Leak fixed. Now too hot?
 

'82 240D

Fixed the leak. Pinhole in the water pump housing. Now...

The temp reads just over 100º when warm. Before, even with the leak, it would BARELY hit 80º, so it makes me a little nervous.

Tried a new thermostat and new temp sensor - same thing. Water pump is less than a month old (brand new, OE, turns fine, not leaking). Seems to have started after doing a hose-water flush of the cooling system with the heat switched on to get the garbage out of the heater core.

So.

Same results with two thermostats (on is Behr and one is made-in-China Napa) and with two temp sensors (old one and new one). Maybe there's still air in the system? But I drove it and topped off (only needed a few ounces), though even after draining the radiator and block (removed plug on side of block) it only took 1.5 gallons of coolant (G-05 and distilled water, 50/50). I figured there must have been some water left in the block. I dunno, just trying to think of every relevant thing.

Ideas?

Thanks again for everything!!!

---
Cam

Park the vehicle facing uphill.

Remove the upper radiator hose and fill the hose fully with coolant. Quickly attach the hose to the radiator to avoid spilling any coolant from the hose.

Drive the vehicle and observe the gauge.

Thanks! I'll try to give the ol' girl a good burping!

Still running hot. Parked up hill, filled the coolant (which was all but full) and ran for about 45 minutes. No bubbles looked to burp out and it won't take any coolant. It might still be a bubble, I suppose. But I'm not sure.

Did I miss something?

it's quite a chore to burp the n/a motors, there's no equalization available. try disconnecting the heater hose from the head, and see if water exits the hose and the head!

Thanks so much, but what exactly am I looking for? Should I expect there to be water? What if there isn't? What if there is? How do I remedy it if it's an undesirable outcome?

Thanks for all of your help. I sincerely hope it's just a bubble. I can't afford for it to be anything else...

you want the water to be exiting the heater connector. with the motor level, you should be able to add in water via the radiator neck, and see water well out of the heater connector. that is the highest point in the waterjacket, so IF the block is level/high in the rear, and you add water in, and water bubbles out, you should be totally full. one of those superflush kit's 5/8" tees with a garden hose connection should allow you to burp the head properly.

How will the back flush kit work? As far as I understand, it'll fill the block with hose water and I'll fill the radiator with pure antifreeze and the two will meet and mix while I drive. Is that the case or am I understanding it wrong?

Thanks again! Sorry to be so thick, but I think I'm starting to pick up what you're putting down.

Can a proper burping be done without losing my expensive coolant? Even by a professional shop?

Back when it was leaking and running about 80 degrees. would it get low on water or were you able to keep water in it. Reason I ask is some sensors cannot read air. so if the water was low when it was leaking it may have been reading low. Now that you have it full it may be reading what is really the water temp. Maybe you have another thread but how about some history. Did it ever run hot, why did it start leaking, did it ever get hot after leaking. Just thinking of some of the things that happen. Thanks

the superflush tee will give you a place to watch air escape. pour in your proper mix of G05 coolant, ignore the instructions in the kit.
and asap, replace the cap from the kit to a brass one. the kit caps are well known to fail under pressure at speed dumping all your coolant all over your windshield!

So. I parked on level ground and disconnected the heater hose. Water poured out. I added coolant to the radiator and water welled out of the hose.

What now? I'm starting to get a little scared!

Oh yeah. When I turn the heat on, it blows hot. If that matters...

Did a grease flush followed by a citric acid flush. (LOTS of hose flushes between and after)
Refilled carefully and meticulously with 50/50 G-05/distilled water.
Took a couple liters less than 10, so there must be some air somewhere.
Parked on a steep hill and ran the heat.
Put another couple ounces of coolant in.
Running right around 90º C now. Better than before but a little warmer than I like.

I'll just drive it around for a few days and try to shake the bubble(s) loose and see what happens. Unless someone has some other advice for me.

Still running hot. Out of ideas.
 

'82 240d

So...

Replaced radiator, water pump, thermostat, all seals and gaskets, hand full of hoses, temp sensor. Hose water flush, degrease flush, citrus flush. Filled with 50/50 G-05 and distilled water. Burped (but didn't notice any significant air bubbles). Drove it for a week, never needed to fill coolant.

It's still hot. Used to ALWAYS stay just under 80º no matter what (even when it was leaking coolant), now it runs between 90º and 100º all the time and kind of drifts back and forth within that range. Loses some water out of the overflow hose just about every time I park. Heater blows hot.

I'm out of ideas. What could I have missed?

Thanks again!

---
Cam

What works for me is a 75 degree Wahler thermostat from a mid-70's 450SL.

That will take 5 to 10 degrees off your running temperature.

If you live in the north, you might need to go back to a normal thermostat for the winter in order to get enough cabin heat.

Temperature gauge? Have you used an infrared thermometer to confirm temperatures?