B5.5 Poor heat after Balance Shaft Delete

Hello everyone.

Questions up front:

1. What's the best way to purge air from the coolant system?
2. Does anyone have any other ideas on what could be happening?

Details:

I deleted the balance shaft on my B5.5 Passat TDI. Of course along with that I changed the water pump and thermostat.

The car now exhibits intermittent poor to no heat in the cabin while driving.

Things I have checked:

• Coolant level is at MIN mark on coolant overflow tank
• Top radiator hose does get uncomfortably hot after highway driving, but not painfully hot.
• Flow control lever in HVAC system (under dash) is moving when I turn the temperature knob in the cabin.
• Coolant temp gauge moves normally to middle while driving. Never "overheats"

I have not ruled out the possibility that the car is just not warming up completely.
It was ~45F this morning, but after ~10 miles highway driving it should have been pumping out some heat. Instead I had "mildly luke warm" air that quickly went cold after idling for a short time.

I have not logged the actual coolant temperature with Vag-Com yet, as this just started happening in the last couple days as I have just recently finished the engine work.

Since noticing this situation, both my wife and I have heard what sounds like a "scratching" sound under the dash. My wife insists something is under there , but I believe it may just be air purging through the system?

Try Bleeding the cooling system

I would double check the bleed too. from my experience a new thermostat does cause longer warm-ups. did you kinda gauge the amount of coolant filled versus drained?

In order, before you do anything - get the actual coolant temperature via VCDS, SGII, etc.

Not uncommon for t-stat to stick open slightly as it ages, and knowing the actual coolant temperature (the gauge is inaccurate) will let you know if your T-stat is operating correctly.

Also no uncommon for the heater core to start to plug up as it ages, worse if coolant has not been changed during the car's lifetime. Some have had some success with backflushing the core, others have replaced the heater core (dash needs to come out) in order to get good heat again.

Finally as above, bleed the air out of the cooling system per the link above. Note that some gurgling noise will always be there. It is a waste of energy to try and completely bleed the air out of these cars - there will always be some air causing a gurgle when starting off most mornings.

Thanks for the responses everyone.

I will definitely confirm the actual coolant temp with VCDS before going any further.
I know from my ALH jetta that quick warm ups in colder weather is a bit of an oxymoron.

hughesjasonk said:

did you kinda gauge the amount of coolant filled versus drained?

Click to expand...

I did not.

The whole balance shaft job took place over the course of about 3 months. Remembering how much came out to begin with was the least of my worries as the down time crept higher and higher.

Gotta love having an 18 month old command all your free time!

Update here..

Bled the system several times. I am now to the point where as soon as I remove the hose enough for coolant to escape, it comes out right away.
I've had the coolant tank held up as high as it would go when doing this.

I now have no heat at all.

I have not verified that the car is getting to full operating temperature yet, as the logistics of doing so have just not worked out. I have however driven the car for upwards of an hour at a time without the heat coming on during all of this.

I have felt both the inlet and outlet hoses for the heater core and they do get hot, but still no heat.

Perhaps a backwards flush is in order?

Are the hoses on the heater core hot enough that you can't keep your hands on them?

If that's the case, the engine is up to temp, but the core is not radiating/transferring any heat.

It would be best you confirm the actual operating temperature of the engine either via scan tool or a non-contact thermometer, but I'd say you have a good chance that your heater core (at the least) needs to be flushed.

Another way to (sort of) confirm is to run the engine up to temp, then park the car with the engine running (maintain heat) and the fan on 0.

leave it that way for a few minutes, and then turn the fan on 1, and see if you get an initial amount of heat which trails off - this would be a good indicator that there is poor flow through the core.

Definitely not hot enough to prevent me from keeping my hands there, neither was the top hose on the radiator.

I have to assume that these cars are similar enough to MK4 TDI's in cold weather, in the respect that cold weather + highway speeds = slow warm up times (despite needle on dashboard).

I'll try to find time to flush the core.
My wife is getting antsy to get her car back. We're quickly approaching the mileage limit on our leased 2013 Jetta!

If you are able to keep your hand on the upper rad hose after "upwards of an hour" then your t-stat is sticking open. I would replace it given your description. Again, confirmation with the thermometer or scantool would be ideal.

I lean towards OEM (despite the increased cost) on thermostats, don't like doing those twice. Get the plastic housing as well - cheap, and the retainer tabs tend to break on removal.

Sorry, drove to work today and could hold my hand on the hoses. That was maybe 10 miles if highway driving.
I did not attempt holding the hoses after said hour of driving the other day.

I'm hoping the thermostat is good, just replaced it with OEM new as part of the t-belt job.

danthemanohhyea said:

Sorry, drove to work today and could hold my hand on the hoses. That was maybe 10 miles if highway driving.
I did not attempt holding the hoses after said hour of driving the other day.

I'm hoping the thermostat is good, just replaced it with OEM new as part of the t-belt job.

Click to expand...

When you replaced it, did you replace the plastic housing too? There are tabs in the housing that can break off and jam the thermostat. Or if you put it back in with broken tabs, the thermostat may not seat properly. You need to get a bluetooth OBD dongle or any OBD cable and monitor your temp in real time.

I back flushed the heater core today.
I could not believe the amount of deposits that came out, probably a cups worth if I collected it.

Refilled the lost coolant and bled the system. Had heat before I was out of the garage on a cold engine, unbelievable.

Still getting some gurgles from the heater core area when driving, I presume those are excess air moving through.
Should I attempt another bleed once the car cools?

These cars gurgle no matter how well you bleed them. Given the flush, I would bleed at the pinhole one more time with the reservoir up in the air, then motor on.

Just saw this thread. Are you using G12 or G13 coolant and mixing it with distilled water?

So much better to fill these Passat cooling systems with a vacuum setup that will draw the coolant in and nearly fill the entire system without air bubbles when done correctly.

The biggest thing is a large difference in coolant flow in relation to the reservoir, which is the fill point for the system.

On a transverse mount car in the VW/Audi world, the lower hose of the reservoir draws coolant out of the reservoir and into the black metal pipe, which is coolant return back into the engine block, BEHIND the thermostat, directly into the water pump. It flows FULL time no matter the status of the thermostat.

On the Passats, the lower hose of the reservoir is one piece with the lower radiator hose. The lower radiator hose does not get any coolant flow at all, UNTIL the thermostat opens up. THAT is the biggest issue with filling these systems and why I cannot recommend enough to use a vacuum system to prime these cars.

Sure, you can also hang the reservoir and fill it from the tiny return/bleed hose. It takes significantly more time and still generally doesn't do as good of a job, but it's doable.

Believe it or not, if you do it right, you can in fact virtually eliminate the heater core gurgle, or at least reduce it to being barely noticeable.

Where do you apply the vacuum and what with?

You fill it from the reservoir.

Use this tool or one similar to apply vacuum and help you fill the system.

The above is the tool I've been using for the last 3-4 years with good luck. Decent price, too.

EDIT: You will need an air compressor to operate the tool as well...

danthemanohhyea said:

I back flushed the heater core today.
I could not believe the amount of deposits that came out,

Click to expand...

What did you use to clean the heater core? I've used CLR before and it worked very well.