problem with '79 e12 based 633

bgriff · Post by **bgriff** » Sat Oct 02, 2010 5:18 pm

Hey guys, I've been playin around with my '79 633 about 3 weeks now, all I needed to do was change out the engine fan, so now after pulling the radiator (first time, by the way), replacing the fan blade and replacing all the belts I put everything back together today, filled the radiator with fresh antifreeze and fired her up. It didn't take but a couple minutes for the temp gauge to start getting way too close to the red zone so I shut 'er off, it's like the coolant isn't circulating, after I shut the motor off I could plainly hear coolant swishing around almost sounded like a washing machine - and sounded like it was coming from the water pump area. What do you think's going on?
Also, the bottom radiator hose outlet has a fitting with 2 male spade connectors, one of the connectors was bent before I started this project and broke off as I tried when I tried to reconnect it - are those 2 connectors for the auxiliary fan? If not, what are those connectors for....since one broke off, I left them both disconnected??

T.Hanson · Post by **T.Hanson** » Sat Oct 02, 2010 10:38 pm

Forgive the basics if you are an accomplished vet.

The cooling system is pretty straight forward. If everything is clean, connected, good shape, not many problems with over heating. Pulling the radiator is good to flush from both ends and see the water is coming out clear.

When everything is connected, clean, tight and coolant tank full, start the engine with the heater dials on, warm up, then open the bleed screw on the top, front of the engine. The idea is to have the coolant flowing through the entire system and letting any air bubbles escape out the bleed screw slot.

When the flow stops bubbling, close the screw. ( Check FAQs or Google search previous posts for more info, photos.) Some rev the engine up to 2000 to inspire more bubbles, but the system is self purging, if you get most of the air out manually. Shut down, cool down, top up overflow tank.

If your bleed screw is old it will have a single slot. Very bad for breaking off when crunchy, stuck. New style has a bolt head. If yours comes out, do coat with anti seize and hopefully replace with the good kind.

Any other problems will require inspecting components. In short, thirty years of coolant makes original steel tubes, etc. Chia pets, lumpy ends.

The big plug at the bottom of the radiator controls the aux fan and temp sensors. Big, small tabs. Trace the wires from each to see what the broken one goes to. The dang things are spendy. No luck here trying to solder back the tab.

bgriff · Post by **bgriff** » Sun Oct 03, 2010 8:06 am

Thanks Tom, I'm anything but an accomplished vet when it comes to working on these cars, I'm learning as I go - I've just never tackled some of the issues that you and most of the guys on this forum could do with your eyes closed....I probably should keep your reply where I can get my hands on it from time to time. Back to this problem I'm having, why do you think I could hear coolant "swishing" (it really sounded just like a topload washing machine in it's wash cycle, swishing water back and forth) - this swishing went on for about a minute after I noticed the temp gauge was getting into the red and I cut her off, the swishing sounded like it could have been the water pump. I'm going to take the radiator back out and retrace what I've done, maybe I can find a reason why the coolant's not circulating - would air bubbles contribute to that? I cracked the bleed screw for a few seconds, but she was idling so high, about 13-1400 rpm's, it just blew coolant back over the motor and windshield and I couldn't tell if there were bubbles or beer coming out of that bleed screw.

pappentl · Post by **pappentl** » Sun Oct 03, 2010 8:15 am

Before removing the radiator again, start the car and when the temp starts to spike feel the upper and lower radiator hoses. If coolant is circulating they will also be hot, if not then they will be cool. You can also squeeze the hoses to see if they have fluid in them. If the hoses are cool I'd replace the thermostat.

Mike W. · Post by **Mike W.** » Sun Oct 03, 2010 12:36 pm

You can usually bleed the system cold. Just open the bleed screw and fill it slowly. When you have solid fluid coming out it's full. One way to tell if it's bled or not is does the heater work? If so it's bled, if not it's not.

GripGreg · Post by **GripGreg** » Sun Oct 03, 2010 1:22 pm

If, after the needle goes too far, shut it down of course, Then feel the slots on the top-side of the radiator, facing the windshield, where ever you can touch, & feel for warmth/hot. Then feel the way down lower slots facing the same windshield from the same position. Go to the other side of the car & repeat. If one spot is cool/normal & the other is hot, it needs to be rodded out by the shop. This clears the passeges from the smush for an even flow. If this is the case, you're lucky. Ask me how I know?
And, replace the sensors. They are definately needed!
Go to 'Links' on the left to find some decent on-line prices,we hope. Add 'Arizonahaus.com' to the list. Good Luck,,,,Greg

GripGreg · Post by **GripGreg** » Sun Oct 03, 2010 1:33 pm

BTW; some guru on this website said to put a piece of gift box cardboard between the radiator & the fan to protect the fins(that's what they're called, not slots! Who said that?) from being chewed up by the fan when you r&r.

bgriff · Post by **bgriff** » Sun Oct 03, 2010 8:05 pm

OK guys, I went back out and fired this 6er up again this afternoon, I figured I know a lot more today than I did yesterday, thanks to all the comments and suggestions from the voices of experience. As I was saying, I fired her up and let the temp gauge get about 3/4 of the way to red, then checked the hoses - the upper radiator hose was hot and the bottom hose coming out of the radiator was cool - does that sound like thermostat or what? I appreciate your help on this one.

Bob

marc79euro645 · Post by **marc79euro645** » Mon Oct 04, 2010 8:43 pm

yes thermostat is sticking

T.Hanson · Post by **T.Hanson** » Tue Oct 05, 2010 10:54 am

If you've not removed steel bolts from aluminum pieces, mortified in time exposure to water, coolant, chia pet corrosion, take your time. Use rust breaker sauce and a hardware store torch ( carefully ) to tap, jiggle, ease the bolts out.

You'll be glad you did, as the clown who coined the term, EZ out should be shot.

Once out, always use anti-seize on the bolt threads in anticipation of the next battle.

thirdrocker · Post by **thirdrocker** » Fri Sep 14, 2012 7:34 pm

haha ''the clown who coined the term EZ out should be shot'' i second that

have question on coolant temp sensors....i have m30 b35 installed that has 2 sensors on the thermostat housing. one is blue and other black i believe...i left the original rad in. This rad has another sensor at the bottom.....
i fairly sure the black one on thermostat housing is for temp gauge instead the car but what do the other 2 sensors do????

Mike W. · Post by **Mike W.** » Fri Sep 14, 2012 9:34 pm

marc79euro645 wrote:yes thermostat is sticking

I'm not so sure. It might be airlocked, does the heater work? If not open up the bleeder screw til you get full water flow with no air.

thirdrocker wrote: have question on coolant temp sensors....i have m30 b35 installed that has 2 sensors on the thermostat housing. one is blue and other black i believe...i left the original rad in. This rad has another sensor at the bottom.....
i fairly sure the black one on thermostat housing is for temp gauge instead the car but what do the other 2 sensors do????

One on the stat housing would be for the gauge, the other is a coolant temp input for the FI system. The switch(s) on the radiator is for the aux fan. E12 530s used one, 528i's used two and early E24s used a double switch, two switches in one housing.

thirdrocker · Post by **thirdrocker** » Wed Sep 26, 2012 4:54 am

hi again thanks for info....
I did a motronic 1.3 conversion e32 engine into e12 based e24 and cannot get coolant temperature gauge to work in dash......and possibly the ECU is getting no temperature signal either as the car is idling a little poor and not as powerful as i expected it to be.....

As you said.....the e12 has just the one sensor.....my e32 has 2(1 blue and 1 black).....would you know the procedure to get these sensors working correctly.......

I have tested them already for resistance in hot and cold water so i am pretty sure they are working.....

Falkenberg · Post by **Falkenberg** » Wed Sep 26, 2012 6:25 am

The blue one is for the motronic, afaik. The black one goes to the dash. The problems are, at least on my E32 engine to E12 conversion, related to the black one.

1. On the E12, the sensor has ground through the termostat housing, and only one connection for the gauge. On the E32 sensor, you have no connection to ground and 2 electrical connections. If you want to use the 2-pin style sensor, you will have to connect 1 wire to ground, ant the other one to the E12 temperature gauge.

2. At least on my car the resistance value of the sensor was wrong. So even after making the ground mod, the gauge still was not showing correct values.

So you might want to remove the black sensor and put in the E12 one, pull a wire to the temperature gauge, and you're done.

I was lucky to find yet another sensor that has appropriate values of the E12 one, has ground through the housing, but fits the E32 wire connector. I have no idea what car it is from.

thirdrocker · Post by **thirdrocker** » Sat Sep 29, 2012 2:42 am

hey falkenberg......thanks......really fast respnse.......invaluble info

i checked out and i have few old temp sensors around so i'll try one of them......
i guess the temp sensor from original jetronic 1979 engine should do fine if going on 1979 car.........

Firstfives.org