Thermostat or water pump?

[TylerDurden]

The metal is better, as it won't warp.

NLA

[Rising]

Okay I changed out the water pump and thermostat with new units. The car still seems to be running warm. Like around 3 bars from the red is normal while cruising. But sometimes it starts creeping towards two bars from red. That seems hotter than normal and its pretty cool outside. Not flogging it just cruising at 55.
 
Fan seems to kick on okay but not till up there that hot. Is this too hot or normal? What else could come into play here?

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[8v-of-fury]

Get a stand alone temperature gauge, the stock in dash unit cannot be trusted.. it is old as s*** and didn't work that well new.

Without a real gauge you have absolutely no idea what is going on in there.

[Rising]

Okay I picked up a mechanical water temp gauge. Where is the old sender for the dash gauge? I can't find it in the bentley. which is frustrating since i know it's in there somewhere. What threads are used on it? 1/8" npt? I have a few different adapters. But anyway is that where i should put the probe or is there a specific place i should put the probe? Is it better to read in one place or another? And once i get it up and running i shouldn't see anything higher than oh say... 180-190 correct? And I guess that would depend on where i put the probe right?

[TylerDurden]

Usually the coolant temp senders are on the water outlets. IIRC, the one for the gauge is on the outlet facing the radiator.

[8v-of-fury]

And once i get it up and running i shouldn't see anything higher than oh say... 180-190 correct? And I guess that would depend on where i put the probe right?

I have seen as high as 200 cruising sometimes, if its a grade.. and 220 if I am pushing it.

[Rising]

Is yours on the water outlet coming out of the head? I would assume so based on that high of temperature. Good to know what to look for. I'll check my gauge inside for accuracy before I install tomorrow.

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[8v-of-fury]

Yes in the bottom of the front neck that goes to the rad. Hottest spot for coolant to be read.

[ORCoaster]

I check water temp gauges by boiling water and letting it roll for a bit.  212 degrees F.  Generally between the 200 and 225 lines on the gauge.  DAS

[Rising]

I check water temp gauges by boiling water and letting it roll for a bit.  212 degrees F.  Generally between the 200 and 225 lines on the gauge.  DAS

perfect! that's about the only constant i could trust i suppose. I'll do so immediately. i went with a cheap mechanical gauge. So i definitely want to know where it is reading.

Yes in the bottom of the front neck that goes to the rad. Hottest spot for coolant to be read.

Okay so i have an mk1. Actually it's an mk2 engine in a mk1. But i still have my metal coolant neck coming off the side of the engine where there are two sensors. I have the plastic necks from the mk2 as well but I have heard it's best to keep the metal. Now what i'm confused about is why there are 2 different sensors on the neck. One for the coolant temp gauge and one for what? My fan temp switch is in the radiator so what does this other mystery plug do?!

However I'm not sure my temperature sender will fit there as it's rather large and i don't think it can be adapted as small as necessary. however the mk2 plastic neck seems to have a large sensor hole, however it isn't threaded so i may have to potential jb weld a fitting in or some other nonsense. I didn't think this would be this complicated :/

[ORCoaster]

Now what i'm confused about is why there are 2 different sensors on the neck. One for the coolant temp gauge and one for what? My fan temp switch is in the radiator so what does this other mystery plug do?!

Coolant or temp sender for one plug the other for GP sensor.  If temp is cold you get GP's if already warm not needed.  

I think they are both the same thread size.  

[smutts]

On the later mk2 diesels, these two temperature senders are the same, so if you have weirdness with either the temp gauge or glowplugs, swap the plugs around. If one of the two senders is duff, the weirdness will have swapped too. Fortunately I do not write technical manuals.
The senders are not that reliable.

[nwcali6]

  I installed a new thermostat last week, sadly it wasn't opening until 200 or so and it would run 220+ on the freeway.  Don't always trust even a brand new one, test before install.

  I always thought if you were getting bubbles out of the radiator (in a system that should not have air bubbles from a new fill up) it indicated a head gasket blown?

 

[CrazyAndy]

NO, keep the metal one as they don't warp or crack like the plastic ones like to do.  I swear, if I see another MK3 ABA with a lower thermostat housing crack . . .  either way, great to see it was the thermostat.  The problem sounded like that from the start.