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General Information => Troubleshooting => Topic started by: rs899 on May 16, 2013, 07:42:49 pm
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It hasn't happened yet, but it seems to take a lot less time when sitting in traffic for the needle to creep up and the fan to come on. Or when running before the fan comes on seems to take a bit for it to cool off.
Just for grins I pulled the front end apart and really cleaned out the fins on the condenser and radiator (original) and took off the rad and backflushed it. It flowed just fine and really looked fine for its age.
Could the water pump impeller be going, or am I just paranoid?
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if it doesn't go up above 3/4 i wouldn't worry is what im told.
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3/4 is where the fan should come on, after the thermo has opened at ~180F and the rad is now subject to 195-205F coolant. The rad fan switch is in the rad, and the gauge reading is from the head.. so your gauge reads a little hotter than the system truly is.
If it is not over heating, and does cool back down when the fan comes on.. I see no worry here.
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Verification is just a $20 IR thermometer away. Useful all around the house, shop, cars.
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8V about nails it, but I don't like the occasional high swings myself.
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I have been watching my 79 rabbit with stock thermostat and aftermarket coolant gage which is in the out port of the head piece.
I have never daily driven an mk1 and I am guessing there isn't much different between it and my 85 except the 2 stage fan?
My rabbit runs close to 190 on the gage steady going on the freeway on flat ground even at speeds of 80mph.
When I start boosting for longer periods though I see the egts rise to a max of 1350 or so thus far and the temps will increase approaching 210+ on the gage. Can't even hear the fan at those speeds so not sure what help it is at that point.
I also do not have those side/top cardboard deflectors on this car. I have been meaning to make up something but have other stuff to do first.
Also in idle traffic I notice within a few minutes the temps slowly rise and the fan will cycle for a bit and bring it down to normal and the cycle continues.
All my stuff is new including mk2 ac alternator
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Manual switch and a fan-on LED is nice to have.
Fan shouldn't come on at speed, and the side ducts to channel air through the rad does help.
190 or 210 isn't a prob, and isn't that much of a swing really, but that hot on flat ground would bug me.
I bet the ducting helps when you get it on there.
Some oil coolage might as well, that's another good gauge to have.
My ideal is the gauge never climbing over where it rides under normal driving.
Call it 12 o'clock on the stock gauge, which is variable of course.
I prefer the temp not to climb to 3/4 or so when stuck in traffic or such
before the fan comes on. I don't see any good reason for it, and can think of
detrimental effects.
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I am "comfortable" so to speak with my fan/fan switch and, after cleaning and inspection, my old radiator, but still my memory from last year tells me that something is not working as well as it used to. And, whatever it is seems to be related to low speed/low rev condition because it's cool at speed- just seems to heat up faster than I recall. I know I will be flamed for this, but I have a 160 degree thermostat on it- that's all I have ever run on these cars for 20 years in hell.
I haven't changed anything from last year.
I have a timing belt change coming up in 5-10 k miles. I will probably just change the water pump on principle then because I have a new one and the one in there is just old. Maybe I will find something there, or not....
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When you do the water pump, do a chemical coolant flush prior to draining the coolant.
Then add fresh stuff with a higher mix of freeze/water, and run some of the chemical "water wetter" or the likes. It effectively makes the coolant better at transferring heat. 160 thermo seems decent for Florida weather.. allows everything to start cooling back down quicker when operating temps are approached.
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1350 egts? That seems critically high?!! :o
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When I start boosting for longer periods though I see the egts rise to a max of 1350 or so thus far and the temps will increase approaching 210+ on the gage.
It peaks 1350, and only after extended high boost high fuel situations. Its all good.
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I don't know. I think if you hit 1350F it is OK, but if the boost doesnt bring it down then I wouldn't let it hang out there. I think 1,200F sustained is the general rule for OK, after that things get a little more dangerous.
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anyone know what the rad fan switch temp is? I would like to install a lower temp switch to get the fan to come on sooner.
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^^ I don't know if this helps any (probably not) but the on temps are inscribed on the switch on your radiator.
Back to my quandry, I have another theory.
I might have a very slight head gasket leak. I had to add about a cup of water yesterday. I needed to add some last week too, but I chalked that up to dumping the rad and having a bubble in the upper hose. Not, I'm not so sure.
It could be that the system is robust enough to overcome the slight leak at speed and full flow, but not at idle/low airflow.
If that is the case, should I try to tweak my headbolts again (these are 12mm stretch on my '91 Jetta) or ....?
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Can you rule out your heater core? I had this oddball problem on my 85 jetta and it was slowly seeping for like a week and I didn't notice it until one day just sitting in the garage I went out there and found a puddle on drivers side floor and tons of moldy stuff growing everywhere! Windows were rolled up and car sat while I had time off. Totally nasty job, had to get rid of all insulation, power wash carpet, take out dash, clean everything, etc.
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Can't rule out the heater core, but I don't think that would be the overheating issue. The coolant level hasn't been down more than a cup, if even that much.
If the heater turns out to be leaking, and it's that much of an issue, I will bypass it. If I can live without air in this hellhole, I can easily live without heat. In fact, I did for a year until I fixed the foam on the vent thingy issue.
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I have a switch to manually turn the fan on. Last week I got stuck in traffic and noticed temp gauge got up to the 3/4 mark and the fan did not come on automatically. I didn't want to wait and see when it would come on so I turned it on and gauge dropped to normal within one minute. I am going to add a temp sensor on the head to turn the fans on. The rad fan switch is on the bottom of the rad and way behind head temp.
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A rad fan switch in the head will have the fan on before coolant flow to the rad even starts happening.
Thus doing nothing to cool your engine down. A lower temp one in the rad will do. Yes it is behind head temp.. but Volkswagen among many others have been that way for a long time. It is a solid system, are you sure your fan circuit is complete.
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A rad fan switch in the head will have the fan on before coolant flow to the rad even starts happening.
Thus doing nothing to cool your engine down. A lower temp one in the rad will do. Yes it is behind head temp.. but Volkswagen among many others have been that way for a long time. It is a solid system, are you sure your fan circuit is complete.
I'm not that dumb to put the same rad fan switch in the head. new switch temp rating will be higher, exact value TBD.
fan circuit was working last summer. not sure about now. will check it out.
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The dumb thing is you are reading an idiot gauge. If it had an accuracy or numbers I would feel a little better for you, but this gauge is basically a little better than an idiot light. I spent some money on an autometer and the funny thing is when the stock gauge that I have that still works would go right up against the red line the autometer wouldn't even be breaking 200F. 190F is where it usually stayed and the stock gauge would do all kinds of weird stuff, but the autometer stayed right there, and I am inclined to think that it is the accurate one. Instead of wasting your time worrying over a 20+ year old idiots gauge go buy a real temp guage and watch that. It shoud save your engine if needed and keep you from installing all kinds of craziness.
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The dumb thing is you are reading an idiot gauge. If it had an accuracy or numbers I would feel a little better for you, but this gauge is basically a little better than an idiot light. I spent some money on an autometer and the funny thing is when the stock gauge that I have that still works would go right up against the red line the autometer wouldn't even be breaking 200F. 190F is where it usually stayed and the stock gauge would do all kinds of weird stuff, but the autometer stayed right there, and I am inclined to think that it is the accurate one. Instead of wasting your time worrying over a 20+ year old idiots gauge go buy a real temp guage and watch that. It shoud save your engine if needed and keep you from installing all kinds of craziness.
The VW gauge is repeatable but not calibrated to any temperature numbers. I can easily calibrate it and put numbers on it if I want and it will be just as good as an Autometer. I am NOT putting in an aftermarket gauge, increase complexity and add another point of failure.
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Where is your Autometer temp sensor located?
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Ever since my brothers wife overheated and locked up my jetta td 13 months I now run auber gages. They have thresholds you can set and its led goes off during the "alarm" and an auxilary power on is triggered as well that I have set with an aircraft alarm I got on ebay :) I only run oil pressure, egt and water temp. I like their stuff and spent the money on their pricey senders as well.
She told me she watched the stock temp gage rise and that it was flashing before it locked up but she just wanted to get over the hill :( Damn that pissed me off I had told them a million times about keeping an eye out. It was a lower burst coolant hose and that darn low coolant light was doing its job :(
Anyway I like my setup now better in addition to the stock gages. Once in a while I have seen goofy things happen with vw clusters but overall looking back I think I have been pretty lucky with them working.
But the auber gages make it so simple, led readout so a glance will tell you what it reads. And there is a click when the led alarm is triggered that I can hear. If its night that led would be picked up by your eye. Day time if you install it right with a cover over the top so the sun doesn't wash it out. And then of course the alarm if you are daydreaming.
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My Vw guage is not linear in any fashion nor repeatable always. My temp sensor is coming off the outlet of the head.
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My Vw guage is not linear in any fashion nor repeatable always. My temp sensor is coming off the outlet of the head.
I agree, put an aftermarket gauge in that is a mechanical temp sensor. 100% truth telling temp gauge. Mine too is in the front neck leaving the head, ie. the hottest coolant temp spot. I usually dont see over 210f when hauling ass.
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I had a toggle on the console gauge to flip flop between oil temp and coolant temp. This has the added benefit of letting one see what the dash gauge is doing. Mine was consistent @600k miles with care to the grounds, cluster voltage reg and such. I haven't checked the 82 in a few years but it was consistent last time I did.
I agree I'd not put much faith in one till it was verified as sane. Pretty much the same deal for all the old VDO or motor-meter or such euro car gauges of the era.
Interesting tidbit, 240 Volvos eventually got a damper circuit on the temp gauge to make it quit swinging so noticeably.
They fail, people bypass them. I've owned early and late examples with good strong cooling systems and never saw much diff myself.
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I run two temp sensors one on water neck on head the other on the water pipe(welded bung). Water pipe temp usually higher than water neck temp except in traffic and when theres is lots of pedal.
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My Vw guage is not linear in any fashion nor repeatable always. My temp sensor is coming off the outlet of the head.
I agree, put an aftermarket gauge in that is a mechanical temp sensor. 100% truth telling temp gauge. Mine too is in the front neck leaving the head, ie. the hottest coolant temp spot. I usually dont see over 210f when hauling ass.
Don't know about VW gauge linearity (which don't really matter) but I can say mine is repeatable. Does yours jump around and stay at different spots? The neck coming out of the head on mine is plastic with 2 sensors with o-ring seals held in by C-clips. You have a MK2 and I assume it has the same plastic neck. What after market gauge/ sensor did you use to fit in that neck? Most after market temp sensors have NPT threads, which won't fit.
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I looked at the wiring diag. for my Jetta and the rad fan switch has 2 sets of contacts, one at 95C and the other at 105C for low speed and high speed fan. I jumper-ed the power input pin of the rad fan switch connector to the low and high speed contacts and the fan works on both speeds. My next task is to pull the rad fan switch and test it in hot water to make sure the switch contacts works at the correct temps.
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I'd like to have a two speed setup in mine.
The 82 isn't nearly as annoyingly loud and the idle
doesn't drop on the 1.9 when the can comes on, but
I'd still rather a low speed at a lower temp and a faster one
later. Might be a retrofit project one of these days..
I replace those fan switches as maintinance every other
cooling system flush. They get lazy. Long as I can get
non-chinese one's anyway. 87-92 Whaler waiting in the
parts pile for mine now.
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I looked at the wiring diag. for my Jetta and the rad fan switch has 2 sets of contacts, one at 95C and the other at 105C for low speed and high speed fan. I jumper-ed the power input pin of the rad fan switch connector to the low and high speed contacts and the fan works on both speeds. My next task is to pull the rad fan switch and test it in hot water to make sure the switch contacts works at the correct temps.
I pulled the rad fan switch and tested it in boiling water and neither sets of contacts worked. The switch has no brand/ temperature, or part number markings on it (probably Meyle or some equiv junk). Luckily I have a spare used radiator from a 91 Eco with a good rad fan switch marked Wahler 191959481C 95/ 102 C. Tested it in hot water to make sure both contacts work and installed it (takes a 29mm socket BTW).
The rad fan switch directly powers the rad fan and that is quite a bit of current going through those poor contacts. My guess somewher's around 12 to 15 amps. I may put a relay in there to increase switch life (hopefully life of the engine) since changing it is a PITA messy job having to spill coolant.
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My rad fans are working again. The low speed comes on at midway between 12 o'clock and the 3/4 mark. My temp gauge normally sits slightly past 12 o'clock so it's not a real big temp swing before the fan comes on. I am happy with the way it works. If I get ambitious, I may calibrate the temperature gauge
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When the low speed fan kicked on, which was supposed to be at 95°c per rad fan switch rating, the hose by the coolant temp sensor at the head was 90C per the IR thermometer. The coolant inside the hose must be hotter than that. I am going to calibrate the coolant temp gauge and put numbers on it.
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I am only getting one speed on the fan, I assume low. What do I do /look for to get it to go high speed too?
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I am only getting one speed on the fan, I assume low. What do I do /look for to get it to go high speed too?
Remove connector on rad fan switch. If three terminals you have 2 speed fan. Two terminals one speed. Jumper the hot terminal to the other two terminals. If both fan speeds work, you have a bad rad fan switch.
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To calibrate the gauge I put a spst switch on one terminal of the temp sensor to measure its resistance by switching it between an ohmeter and the temperature gauge. Once I get the resistance readings at the points of interest on the gauge then I can go on to the next step.
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You guy`s are nothing!
Fan go ON on idle but in drive no???
Manuel swich,new rad,pump,fuel and oil fiter(to clean cooalant) vinager.....etc
Nothing?
Shpo man didn`t belive me.
A...It`s is AIR -for most of time.
or gremilin from ORCoaster.
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I have a diesel cluster I just picked up with a red LED at top center of the coolant temp gauge. Is that an overheat warning? How does it work (what triggers it)? What model/year is the cluster from?
I been driving around with a working rad fan again and there's no big swing before the fan comes on, (needle moves 1/16 inch). I have a 195F T-stat
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Low coolant level light from a later jetta/golf I believe. My 85 TD had one. Two prong sensor in the tank, think it might read coolant mixture too, can't recall but it isn't an on/off switch though I'm pretty sure.
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I'm paranoid about this too. But an aftermarket mechanical gauge measuring off the front coolant neck really put me at ease.
Although I'm curious about these radiator shrouds you guys mentioned. I've been thinking of fabbing some up for mine just on principle. Too much room for air to go elsewhere.
Does anyone run oversized radiators or the like from other cars? I'm always interested in keeping this thing cool.
And can a coolant level sensor be added to a mk1? What cars came with them. I def want one after my little incident....
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You can get a tank that has the threaded opening for the sensor, all cheap.
I believe the wiring isn't straight foward.
The A2 Bentley has a section on it I'm pretty sure.
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I had to change the oil on my rabbit the other day and noticed that my vbelt was really loose. Like one finger on the pulley and I could move it loose. To be honest I haven't touched this since I installed it new almost 10,000 miles ago when I put the car on the road :(
I also had the manual gage on the car that whole time but now wonder if mine is running right or was heating up too much before from that loose belt. I put in a "better" rtd sender for my auber gage and noticed the car runs real close to 175 steady with the sender on the head to radiator flange. Car really didn't heat up much when stomping on it unless pulling a hill, but sitting in dead stop traffic is what showed the gage hit 185 and then the fan would come on and soon bring it down to 175 again.
I have a stock thermostat I thought. I think I need to get one of those temp guns :)
All I did was take the fan sensor off what was on the car, never even looked into its setting. I tested the thermostat in a pot and it did the job.
I am still guilty of not having the radiator diverters even though I don't believe I have any cooling issues.
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175 seems pretty low. Stock t-stat starts to open at 186 or so.
Only ten degrees but still. I'd prefer a higher and more static temp if
I was given a choice. FWIW a belt can sure slip on a pump, but it does not
take much to drive one, especially with a lot of contact area, even if it's loose contact.
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175 is low. I run a 195F stat and my gauge sits 1/4 of the way between the mid and 3/4 mark in normal driving. No big hills around here but going up short hills the needle does not move. Only when in traffic for 5 minutes before the gauge moves enough then the fan kick on low for a minute then shuts off.
I have been monitoring the resistance of the temp sensor and the voltage across it while I drive in my effort to calibrate the gauge. So far so good. I can see minute changes in the sensor that is not perceptible in the gauge. E.g. if I let off the throttle and put it in neutral rolling down a hill, the temp as seen by the sensor actually goes up. I would have thought it would go the other way since the engine is idling doing less work. The explanation I came up with is that the water pump is not moving as much coolant at idle as cruising and the heat from the head is heating up the stagnant coolant more.
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175 is low. I run a 195F stat and my gauge sits 1/4 of the way between the mid and 3/4 mark in normal driving. No big hills around here but going up short hills the needle does not move. Only when in traffic for 5 minutes before the gauge moves enough then the fan kick on low for a minute then shuts off.
I have been monitoring the resistance of the temp sensor and the voltage across it while I drive in my effort to calibrate the gauge. So far so good. I can see minute changes in the sensor that is not perceptible in the gauge. E.g. if I let off the throttle and put it in neutral rolling down a hill, the temp as seen by the sensor actually goes up. I would have thought it would go the other way since the engine is idling doing less work. The explanation I came up with is that the water pump is not moving as much coolant at idle as cruising and the heat from the head is heating up the stagnant coolant more.
Makes sense.
Reminds me of another counter intuitive thing I noticed on a TD years ago, coolant, and oil, temps were higher with less fuel when under sustained boost (interstate with AC on).
I wish there were more clean places to put gauges in a Rabbit, I've got the three in the lower console but anything else is going to be kinda gaudy.
I guess if I was less lazy I could recess small LCD displays somewhere.