Overheating Paranoia

[rs899]

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.

[92EcoDiesel Jetta]

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.

[8v-of-fury]

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.

[92EcoDiesel Jetta]

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.

[theman53]

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.

[92EcoDiesel Jetta]

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.

[92EcoDiesel Jetta]

Where is your Autometer temp sensor located?

[damac]

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.

[theman53]

My Vw guage is not linear in any fashion nor repeatable always. My temp sensor is coming off the outlet of the head.

[8v-of-fury]

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.

[wolf_walker]

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.

Sent from my SCH-I535 using Tapatalk 2

[bbob203]

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.

[92EcoDiesel Jetta]

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.

[92EcoDiesel Jetta]

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.

[wolf_walker]

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.