Jetta 1.6 TD ECODiesel operating temps?? What's normal??

[Quantum TD]

So, I've got a 1991 ECODiesel Jetta (same as Canadian 1.6TD, but with a Catalytic converter). The one with the 1V motor: k14 (24?) turbo, catalytic converter, and no boost aneroid.

I bought the car a few months back, and the PO claimed he blew the head gasket, as it kept pushing water out of the coolant system: first the front flange, then the overflow tank. He did not drive it much. He just bought it to drive in the winter, instead of riding his motorcycle. He said he stopped driving it for fear of blowing the head completely.

So I bought the car assuming I would have to replace the head gasket, but I started out on the simple first:

1) I removed the overflow line restrictor. It was clogged and was preventing the coolant from moving thru the system.

2) I fixed all the wonky wiring for the fan system. Before I did this, none of the fan speeds worked (except with the AC/defrost on), and the wiring for the dual fan setup had been scorched by some hack wiring. Thankfully, I had a spare harness to use. It all works as it should now.

3) I installed a new waterpump, timing belt, low-temp thermostat, and a new fan switch (kinda high-temp though).

4) I put in some used antifreeze, expecting that it would blow out of the system.

After all that, and myriad other repairs, the car runs fantastic. It starts right up everyday. Granted, it's summer, but I tested all the glow plugs and they work fine.

It runs like a champ. Granted, the turbo is puny, but it works flawlessly and there is no play in the shaft (amazing even at 180K miles).

So, I've driven it a few times on the highway and around town over the past week or so. It's been about 93-101 degrees every day here in Tennessee for the past few weeks, so it may have something to do with the “problem” that I'm experiencing.

The car seems to run a bit WARM for my tastes. I am accustomed to my Rabbit D, where the needle is always DEAD-CENTER on the gauge. This ECODiesel runs to the right of center: BETWEEN the center point, and the tick to the right of it.

Now, the car does not overheat, does not loose coolant, the fans come on at idle and in traffic at both speeds. It even comes on, as it should, when I turn the car off after some highway driving.  I just did a compression test today on it. Here are the readings:

#1: 420 PSI
#2: 420 PSI
#3: 420 PSI
#4: 420 PSI

You can't ask for better numbers in terms of consistency. Admittedly, the compression is near the wear limit, but that they're all even indicates to me that the head gasket is NOT BLOWN.

SO...

I've come up with several possibilities about my problem:

1) I'm a neurotic freak who worries too much.

2) The temperature is normal for ECODiesels, as the turbo creates more heat than a NA.

3) The radiator is not performing at optimum

4) The Catalytic converter is clogged, thereby causing overheating? Not sure how that could happen, but I guess anything is possible.

5) The fan switch I have is rated too high. It's the standard fan switch for the model. But I would assume that when cruising on the highway, the temps should be low even if the switch is rated too high. No?

6) The outside temperature is so high,, that it's not cool enough to dissipate the heat from the motor via the radiator.

7) The antifreeze is mixed in the wrong proportions, and/or is the wrong brand. Currently, I've got some mixed GREEN antifreeze (I know, not the right stuff according to VW). I think that it's mixed at about 30-40% water, 60-70% antifreeze, but I can't be sure.

The temp sender is off, and it's really operating at normal temps.

That's the story. I know there aren't many of these cars out there, but I figure our friends over the border can lend some insights eh? Basically, I really just want to know where the temp needle SHOULD be, and then I'll go from there.

[Doug]

You are right about the N/A diesel seemly running cooler. My old rabbit was the same. I have a similar experience to yours with an '87 Golf TD. Your temperature guage seems to be in about the more or less normal position. I will say that after pulling my engine apart due to excessive oil consumption, I found the head gasket to be intact. After new rings, valves and guides and greatly reduced oil consumption, temperatures dropped from 7/8 to +1/2 on the guage indications. The turbo has to increase the intake heat load somewhat. The coolant shouldn't make a whole lot of difference. Use distilled water and a premium glycol so you don't get cavitaion inside the block. My theory is that the added oil blowby was overfueling the motor making it run hotter. As well, the cylinder and exhaust valve blowby contributed to higher block temperatures instead of the heat moving out the exhaust pipe. Without an exhaust gas temperature sensor it would be difficult to confirm that theory though.

[Vincent Waldon]

One notch over from centre is about right as far as I'm concerned, and I think you'll find it a bit more "responsive" to load than your NA diesel was... particularly on hot days and steep hills.

Make sure she has good coolant, run a good summer oil, and ease up on the throttle if the gauge heads to the top... you should be fine.  

Just for fun I run a manual fan switch... turn it on in advance of a big hill or traffic jam or for a few minutes when idling down... helps control temperature quite a bit... thats *my* neurosis !!


BTW your compression is fine as well... btw are you an appreciable height above sea level ??  Might raise the numbers a bit ??



Vince

[Quantum TD]

Thanks for the tips guys. I'm still looking for other responses about normal operating temps. So, please keep them coming...

In the meantime, I think I will:

1) Flush the system with clean water and coolant flush

2) Put in a lower temp fan switch

3) Put in fresh (correct blue) antifreeze with distillled water (good idea Doug)

4) Maybe have the fins on the radiator cleaned by a shop for maximum efficiency.

I think that part of the problem may lay in the antifreeze I'm using. As I noted, I have the green in there, mixed with spring water. All of the southern states sit on a limestone plateau, and so our tap water is high in calcium, and probably gypsum too. So, I doubt that helps matters.

Anyway, I figure if I attack it on all those fronts, I should be able to drop the temp to a point where at least I feel comfortatble.

If there is no difference after all that, then I guess I'll just have to live with it. I plan on selling the car eventually, and I really don't want to have to install a manual switch (a la Vincent), for the next owner.

[Quantum TD]

Well, I went thru it all this weekend. Here's what I did:

1) Checked IP timing. It was spot on at 1mm advance

2) Flushed radiator at a shop nearby ($20) and they cleaned the fins with an alluminum cleaner. They also pressure tested it too (it's fine).

3) Flushed the whole system with Prestone coolant flush. I did this without the thermostat. The strange thing is that the car ran COOL (about 1/3 gauge) for the flush, but the fans came on as usual

4) Rinsed the system and filled with Prestone Phosphate free coolant (the orange stuff). I've had good luck with it in my Rabbit. I would have used the factory blue goo, but I'm selling this car to a girl, and didn't want to complicate her life too much

5) Changed the oil. Put in Mahle filter and Rotella 15w/40 oil.

6) Cleaned the fins on the AC condensor

7) Swapped in a different fan switch. The one that was in there was rated for 75/83 C, and I put in one rated for 85/90C, and the EKTA calls for one rated at 95/102!. I've never seen a switch rated so low as the one I had in there. I got it from my dad, and I don't know what it was originally supposed to fit.

    I think I may have been working against the thermostat with that switch. The Thermostat is rated at 87C. The thermostat MAY be for a gasser (056 121 113D), but I'm pretty sure that they're the same. Bentley claims that the diesel thermostat has a FULL OPEN position. I thought that they all did? Anyway, I figure, if the fan comes on at 75C, the water is routed from top to bottom of the rad, the fan switch is located at the bottom of the rad, and then the water goes to the thermostat located on the bottom of the engine. If the fan comes on at such low temps, it may be cooling the water TOO MUCH before it hits the 87 degree thermostat, making it close again, and keeping water in the engine. This stop/go may be making the car run warmer than it should.

Reassembled and took for a test drive.

After a trip on the highway, the temps are the same as they were before (as read on the gauge). At idle, it doesn't go over 1/2 to 3/5 (3rd tick on the gauge). As I get up to speed on the highway at 80 MPH (I have an AVX trans on the car, which keeps RPMS high), the gauge rises a little between the 3rd and 4th ticks on the gauge. Not too bad, but I have no idea what the absolute temps are. I may go buy one of those IR thermometers at Harbor Freight and see what I got.

I spoke with my pops, who used to have a 1991 Canadian 1.6TD w/o AC, and he said his always ran 3/4 on the gauge for the 10 years he owned it. I drove that car, but don't seem to recall the temp gauge reading high.

So, I guess the bottom line is that:
1) The sender is ***

2) The gauge is ***

3) BOTH are ***

4) I need to revert to the factory Thermostat and fan switch setup (90 degrees on the thermostat, and 95/102 on the fans).

OR

5) Everything is working as it should, and that's just where these cars run.

I think I'm sticking to #5, as the girl is coming today to pick up the car.
 :laugh:

She's a friend of my GF, so I'll probably be her mechanic after she buys it anyways. I can always take a look at it later.

[jtanguay]

i was having similar problems.  turns out it was my t-stat.

i wish i had a gauge that showed me the temp in celcius... instead i bought a colder t-stat (okay for the hot summer, but crap for winter)

seems like i need to change my t-stat already (160F... pretty cold!) since i get weird smells from my car that weren't there when the high temp t-stat was in.

my gauge would creep right up past 3/4 on the gauge.  faster i drove, hotter it was, and if i pulled over, my rad was COLD.  it was only until i idled the car that the rad would start to get hot.  sometimes the fan would come on, but that was rare.  if i let the car idle, the fan would come on at approx between middle and 3/4.  needless to say i was pretty concerned... at -20C on the highway doing 100-105km-ish, heater was on max, and my temp was at 3/4 or so.  

when i changed my t-stat i boiled my old one, and it opened a little before 100C, and then started opening more, but never fully.  faulty part right from a VW dealership.  i wonder if they installed it, and my car blew a motor because of it, would they be responsible for getting me a new motor??  :lol:

hope all goes well with the car

[rob76]

SO which thermostat should be used in a turbo diesel?
There seems to be options for a 70, 80, 87 and 92 Celsius T-stats to purchase online.

My fan comes on at around 92 and shuts off at around 82.

Where does the temp need to be for proper combustion?

[jtanguay]

general concensus here is 87C.  maybe in colder climates a 92C t-stat would be in order, but IMO it would lead to a blown headgasket on a really hot summer day (especially if the rad fan quit for some reason  :roll: )

[rob76]

Ah I just found a table on page 4-12 in my Bentley.
It says:

For diesel:
begins to open: 87
fully open:        102

You were right jtanguay!  Thanks