides will be worn, a headgasket.. and drive it... keep those receits handy as in 25k when you retire it.. you can sell i tto anyone wanting to shoe horn it into their other car and you will be able to prove a top end rebuilt increasing its value, to melt it down or blow it up will in return give no return..

If the heater core is leaking, you'll smell coolant when you open the heat door. I still smell it, from when it leaked on a PO 100k miles ago.

Try looking at the 3-way hose and the one besides that. just next tot the oil cooler. Had the same problem a few years ago. turned out to be a crack in the hose invisible from above. Car running, hose gets warm, crack opens, looses coolant.

I like how the OP is here asking about a mystery coolant loss, yet claims the use of the wrong coolant has had no ill effects.

If you do not care about the car, and do not want to spend any money, just keep topping it up. Don't ruin it any more for the next guy by adding any stop leak garbage, because then the heater core and radiator will also be ruined.

A pressure test of the cooling system may help track down the source, but it sounds like you do not even want to fix it, so why bother looking?

Shame to hear of a one owner car, especially a B4 TDI, get to this point. I just hope maybe it gets sold on to someone that can make use of it. Sadly, so many parts are NLA for these now.

HI Jeff,

have a trusted shop do a pressure test on it... you'll find out of it's an internal or external leak... if you're handy, you can do the replacement hoses (Like a poster above, I've had a cracked connector not show up under normal running conditions, but the pressure test found it easily). if it's a head gasket, you can TRY retorquing the headbolts a 1/4 turn... it's gotten me out of the woods before and lasted a year before I needed to do the headgasket replacement.

If it's a B4V (wagon) put me on the short list for when you do sell it.

regards,
Steve

X2 on the 3-way off the pump to the oil cooler and the heater. The little piece of hose that mates the plastic 3-way to the pump likes to develop pinholes, or the plastic 3-way might be split. Took me months to find my phantom cooling leak because I was assuming it would leak when it was cold too...

members have also had any of the plastic flanges crack and have a hard time tracing down.
it -could- be going into motor (cracked head, or blown head gasket) however if thats the case it would go out the exhaust, that odor is obvious, it can make smoke, it can also end up in oil, it also should pressure cooling system.

also the O-rings for the flanges, and O-rings for the "quick disconnect" things with the wire clip at either end of the lower radiator hose.

it might take you a while to find it, unless it gets worse, but it will probably be a cheap fix.

oh and a third vote for that 3 way hose under the injection pump. ive replaced it more than once on my cars. if it looks swelled up, its bad. diesel leaks on it from the pump and it basically de-laminates until it falls apart.

oilhammer said:

I like how the OP is here asking about a mystery coolant loss, yet claims the use of the wrong coolant has had no ill effects.
If you do not care about the car, and do not want to spend any money, just keep topping it up. Don't ruin it any more for the next guy by adding any stop leak garbage, because then the heater core and radiator will also be ruined.
A pressure test of the cooling system may help track down the source, but it sounds like you do not even want to fix it, so why bother looking?
Shame to hear of a one owner car, especially a B4 TDI, get to this point. I just hope maybe it gets sold on to someone that can make use of it. Sadly, so many parts are NLA for these now.

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Although I really didn't need the lecture, thanks for the reply anyway. My decision is a matter of economics. The car has little monetary value. As I said, the body and interior are pretty rough. It would not make sense from a monetary standpoint to spend several hundred dollars to get the HG replaced. It would probably cost more than the car is worth. I have the ability to do it myself but not the time.

Anyway, I looked again today and the block is wet with coolant on the outside, below the head, on the rear righthand side of the engine. This is probably the best type of head gasket leak to be a candidate for a stop-leak type of "repair". Thoughts?

As far as "the next guy" is concerned, I highly doubt that there will be one.

Regarding my antifreeze of choice, regular Prestone "green" is compatible with all materials found in a modern engine (aluminum, plastics, rubber, etc.). It is also compatible with all other types of automotive coolant. What is so special about these engines that they need the expensive VW coolant? I think that over 200K miles on Prestone (it's been in there since the 100K mile warranty ran out) is a pretty good track record.

oilhammer said:

I like how the OP is here asking about a mystery coolant loss, yet claims the use of the wrong coolant has had no ill effects.

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That's rather specious logic. If someone has a headgasket leak and uses the "correct" coolant, should I jump to the conclusion that the G whatever, caused the leak? These cars are old... stuff happens.

I've run a 50/50 mix of Prestone and distilled water in all of my cars, for decades. I'm not seeing corrosion or anything out of the norm, if/when I drain the system.

-Todd

jeffk14 said:

Anyway, I looked again today and the block is wet with coolant on the outside, below the head, on the rear righthand side of the engine. This is probably the best type of head gasket leak to be a candidate for a stop-leak type of "repair". Thoughts?

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what is your fixation with that 'stop-leak' stuff, do you even know what it does?
anyways like i posted look around that flange, that it could be, or the hose.

iluvmydiesels said:

what is your fixation with that 'stop-leak' stuff, do you even know what it does?
anyways like i posted look around that flange, that it could be, or the hose.

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Yes, I'm aware of what the stop leak products do. Most use sodium silicate and/or copper particles to plug small holes. I know that they can possibly clog internal coolant passages as well.

I don't think that there are any plastic flanges above where my block is wet. I was looking at it in a parking lot today though. I'll have to put the car up on ramps with the lower shroud off and take a better look when I get a chance.

so your saying by the right side of engine, trans side? trans is right there? look right there its a small section of the head, there is a water outlet flange right there, you dont need to get underneath. look for the hose coming out of the head.

iluvmydiesels said:

so your saying by the right side of engine, trans side? trans is right there? look right there its a small section of the head, there is a water outlet flange right there, you dont need to get underneath. look for the hose coming out of the head.

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Rear of engine, passenger's side, behind the timing belt cover. I don't see a water outlet there. Thanks.

Update; Turns out, the water pump is leaking, slinging coolant all around, thus the difficulty finding the exact source. I've changed it out before using the "alternate" method where you don't remove the timing belt but since the TB is due anyway, I ordered the parts to do both.

makes sense; i suppose. sounds like you need to clean/dry back there, prob when you remove belt. dont forget seals, also takes 1 special o-ring, and possibly the crank flange (gasket), and ?bolt?.