New Owner with Temperature Concerns

[DrinkMan]

Hi,

 

Been lurking here for a while. A few months ago we purchased a 1972 BMW 2000tii touring from an Estate Sale in Vienna Austria. It was inspected, we had great references from the Austrian 02 club and our correspondence with the  Estate representative was fantastic so we felt good about buying it sight unseen and shipping it over. Well, 3 months later with numerous delays due to the supply chain and shipping issues, we finally got it. The car lived up to expectations as soon as we saw it. Picture below.

 

One thing that was in the back of my mind is that the engine had been rebuilt about 200 miles ago and was still on break in oil and quite frankly, when I have rebuilt engines, it seems to take about 500 miles to get everything sorted out completely so I was expecting a little learning curve. And sure enough - on the drive from the Port to our local location (about 20 miles), I wasn't happy about the indicated temperature. Note - it was about 90 degrees outside (Port of Brunswick, GA). We brought the car to our vacation home on St Simons Island to learn about it a bit and our original plan was after a day or two of making sure all is ok, drive it the 350 miles home to where we have a full set of tools and a lift so that we can get under the car and go over everything and we would be close to the point of completing break-in and change the oil, retorque the head, adjust the valves, and begin to enjoy the car more.

 

 

That temperature is my number 1 priority. So after cooling off in the garage, I tested the coolant. It was highly diluted with just a touch of green antifreeze and a little low. I topped it off, tried my best to burp the bubbles out of the system. I also drained off a liter or so from the bottom of the radiator and it was clean. After filling the system, I restarted the car with the radiator cap off and a thermometer in the fluid at the top. The fluid stayed cold for a while as expected, then when the thermostat opened (top hose got hot), it jumped to 160 - 165 degrees. The indicator was showing at about 70% towards the red (about 1/2 way between mid point and the picture I posted above). It climbed rather quickly to the same as the picture and then crept slowly toward closer to the red. The temperature indicated by the thermometer never exceeded 180 degrees F.  I don't have an infrared thermometer here at our vacation home to check the temperature from top to bottom of the radiator. 

 

 

We noticed that when we turned on the headlights, the needle jumped up to a higher indicated temperature. Also, the fluid level dropped (no leaks). We did turn on the heater in the car to get the fluid fully circulating in the system. My theory is that we may have a ground issue with the gauge and that there was a lot of air in the system and the thermometer wasn't fully in fluid. We decided we don't have the confidence to just drive it home yet until we straighten all of this up. 

 

My questions - how representative of actual temperature of the cooling system is the fluid at the top of the radiator when engine is running? Is the temperature gauge responding to headlights normal or as I think, a concern? 

 

Any input would be appreciated. 

 

Dan

 

 

 

[dlacey]

Hey Dan,

The temperature gauge.and fuel gauge are susceptible to bad earths... Its common to add extra earth point to the back of the gauge pod to stop the flickering gauges. You may also wanna look at the sender unit itself...they can corrode in the alloy causing bad earth ...take it out, clean it up, put it back (dont use any jointing compound or tape, you need good earth, the seal is the copper washer).

A tii should run middle of the gauge... if its running higher then ignition may be too far retarded...it runs cooler with more advance (but avoid full-throttle pre-ignition).

The engines are rugged..driving anywhere in the white zone is no issue.

[JerryC]

Welcome to '02ing! Sounds like, and looks like, you got a good one.

 

You're correct to be concerned about temperature indications. You really don't want to overheat that engine. The '02 temperature gauge is a known weak link in the electrical system due to poor grounding between the cluster and the chassis that deteriorates over time. Normally, it will show about the 3 o'clock position when warmed up. You state that turning on the headlights changes the temperature indication, and that is a "good" sign that the problem is caused by grounding (earth) issues. Actuating the blinkers may cause the needle to jump also. There are numerous forum conversations about this. Fixing it is not difficult, and can be quite gratifying.

 

You can try to improve the voltage regulator grounding by cleaning up the regulator mounting screw. The regulator (if it is still present, assuming original alternator is still there) is mounted on the inner fender near the battery.

 

Hot coolant enters the radiator from the cylinder head at the top, so the temperature there should be the maximum, as you guessed. If there is a possibility of air entrapment in the system, try raising the front wheels slightly and run the engine with the heater on and the radiator cap off to fully purge trapped air. The heater controls adjust coolant flow through the heater core. That's a whole 'nother project...

 

Good luck with your "new" '02!

 

Jerry

[Mike Self]

+1 on previous comments WRT the temp gauge grounding and sender ground issues.   Both issues are easily repaired.

 

When you said the temp on your thermometer placed in the radiator fill suddenly jumped, that's when the thermostat opened.  It does that.  And when the coolant level dropped, that was the last of the air being purged from the system.  Getting the air out of the heater is a chore due to its height vs the engine, and the lengths of the hoses.  Whenever messing with coolant--changing, adding etc--always open the heater valve to full open to allow full circulation.

 

That brand new engine is gonna be generating more friction than one with some mileage on it, as those new parts get used to each other,  so it will tend to run a bit hotter than normal.   

 

Finally--if you don't know the weight of that break in oil currently in your engine, I'd think twice about a 350 mile road trip--at highway speeds--on what might be thin oil.  I broke my new engine in on conventional 20w-50 oil on an 800+ mile round trip to Vintage, varying the speed on the highway by shifting between 4th and 5th; once back home I then retorqued the head, adjusted the valves and changed to synthetic 20W-50.  That was 18 years and 67k miles ago, and the engine's just doing fine.  

 

Welcome to the 02 fraternity/sorority.  And we expect to see you and your car at Mid America 02Fest next April and/or Vintage next May.  

cheers

mike

[resra]

Look here: 

 

 

[DrinkMan]

Thanks for all the replies.

 

When we return to car next week, I'll work on grounds and see how that works.

 

Note - I do know what the break-in oil is. It is a conventional 20w-50 break in oil. I don't remember the brand that the sellers representative told me, it was a German brand. 

[Mike Self]

2 hours ago, DrinkMan said:

I do know what the break-in oil is. It is a conventional 20w-50 break in oil. I

Good.  Just what you want.  

[Leucadian]

FWIW, many of us run a secondary temp gauge as a means to keep the stock gauge honest.  If you find a later model water divider with 2 ports, you can tie in a temperature sender at that location for a more accurate reading.

 

 

Unless you want to keep your interior completely stock looking.  

 

Beautiful Touring!

[jgerock]

1 hour ago, Leucadian said:

FWIW, many of us run a secondary temp gauge as a means to keep the stock gauge honest.  If you find a later model water divider with 2 ports, you can tie in a temperature sender at that location for a more accurate reading.

 

 

Unless you want to keep your interior completely stock looking.  

 

Beautiful Touring!

These water manifolds are good for a carbureted car, not so much a tii. If there was one available, I’d buy one for my tii.  The tii one has a second port for the thermo time switch sending unit.

[2002iii]

20 minutes ago, jgerock said:

These water manifolds are good for a carbureted car, not so much a tii. If there was one available, I’d buy one for my tii.  The tii one has a second port for the thermo time switch sending unit.

The e30 m10 water divider has 3 ports.

[Leucadian]

25 minutes ago, jgerock said:

These water manifolds are good for a carbureted car, not so much a tii. If there was one available, I’d buy one for my tii.  The tii one has a second port for the thermo time switch sending unit.

 

Good point.  

[jgerock]

2 hours ago, 2002iii said:

The e30 m10 water divider has 3 ports.

But it doesn’t have the water outlet port for the KF warm up regulator. I have the e21 one on my 69 M10 engine (dual carbs).

[Son of Marty]

I've found that with the extra ground for the gauges added the standard VDO water temp gauge is rock solid and very accurate.

[2002#3]

I found grounding the back of the instrument cluster (as wisely stated above) helped a lot but not as much as  adding a good, strong ground cable from the block to the chassis.  In fact, it solved 3 or 4 grounding issues.

[DrinkMan]

19 minutes ago, 2002#3 said:

I found grounding the back of the instrument cluster (as wisely stated above) helped a lot but not as much as  adding a good, strong ground cable from the block to the chassis.  In fact, it solved 3 or 4 grounding issues.

I noticed that there is a good flat ground strap from battery to engine block and chassis and another one in the trunk. When I get back to the car next week, I'll be looking at every ground I can find.