TDI heater works... sometimes...

[Brock_from_WI]

I have had the TDI heater for 3+ years now. Anyway I use it a lot and just towards the end of last winter sometimes I would notice the coolant only about 100F after the heater being on 2 hours. This fall it is doing this more and more often. Right now we have been in the 15-25F range

So I checked the heater still pulling a nice 915w, left the meter on all night to find it only used .5kw in 2.5 hours, so it is obviously cycling on and off and the coolant was only about 100F again. If the car is at all warm the coolant heater will keep the coolant right up at 190F.

So my guess is one of two things and I would like your opinions.

First the over temp or regulator on the heater is failing and it shuts off before it should, causing the coolant to not circulate around the engine, but this seems odd because if the coolant starts warm the heater will keep it warm.

Second, for some reason the coolant isn't circulating like it used to. This would cause the coolant right near the heater to warm up and then the heater would shut off without circulating it around the engine. What might cause this? A bad thermostat? Thoughts?

 

[LeeM]

My guess is that there is air trapped somewhere in the hose leading to or from the heater preventing the convection flow through the heater.

 

[freewheel]

Brock,

I'm into only my second winter with the TDI heater, but what you're describing as an emerging "problem" is the way the TDI heater has always worked for me. I can probably leave the heater on all night and never see the temperature be 190F at start-up. The coolant is warm enough for a quick and easy start, but it still takes me a few miles of driving to hit the 190F mark. Either your heater is functioning the "correct" way now, or mine has never worked correctly!

Anyway, just how warm is the TDI heater supposed to get the coolant after being plugged in for 2 hours when it's 15 to 25F outside? I guess I'd like to know too.

 

[40X40]

Well Guys,

What did the manufacturer tell you when you asked them? You DID ask them, didn't you? (if either of you haven't, please do!)
I am thinking of buying a Frostheater (two actually) and really want to know what to expect.
Do you leave the temp control on the car on high and select defrost? Does this keep the windshield deiced?

Keep us posted and Thanks!

Bill

 

[PDJetta]

My experience has always been that after a 3 hour heat with the TDI heater in a garage where its 25 degrees outside (about 35 in the garage), when I start the TDI, the temperature gauge immediately goes up to 190 degrees and within about 30 seconds to a minute comes down about half way or so and then within 5 minutes of driving, is at full operating temperature.

It is important to mount the TDI heater as low as possible so the heated water will rise and get a convective flow going, so it will circulate through the engine. I mounted mine per the instructions.

--Nate

 

[gern_blanston]

My experience has always been that after a 3 hour heat with the TDI heater in a garage where its 25 degrees outside (about 35 in the garage), when I start the TDI, the temperature gauge immediately goes up to 190 degrees and within about 30 seconds to a minute comes down about half way or so and then within 5 minutes of driving, is at full operating temperature.

Ditto.

 

[freewheel]

Bill 40X40,
I've just always assumed my TDI heater is working correctly. But that's because the four other coolant heaters I have (2 tractors, 1 pickup, 1 delivery van) all work the same way in the sense that none of the other engines are anyway near "operating temperature" after using their coolant heaters for a few - or more than a few - hours. All of these engines, including the TDI, live in an unheated machine shed, and only on rare occasions do I ever plug them in above 25F. When I do use the heaters, the engines all start-up quick and easy, but there's a variable number of minutes of running time before the needles on the temp gauges get to the normal operating range. At the extremes, one tractor (a 35HP diesel) takes about 4 minutes at a fast idle; the pickup (diesel F250) takes about 10 (yes, 10!) minutes of drive time. And both have OEM coolant heaters. I have always taken these time differences to be due to the differences in the wattage of the coolant heaters coupled with the actual volume of the cooling system determining just how close to normal operating temperature the engines are at start-up. Big wattage and small system in the tractor = a faster "warm-up." Little bigger wattage but way bigger system in the pickup = a slower "warm-up." Yet even at 0F, both engines are "warm enough" to start-up quickly and easily - with no smoking - if their heaters have been on for a few hours.

As for the TDI, it takes about an average of 5 to 6 minutes of driving time before it's at 190F. Obviously, the colder it is out, the longer it takes. I don't have the heat "on" inside the car when the TDI heater is plugged in. I just adjust the temp and defrost settings as I'm going down the driveway. The coolant is warm enough such that unless it's really, really stinking cold out (like -20F), I've never had a fogging-up problem.

 

[Brock_from_WI]

I have a scangauge so I can see coolant temp just after startup. When I think the heater is working what I would call "normally" I see the coolant about 190F right after start up and it quickly drops to 150F-160F depending on outside temps and warm up from there. When it does this weird thing the coolant will start at 100F and drop to 80F and then slowly warm up from there again.

I am convinced something is not right when it does this. Again typically the heater will pull 900+ watts for about 2 hours and then start cycling on and off (25F ambient) to maintain about 190F coolant temp. Now it seems to start cycling at about 20-30 minutes. Also the way it used to run the entire engine was warm, the hood was warm, if I set the selector to defrost it would event melt my windshield and slightly warm the cabin. When it does this none of that happens, the main part of the engine is cold and the only part that is hot is right by the heater and a bit in either direction, just warm at the engine, but not hot.

I do have a frost heater and mounted it in my A4 down under the battery where it said to and it has worked great for 2+ years until it started doing this.

I don’t think I could have a coolant air bubble since everything else works fine and this problem seems intermittent, but increasing in occurrences.

My honest guess is the thermal shut off on the heater is going, but the part that confuses me is why it will maintain 190F if I start with the coolant at all warm. This makes me think for some reason the coolant isn’t circulating from convection from the heater for some strange reason, but heck if I know why.

My next step is to let it run for much longer to see if eventually the convection starts. I have “off peak” electricity of cheap electricity from 9 pm until 8 am. So I will set the timer to come on at midnight and see what it has done by 7:30. Again the weird thing is sometimes it is right up there and warm and sometimes it’s not.

 

[40X40]

Thanks for the replies, Guys!

Bill

 

[freewheel]

Brock,
I have neither a watt meter nor a scangauge, so you have much better data than I do about both the electrical performance of a TDI heater and how the TDI heater interacts with our cooling systems. I guess I could come up with an explanation as to why your TDI heater can keep your engine at 190F if it's already there, yet when the engine is cold, your TDI heater isn't working as it used to. But let's face it ... any explanation of mine would be a lot of "hand waving" and probably just a lot of BS. The bottom line is that your heater isn't working consistently like it used to, and given what Nate and Gern have said, it SHOULD be working like it used to. Maybe the only thing to say is that when they were handing out defects, your TDI heater was at the front of the line. I hope it's not so, but I now suspect that this isn't going to end on a happy note.
Anyway, keep us posted.

 

[Brock_from_WI]

After turning on at midnight via the timer and leaving at 7:30 am it used a total of 3.2kw and was up to 175 when I started. I am now leaning again towards an over sensitive temp cut out on the TDI heater. I guess the way to know for sure would be to replace the heater. Does anyone know if you can replace just the over temp cutout or should I just replace the whole thing. I haven't looked yet, but what brand of heater is the TDI heater? I know it's suppose to be 1kw (but mine pulls 915w when on). I will email Terry.

 

[DPM]

Indeed sounds like the thermostat/ cutout is getting iffy.

 

[Fix_Until_Broke]

I've been plugging mine in when I get home at night ~7PM and unplug it in the morning when I leave ~7AM. The longer it runs the warmer it gets, but it's never at 190 (either by dash or scan gauge) when I start it, no matter how long it's been plugged in.

If I start it the temp will be 150 ish and then drop as I drive and come back up after a 3-4 miles. If I turn the heat on the gauge will drop all the way to cold and stay there. It's always been like this. I've always been perplexed by those who say they have "instant heat" in the morning.

 

[red golf tdi]

Brock, check the cord insulation right where it connects to the plug end, the insulation may be cracked from use/bending. You may just need a replacement plug end. If you have a ohmeter, check the resistance while flexing the cord plug end and see what happens. Resistance of the heater is normally 14.5 to 16.5 on the Rx1 scale.
Terry

 

[Brock_from_WI]

Terry I will check on that.

FUB, that is the weird thing, until recently even if it were 0F out and I had it running for 3 hours I would have full 190+ temps on scangauge then quickly fall off. Now mine is behaving the way you describe yours. I just plugged mine in when I got home last night at 11p and this am it was at 193F and dropped back to 165F, which is normal, but then again it was plugged in all night.

 

[Brock_from_WI]

Well I wiggled the heck out of it and it was a rock solid. I ahve just been running it since midnight now and it heats up fine in 6 hours. It has to be the cut out thermostat.

This makes me wonder I used to loose coolant slowly while using the heater. I bet I won't now since it doesn't get as hot right at the heater. I will throw the watt meter abck on it and see how much power it is pulling in 7 hours again.

 

[Zero10]

Mine has recently picked up this behavior as well. My assessment of the situation is that something has messed up the coolant flow causing convection to provide insufficient coolant flow and as a result the heater cycles on the high limit switch all the time. I no longer have a clear windshield if I leave the heater on defrost, and the temps never reach 90*C

Only change is I am now parking somewhere that causes my nose to point down-hill.

 

[Brock_from_WI]

Hummmm, you would think pointing the nose down might help with the heater being even lower. My parking spot has been the same the whole time. I would swear it has to do with natural convection in the coolant system as well. I have even toyed with the idea of a 12v circulation pump stuck in some non-critical spot.

So if the cars thermostat is closed would that stop the coolant from circulating from the coolant heater? Or at least until the coolant get warm enough to open the T-stat? That was my first guess and would be more logical if the thermostat on the car is somehow not behaving the same.

 

[SpeedFreek]

Not sure if this will help but in my A5 the temp goes up to 190 and slowly comes down to the half way mark, then after a few minutes it holds at 190.

This is after leaving it plugged in for quite a while, more than 3 hours, but even if I had it pluggen in for only an hour it still starts easier and gets up to temperature quicker.

I only had mine in since the GTG on october 27th but its been working fine for me.

off topic: Does anyone else try to find outlets where they park, I found some at school close enough to the parking lot that I probably could use. If I could plug in at work it would be all good.

 

[jasonTDI]

It is probably going out, they are Zerostart 1000w units. I think you got your monies worth after 3 1/2 years though. Aso if you have the heat setting on hot the heater core is getting circulated and you'll see the results of melted snow on your windscreen. Keep that loop closed (set to cold) and you'll stay a lot warmer and warm up more quickly. Especially if the car sits outside.

And there is ZERO chance there is air. The VW system returns all coolant to the highest spot and then right into the reservoir.

 

[Brock_from_WI]

Thanks, now of course this morning I had it on for just over 2 hours and it was up at 192 when I started. I think it is possessed!

Jason I also used it more then just in winter to check if it made a difference in mileage on my short 11 mile trips, it does. So I used it almost all year round so it has seen a LOT of use and certainly wouldn’t blame the heater.

If it continues to do this I will try swapping out the heater with a new one.

Either way it works it is sooooo nice and I can't say enough nice things about Terry and www.frostheater.com I am telling you if you like to be warm or like to be nice to your engine you need to get one

 

[jasonTDI]

They are the bomb.

 

[redlinedave]

off topic: Does anyone else try to find outlets where they park, I found some at school close enough to the parking lot that I probably could use. If I could plug in at work it would be all good. [/quote]

We have big trucks at work...lots of plug ins with 50ft cords

 

[LeeM]

I had air in the hose from the oil cooler to the heater but that was because I have an oversized oil cooler and the hose has a 180 degree curve in it.