[cjscopp]

OK, feeling a little bit like an idiot here. Changed the two radiator hoses and the coolant last week and now have higher temp at idle and a slower cool down time while cruising. Used Pentosin coolant right at 50/50 but have noticed that while cruising temp is normal, right at 80c, at a stop the temp climbs rather quickly to right at 100 c and then when I take off it goes slowly back to 80c. Fans come on fine but I want to know what I did wrong with the coolant change to cause this because before old knucklehead (me) got his mitts on it it was fine, usually rock steady at 80c. Can air get trapped in this system and cause this? I let it run without the rad cap long enough after the thermostat opened but I wonder now. Any ideas? With hot Sacramento summer temps coming soon don't want to let the old girl get hot.

 

[Robbo55]

Sounds like an air lock - same thing happened to me. Try it again with the heater
on full and remove the overflow cap, leave the motor idle until the thermostat
opens and watch the bubbles.
Cheers

 

[jhodg5ck]

you know you have bleeder bolts on the drivers top of the block? You might try cracking them open as well.

Also, I like Pentosin oil but I know nothing of their coolant.. I also would have gone w/ a 30/70 coolant/water mix given where you live.

Jonathan

 

[cjscopp]

I looked up the procedures on ALLdata and saw a note that no bleeding procedure applies to the 103 enigne but I know there is a bleeder on top of the thermostat housing. Gonna try again tonight to purge any air out through the reservior with the system open. We'll see what happens.

 

[jhodg5ck]

yeaa...alldata..not such a fan. There are two more bleeders on the head..you might want to try those as well.

Jonathan

 

[cjscopp]

Cannot find a locator for the bleeders, anyone have pics of them?

 

[jhodg5ck]

Well, there are a few bolts on top of the engine that look as though they don't do anything...that's them. Just to the drivers side of the valve cover. Just turn things, if coolant comes out you found it..if not, you didn't.

Jonathan

 

[cjscopp]

I thought that might be them, two 13mm heads with copper washers under them? Seems kind of strange to have 2 so close to each other. Anyway, I ran it last night with the cap off until I had a hot return hose from the top of the radiator, did not see any air or bubbles so maybe it's OK now. We'll see. Thanks Jonathan

 

[300se126]

I like Pentosin oil but I know nothing of their coolant..

It's great. I've been using it in my Audi for years. It's the only coolant most Audi tuners and shops use, as it really does a nice job of keeping the engine free from deposits. Plus, it's red, so it looks cool!

 

[cjscopp]

300se126- the Pentosin I got is blue. You got it in red? What, do they offer designer colors???LOL BTW I like your 250,000 km badge, I have one on mine too.

 

[300se126]

300se126- the Pentosin I got is blue. You got it in red? What, do they offer designer colors???LOL BTW I like your 250,000 km badge, I have one on mine too.

You have G11 coolant; the Audi juice is G12. As for the badge, it stays firmly put on my desk where it won't get stolen or crudded up with dead bugs. I need a new grille surround soon, as the old one is tarnished, and I was thinking about doing a custom install of the High Mile award in place of the stock Mercedes emblem - yet keeping the hoodstar of course! The award looks so close to the stock emblem, I think it would be cool.

 

[cjscopp]

Found and used the cylinder head coolant bleeders with little success in decreasing the operating temp. Strange thing is last night while I was trying to figure this out, I had the overflow cap off and the engine idling and the temp was over 100c and the fans even came on with the cap off. I coudl feel the hot coolant flowing through the return hose to the reservoir so I know the thermostat is opening. Now I am questioning if the coolant/water mix is not correct and causing the increased temp. I mixed it right at 50/50 but now I wonder if I need to increase the water amout.hmmm? Anyone care to offer any opinions?

 

[300se126]

Maybe the temp sending unit is shot? I hate to say it, but I needed to unclog my radiator when this happened. It never got perfect, and I'm putting in a new one soon. Also, try drilling a 1/8" hole in your thermostat - it really helps - and make sure you don't leave any shards of metal loose in there when you are done! I filied my thermo-hole mod with a small round metal file when done and then rinsed it thoroughly with alcohol, then distilled water.

 

[cjscopp]

It was the thermostat all along. Just a coincidence that it went when I did the hoses. Replaced and all is well.

 

[zviratko]

It's more likely your thermostat just got clogged with the junk that accumulated from the previous fill... people often seal water pumps and hoses with some sort of gummy paste garbage that dissolves in coolant over time and clogs the hoses and water channels...

 

[KAZ_300SE]

It's more likely your thermostat just got clogged with the junk that accumulated from the previous fill... people often seal water pumps and hoses with some sort of gummy paste garbage that dissolves in coolant over time and clogs the hoses and water channels...

Agree with you. And, when it comes to old benzes like ours everything matters. I finally came to changing radiator and it worked.

 

[300se126]

I finally came to changing radiator and it worked.

Me too. I found a lot of "leak-stopper" in the core. They should call that stuff something more appropriate, like "instant death" or "cooling system ruination solvent." Grr. I de-crudded the monovalve assembly with a toothbrush for good measure while I was at it, since the crud particles do like to amass in there. The thing hasn't crossed the 87-degree mark since. Hooray!