MKV heating issues

Been having issues with my car not building heat ever since the temp dropped below 0. I let the car sit and run for half an hour to warm up and my temp gauge will barely make it up to the 70 mark, half the time it wont even come off 50. I have an hour drive to work and the temp gauge will climb to around the 70 mark in slower driving but drops below that on the highway. At first I figured it was the thermostat so I put a new one in and no change. My blower motor crapped out and I changed it which gives me a bit more heat in the cabin when it sits and idles for awhile but I can feel the temperature drop off as I start highway driving. I also blocked off the rad with cardboard which improved my problem only slightly. I feel like the car should be able to build way more heat, considering temp in ottawa has only been between -5 and 0 lately. Any ideas of something I have not tried would be appreciated!

TDIs produce very little waste heat, so letting it idle for half an hour is a waste of fuel and not doing your engine any favors. Get in, start it and drive it. Shift at 2000-2500 RPM until the temperature gauge needle starts to move, then you can increase the shift point. I have a ScanGauge and see the temperature drop on cold days sitting at a traffic light even down here in MD. You might consider a FrostHeater.

OP does your car still have the EGR cooler?

That is usually where I am shifting at but the needle barely moves..

Carlos_TJ; my car has the EGR deleted

Jettario said:

...my car has the EGR deleted

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Another reason it takes longer to heat up. Also, it is not uncommon for a t'stat to be bad out of the box. Do you have VCDS, a ScanGauge, or an app like Torque to read the actual coolant temperature? You can't trust the temp gauge in the cluster.

Do you have a belly pan and side skirts? If those are off it's difficult to build heat in those temperatures...

What temperature thermostat do you have? Lower temperature thermostats have holes seeing more coolant to follow before it opens...

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Check cabin air filter. EGR delete may be a culprit.

Thanks for the replies guys!
So I have a new head unit in that has the torque app, just need to install the obd2 connector to use it.

Side skirts are still there no splash guard/ belly pan guard tho, I was wondering if that might be part of my problem also. I can get another at a local pick n pull scrap yard.

Not sure about the thermostat rating, it was identical to the one I took out I know that.

Will replace cabin air filter, probably due anyways seeing as I just changed the motor and don't know when it was last changed.

I don't know much about the EGR system, I bought the car with it deleted.. how is it being gone causing the engine to take longer to warm up.

Thanks again for your inputs!

Belly pan is definitely effecting the engines ability to warm up. You basically have all the roads cold air hitting it from below and icy water and slush splashing up on it. This affects it more than the EGR delete.

The Exhaust Gas Recirculation system circulates warmed exhaust through the intake, especially early in the warmup cycle. This increases the speed at which the vehicle warms up tremendously.

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Hot exhaust passes through the EGR cooler, which is connected to the cooling system. This speeds up the warming of the engine coolant...

Jettario said:

...I don't know much about the EGR system, I bought the car with it deleted.. how is it being gone causing the engine to take longer to warm up.

Thanks again for your inputs!

Click to expand...

The egr cooler heats the coolant by exhaust gas temp when the engine is cold, but that is not your problem if the engine is not reaching temp, it only assists the time required to start heating up. I have egr deletes on both ours and they both build good temps and cabin heat without blocking airflow to the radiator.

Plugged cabin air would definately affect interior heat. Your dash gauge is radiator temp not engine temp. Engine temp is the sensor at the outgoing coolant off the head. Can be read with VCDS.

Run it under a load hard and warm it up. If the thermostat is open the hose off the head to the top of the radiator should be hot and the lower out of the radiator cooler. If stat is closed, lower one will be much cooler or cold.

You can do the same with your heater hoses close to where the heater core is to check for blockage in your heater core and weather the heater core is pulling heat out of the coolant.

I wasnt trying to start the edr cooler vs coomant temp debate. IMHO a no heat because of weak thermostat will be more visible on a car with no egr cooler

Pretty strange one, really seems to point to the thermostat. Long shot- A small leak in the cooling system can cause reduced efficacy.
Lots of causes for the bits in the HVAC, but if the engine doesn't reach operating temperature something is wrong. 0c ain't that cold.
Lower engine cover? just don't know, but if you do much high speed urban driving you might consider putting something metal down there.

OK, yea im mostly highway driving to work and back, cruise around 110/120km/hr so makes sense that not having that bottom cover would just allow freezing air to circulate in and around my engine, ill try to grab another 1 of those or maybe I can fabricate 1 out of a thin sheet of aluminum?

jmodge: thanks for differentiating engine temp/coolant temp, I will try that test to see maybe it was a bad out of the box t-stat. also going to check the box and make sure its not a high-flow t-stat XP.

Ill grab a new cabin filter tonight and try that. Good possibility I will get more heat in the cabin from that alone seeing as I had an improvement from replacing the blower.

Going to also order the OBD2 sensor that plugs into my headunit so I can read actual temps to see what is really going on and I got a buddy bringing home a IR camera from his work so we can take a look-see at how where the engine is heating and cooling.

Ill keep you guys posted sometime next week when I have some results, thanks again for your help!

So I replaced cabin filter the other night, get a bit more warmth out when I'm cruising on the highway. I got looking at my old thermostat and the package the new one came in. Old one was jammed slightly open it won't close all the way. The new one is called a "fail safe" and says it will always fail in the open position. So im thinking it was probly a dud and failed the first time it popped open.

Last night I was at a buddies place who had an IR gun. We drove the car around for awhile then threw the gun on it. Engine block was around 130-140 degrees, the upper hose going into the rad was also around 130, rad hose going into the engine at the thermostat was 80 degrees close to the rad and 40 degrees about 16" down from the thermostat. Going to get new t stat at napa today that's not a fail safe and 195 degree rated