Overheating w123 - Page 6 - PeachParts Mercedes-Benz Forum

funola · #76 05-08-2013, 01:33 PM

Quote:

Originally Posted by digieditny

It was about a liter

A loose cap should not lose that much coolant unless it was from hard cornering splash out. Try this dangerous test. Wear goggles/ mask/gloves/long sleeve jacket.

With engine driven hard under high load, put a towel over the cap and release pressure a little at a time till fully released by twisting cap (very slowly) open/ closed a little bit a bunch of times. Point is do not take the cap off in one shot!

In a normal engine, there should just be air released. If coolant gushes out, chances are head gasket is leaking and over pressurizing the cooling system. With the cap open and engine running, there should be no bubbles in the expansion tank. Bubbles= bad head gasket.

digieditny · #77 05-08-2013, 02:01 PM

Hey funola. Wouldn't the lack of coolant loss (even driving nonstop for 5hrs) show that the coolant is not pressurized? Would there be proof of this by losing coolant through the overflow opening (whatever its called) in the expansion tank?

ROLLGUY · #78 05-08-2013, 06:04 PM

Quote:

Originally Posted by funola

Did the new radiator fix the run hot problems?

From all I've read, these 617 engines (cast iron head/block) can take a lot of abuse as far as overheating and still be ok. They supposedly can run up to before the red line on the coolant temp gauge and still survive. Did your friend severely overheat his engine? What if you replaced the radiator first before replacing the head gasket? Maybe the head gasket was not necessary? I guess we will never know.

I believe the run hot problem is fixed, and yes there was evidence of a failed head gasket. Dark spots around the metal ring, and very clean piston tops on the rear 2 cylinders.

BenzTurbo · #79 05-08-2013, 07:24 PM

I added a fan from a 560sel to my 300cd. In hot weather with the a/c on in traffic, the engine temp would begin to creep up. The hottest day with the 560 fan so far has been 92 and there was zero movement of the gauge no matter how i drove it... Maybe an "upgrade" to think about.

http://www.peachparts.com/shopforum/diesel-discussion/337178-fan-upgrade-1983-300cd.html

funola · #80 05-09-2013, 10:39 AM

Quote:

Originally Posted by digieditny

Hey Funola. I have a dentist appointment today so I'll drive the car hard on the way home and check the temps again. Ya the car has had overheating problems for about 2 years. I just drove the car with the heat on high with only the passenger vent open and the windows down. Sweating like a maniac. The coolant level is always the same. Not low. I don't lose coolant. I can't remember when the car started overheating. It just suddenly one day started.

There's a thread somewhere where I suspected it was a bad temp sender. I bought one but the readings I was getting from it were extremely low. I drove the car a bit with it on. A car next to me at a red light said I was losing coolant all over the road. So I pulled over, refilled it, waited till the car cooled, and drove it straight home. I suspect that I left the cap loose since it was not on properly when I pulled over.

Did you notice your overheat problem after you lost the coolant "all over the road" or before that? So you have been driving around for 2 years with an overheating problem? Why have you waited so long to attend to it? Is it getting worse?

funola · #81 05-09-2013, 11:02 AM

Stupid question: Was the thermostat installed with a gasket?

funola · #82 05-09-2013, 11:05 AM

Quote:

Originally Posted by digieditny

Thanks for all the replies!

Funola. With the thermostat removed, the car takes about 20mins of city driving (stop and go) to get up to about 85c. I'd say from there it'll take about 7 to 10 mins to get to 100c. Once it gets to 100c, it'll continue to climb unless I turn on the heat. When the heat is turned on, it's only takes a quick 15secs to get it down to 85 again. Then I'll shut the heat off and wait till it gets to 100c and turn on the heat. Over and over. It's a fun little game.

Something probably worth mentioning is that the temp needle does tend to bounce once it hits 90ish. I happen to capture a little of it on this VIDEO Starts around 35 secs in.

Other then the overheat, the car is driving beautifully Funola. No more fuel issues after your fix.

Your video is private and requires a login. Reading your description again I am wondering what's going on? The temp needle should not bounce! The coolant can't change temp that fast. What other symptoms of overheating do you have other than what the gauge says? You are not losing coolant? You don't see steam? Maybe you just have an electrical problem in the coolant temp gauge circuit?

digieditny · #83 05-09-2013, 07:26 PM

Hey Funola! Yes the gasket is installed. I just made the video public. Sorry about that.

Ya I should have taken care of this earlier... After the coolant incident, the car overheated the same as before the incident.

Well this is my second gauge and both have acted and read the same. Where would I even begin to look if it's an electrical problem?

funola · #84 05-09-2013, 09:46 PM

The cluster internal ground has a weak spot between the pc boards.

Check and tighten cluster to chassis ground, engine to chassis ground strap, battery to chassis.

Have you verified with the IR thermometet that when the gauge says it's overheating, the temp sender on the block and the upper rad hose coming out of the engine shows similar temp as the gauge?

funola · #85 05-10-2013, 10:14 AM

Just watched your video. That's within normal range other than the spike. The spiking at :035 I is electrical. You did not step on the throttle or do anything else at :035 right? Nevertheless, coolant temp can't jump that fast. I'd start by cleaning the sender connector and make sure it fits tight, if that does not fix it then do the other stuff mentioned above and also clean the cluster circular connector.

Was the video shot while the car was idling or driving?

Shoot another video showing overheating and turning on the heat to decrease temp.

rscurtis · #86 05-10-2013, 11:12 AM

I agree with funola, that spike in the gauge is electrical. My signature car will do the same thing. Several thoughts come to mind. First, it takes too long for your engine to warm up- that could indicate a partially open thermostat. Second, the heating up at idle usually indicative of an air flow problem, not a coolant flow problem, which will manifest itself at load. I wonder if you have a thermostat that is not opening fully and closing off the bypass like it's designed to.

digieditny · #87 05-10-2013, 11:13 AM

Hey Funola. I will check all my grounds. Well I didn't verify it when it was overheating. I just verified it when was at 80c.

Ya the car was not overheating in that video. I just wanted to show the needle spiking. The car was parked just idling. I'll shoot another video for ya soon.

I'm not losing coolant and I've never had steam but I've never let it get all the way to 120. It's been close but every time it gets close, I turn on the heat.

digieditny · #88 05-16-2013, 04:11 PM

Ok I checked the grounds. All seems good. I did find a ground behind the cluster that was cut. I found where it connected and suddenly my buzzer now works which is fantastic! The car still reads as if it's overheating.

I made 3 videos.

1. W123 different temps gauge and block - YouTube This video shows the gauge reading about 110c. I pointed my ir gun in the area where the temp sensor screws in and it reads 15c cooler.

2. W123 Jumping needle - YouTube This video shows what the needle does when I play with the wire snake that plugs into the back of the cluster. Not sure which one of those wires I should look into...

3. W123 air bubbles in coolant? - YouTube This video shows the coolant tank. Funola mentioned air bubbles in coolant could point to a bad head gasket.

JB3 · #89 05-16-2013, 04:52 PM

id carefully go around the joints between plastic and aluminum on the radiator just in case. I had a very similar overheating problem for over a year, and ultimately it turned out to be the radiator, specifically the joint between the tank and the aluminum core.

This was concealed by the fan shroud, and was small enough that it was hard to track down until if finally popped for good.

funola · #90 05-16-2013, 06:34 PM

I can't get any of the videos to load. If you see bubbles in the expansion tank, the next step is to test for combustion gas in the coolant to verify before doing any major work.