Coolant Mystery - Loss but no Evidence

[CAPwTDIs]

The coolant light on my '96 Passat began flashing, but the temperature guage was in normal position. I checked the reservoir which was nearly empty. Upon refilling, it has lost ~1/4-1/2 inch a day, but I cannot identify any leakage. Local shop checked it over and said they do not see any leaks but suggested it may be losing fluid in the engine. Only solution would be to rebuild. Car has new transmission. Could this become a driveability/safety issue if not addressed ASAP, or should I continue to monitor and supplement fluids as needed?

 

[MayorDJQ]

Upon refilling, it has lost ~1/4-1/2 inch a day, but I cannot identify any leakage.

Never go back to this shop. They obviously think you're an idiot who will believe any diagnosis they give you.

Local shop checked it over and said they do not see any leaks but suggested it may be losing fluid in the engine. Only solution would be to rebuild.

You could have something as simple as a slow leak that only happens at operating temps, and while driving, so that you're not finding spots in your garage. Or it could be a blown headgasket or cracked block/head, but that seems unlikely.

There are a few ways to tell if coolant is leaking into the engine: Pull the dipstick and look for greyish sludge, could mean a blown headgasket. Look under the oil cap, again for presence of sludge. Cloud of white smoke, which could also mean a blown headgasket. Pressure test the cooling system.

Car has new transmission.

Maybe someone screwed something up during the transmission change.

Could this become a driveability/safety issue if not addressed ASAP

You might get stranded on a busy interstate late at night because the engine overheat due to low/no coolant, so this would be a safery/driveability issue.

If you live in a cold area, a leaking headgasket could cause starting issues.

should I continue to monitor and supplement fluids as needed?

I wouldn't keep putting a band-aid on the problem. Either take it to another competent shop or find a guru in the regional thread appropriate for your location. Continued driving, even if you're vigileant about topping up the coolant, could lead to further damage to the engine.

 

[dieseldorf]

Cap, welcome to Fred's! Let's see, my best rec is to get to your nearest TDI go-to person and have them perform the required investigational work to figure out where the coolant is going! Stay away from mechanics at the corner gas station!

 

[TheGrove]

As the others have said get a good guru to check it out. In my case it was a head gasket that had to be replaced, but there are a lot of other things to check first.

 

[CAPwTDIs]

I'm in desperate need of the guru you speak of; there is a very limited supply in New Jersey according to the most-trusted list. Complicating factor is that it appears my cluster is failing -- needles and guages drop to zero at least once during every drive, will come back to normal if I tap the top of the dashboard, but then CEL light stays on for a while. Was surprised to see the coolant light functional in the first place. Just replaced glo plugs and harness after getting code read. Not sure what code I would get now since I can get the CEL light to come on at will by hitting the dashboard. Last week's oil check did not reveal presence of sludge but I'll check again. Minor smoke puff at start-up only. Still getting 49 mpg...

What could have been done improperly during transmission change to cause this problem?

 

[dieseldorf]

Lack of support in Joy-zee? Hardly. You're surrounding by qualified folks. Jason up in Pt Jervis comes to mind. You've also got the Metal Man in PA who offers excellent service/parts. There is no shortage of local folks who can tend to the issues.

Take care and stay away from the HACKERS !!!!!!!